## General Mechanical

#### Calculating shear modulus

• CAEsher
Subscriber

Hello I try to calculate mechanical moduluses for cellular structures made of aluminium kinematic-isotropic alloy. And I have an issue, shear modulus is bigger then Young`s it can be true if only Poisson`s ratio is less then zero. Can you suggest me a methodology of correct calculation of shear modulus? And also I read about material designer can it be used for calculating mechanical moduluses of cellular materials?

• Aniket
Ansys Employee

And also I read about material designer can it be used for calculating mechanical moduluses of cellular materials?

Yes, if you can model it as a single cell which is repeating again and again, yes.

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v195/acp_md/acp_md_tutorials.html

Also, how are you calculating Shear Modulus and Young's modulus?

-Aniket

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• CAEsher
Subscriber

Well for Young`s modulus I simply do uniaxial loading with fixing bottom of my cell, load I took from nonlinear buckle analysis. For shear modulus I fix down half of cell and apply the same load to upper half, frankly I am not shure that it is right loading scenario.

• Aniket
Ansys Employee

The experimental method for Young's modulus looks ok and is what is commonly used, but I am not sure about the method for shear modulus. Also it does not come under software support scope, unfortunately.

And auxetic materials (https://en.wikipedia.org/wiki/Auxetics) do display negative Poisson's ratio, it is not a common occurrence in the engineering materials.

I would recommend checking your experimental method for getting shear stress.

• CAEsher
Subscriber

Therefore, I wrote here

• peteroznewman
Subscriber

The definition of shear modulus is given on Wikipedia.

Have you taken a block of material, fixed the bottom, applied a lateral force to the top and measured the lateral displacement of the top? If you do that, you would calculate G from F, l, A and delta x using the formula above.

• CAEsher
Subscriber

Thank you dear Aniket and peteroznewman I kinda figure out this. Using Ansys approach I need to calculate 2 thing for this modulus (right click on "solution">>insert) "Shear" and "Directional deformation" in the co-directional to  load application axes and then just devide it on high of the "my block", and again to devide, am I right?