Manjinder Singh Sidhu

Assistant Manager,R&D

Weight reduction of bus tubular structure by using

Optistruct/PBS e-Compute

SML ISUZU

Date : ATCx Date 29th July 2016

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Background of Organisation

SML ISUZU LIMITED (formerly SWARAJ MAZDA LIMITED) is engaged in

commercial vehicle & spares. The company products are as under:-

1. TRUCKS

2. BUSES

3. SPECIAL VEHICLES LIKE SLEEPER BUSES, TIPPERS etc.

4. OVERSEAS VEHICLES

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Weight reduction of bus tubular structure

• Objective of case study

The main objective of this simulation is to reduce the weight of Bus

Structure while maintaining Stress constraints. This will be done by

using Optistruct/ PBS e-compute.

• Statement of problem

To simulate the structure by using the thickness/shape optimization

technique with normal static gravitational loading condition(3g).

1. Simulate the base line structure by static 3g loading condition.

2. Then ,simulate low weight structure ,if the stresses in first step

are less than yield stress of structural material.

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SOFTWARE USED

• Weight/Cost reduction is done by using Hyperworks v14/PBS 14.

• Preprocessing is done by using Hyper Mesh.

• Analysis is done by using Optistruct/PBS e-Compute .

• Post Processing is done by using Hyper View.

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Process Methodology (Stage 1)

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Process Methodology (Stage 2)

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BASE LINE DESIGN

• STAGE 1:-ANALYSIS OF BASE LINE DESIGN USING OPTISTRUCT.

• MAXIMUM STRESSES BY USING STATIC 3G LOADING CONDITION

=162 MPa , WHICH ARE VERY MUCH LESSER THAN YIELD 240 MPa

PBS

PBS E-Compute

THERE WILL BE THE SCOPE OF OPTIMIZATION IN STRUCTURE

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OPTIMISED DESIGN

• CONVERT THE DIAGONAL MEMBER OF FLOOR STRUCTURE FROM

30X40X2 TO 20X40X2.

• CONVERT THE FLOOR LONGITUDIONAL MEMBER FROM 30X30X2 TO

30X20X1.5

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OPTIMIZED DESIGN

• RUN THE OPTIMIZED STRUCTURE

• STRESSES OBSERVED =205 Mpa ,LESSER THAN YIELD LIMIT (240 Mpa)

OPTIMIZED DESIGN IS OK

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Benefits summary

• After studying the results and the stress pattern on the bus after

simulation, benefits of Optimization of structure using Hyperworks

/Optistruct are as under:-

1. Weight Saving:-9 kg

2. Cost saving:-Rs 513/bus(250 buses manufactured/month)

3. Time saving:-Weight reduction in quick time with PBS e-compute.

4. Design change suggestion to design team as per analysis report.

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Challenges faced and solutions presented

• Selection of appropriate element type, size and control cards for

element properties for getting accurate results.

• Selection/Availability of material with different thickness/shape.

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Conclusion

• Optimization by using “Optistruct” proved to be an effective method to

reduce the weight of bus super structure. The software gave the

freedom to study and analyze the output in different forms and sections

which is difficult to workout practically. Hyperworks/Optistruct is an

effective tool to validate the result efficiently.

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Acknowledgements/Credits

I would like to thank the followings for kind support:-

• SML ISUZU Ltd.

Mr. SANJIV KUMAR SHARMA, Sr. MANAGER, R&D.

• ALTAIR SUPPORT TEAM