Paper number 1240

DESCRIPTION OF FATIGUE FAILURE PROCESS FOR LAMINATED COMPOSITES STRUCTURES

A. Muc

Institute of Mechanics and Machine Design, Cracow University of Technology,
ul. Warszawska 24, 31-155 Krakòw, Poland

Summary

The aim of the work is to propose the numerical method of fatigue stiffness degradation and life estimations for composite structures subjected to arbitrary loading and boundary conditions. The analysis is based on three assumptions: (i) the definitions of the damage initiations, (ii) the approximations of the stiffness degradation with the number of cycles and (iii) the form of fatigue life correlations. The numerical investigations are conducted with the use of physical nonlinearities describing the stress-strain relations for each individual ply in the laminate independently (different behaviour of loading and unloading phases) and of geometrical nonlinearities. A nonlinear, finite element technique is used for the stress analysis. Based on the state of stress, different failure modes are detected by a set of fatigue failure criteria. To remove the requirement of the large experimental data base for the development of the fatigue process a simple technique is established. Finally, the numerical results are compared with the experimental ones - the example of plate with a hole, subjected to fatigue loading. The results demonstrate a very good agreement between experiments and numerical studies.

Keywords

fatigue analysis, stiffness degradation, numerical modelling, plates, experimental studies, progressive failure.