What is the typical bending stiffness and torsional stiffness of a chassis of hatchback car? 1

[SteveFinnan]

I know there are lots of factors come into play when determine the bending stiffness. I am more concerned about the material and the design.

I'm using high carbon steel as the material. The density is 7490kg/m^3, Young Modulus=198000 MPa, and Poission's ratio=0.29.

I modeled the frames of the chassis using hollow rectangular tube. (One PHD student told me the hollow tube will give a better answer).

the value of bending stiffness is 31931.87866 N/mm
the value of torsional stiffness is 27646.14029 N.m/deg

please spare some times to answer

thanks

 

[GregLocock]

28 kNm/deg is certainly possible, it is a little higher than I'd expect. But numbers between 4 and 40 have been measured. see

http://www.eng-tips.com/viewthread.cfm?qid=354865

The bending stiffness is usually numerically smaller than the torsional stiffness in those units.

This of course assume sthat you test technique is correct, it is easy to get big errors in this test both in real life and FEA.

Incidentally modelling a modern car structure as a series of rectangular beams rather misses the point. The hard bit is the joint design.

Cheers

Greg Locock


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[ahsebihk]

i am interested in knowing
what should be MINIMUM MANDATORY VALUES for BENDING STIFFNESS AND TORSIONAL RIGIDITY for MONOCOQUE CARS ?
are there any particular rules , regulation or standards specifically defined for these parameters ??

 

[GregLocock]

There are are no rules in any legislature that I am aware of, for production cars.

Cheers

Greg Locock


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