# research

## UMAT for isotropic hardening

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Hello,

I'm new here and I'm not sure if this a right place to ask a question or not.

I'm trying to practice writing UMAT code and I just finished the (Coding for isotropic Mises plasticity) from the the attached document. I'm trying to check validity of this code with simple model: what kind of this simple model? how can I do that?

Regards,

Qusay

## Incrementally linear constitutive model. Nonlinear solution procedure

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Hello everyone,

My doubt is related with the obtenion of the true stress when using incrementally linear constitutive models (hypoelastic models). These models, alternatively to total stress strain models, related increment of strain and increment of stress. The predicted stress is obtained by adding to the previous stress the stress increment obtained by using the tangent matrix. By using total stress-strain models it is clear that the true stress is obtained by substituting the current strain into the constitutive equation. How do we do this for hypoelastic models?

## PolyFEM: Obtaining polygonal mesh from structured T3 Mesh

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Hello,

I am developing a solver implemeting Polygonal Finite Element Method (PolyFEM). Currently my code can handle n-gons with nmax=6 (hexgon).

I am trying to test the code with comlex geometries for which I need to obtain polygonal meshes. PolyMesher developed by Dr Paulino's group can obtain polygonal mesh using voronoi doagrams but the code doesn't provide control over the maximum number of edges of a polygon in mesh and ends up creating octagons etc. Hence I am thinking of using a code which can convert a structured  T3 mesh into hexagonal mesh.

## Why Natural Frequency of Functionally Graded Material Plate decreases with increase in temperature

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Dear Colleges i want to know why natural frequency of FGM plate reduces with increase of temperature