VM224

VM224
Implicit Creep under Biaxial Load

Overview

Reference:

A. A. Becker, T. H. Hyde, Fundamental Test of Creep Behavior, 2nd Edition, NAFEMS, Ref.: R0027, Test 10a.

Analysis Type(s):

2D Plane Stress - Biaxial (Negative) Load

Element Type(s):

2D 4-Node Structural Solid Elements (PLANE182)

2D 8-Node Structural Solid Elements (PLANE183)

Input Listing:

vm224.dat

Test Case

A specimen under plane stress conditions is constrained on the left and bottom edges. It is biaxially loaded with tensile stress σ₁ on the right edge and compressive stress σ₂ on the top edge. Determine the creep strain after 1000 hours.

Figure 372: Implicit Creep Under Biaxial Load Problem Sketch

Material Properties

Geometric Properties

E = 200 x 10³ N/mm²

ν = 0.3

Creep Law

ε = A σⁿt^m

A = 3.125 x 10^-14 per hour

n = 5

m = 0.5

L = 100 mm

σ₁ = 200 N/mm²

σ₂ = - 200 N/mm²

Total creep time 1000 hours

Analysis Assumptions and Modeling Notes

For a 2D plane stress condition a biaxial load is applied as follows:

In this case the effective stress is given by the following equation, where α = -1

And the creep strains may be obtained as follows:

This gives the following reference solution:

Results Comparison

@ Time = 1000	Target	Mechanical APDL	Ratio
PLANE182 2D 4-Node Structural Solid
ecrxx	4.2691	4.2677	1.000
ecryy	-4.2691	-4.2677	1.000
PLANE183 2D 8-Node Structural Solid
ecrxx	4.2691	4.2677	1.000
ecryy	-4.2691	-4.2677	1.000

Figure 373: Creep Strain