ME 4054-Design Projects May 7, 2013

Fluctuating Stress Experiment for ME 3221 Volume 2

Team Members

Michael Daniels Erik Sauber Robert Jennings Aaron Schmitz Stephanie King Zhengmu Wang

National Instruments Advisors

Sunaina Kavi Samuel Strickling

Department of Mechanical Engineering Advisor and Client Professor Susan Mantell

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Contents Problem Definition Support Documents ....................................................................................................... 3

Annotated Bibliography ............................................................................................................................ 3

Summary ............................................................................................................................................... 3

Patent Search ............................................................................................................................................ 7

User Need Research .................................................................................................................................. 8

Concept Alternatives ............................................................................................................................... 12

Concept Selection ................................................................................................................................... 14

Design Description Support Documents ..................................................................................................... 16

Manufacturing Plan (Product) ................................................................................................................ 16

Manufacturing Overview .................................................................................................................... 16

Part Drawings ...................................................................................................................................... 17

Bill of Materials ................................................................................................................................... 20

Manufacturing Procedure ................................................................................................................... 20

Implementation Plan (Process) ............................................................................................................... 22

Implementation Overview .................................................................................................................. 22

Process Drawings ................................................................................................................................ 22

Component List ................................................................................................................................... 22

Implementation Procedure ................................................................................................................. 23

Evaluation Support Documents .................................................................................................................. 24

Evaluation Reports .................................................................................................................................. 24

Cost Analysis ....................................................................................................................................... 24

Environmental Impact Statement ........................................................................................................... 25

Purpose ............................................................................................................................................... 25

Environmental Impact ......................................................................................................................... 25

Alternatives ......................................................................................................................................... 25

Regulatory and Safety Considerations .................................................................................................... 26

Appendix I: Interviews ................................................................................................................................ 27

Appendix II: Improvements to Bicycle Experiment ..................................................................................... 33

Appendix III: Project Gantt Chart ................................................................................................................ 34

Appendix IV: Strain Calculations ................................................................................................................. 35

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Appendix V: Strain Gage Installation Procedure ......................................................................................... 38

Appendix VI: LabVIEW Block Diagram ........................................................................................................ 39

Appendix VII: Teaching Assistant Manual ................................................................................................... 41

Appendix VIII: Student Manual ................................................................................................................... 42

Appendix IX: ANSYS models ........................................................................................................................ 49

Appendix X: Strain Gage Tests .................................................................................................................... 56

Appendix XI: Dry Run Evaluations ............................................................................................................... 57

Appendix XII: Specification Sheets .............................................................................................................. 64

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Problem Definition Support Documents

Annotated Bibliography

Summary The material researched covers a range of material from the theory behind stresses and strains to various models of the components that were considered for purchase. Currently theory behind cyclic stresses and strain is well established. The measurement of those strains is also well established, with methods ranging from strain gages transmitting wireless signals to strain measurements using optics. The researched college laboratory experiments measuring cyclic stress were all based on the same measurement techniques. They all relied on strain gages that were attached to a slip ring. Personnel resources indicate that this method is outdated, so wireless data acquisition was pursued.

The research pursued affected the design developed in this project based on what was commercially available. Several resources acted as guides to the implementation of certain aspects of the design, such as the attachment and orientation of the strain gages. Other resources produced specifications to the materials that were purchased so that analysis could proceed prior to the arrival of the equipment.

[1] K. M. M. Robert C. Juvinall, Fundamentals of Machine Component Design 4th Edition, Wiley, 2006. This textbook is one of the books used in ME 3221. It covers basic solid mechanics and fatigue analysis. These principles are then applied to machine component design later in the book. This book provided the fundamental principles that our lab apparatus teaches. It supplied the equations for stresses generated by a load on a shaft. Our initial research on strain rosettes also used this book. This textbook is one of the books used in ME 3221. It covers basic solid mechanics and fatigue analysis. These principles are then applied to machine component design later in the book. This book provided the fundamental principles that our lab apparatus teaches. It supplied the equations for stresses generated by a load on a shaft. Our initial research on strain rosettes also used this book.

[2] OMEGA Engineering Inc., "3-Element Strain Gage Rosettes 0/45/90," OMEGA Engineering Inc., 2013. [Online]. Available: http://www.omega.com/ppt/pptsc.asp?ref=SGD_TRIAXIAL&Nav=pree02. [Accessed 2 March 2013].This document summarized how you position strain gauges on a material to measure certain strains as well as how those strains are calculated. It gives the equations for bending, axial, shear, and torsional strain. Finally it provides a table that shows the output of the gauges for each kind of strain and bridge type. This document provided us with the equations we used to predict the strains in our crankshaft. It also shows how the strain gauges should be mounted onto the crankshaft and how they should be wired.

[3] United Equipment Accessories, Inc., "How A Slip Ring Works," United Equipment Accessories, Inc, [Online]. Available: http://www.uea-inc.com/products/slip-rings/how-a-slip-ring-works. [Accessed 2 March 2013]. This page explains mechanically how a slip ring works to send a signal through a rotating collar.

[4] "Rotating Vibration Transient Strain Experimental Apparatus," Cal Poly Ponoma, [Online]. Available: http://www.csupomona.edu/~kranderson1/ME435L/LABS/ROTATING%20SHAFT%20STRAIN%20GAGE%20EXPERIMENT.pdf. [Accessed 2 March 2013]. This laboratory manual for the Californial Polytechnic University in Ponoma shows gives a baseline of a non-University of

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Minnesota experiment studying cyclic stress.

[5] National Instruments Corporation, "Products and Services," National Instruments Corporation, 2013. [Online]. Available: http://www.ni.com/products/. [Accessed 9 March 2013]. This website provides links to all of National instruments various types of data acquisition units. On the product pages specifics about the unit can be obtained as well as datasheets and user manuals. This website was pivotal in selecting the appropriate data acquisition equipment.

[6] J. M. Tjensvold, "Comparison of the IEEE 802.11, 802.15.1, 802.15.4, and 802.15.6 wireless standards," 18 September 2007. [Online]. Available: http://janmagnet.files.wordpress.com/2008/07/comparison-ieee-802-standards.pdf. [Accessed 9 March 2013]. This article provides information on the differences between the IEEE 802 standards. Specifically it names 802.11 (WLAN/WiFi), 802.15.4 (Zigbee), 802.15.1 (Bluetooth), and 802.15.6. Notably 802.15.4 is an ad-hoc only network. This information was useful for exploring the different wireless options. This also allowed us to assess the inherent security risk that we would be asking the university’s I.T. departments to assume. 802.15.4 (zigbee) posing an insignificant threat.

[7] F. T. Peng, "Hand crank generator device". Patent EP2161817 A2, 10 March 2010. This patent explains one type of method of measuring stress on a shaft, which was not used in this method

[8] S. K. F. Ansel C. Ugural, Advanced Mechanics of Materials and Applied Elasticity, Upper Saddle River, NJ: Prentice Hall, 2012. Ansel and Ugural, engineering professors at the New Jersey Institute of Technology, describes the mathematics and theoretical approaches to stress and strain analyses in this textbook.

[9] B. B. J. B. J. K. Y. K. K. L. J. P. J. S. Erik Berg, "Fluctuating Load and Stress Analysis," University of Minnesota, Minneapolis, 2001. This senior design report from the original bicycle experiment which studies the cyclic stress on the pedal of a bicycle. This is the project that must be improved upon.

[10] Rexnord Corporation, "Coupling Products," Rexnord Corporation, 2013. [Online]. Available: http://www.rexnord.com/sites/process/Pages/CouplingProducts.aspx?platformkey=1&businessunitkey=30&nodekey=-6008. [Accessed 10 March 2013]. This website details couplings. It describes the advantages and disadvantes of the various different types of couplings and the typical type of use a certain type of coupling sees. Rexnord also provides detailed specifications on their couplings. This website is not applicable to the current experimental design. It would have come in handy if there was a need to directly couple a hand crank to a shaft.

[11] M. French, "Strain Gauge 3 - Bridge Circuits," 25 January 2011. [Online]. Available: http://www.youtube.com/watch?v=V0N1zmBqEkc. [Accessed 2 March 2013]. This video informs us that strain gauges need to be part of a bridge circuit. This clip shows how a simple bridge circuit works. It includes the equation for output voltage and an example calculation. This information is applicable to our experiment since we are using strain gages to measure strain and need to know how to properly use a strain gage.

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[12] M. French, "Strain Gauge 2 - Gauge Factor," Purdue MET, 24 January 2011. [Online]. Available: http://www.youtube.com/watch?v=0q_U2a7xPjM. [Accessed 2 March 2013]. This clip shows where gauge factor comes from. To simplify the calculations, I show how to calculate gauge factor for a liquid metal strain gauge. This is much simpler than the calculation for a printed wire gauge and gives almost the same answer. This information is applicable to our experiment since we are using strain gages to measure strain and need to know how to properly use a strain gage.

[13] M. Rothman, "The Importance of Simultaneous Sampling in Data Acquisition Systems," SparkNET, 2013. [Online]. Available: http://ezinearticles.com/?The-Importance-of-Simultaneous-Sampling-in-Data-Acquisition-Systems&id=2852529. [Accessed 2 March 2013]. This website describes the various types of analog to digital conversion systems used in DAQs and the differences between them. The article includes the pros and cons between the two systems. This article allowed for better assessment of what type of data acquisition unit was needed for the experiment’s various outputs to be sampled. The strain data needed to be sampled simultaneously if we want to have a data output graph that represents the trends we are trying to convey. However, for accessory data acquisition, a few milliseconds to a few seconds isn’t going to make a big difference in the trends we are presenting.

[14] Moeller Engineering, "Crank A Watt," Moeller Engineering, 2013. [Online]. Available: http://www.prestowind.com/?mainURL=/store/item/39cdg/Crank-a-Watt_Hand_Crank_Generators_-Emergency_and_Survival_Products/Crank-a-Watt_TM_Deluxe_400_Watt_Bike_and_Hand_Crank_Emergency_Generator.html?item_id=39cdg. [Accessed 26 February 2013]. This page identifies the technical specifications of the Crank A Watt generator – the generator that the team used as a base for their design. In particular, it lists several important dimension of the moving components on the generator and it has several photos/videos of the device which show its modular internals and allowed us to make a final decision to use this device.

[15] ASM Aerospace Specification Metals, Inc., "Metal Distributor," ASM Aerospace Specification Metals, Inc., 2013. [Online]. Available: asm.matweb.com. [Accessed 28 February 2013]. This site provides the material properties of materials often used in engineering applications. It gives ranges for mechanical, thermal, and chemical properties of pure metals and alloys. In addition it highlights applications and unique facts about each material it offers a data sheet for. Material properties for specific alloys were collected from this site when doing the force analysis on the crank of the generator. Also we checked this sited to see how we could potentially work the material.

[16] National Instruments Corporation, "Measuring Strain with Starin Gages," National Instruments Corporation, 2013. [Online]. Available: http://www.ni.com/white-paper/3642/en. [Accessed 28 February 2013]. This article describes in detail different bridge circuits and the advantages and disadvantages between the different bridges. The article also describes signal conditioning, calibration, offset nulling, and other pertinent information. This information is applicable for setting up, calibrating, and adjusting our strain gages. It also helped us to pick the ideal bridge type to use for our application.

[17] The United States Department of Defense, "Department of Defense Design Criteria Standard," The United States Department of Defense, Washington D.C., 1998. This guideline provided by the Department of Defense, gives baselines for designing ergonomic mechanisms.

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[18] P. M. Fishbane, S. G. Gasiorowicz and S. T. Thornton, "Generators," in Physics for Scientists and Engineers Volume 2, Upper Sadle River, Pearson, 2005, p. 863. This section of the book deals directly with the theory of a generator. It relates electrical and mechanical power of the generator. It also provides equations that consider the electromagnetic field. The experimental design uses a generator to create a reaction to provide the torsional resistance needed to cause the crank handle to experience significant strain. Accordingly, it is necessary to understand the relationship between the electric output of the generator and the mechanical input in order to provide the necessary reaction torque.

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Patent Search Due to the academic nature of the Stress project for ME3221, patents will not be sought for the manufactured apparatus or the laboratory procedure. However, to forestall any possible litigation, a quick patent search was conducted. The stress project has two components: the strain measurement system and the process of strain analysis. Using Google Patent Search the keywords: "strain measurement of rotating shaft", the results were assessed for possible solutions for the stress measurement experiment. Two patents describing strain measurement solutions that were described used a wireless transmitter and receiver, while the other used lasers and optics to transfer the information.

Both of these patents describe novel ways to measure torque on a rotating shaft, however, due to budgetary constraints and possible breach of patent, the laser technology was not investigated further. Stress measured using strain gages and transmitted wirelessly, however, was. Wireless transmission of strain measurements was compared to the common practice of using slip rings. Due to the resources available during this project, including free National Instruments hardware, wireless transmission was pursued.

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User Need Research Three major consumer groups were identified and interviewed: professors who taught ME3221, teaching assistants who ran the ME3221 experiments and students who took ME3221. Two minor consumer groups were also considered: National Instruments and the faculty for ME4054. Based on the interviews and a site visit during one of the current stress experiment, product specifications were developed and project deliverables were established. Detailed interview notes and email correspondences can be found in Appendix I or the notebook of the project member conducting the interview.

National Instruments, as the sponsor for the Stress experiment, delivered only one design requirement: that the final apparatus created must help advertise National Instruments. This meant that the apparatus developed must use NI hardware and software and an additional 2 minute video demonstration and an additional case study must be developed.

The 3 professors (including our advisor) who previously taught ME3221 laboratory, as well as one professor who only taught the ME3221 lecture were all interviewed. During these interviews, the following list was compiled:

• Lab must coincide & demonstrate material presented in lecture

• Needs to be interesting & hands-on for the students

• Need to involve students with hand calculations to verify model

• Must measure strain in multiple directions (strains will be used to calculate stress)

• Must be roughly the size of the bike experiment or smaller (manageable size)

• It must use National Instruments’ equipment

• Should be easy to diagram and setup

• Needs to be robust

• Must be “approachable”

• Should involve multiple people (roughly 10 students) during experimentation

• Prove why the project doesn’t fail

• Can use CAD/FEA animations as supplementary

• Possibly be cyclic

• Should be easy to calibrate

Three teaching assistants were approached in the same way as the professors, with two of them demonstrating on the previous bicycle experiment what the strengths and flaws of the previous experiment were. The TA interviews were compiled into a similar list:

• Manageable size

• Easy to setup/demonstrate

• Accurate data output

• Needs to measure an appropriate range (ex: needs to measure light & heavy objects)

• Should be visually appealing (the programming should also be appealing)

• Should be stable when moving (or stationary)

• Short discussion, more focus on.

• Interesting for students

• Prefer setup to be convenient, durable, quick

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Since every member of the project group had taken ME3221 and participated in the laboratory stress experiment on the bicycle the first students interviewed were ourselves. After interviewing ourselves (the six of us) we consulted classmates to hear about their experiences. The feedback was then compiled into the following list:

• Apply what is learned in class (Rosette’s)

• Easy to operate

• Safe

• Better understandable output on program

• Manual/instructions should be intuitive or easy to read (good visuals, etc.)

• Lab duration should be shorter

• Interesting/fun

The faculty of ME4054 was also consulted when looking at concept alternatives. Due to the popularity of the previous experiment (the bicycle), the faculty was also consulted to determine whether the scope of this project could or could not be large enough if the experiment were based on another bicycle.

During the site visit during one of the bicycle experiment labs, many of the points noted by other groups were confirmed. However, the site visit also illuminated aspects of the entire procedure that are addressed in the laboratory manuals. The introduction to the experiment was much longer than the experiment itself. While the introduction to the concepts took approximately 40-50 minutes, the experiment took approximately 5 minutes per pair of students. It was also notable that while 2 students ran the experiment, the rest of the students did not have anything to do. It was also notable that the pre-lab questions were not addressed during this laboratory. This is another aspect of the laboratory manual that is addressed.

Based on the feedback given by all of the consumer groups and the site visit, the consumer needs (as seen in Table 1Table 1) were compiled father, redundancies were removed and degree of importance was assigned.

Table 1: Customer Needs Summary

# Customer Needs Importance 1 Lab must coincide & demonstrate material presented in lecture 5 2 Must measure strain in multiple directions (strains will be used to calculate stress) 5 3 It must use National Instruments’ equipment 5 4 Real World Meaning 5 5 Possibly be cyclic 5 6 Safe 5 7 Manual/instructions should be intuitive or easy to read (good visuals, etc.) 5 8 Project should have a reasonable scope (have done by the end of the semester, etc.) 5 9 Should be within budget 5

10 Want to obtain a good grade 5 11 Needs to be interesting & hands-on for the students 4

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12 Needs to be robust 4 13 Must be “approachable” / familiar to students / intuitive 4 14 Should involve multiple people (roughly 10 students) during experimentation 4 15 Easy to demonstrate 4 16 Accurate data output 4 17 Needs to measure an appropriate range (ex: needs to measure light & heavy objects) 4 18 Should be visually appealing (the programming should also be appealing) 4 19 Easy to operate 4 20 Labeled output on program 4 21 Should be possible for us to manufacture within reason 4 22 This lab should help market NI equipment 4 23 Need to involve students with hand calculations to verify model 3 24 Should be easy to diagram 3 25 Can use CAD/FEA animations as supplementary 3 26 Should be easy to calibrate 3 27 Easy to setup 3 28 Should be stable when moving (or stationary) 3 29 Short discussion, more focus on lab. 3 30 Must be roughly the size of the bike experiment or smaller (manageable size) 2 31 Prove why the project doesn’t fail 2 32 Would like to purchase safety glasses specifically for that lab (for the students) 2

Using the consumer needs as a guideline, product design specifications were then developed, as shown below:

Table 2: Product Design Specifications

Need # Metric Importance Unit Marginal Value Ideal Value 1, 2 Number of strain measurements 5 integer 2 3

27, 31 Width 3 m 2 1 27, 31 Height 3 m 3 1 27, 31 Length 3 m 3 1.5 11, 14 Number of operators 4 integer 2 4

13, 15, 24 Time to introduce lab 4 min 60 15 27 Weight 3 kg 60 30 12 Cycles to failure 4 Cycles 100000 infinite

9 Cost 5 US $ <3000+ 2500 19 Time to conduct experiment 4 min 10-90 15-60 27 Time to transport/set up 3 min 2-120 2 26 Time to calibrate 3 min 5-120 5

23, 32 Hand calculations possible 3 binary No Yes 25 CAD/FEA animations 2 binary No Yes

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5 Cyclic measurements 5 binary Yes Yes 4, 11 Real life application 5 binary Yes Yes 3, 22 Use NI software and equipment 5 binary Yes Yes

20 Labeled output data 4 binary Yes Yes 6, 28 Immobile footprint 5 binary Yes Yes

16 Precision of measurements 4 decimal 0.01-0.001 0.001 17 Data signal range 4 lbf 50-200 3-250

16, 28 Accuracy of measurements 4 % 90-100 95

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Concept Alternatives After several brainstorming sessions, ideas were generated and explored. During this process the most plausible projects were separated into groups based on the nature of the stresses applied. In the first group, stresses are applied on a crank and the strains are measured on the corresponding shaft. The second group was more direct stresses on a shaft caused by direct torsional and/or normal loading. The third group examined stresses caused by force applied along a shaft. The fourth group examined strains on unusual geometries and the final group were experiments that measured non-cyclic stresses. This section discusses examples of these designs and the location of the strain measurements in each of these situations.

In the first group of experiments, pedals and cranks applied forces on a shaft that rotated using bearings. Several concepts that were explored were improvements on the bicycle laboratory, including a simply improved bicycle with an additional side experiment and a bicycle experiment with a connected generator. Along the same lines, hand cranked devices were also identified, including hand-cranked generators and car jacks. In all of these experiments the strains would be measured on the shafts connected to the crank, and the cranks would be fully rotated to generate cyclic loading samples (see Figure 1). In addition to the stress measurements, the generator examples also take measurements of power output.

Figure 1: Simplification of strain measurement and motion on a crank/pedal. Boxes represent strain gauge locations and arrows represent motion of the crank

Experiments on shafts without cranks were also examined. These experiments focused on one type of cyclic loading. In the case of the stresses on the shaft holding up a pendulum, propeller or a tire tester that measures strains on the axel, only bending forces are applied. On the piston of an engine compressor, only a compressive force is applied. On the shaft of a motor, only torsional stresses were applied. In these experiments strains is measured at one point along the shaft as the shaft rotates.

A belt drive was considered where force would be applied along the long end of a shaft and the stress would be measured at different locations along that shaft. As the belt drive ran, the shaft would rotate, and the force would be applied to a different location relative to the strain gauge as it rotated. The cyclic loading is demonstrated by this motion.

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Cyclic loading is not limited to shafts. Boats are subject to cyclic stresses caused by waves. An idea of determining the stresses on the hull of a scaled boat inside a wave pool was suggested. The measurements would indicate the strength and the natural frequency of the boat.

Non-cyclic stress experiments were also considered. Due to the 35W bridge collapse and the equipment available from National Instruments, one idea was to measure stress on the bridge as the to-be completed light rail passes across it. A cantilever was also considered where strain could be measured at any point along the beam and forces could be applied with equal variety.

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Concept Selection A large pool of concepts was filtered through based on merit and the design specifications developed from customer interviews. The first major filter eliminated all experiments that did not involve cyclic loading, as that criterion was both listed in the project description and by several of the professors. From the remaining detailed ideas, a Pugh Matrix (Table 3) was used to compare their merits compared to the current bicycle design.

Table 3: Pugh Matrix

Crite

ria

Crite

ria W

eigh

ting

Bike

Pend

ulum

Engi

ne/

Com

pres

sor/

Pis

ton

Mot

or a

nd S

haft

(s)

Belt

Driv

e

Gen

erat

or

Gen

erat

or a

nd B

ike

com

bine

d

Prop

elle

r

Boat

and

Wav

e Po

ol

Tire

Tes

ter a

nd W

heel

Car S

ciss

or Ja

ck

Lab must coincide & demonstrate material presented in lecture 5 0 0 0 0 0 0 0 0 -1 0 0 Must measure strain in multiple directions (strains will be used to calculate stress) 5 0 0 0 0 0 0 0 0 -1 0 0 It must use National Instruments’ equipment 5 0 0 0 0 0 0 0 0 0 0 0 Applicable in Real world 5 0 -1 0 0 0 0 0 0 0 0 0 Extract realworld meaning from data 5 0 0 0 -1 -1 1 1 -1 0 1 0 Possibly be cyclic 5 0 0 0 0 0 0 0 0 0 0 0 Safe 5 0 0 0 0 -1 0 0 -1 0 -1 -1 Manual/instructions should be intuitive or easy to read (good visuals, etc.) 5 0 0 0 0 0 0 0 0 0 0 0 Project should have a reasonable scope (have done by the end of the semester, etc.) 5 0 1 -1 0 0 0 -1 1 -1 0 1 Should be within budget 5 0 1 -1 1 0 0 -1 1 0 0 1 Want to obtain a good grade (Wow Factor) 5 -1 -1 1 -1 -1 0 1 0 1 1 -1 Needs to be interesting & hands-on for the students 4 0 -1 0 -1 -1 0 1 -1 1 0 0 Needs to be robust 4 0 1 -1 0 0 0 0 0 -1 0 1 Must be “approachable” / familiar to students / intuitive 4 0 1 0 0 -1 0 0 0 0 1 0 Should involve multiple people (roughly 10 students) during experimentation 4 0 -1 0 -1 -1 0 0 -1 1 0 0 Easy to demonstrate 4 0 1 0 0 0 0 0 1 -1 0 1 Accurate data output 4 0 1 1 1 1 1 1 1 -1 1 1 Needs to measure an appropriate range (ex: needs to measure light & heavy objects) 4 0 1 1 1 1 1 1 1 1 1 1 Should be visually appealing (the programming should also be appealing) 4 0 1 1 1 1 1 1 1 1 1 1 Easy to operate 4 0 1 0 0 0 0 0 0 -1 0 0 Labeled output on program 4 0 1 1 1 1 1 1 1 1 1 1

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Should be possible for us to manufacture within reason 4 0 1 -1 1 0 0 0 1 -1 0 1 This lab should help market NI equipment 4 0 1 1 1 1 1 1 1 1 1 1 Need to involve students with hand calculations to verify model 3 0 1 1 1 0 1 1 1 -1 -1 1 Should be easy to diagram 3 0 1 1 1 0 1 1 1 -1 0 1 Can use CAD/FEA animations as supplementary 3 0 Should be easy to calibrate 3 0 1 0 0 0 0 0 0 -1 0 0 Easy to setup 3 0 1 1 1 0 1 0 1 -1 0 1 Should be stable when moving (operation) (or stationary) 3 0 0 0 0 0 0 0 0 -1 -1 1 Short discussion, more focus on lab. 3 0 0 0 0 0 0 0 0 1 0 0 Want it to be a good learning experience (and help prepare for our future jobs) 3 0 -1 1 1 1 1 1 1 0 1 0 Must be roughly the size of the bike experiment or smaller (manageable size) 2 0 1 1 1 1 1 0 1 0 1 1 Prove why the project doesn’t fail 2 0 Sum of Positives 0 17 11 12 7 11 11 14 8 10 15 Sum of Negatives 1 5 4 4 6 0 2 4 13 3 2 Sum of Sames 32 9 16 15 18 20 18 13 10 18 14 Weighted Sum of Positives 0 64 39 43 25 39 43 52 32 39 56 Weighted Sum of Negatives -5 -21 -18 -18 -27 0 -10 -18 -50 -11 -10 Overall Weighted Score -5 43 21 25 -2 39 33 34 -18 28 46

The car jack, pendulum, generator, propeller and the bicycle generator were the strongest candidates for development, based on the results of the Pugh matrix. These ideas were then further developed, and the scope of the experiment during a laboratory session was considered when establishing a final decision. Upon further review, the car jack and pendulum were eliminated due to a lack of scope and a lack of “real world application”, respectively. As a result, the generator idea was selected as the final project to pursue.

While the car jack was a real life application, it is a very simple machine and does not contain as many parts that can be used as examples in a teaching environment as a hand-crank generator does. While the hand-crank generator and car jack use the same application of forces and examine the same strains, the hand-crank generator also uses other basic mechanical elements such as gear and energy conversion.

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Design Description Support Documents

Manufacturing Plan (Product)

Manufacturing Overview The hand crank generator apparatus was purchased pre-fabricated but the shaft and crank were replaced. The crank was designed and constructed to control the amount of strain on the shaft and allow for the mounting of wireless transmitters. Two strain rosettes were bonded to the shaft and connected to wireless transmitters with internal signal conditioners. The transmitters send data to a receiver that was hooked up to a computer. LabVIEW software records and displays the incoming stress data. An overview of the system is shown in Figure 2.

Figure 2: Overview drawing of apparatus

Generator

Wireless transmitter with internal signal conditioning

Crank/transmitter mount

Strain rosettes (2)

Wireless receiver

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Part Drawings

Figure 3: Generator Drawing

Figure 4: Dimensioned Drawing of Crank and Shaft

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Figure 5: Drawing of Strain Gage Locations

Figure 6: NI WSN-3214 Strain Gage Node (signal conditioner and wireless transmitter)

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Figure 7: NI WSN-9791 Ethernet Gate (wireless receiver)

Figure 8: Front panel of LabVIEW program

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Bill of Materials No. Part # Description Manufacturer Distributer

Qty Unit

Cost (Each)

Cost (Total) Notes

1 12063 ASTM B221-08 6061-T6 Aluminum Round Bar 3/4" (36" long)

Discount Steel & Aluminum

Discount Steel & Aluminum 1 each $11.58 $11.58

2 30531 Fender washer 3/8" zinc N/A Home Depot 6

2-pack $0.25 $1.50

3 80050 Clear Silicon RTV Permatex NAPA 1 each $6.29 $6.29

4 85352 3/8"-16 Bolt Handi-Pack Menards 2 each $0.49 $0.98

5 177124 Self Adhesive Anti Skid Pads Everybilt Home Depot 1

8-pack $2.48 $2.48

6 265136 Flat Black Spray Paint Rust-oleum Home Depot 1 each $3.44 $3.44

7 353729 6" Adjustable Adjustable Wrench Iron Bridge Tools Home Depot 1 each $1.97 $1.97

8 563959 Allen Wrench Set Husky Home Depot 1 each $6.47 $6.47

9 2329857 3/8"-16 Zinc Lock Nut w/Nylon Insert Grip FAST Menards 1

20-pack $1.89 $1.89

Will only need 6

10 00742 ASTM B209-10 6061-T6 Aluminum Plate (1/2"X4"X12")

Discount Steel & Aluminum

Discount Steel & Aluminum 1 each $20.00 $20.00

11

008-004-NOB #2 x 4" Phillips Screwdriver Iron Bridge Tools Home Depot 1 each $0.98 $0.98

12 1420-C 2" C-Clamp Adjustable Home Depot 2 each $2.26 $4.52

13 17201ES Command Strips Command Home Depot 1

6-pack $3.18 $3.18

14 2020-1.5A Masking Tape Scotch Home Depot 1 each $2.97 $2.97

15 278-1223 Shielded Hookup Wire (18-gauge) NA RadioShack 1 ft $7.99 $7.99 For DAQ

16 4218-BA-40 Electrical Tape Scotch Home Depot 1 each $1.97 $1.97

17 7010 MT Desktop Computer Dell Best Buy 1 each

$801.99 $801.99

Free from MEnet

18 780996-01 Wireless Gateway (NI WSN 9791) National Instruments NA 1 each

$823.00 $823.00

Free from NI

19 781636-02 Wireless Node (NI WSN 3214) National Instruments NA 1 each

$800.00 $800.00

Free from NI

20 BTP-1 Strain Gauge Terminal Pads Omega NA 1 1-pack $18.50 $18.50

21

CRANKAWATT Generator PrestoWind

Into The Wilderness 1 each

$487.60 $487.60

22

E91SBP-4 AA Batteries Energizer Home Depot 1

4-pack $3.78 $3.78

23

SgD-2/350-rY53 Strain Gauge Rosette Omega NA 1

5-pack

$125.00 $125.00

24 TT300 Strain Gauge Application Kit Omega NA 1 1-kit

$220.00 $220.00

Table 4: Bill of Materials

Manufacturing Procedure The hand crank generator apparatus was purchased pre-fabricated, however, due to the objective of this experiment, slight modifications were made to the original design. The crank and shaft were replaced. The shaft and crank arm were manufactured from stock aluminum 6061 to the specifications shown in Figure 4. The shaft was welded onto the crank arm. The screw-on crank was taken from the original generator and screwed onto one end of the crank arm, where a screw is set in place with a bolt. The other major change was the ends of the generator were short circuited to add resistance to the system.

The two SgD-2/350-rY53 rosettes were bonded to the base of the shaft at a 90 degree offset from each other using the TT300 Strain Gauge Application Kit, as shown in Figure 5. The BTP-1 Omega terminal pads were bonded directly behind each individual strain gauge, and the lead wires from the strain

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gauges were soldered to the terminal pads. A more detailed installation guide is listed in Appendix III: Strain Gage Installation Procedure. The 278-1223 18-gauge hookup wire was soldered to the positive and negative terminals of the terminal pads and hooked up to the NI WSN 3214 wireless transmitters. The NI WSN 3214 wireless transmitter (seen in Figure 6) was bonded to the crank plate using poster fasteners.

On the receiving end, the receiver was hooked up to the computer via USB. The LabVIEW software program takes in the data and records and visually display the strain and stress data (as seen in Figure 8).

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Implementation Plan (Process)

Implementation Overview The project was designed for use as a laboratory experiment and is ready for hand off. The construction of the apparatus has been completed as specified in the manufacturing procedure. The handoff requires no training, since documentation for the maintenance and experimentation has already been prepared. Two run through with current ME3221 teaching assistants were completed to assure the thoroughness of the manuals. The maintenance of the apparatus is specified in the teaching assistants’ manual (Appendix V: Teaching Assistant Manual), while the laboratory procedure is specified in the student manual (Appendix VI: Student Manual). At the final handoff, Professor Susan Mantell will receive these manuals and the apparatus in preparation for future ME3221 Design & Manufacturing I lab sessions.

Process Drawings

Figure 9: Major Deadlines

Component List The Bill of Materials in Table 4 lists more detailed information about the material components necessary to implement a successful laboratory session. Table 5 is a more generalized list of components necessary for the session to run smoothly.

Table 5: Component list

No. Description 1 Generator (see Bill of Materials) 2 Student Manual 3 Teaching Assistant Manual 4 Computer with LabVIEW Program

Lab Manuals Drafted (4/9/2013) • Student experiments • Maintenance

instructions

Completed Construction (4/6/2013) • LabVIEW • Apparatus

Evaluation (4/25/2013) • Lab Run-throughs • Apparatus Testing

Handoff to Professor Mantell (5/7/2013)

Implimentation of Laboratory (Fall 2013)

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5 Wireless Gateway (NI WSN 9791) 6 Wireless Node (NI WSN 3214)

Implementation Procedure Using the implementation process is outlined in Figure 8, the generator laboratory experiment will replace the bicycle experiment. During this process, lab manuals were developed, the apparatus completed and dry runs of the lab were completed. Based on the feedback of the teaching assistants and the student who followed the lab manuals and completed the procedures, the new procedure is preferred. The labs will now be handed over to Professor Susan Mantell, and should be implemented this following semester.

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Evaluation Support Documents

Evaluation Reports

Cost Analysis The lab apparatus is a one-off design that did not have a functioning prototype. However, these costs would be comparable if the Mechanical Engineering department decided to construct another. The cost of hiring a student worker to assemble another apparatus would be about $10.00/hr while the cost of hiring someone to weld together another crank would be about $20.00/hr.

It might be less expensive to build a mounting from scratch and source a different motor, but this would require additional design and construction time.

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Environmental Impact Statement

Purpose The lab apparatus’ purpose is to teach engineering students about fluctuating stress using an approachable example. It has no other practical use than education as it is configured. As a result of its use in higher education, students who use it in ME 3221 will have a better understanding of fluctuating stress.

Environmental Impact To produce this lab, there are three main components that need to be manufactured: the generator, the computer, and the crank. The generator’s toolbox is made of high-density polyethylene, which must be synthesized and molded into the box. The permanent magnet motor in the generator box contains iron, neodymium, and boron that must be mined, processed, and machined in order to create the motor. The computer selected uses a case made from 10% recycled materials and contains no mercury or arsenic. The computer internals require mining and manufacturing overseas. The crank is machined from aluminum bar stock and welded.

During the life of the lab apparatus the computer and NI receiver will require electricity to function. The impact of this will depend on where the electricity is generated. Also the NI sensor nodes will require AA batteries. The NI WSN 3214 requires alkaline batteries and does not accept rechargeable due to tolerances specified in the owner’s manual.

The toolbox the generator is housed in can be recycled easily. The computer will need to be process through a manufacturer or university e-waste program to dispose of its contents and data responsibly. The aluminum crank can be recycled at a scrap metal facility. The strain gauges and wires will be disposed of in conventional garbage. The batteries used in the sensor nodes will also require a battery recycling facility to be disposed of. Spent batteries must be disposed of as hazardous or industrial solid waste.

Alternatives The computer used in this configuration is a midsize desktop computer with a 21-inch LCD monitor. A smaller laptop computer with a smaller current draw would be an easy way to decrease the amount of electricity required to run the experiment and the amount of raw materials needed to manufacture it. The generator could be sourced independently of the toolbox if a new set of bearings could be efficiently designed and manufactured.

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Regulatory and Safety Considerations Anything that contains a printed circuit board and is unwanted, or e-waste, is considered to be hazardous waste by the state of Minnesota. This waste must be picked up by the Office of Information Technology after the data has been removed by the computer’s department. Used batteries must be disposed of as hazardous or industrial solid waste. Failure to do so is prohibited by the Minnesota Pollution Control Agency.

OSHA requires that wherever there is a walking or working surface it must remain as clean and dry as possible or has a drain. Since this is a hand-operated device, the university is responsible for making sure it is in safe operating condition.

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Appendix I: Interviews

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Appendix II: Improvements to Bicycle Experiment List of Repairs for ME 3221 Bicycle Lab

In order to keep the bicycle lab functioning for another 10 years there are a few tasks that can be done to help extend the life of the current apparatus.

1. Obtain a new computer The current computer that is part of the bicycle lab is using an old version of LabVIEW and a release of Windows 95. Upgrading the computer and software will make updating the lab program and getting data much easier.

2. Obtain a new analog to digital converter The hardware being used for conversion to the computer is cumbersome to calibrate and alter. A new NI data acquisition module would decrease the footprint of the setup and make calibration much easier.

3. Obtain new shielded data cables Currently the apparatus uses long, unshielded cables to transmit the data from the strain gauges to the analog to digital converter. Shorter, shielded cables would drastically decrease signal noise and give better data.

4. Tune-up the bicycle The components on the bike need to be tuned by either a bike shop or someone with experience working on multispeed bikes. Students are only able to select 2-3 gears with the selector on the bike. A new gear selector would allow the selection of all 21 speeds. This, in addition to tuning the derailleur, would make the bike more versatile. The brakes also need to be tuned if their function is ever needed. The cost of a tune-up is about $70 to $80.

5. Replace the rear bicycle wheel The rear bike tire is damaged beyond repair and the tube with it. The tire and tube must be replaced and the stand readjusted. This will allow for easier operation and transport of the apparatus. The cost of a new tire is about $40 and the cost of a new tube is about $7 to $16. The wheel/rim may also be damaged. You need to check and see if the spokes are poked through the rim or not. If they are they’ll damage any inner-tube you replace.

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Appendix III: Project Gantt Chart

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Appendix IV: Strain Calculations Before development, stresses on the shaft were predicted to estimate the strains experienced by the shaft, to prevent failure and estimate the measureable strains. Estimates for the dimensions were developed using the specifications of the pre-fabricated generator. The dimensions are given in Figure 4.

Based on the geometry of the shaft and handle, the greatest bending stresses are expected to come at the positions shown in Figure 10.

The bearing constrains the lateral movement of the shaft, so for bending stresses, this location was assumed to be static. Based on these assumptions, estimates for bending stresses were calculated using Equations 1-3.

𝝈 = 𝑴𝒚𝑰

Equation 1

𝑰 = 𝝅𝒅𝟒

𝟔𝟒 Equation 2

𝑴 = 𝑭𝒍 Equation 3

After calculating the bending stresses, the torsional stresses were calculated. The torsional resistance of the generator was assumed to be a maximum of 5lb-in, and the only source of torsion. As a result, Equations 4 and 5 show how the torsional stress was calculated.

𝝉 = 𝑻𝒓𝑱

Equation 4

𝑱 = 𝝅𝒅𝟒

𝟑𝟐 Equation 5

Transverse stresses were also calculated, using equations 2 and 6, however their magnitude was insignificant compared to the other two measurements, and therefore its measurement was not pursued during this experiment.

𝝉 = 𝑽𝑰𝒃

∫ 𝒚𝒅𝑨 Equation 6

Stresses were then converted into strains using Equations 7 and 8, since the strain gages measure strains and not stresses.

Figure 10: location of largest stress

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𝝈 = 𝑬𝝐 Equation 7

𝝉 = 𝑮𝜸 Equation 8

The Excel spreadsheet was then formulated to quickly complete these calculations as more information was obtained.

Table 6: Excel Strain Calculator

US Engineering Metric Length 1 8.00 in 0.20 m

Strain/resistance conversion

Length 2 5.00 in 0.13 m

10V exitation output and 1/4 bridge

Length 3 4.00 in 0.10 m

Bending 5 muV/muepsilon

Diameter 1 0.75 in 0.02 m

Axial 5 muV/muepsilon

Diameter 2 0.75 in 0.02 m

Shear/Torsional 10 muV/muepsilon

Diameter 3 0.75 in 0.02 m Torque 5.00 lbs-in 0.56 Nm

independent cell Max Load 60.00 lbs 266.89 N

results cell

Min Load 5.00 lbs 22.24 N

material property Safety Factor 2.00 2.00

past yield w/ SF

Yield Strength 31.18 ksi 215.00 MPa

past tensile w/ SF Ultimate Strength 73.24 ksi 505.00 MPa

Elastic Modulus 29007.55 ksi 200.00 Gpa Shear Modulus 12473.25 ksi 86.00 GPa Max Bending Stress 15.57 ksi 107.37 MPa Max Bending Strain 536.86 microstrain 536.86 microstrain Min Bending Stress 1.30 ksi 8.95 MPa Min Bending Strain 44.74 microstrain 44.74 microstrain Max Shear Stress 0.18 ksi 1.25 MPa Max Shear Strain 6.24 microstrain 6.24 microstrain Min Shear Stress 0.02 ksi 0.10 MPa Min Shear Strain 0.52 microstrain 0.52 microstrain Max Torsional Stress 6.34 ksi 43.69 MPa Max Torsional Strain 508.06 microstrain 508.06 microstrain Max Bending Output 536.86 microvolts 536.86 microvolts Max Torsional Output 5080.56 microvolts 5080.56 microvolts Max Shear Output 31.21 microvolts 31.21 microvolts

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Appendix V: Strain Gage Installation Procedure Since the University of Minnesota provided us with an appropriate adhesive kit (Micro-Measurements BAK-200 Basic Application Kit F022335) the TT300 Omega adhesive kit was no longer needed, and the Micro-Measurements kit was used instead.

The steps for surface preparation were executed in the following order:

1. The surface area of the aluminum shaft that the strain gauge was to be applied was first degreased with the Micro-Measurements CSM degreaser. The degreaser was sprayed into a gauze sponge and the surface was wiped until clean.

2. 320 grit silicon carbide paper was used to dry abrade the surface area. Following the 320 paper was used to wet abrade with the MPrep Conditioner A solution. 400 grit silicon carbide paper was used to wet abrade the surface along with the MPrep Conditioner A. A gauze sponge was used to wipe the surface clean.

3. Layout lines were burnished with a 4H pencil by drawing the alignment lines on the shaft in order to mark the orientation of the strain gauges.

4. The next step was to condition the surface by applying MPrep Conditioner A and scrub the area with a cotton swab. A gauze sponge was used to wipe the surface clean.

5. The last step was to neutralize the surface by applying MPrep 5A Neutralizer and scrub the surface with a cotton swab. The gauze sponge was used to wipe clean the surface.

The steps for strain gauge bonding were used in the following order:

1. The strain gauges were removed out of their packets by grabbing them with tweezers. 2. The strain gauge was transferred to Scotch tape. 3. The tape was placed and positioned on the shaft so that the strain gauge was in line with the

burnished lines on the shaft. 4. The tape along with the strain gauge was lifted and allowed for ¼ “ of space between the shaft

and the bottom of the strain gauge. 5. A thin layer of 200 Catalyst-C was applied the back of the strain gauge and was let dry for

approximately 1 minute. 6. A gauze sponge was folded in quarters in order for preparation for the next step. 7. 1 drop of M-Bond 200 Adhesive was placed on the shaft at the ¼” space between the strain

gauge and shaft. 8. The tape was quickly aligned over the adhesive drop and the back of the tape was pressed

against the shaft by wiping it with the gauze sponge. Immediately thumb pressure was applied to the strain gauge and was held for 1 minute. At the end of the 1 minute the thumb was twisted with pressure on the strain gauge, and the thumb was removed. The strain gauge was left to sit 2 minutes before removing the tape.

9. Steps 1-8 were performed for second strain gauge that was located at a 90 degree offset on the shaft and the bond terminal pads.

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Appendix VI: LabVIEW Block Diagram

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Appendix VII: Teaching Assistant Manual

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Appendix VIII: Student Manual

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ME 3221: Fluctuation Load and Stress Analysis

Stresses on a Generator Shaft

Purpose:

• Introduce cyclic stress analysis in a realistic application • Review stress and load analysis

Background:

One of the primary concerns of any engineer is the component failure. When a component fails, it no longer preforms its function properly. As a result, stresses are studied and quantified. Cyclic stress is one of the most effective causes of material failure. As the lecture portion of this class has demonstrated, material failure can be described in terms of stresses. This laboratory experiment demonstrates the measurement of those stresses.

The shaft of a hand-crank generator is used in this experiment to demonstrate cyclic stress. The shaft of the generator is supported by ball bearings that allow for rotation but no lateral movement. As a result, the bending force on the external part of the shaft can be modeled as a bending beam while the torsional force is caused by an electrical resistance applied within the generator. The handle of this generator is demonstrated in Figure 1.

2 Strain rosettes are mounted on the shaft, close to the bearing, 90 degrees from each other, as seen in Figure 2.

Figure 11: diagram showing locations of strain gages (red dots).

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This laboratory experiment covers the measurement of stress in a cyclic environment. There are two stress components to this experiment. There is a constant torsional resistance, which is produced by power dissipation within the generator. This is described by Equation 9 and Equation 10:

𝑃 = 𝑇 ∙ 𝜔

Equation 9: Rotational Power

𝑃 = 𝑉 ∙ 𝐼 = 𝐼2𝑅 =𝑉𝑅2

Equation 10: Electrical Power

Since the current (I), resistance (R) and angular velocity (ω) all remain constant, the torque (T) and torsional stress will also remain constant. The bending stress caused by the force applied on the crank handle will be cyclic. While the force applied to the crank remains constant, the rotation of the shaft causes different geometries of these measurements.

In this experiment, the strains on the shaft of a hand-crank generator are measured using strain rosettes. In this apparatus, the rectangular rosettes, or rosettes with strain gages oriented 45o offset from one another, were used. Each individual strain gauge acts as a variable resistor, which is then interpreted using a Wheatstone bridge. Since the shaft is a 3-dimenstional surface, the orientation of the rosette is significant in measuring the torsional strain. This orientation of the strain gages measuring torsion are demonstrated in Figure 1:

Figure 12: Orientation of 2 strain gages (part of a strain rosette) that measure torsional strain1

Using the strain direct strain measurements, the bending and torsional strain are then calculated. These raw strain measurements are translated using Equation 11 and Equation 12:

𝛾 = 2 × 𝜖 @ 45° =𝜏𝐺

Equation 11: Torsional Strain

𝜖𝐵 = 𝜖𝐵

1 OMEGA Engineering Inc., "3-Element Strain Gage Rosettes 0/45/90," OMEGA Engineering Inc., 2013. [Online]. Available: http://www.omega.com/ppt/pptsc.asp?ref=SGD_TRIAXIAL&Nav=pree02. [Accessed 2 March 2013].

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Equation 12: Bending Strain

The laboratory analysis will not cover the conversion of strain rosette measurements to bending, torsional and transverse strain measurements. The conversions between strain gage resistances to strain will be performed by the LabVIEW software.

This lab will focus on an Aluminum 6061 shaft with the dimensions given in the figure below. The strain gages are applied 4 inches from the crank arm.

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Pre-Lab Questions:

1. What are the equations for a. Bending stress on a beam b. Transverse stress on a beam c. Torsional stress on a beam

2. The generator produces a current of 0.2 amps and a resistance of 5 ohms when the angular velocity of the crank handle is 20 rpm. What is the torsional resistance placed on the shaft? What is the force is necessary to create that torque when the radius of the shaft is ¾”?

3. Complete the chart below, indicating the sign of the stress at this location. Angles are defined by the direction of the handle from the center (see figure below)

Theta Rosette 0o/360o 90o 180o 270o Torsional A

B Bending A

B

0 degrees

90 degrees

180 degrees

270 degrees

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Experimental Procedure:

1. Make sure that all components are turned on, including the wireless transmitters 2. Open the LabVIEW program on desktop 3. Select the location to save the data file

a. Save to the desktop with your lab section number under the format: Stress01Real 4. Calibrate the LabVIEW program

a. Press first calibrate button when handle is at 0 degrees b. Press second calibrate button when handle is at 180 degrees

Simplified case:

5. Detach the handle from the rectangular crank and reattach it to the circular side 6. Select the new location to save the data file

a. Save to the desktop with your lab section number under the format: Stress01Simple 7. Clamp 5lbs centered around the pin on the rectangular crank 8. Repeat steps 6-9 with this setup. Keep the three experimenters constant and try to keep the

angular velocity as consistent between the realistic and simplified cases as possible. 9. Attach handle piece to rectangular crank attached to the generator

Realistic case:

10. Start recording the data 11. One person will rotate the crank steadily (uniform angular velocity) until the program has

recorded at least 5 rotations a. It would be helpful if another person pushes down on the box holding the generator to

help restrain it. 12. Click the stop button or “stop” to finish collection 13. Repeat steps 6-8 with 2 other experimenters

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Lab Report:

This laboratory experiment should be completed with the following sections and information. Additional requirements, expectations and grading information will be posted on the class website.

Report Section / Content Points

Title Page - include name, partners' names, date, section and title of experiment Objectives Introduces cyclic stress analysis in realistic application Reviews stress and load analysis Experimental Methods Overview of method Guiding equations Apparatus sketch and explanation Detailed experimental procedure Results and Discussion Part 1: Graphical Comparisons Convert measurements from strain to stress Plot and compare the stresses at 0 and 90 degrees in the realistic case Plot and compare the stresses measured in the realistic and idealized cases Determine the rotational velocity of the system Part 2: Stress Calculations Determine the force required to cause the greatest measured bending Determine the torsional resistance acting on the shaft Explain why torsion fluctuates during the idealized case Explain why transverse stress is not significant Determine the ideal power output Conclusion / Summary Appendices Raw data and other information that would detract from report body Regression summaries (when needed) Lab notebook copies Overall Report Structure, Style, and Formatting Logical organization and flow Report formatting - page numbers, white space, and use of headings Total Points

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Appendix IX: ANSYS Models

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Appendix X: Strain Gage Tests drop test

trail # ε before drop

trail # ε after drop

1 -0.27744 1 -0.27745 2 -0.27745 2 -0.27744 3 -0.27743 3 -0.27745 4 -0.27744 4 -0.27745 5 -0.27743 5 -0.27745

mean -0.277438 mean -0.277448 differemce 0.00%

heat test

trail # ε before heat

trail #

ε after cool down

1 -0.27745 1 -0.27748 2 -0.27744 2 -0.27747 3 -0.27745 3 -0.27747 4 -0.27745 4 -0.27748 5 -0.27745 5 -0.27749

mean -0.277448 mean -0.277478 Difference 0.01%

pull test

no effect on the strain gauge

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Appendix XI: Dry Run Evaluations

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Appendix XII: Specification Sheets

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For Bicycle Pedaling

1- Remove the drive belt from the pulleys. Caution: Don't pinch your fingers!

2- Align the 3" generator pulley to the bicycle tire. Using an Allen wrench, loosen the Allen fitting on the pulley. IMPORTANT This is the Allen fitting nearest to you, not the one nearest to the generator! Turn the adjustable pulley in or out, until the desired width is achieved for the bicycle tire.

3- Restrain the generator case so it doesn't move. A rubber bungee strap can be useful!

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4- Pedal at will!

Caution: Risk of pinching. Risk of shock. Keep away from children and pets!

Wiring instructions

The Crank-a-Watt(TM) is equipped with a rectifier that converts ac current to dc current. Dc current is used for charging batteries. Do not operate the unit without the rectifier. Do not plug the unit directly into a wall outlet. The rectifier and battery cables(supplied) are marked with a +(positive) and a -(negative). These go to the positive and negative on your battery. Install the battery cables to their corrisponding terminals only. Do not allow the interior contents of the Crank a Watt to become wet!

Installing the power inverter

If your unit is supplied with an inverter, connect the POS. (+) RED, and NEG. (-) BLACK leads from the inverter to the positive and negative on the battery. You may now plug 120 volt household appliances into the inverter. Caution: If you install the battery cables improperly to the NEG.(-) and POS.(+) battery connections, it will blow the fuse inside the power inverter! The inverter must be opened to change the fuse. Consult instructions. Remember to crank the handle whenever drawing a load from the generator and battery! Do not allow the interior contents of the Crank a Watt to become wet! Please call or email if you have questions. 513.232.1457 or prestowind@yahoo.com

Notice: Do not drain the battery! The ac inverter supplied with your unit will sound an alarm when the battery is too low to operate efficiently. You must recharge the battery to the proper level before reusing your generator.

Important Battery info: All Crank-a-Watt(TM) models are designed to be portable and self contained. Therefore, the battery must be powerful, yet small enough to fit into the case. Our engineers have specified the Interstate Brand (or equal), lead acid tractor-lawn-utility battery. Although they are not considered deep cycle batteries, they are very robust and good quality products. They operate in an excellent temperature range and are typically 145 cold cranking amps @ 12 volts, which is quite suitable for your Crank-a-Watt(TM) generator. Additionally, a deep cycle battery is not required because the ac inverter supplied with your unit will sound an alarm when the battery is too low to operate efficiently. You must recharge the battery to the proper level before reusing your generator. The battery can be purchased at Home Depot, Lowe's, Sears etc. The battery cables included with your Crank-a-Watt(TM) are compatible with this style of battery. The battery voucher value is intended to cover the entire cost of the battery and "core" charge. Due to

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fluctuating battery prices, we can't guarantee the exact price of the battery.

*For best results do not operate your generator below 11.8 volts.

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Moeller Engineering Cincinnati, Ohio is the home of Crank-a-Watt(TM) "Human Powered" Electrical Generators. For technical questions please email Prestowind@yahoo.com or call 513-232-1457 engineering. Crank-a-Watt(TM) is proudly

manufactured in Cincinnati, Ohio.

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