biohorizons fatigue test system
Post on 03-Jan-2016
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BioHorizons Fatigue Test System
Corp 3
Midterm Concepts Presentation
Team Members
Jonathan Hill
John Maddox
Allen Lindsay
Crichton Neal
Chris Howell
Felicia Craig
Bradley Johnson
Project Overview
General Specification ISO Standards Primary Concept
• Solid Edge• Advantages/Disadvantages• Water Bath• Economic Analysis
Secondary Concept Phase II
Specifications and Constraints General Constraints
small and light enough to operate on a tabletop clean and quiet enough to operate indoors at the
BioHorizons offices Able to perform fatigue tests as well as static load tests Control system and sensors must measure failure load and
cycles to failure and discontinue operation at this point Entire system must be able to be calibrated accurately
enough for continuous operation within ISO 14801 specifications and constraints
Economic Constraints to produce a fatigue testing machine that can be reproduced
and used for less than it currently costs to have the dental implants tested from an outside company
ISO Standards
ISO provides more specific specifications and constraints in ISO 14801—Dentistry—Fatigue test for endosseous dental implants
Several of the more pertinent specifiations are covered below, obtained from the ISO document: The testing machine should be capable of applying the
specified load with an error not exceeding ± 5% at maximum load.
The endosseous dental implant shall be clamped such that it makes a 30° ± 1° angle with the loading direction of the testing machine.
The device shall clamp the specimen at a distance 3.0 mm ± 0.1 mm apically from the nominal bone level as specified in the manufacturer’s instruction for use.
ISO Standards (continued)
More constraints and specifications: The dimensions of the loading member shall be chosen to
define a distance l = 11.0 mm ± 0.1 mm from the centre of the hemisphere to the clamping plane.
For endosseous dental implants that include materials in which corrosion fatigue has been reported or is expected to occur…testing shall be carried out in water of Grade 2 according to ISO 3696, in normal saline [.09%]* or in physiologic medium. The fluid and the test specimen shall be kept at 37°C ± 2°C during the testing.
Fatigue testing shall be carried out with a unidirectional load. The load shall vary sinusoidally between a nominal peak value and 10 % of this value. The loading frequency shall be ≤ 15 Hz. Testing in liquid media shall be conducted at frequencies ≤ 2 Hz.
*As specified by BioHorizons
Other Applicable ISO Standards ISO 1099: Metallic materials—Fatigue testing—Axial force
controlled method
ISO 1942-1: Dental vocabulary—Part 1: General and clinical terms
ISO 3696: Water for analytical laboratory use—Specification and test methods
ISO 4965: Axial load fatigue testing machines—Dynamic force calibration—Strain gauge technique
ISO 7500-1: Metallic materials—Verification of static uniaxial testing machines—Part 1: Tension/compression testing
machines—Verification and calibration of the force- measuring system
Concept Overview
Different Views
Exploded ViewTemperature Sensor
Liquid Bath Container (Pyrex)
Washer (Rubber)
Container Base
Linear Motor/Load Cell
Frame (steel)
Thumb Screw
Insert (will be tapped to hold test piece)
Mounting Screws
Base (steel)
Exploded View
Advantages
Long life Excellent precision and
reliability Ease in varying load and
frequency Low maintenance Easy setup Small number of parts Conduct static and
fatigue tests without changing setup
Disadvantages
Initial costs are high Replacement parts would
be high Possible motor cooling
may need to be addressed
Different inserts need to be tapped for each implant tested
Water Bath
Major Components Heating element
Small and compact Low fluid volume rated
Temperature switch Small and compact +-2°C tolerance
Dish Metal bottom Glass sides Water tight
Water level switch Small and compact Safely maintain water
level
Dish
Metal base Base for mounting heating
components Able to drain the dish
through a ball valve Glass tube
Forms sides Able to withstand high
temps incase of heating problems
Able to see the test specimen during testing
Washer Or sealant as of yet to be
determined Seals the base to the glass
Standards
ISO 14801:2003 5.4 Testing Environment
testing shall be carried out in water of Grade 2 according to ISO 3696
fluid and the test specimen shall be kept at 37 °C+2°C or -2 °C
Heating Element
Compact Cartridge-Style Immersion Heater 1 5/8" long type 316 stainless steel element Maximum temperature of 100° C CSA Certified and UL-Registered Can be fully immerged in saline solution
Temperature switch
Submersible Cartridge Temperature Switch Operates as a thermostat 300 series stainless steel outer shell adjusted between -73° and +315° C 2” long element UL-Registered
Search continues to refine this component
Water Level Switch
Vertical-Mount Liquid-Level Switch Maintain a safe water level for the
Immersion heating element Over all length of 1 7/8“ Max temperature rating of 105°C When the fluid level drops too low
cut power to the heating element turn on a warning light or trigger a
system warning in the testing program letting the tester know to add more fluid
Linear Servo Motor
Handles static loading up to 500 lbf. Handles a cycling load from 0 to 150 lbf. at a
rate up to 15 Hz
Load Cell
Piezoelectric sensing cell
Highly repeatable Fatigue Rated load cell Low profile to fit easily
within machine
Controls
Load cell sends a signal through a DAQ card to LabView
LabView takes the data and depending on the load it will send a signal to the Driver which will in turn increase or decrease the current
Economic Analysis
Linear Motor, Cooling Jacket, Controller, and Driver: $19600Load Cell: $1000Lab View: $1200 per yearJig Frame and Base: $2000Computer: $600Heating Accessories: $300Cables and Connectors: $200
Total Costs: $25000
Alternative Design
Advantages
Cheap saline bath container
Rotary motor is cheaper than linear motor
Disadvantages
Bearings (maintenance)
Expensive to machine Small error in load cell
reading due to the bearing friction
Angle of applied force will be less reliable
Complicated – many possible places for failure
Phase II-Completed by Dec.
Obtain more quotes on linear motors Dimension Concept Stress Analysis Finalize Concept
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