Torsional stiffness of rectangular plate
Torsional stiffness of rectangular plate
(OP)
Hi all,
a response to the following general problem would be appreciated very much.
I have a rectangular plate made of n plies , its section is rectangular . Long edges aligned with x axis, short ones with y axis
It is constrained (built in) at its left edge, free on other edges; pure torque is applied on right short edge and acting around x axis .
My question: if torsional stiffness around x axis must be maximized, is it worth to maximize the membranal shear modulus only, or also the bending shear modulus should be investigated ?
a response to the following general problem would be appreciated very much.
I have a rectangular plate made of n plies , its section is rectangular . Long edges aligned with x axis, short ones with y axis
It is constrained (built in) at its left edge, free on other edges; pure torque is applied on right short edge and acting around x axis .
My question: if torsional stiffness around x axis must be maximized, is it worth to maximize the membranal shear modulus only, or also the bending shear modulus should be investigated ?





RE: Torsional stiffness of rectangular plate
Provided the laminate is symmetric, the stacking sequence will not affect the in-plane shear stiffness. However, the d66 term can vary significantly with various layups, and hence so would the torsional stiffness.
Pushing the higher in-plane shear stiffness layers towards the outside will increase the torsional stiffness. I also verified this eLaminate.
Brian
www.espcomposites.com
RE: Torsional stiffness of rectangular plate
thank you for your quick reply.
I did the same, and I reached the same conclusion ( laminate is symmetric and balanced). After some hand calculation and some runs on ABD matrix, I run a simple case on fem; cross-checking all procedures I saw that, effectively, d66 terms influence G modulus but also a66 term does it.
Nevertheless I wondered if it was correct to discard a66 term and consider d66 terms only; this doubt came from ther fact that , imaging the plate under pure torsion, "I saw" only membranal loads acting, while it was more difficult to understand how bending shear applied.
About your last sentence: as expected I reached the max. torsional stiffness placing outside the higher in-plane shear stiffness layers.
Cpinz
RE: Torsional stiffness of rectangular plate
Clearly, the max torsional stiffness occurs by having the highest A66 layers located towards the outermost surface.
Brian
www.espcomposites.com
RE: Torsional stiffness of rectangular plate
> draw a FBD; you do not have a case of pure torsion, therefore the entire ABD matrix will effect the displacement. How did you determine "G modulus" from the FEM?
SW
RE: Torsional stiffness of rectangular plate
- I didn't use the fem to determine G modulus;I used it only to check the angle of torsion; I compared this value with that obtained from two hand calculation where I used the G moduli obtained from a66 (G_membranal)first and b66 (G_bending) then.
-"you do not have a case of pure torsion, therefore the entire ABD matrix will effect the displacement"
Could you explain that further please ?