nastran manual


Material

MENU SEQUENCE:

 


Defines new materials. It is possible to define an isotropic, temperature-independent material with the following properties:

         -Stiffness Page: In this page it is possible to define mechanical         properties of a material.

                   - E, Young Modulus

                   - G, Shear Modulus

                   - nu, Poisson coefficient.

- Limit Stress: Allowable stresses in tension, compression,       and shear. Required if composite element failure index is desired.

         -Thermal Page: Defines thermal material properties for temperature-independent, isotropic materials.

         -Others: Defines different properties not defined in previous    pages.

A mouse-over help is available for all labels of all entries.

 

Stress-dependent material properties

Defines stress-dependent material properties for nonlinear analysis. Click the Nonlinear… button to open the properties window.

Nonlinear elastic materials are defined by stress-strain curve. This curve can be defined by clicking at the Function… button. Stress-strain curve should be defined in the first and third quadrants to accommodate different uniaxial tensions and compression properties. All other properties do not apply to this type of materials.

It is posible to define elasto-plastic materials in two diferent ways:

         -Use the linear constants coupled with the plasticity modulus H.         This is the work hardening slope, and it is related to the tangential

         modulus, ET(the slope of stress vs. plastic strain) by the following:

         -Define a curve in stress-strain plane. The curve must be defined       in the first quadrant. The first point must be at origin

         (X1 = 0, Y1   = 0) and the second point (X2, Y2) must be at the       initial yield point (Y1 or 2c). The slope of the line joining the origin   to the yield stress must be equal to the value of E.

 

Figure 7 – Composition Material Combo Box