*Compos.Sci.Technol.* **66**(13), 2054-2062, 2006

### ACCOUNTING FOR RESIDUAL STRESSES IN FEM ANALYSES OF LAMINATED
STRUCTURES USING THE PUCK CRITERION FOR THREE-AXIAL STRESS
STATES

C. Schuecker, D.H. Pahr, H.E. Pettermann

Austrian Aeronautics Research (AAR),

Institute of Lightweight Design and Structural
Biomechanics,

TU Wien,
Vienna, Austria

**Abstract** -
A computer program for handling non-proportional loading in First Ply Failure
analyses of layered fiber reinforced composites is developed.
To this end, stresses are split up into a constant and a variable part, such
that for the latter the assumption of proportional increase of stress
components is valid.
The risk of failure is assessed in terms of a stress based failure envelope and
four risk parameters, which are defined as linear combinations of the constant
and variable stress contributions.
Amongst others, the Puck failure criteria for plane and three-axial stress
states are implemented for stress assessment. By hooking the program up onto a
Finite Element package as a post-processing tool, it can be utilized in
structural failure analysis.
The approach is used to study the effect of residual ply stresses on the
failure behavior of a typical laminated structure under complex loading.

(hjb,060726)