Finite Element Analysis to re-engineer a product

JNDC were contracted to check the strength of a seat pad.
A linear static analysis was performed. Two load cases were considered as indicated in BS EN 12520:2010:
A vertical 1600N load 150mm from the centre and 100mm load from the front edge of the pad. Along with a vertical 1600N load representing a pad used in BS EN 12529:2010.

Results Case 1

Von Mises results shows a max stress of approx 68 MPa as shown in the figure below.  

When investigated further by extracting the max principal stress this was found to be 35MPa as shown below to the right. 

This is below the material limit and therefore acceptable.

Results Case 2

Von Mises results shows a max stress of approx 41 MPa as shown in the top figure.  

When investigating this further by extracting the max principal stress this was found to be 28MPa as shown in the bottom left figure. 

This is below the material limit and therefore acceptable.

Conclusions

- Seat pads to be re-engineered based on the rapid prototyped material.

- To redistribute stress concentrations, “fingers” of seat pad structure to be redesigned.  

- Stiffness of seat pad has increased in comparison with previous prototype manufactured.