MATX44

Bulk Data Entry

MATX44 – Material Property Extension for Cowper-Symonds Elastic-plastic Material for Geometric Nonlinear Analysis

Description

Defines additional material properties for Cowper-Symonds elastic-plastic material for geometric nonlinear analysis.

Format

Field	Contents
MID	Material ID of the associated MAT1. No default (Integer > 0)
A	Plasticity yield stress. (Real > 0)
B	Plasticity hardening parameter. (Real > 0)
N	Plasticity hardening exponent. Default = 1.0 (Real)
ICH	Hardening coefficient. 0.0: The hardening is a full isotropic model. 1.0: Hardening uses the kinematic Prager-Ziegler model. Between 0.0 and 1.0: Hardening is interpolated between the two models. Default = 0.0 (Real > 0)
SIGMAX	Maximum plastic stress σmax0 Default = 1030 (Real > 0)
C	Strain rate coefficient. Default = 0.0 (Real)
P	Strain rate exponent. Default = 1.0 (Real)
ICC	Strain rate dependency of σmax flag. See comment 5. Default = ON (ON or OFF)
FSMOOTH	Strain rate smoothing flag. Default = OFF (ON or OFF)
FCUT	Cutoff frequency for strain rate filtering. Default = 1030 (Real > 0)
EPSMAX	Failure plastic strain. Default = 1030 (Real > 0)
EPST1	Tensile rupture strain 1. Default = 1030 (Real > 0)
EPST2	Tensile rupture strain 2. Default = 2.0 * 1030 (Real > 0)

1.	The material identification number must be that of an existing MAT1 bulk data entry. Only one MATXi material extension can be associated with a particular MAT1.

2.	MATX44 is only applied in geometric nonlinear analysis subcases which are defined by ANALYSIS = EXPDYN. It is ignored for all other subcases.

3.	The Cowper-Symonds models an elastic-plastic material, only for solids and shells. The basic principle is the same as the standard Johnson-Cook model; the only difference between the two lies in the expression for strain rate effect on flow stress

matx44_1

with εp being plastic strain, and being the strain rate.

4.	Hardening is defined by ICH.

matx36_image1

5.	ICC controls the strain rate effect.

matx02

matx02_eq3

6.	No strain rate effects are considered in rod elements.

7.	Strain rate filtering is used to smooth strain rates. The input FCUT is available only for shell and solid elements.

8.	When the plastic strain reaches EPSMAX, the element is deleted.

9.	If the first principal strain ε1 reaches εt1 = EPST1, the stress σ is reduced by:

matx43_3

with εt2 = EPST2.

10.	If the first principal strain ε1 reaches εt2 = EPST2, the stress is reduced to 0 (but the element is not deleted).

11.	If the first principal strain ε1 reaches εf = EPSF, the element is deleted.

12.	This card is represented as an extension to a MAT1 material in HyperMesh.