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8/3/2019 CAD Report Recent

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REPORT BY

VINCENT ASHIKORDI

8 DECEMBER 2011

SURFACE MODELLING ERGONOMIC EVALUATION RAPID PROTOTYPING


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EXECUTIVE SUMMARY 3

SURFACE MODELLING

01 INSERTING REFERENCE IMAGES 5

02 THE DOOR FRAME 5

03 THE TYRE FRAME 6

04 THE CAR BONNET 6

05 THE WINDSHIELD, ROOF & BONNET 6

06 THE DETAILS 6

07 SURFACE CONTINUITY EVALUATION 7

08 RENDERING 7

VIRTUAL HUMAN EVALUATION

09 AIM 9

10 THE HUMAN 9

11 SETTING THE PARAMETERS & TASKS IN JACK 6.0 9

12 SIMULATION 10

13 ERGONOMIC EVALUATION 10

14 SIMULATION RESULTS 11

RAPID PROTOTYPING

15 RAPID PROTOTYPING TO 3D PRINTER CAPACITY 13

CONCLUSION 14

CONTENTS

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EXECUTIVE SUMMARY

The project sets the task to evaluate and select appropriate computer-aided design techniques

and tools for the design project herein. Lamborghini Gallardo has been selected as the carof choice of which a surface model has been produced in SolidWorks. Its design has been

evaluated ergonomically with a virtual human in Jack 6.0. A dened scale model of the car

has been produced via Rapid Prototyping. This report presents a detailed process through

which the project objectives have been managed.

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SURFACE MODELLING


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INSERTING REFERENCE IMAGES01

02 THE DOOR FRAME

The blueprint employed in the modelling of the Lamborghini Gallardo was obtained from

carblueprints.com and then separated into four different elevations in Photoshop and then saved

in their respective .tiff formats. Each elevation was placed on a plane as a sketch in SolidWorks

using >plane>Sketch>Tools>Sketch Tools>Sketch Image and then adjusting the imageproperties based on the given reference dimensions.

Figure 1 - Lamborghini Gallardo blueprint used for surface modelling in SolidWorks

Objective

To model the door frame from a single boundary surface for surface continuity.

Method

Select the Right plane, select the right elevational view

Select Sketch and then sketch the area around the top of the door frame starting from

the bonnet to the boot of the car, adjust the spline control arms to align the splines to the

corresponding lines on the reference image. Exit the sketch.

Select the Top plane and sketch the same line as sketched on the Right plane applying the

same methodology

Exit the sketch and select the two sketches, click Features and go to the drop-down menu

of the Curve tool, select Project Curve to generate the prole of both sketches in 3D space.

Do the same for the other line needed to generate the boundary surface

Use 3D Sketch to join the two projected curves by selecting the whole car body rst

Use the Boundary Surface tool to connect all the 3D lines to generate the overall surface as

shown in Figure 2

Sketch the inner outlines of the door frame on the Right plane, this should be used for thewindows later on

Exit the sketch and then trim the unwanted surface to generate the door frame.

Figure 2 - Car frame modelling

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THE TYRE FRAME03

04

05

06

THE CAR BONNET

THE WINDSHIELD, ROOF & BOOT

THE DETAILS

The tyre frames were modelled next with the intention of producing an aspect of the extreme

edge of the side of the car in 3D space to provide an anchor for 3D sketching. This was

produced from a boundary surface produced on two planes (see g. 3) then trimmed to the

desired form using a sketch produced earlier on the Right plane as the trim tool.

Modelling the bonnet involved creating an extruded

surface outwards from the area being modelled, this was

created with the intention of producing an anchor for - a 3D

sketch of the required bonnet and tangency.

Modelling these aspects of the car was

made possible by mirroring the right side

of the car. Both sides served as anchors

for 3D sketching. The 3D sketches were

made tangent to the door frames and

then readjusted to the desired proles.

Boundary surfaces were created from the

3D sketch proles and the door frames.

Adding the details involved utilising the 3D Sketch

tool, Trim Surface tool, making 3D sketches tangent

to existing surfaces as needed, the Boundary

surface tool, the Type tool and the Extruded

Boss/Base tool.

Figure 3 - Tyre frame modelling

Figure 4 - Car bonnet modelling

Figure 5 - Windshield, roof and booth modelling

Figure 6 - Car model detailing6


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SURFACE CONTINUITY EVALUATION07

Surface continuity evaluation was performed to check for surface tangency and alignment and if

necessary, sketches or boundary surfaces that make up the surfaces were made tangent to the

corresponding/continuing surfaces.

The main options selected for the rendered visualisation in PhotoView 360 included:

Courtyard background for the scene, Car paint - Black for the car body, Frosted glass for the

headlights, Tinted clear glass for the windshield and windows, Textured aluminium for theradiator grills and Textured rubber for the tyres.

Figure 7 - Zebra stripes showing details of surface continuity

Figure 8 - Rendered view of Lamborghini Gallardo

08 RENDERING

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VIRTUAL HUMAN ERGONOMIC EVALUATION


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AIM

The major objective for undertaking the Virtual Human Ergonomic Evaluation was to test the

impact that the size of the Lamborghini Gallardo would have on a 95th percentile human. As the

Lamborghini Gallardo is a compact sports car designed for high performance and aerodynamic

efciency, features such as its low centre of gravity and reduced overall height to give the car

more traction to the tarmac are trade-offs for interior space available to the occupant. Thisevaluation will test for comfortability and the impact of the low-to-ground nature of the car on the

driver/occupant.

The human is a 95th percentile male with anthropometric data as follows:

Height: 185cm (6ft 1.6in)

Weight: 79kg

The tasks to be performed by the human in the environment would help assess how

comfortable it would be for a 95th percentile man to get out of the vehicle and carry out the task

of moving a tool-kit to x any fault in the vehicle.

The objective here was to setthe scene for the evaluation,

selecting the objects within

the environment that would

serve as actors during

the simulation of the set

parameters.

Figure 9 - Virtual human anthropometric data

Figure 10 - Selecting actors in Jack 6.0

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THE HUMAN

SETTING THE PARAMETERS & TASKS IN JACK 6.0

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SIMULATION12

01 02

0403

05 06

The simulation tasks were set in the TSB simulation environment within Jack. With the actors

added, the major tasks performed by the human (Worker) for the simulation included:

A series of poses set to enable the Worker position himself to get out of the car; Go task - to

enable the Worker get out of the car; Get Object - to enable him get the tool-kit; Go task - toenable the Worker move the tool-kit into the car or to an area where he can repair the car;

Put_Object task - to enable the Worker place the tool-kit on where it is needed.

01 Car interior space evaluation - car interior space in relation to 95th percentile body size

02 Upper body movement in the sitting position - can the occupant move freely?

03 Getting out of the car evaluation - how possible is it?

04 Get tool-kit to perform task inside or outside the car05 Moving object into the car evaluation - how difcult is it considering the workers height?

06 Bending down low to perform task on a low-to-ground car evaluation - what are the

implications for the worker?

13 ERGONOMIC EVALUATION

Figure 11 - Simulation human tasks

Figure 12 - Ergonomic evaluation

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SIMULATION RESULTS14

INTERPRETATION

The results show that the

low back compression of

1074N is below the NIOSH

Back Compression Action

Limit of 3400N. It represents

a nominal risk of low back

injury. All other forces are

very minimal with Internal

Oblique tension more

profound than the othermuscle tensions.

INTERPRETATION

Here, the results show thatthe low back compression

of 2702N is still below the

NIOSH Back Compression

Action Limit of 3400N. It

represents a nominal risk

of low back injury for most

healthy workers.

CONCLUSION

The results indicate that for a 95th percentile man, the

experience of driving the car comfortably or carrying out

tasks inside or outside the car would be compromised by

his size and the overall size of the car.

GETTING OUT OF THE CAR COMFORT RANGE

Key:

Green: within comfort range

Yellow: out of comfort range

BENDING DOWN LOW COMFORT RANGE

Figure 13 - Getting out of the car simulation results

Figure 14 - Bending down low to carry out task on a low-to-ground vehiclesimulation results

Figure 15 - Comfort range simulation results

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RAPID PROTOTYPING


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RAPID PROTOTYPING TO 3D PRINTER CAPACITY15

In order to get a 3D printing outcome that was more dened for better aerodynamic efciency

and easier for the 3D printer to cope with, another surface model was made in SolidWorks and

then exported as a .stl le (this time reducing the model to its main features). The 3D printer

capacity required the model to be split into two equal halves and then joined together after

printing. All surfaces were knit to ensure there were no gaps in the model. The model was

scaled down to the ratio 1:29. The car body and the tyres were rapid prototyped separately

and then assembled after manufacture.

Figure 16 - Rapid prototyping process

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CONCLUSION

The project has provided an opportunity to understand and apply the various computer-aided

design methods utilised in design and manufacture.

Modelling a car in SolidWorks provided an in-depth understanding of parametric surface

modelling and the relationships that exist between the different surfaces that make up the outer

structures of complex shapes.

Modelling complex shapes via parametric surface modelling requires a methodical approach

and must be undertaken with the nal outcome in mind as mistakes made later in the modelling

process could affect earlier features.

Carrying out virtual human ergonomic evaluation in Jack 6.0 provides opportunities to evaluate

the ergonomic performance of a given design in a virtual environment prior to user testing and

manufacture saving time and costs in the design process.

The whole process highlighted the need to understand ergonomic and manufacturing

constraints early on in the design process. This is imperative for a well streamlined design

and manufacturing process and cost-effective design outcome.

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