## General Mechanical

#### Nonlinear problem(geometry nonlinear)

• Suvan
Subscriber

As far as I know,for  the FEM,there are exist nolinear problem,it included geometry nonlinear?boundary nonlinear and contact nonlinear,now there is some puzzle about geometry nonlinear,sometimes we also said large displacement?large strain?revolve are belong to geometry nonlinear,however what kind of deformation can be thought large displacement,it is 0.2%?are there some sure principle to judge the geometry nonlinear?

if you have some ideals,please tell me ,thanks

regards

Ansys Employee

Moving this to Structural Mechanics category so that you will get better response.

Regards,

Keyur

• Sandeep Medikonda
Ansys Employee

Hi Suvan,

As you mentioned, structural nonlinearities are typically caused by either material, geometric and contact nonlinearities i.e., the strains exceeding the material’s elastic limit, deformations changing the structural stiffness, and/or the contact status changing. All of these nonlinearities add to the complexity of the solution and there is no one rule but just guidelines as they are case dependent, i.e. for example, the use of a different type of material (say hyper-elastic) can affect the structural stiffness of your model. Geometric non-linearities can be tricky, please check out this article by our channel partner that should explain this quite well and provides some general guidelines as well.

Regards,

Sandeep

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• Ashish Khemka
Ansys Employee

On nonlinearities:  Presence of these may indicate the same: Plasticity, hyperelasticity, large deflection, contact of any type other than bonded other nonlinear element types (combin37, combin39, prets179, etc).

Regards,

Ashish Khemka