Application of the shakedown analysis in the elastic: plastic assessment of cracked plates

摘要

In this work, a new method in the elastic-plastic calculation of cracked plates, based on shakedown analysis, is presented. This method presents an interesting alternative to classical methods in the structure design, especially when the loading is variable. It permits, via a simple elastic calculation and a mathematical optimisation, the determination of a load domain situated between the elastic and the limit load domains, within which the loading can evolve arbitrarily, while insuring the reliability of the cracked structure versus the plastic ruin and the unstable crack propagation. Also, by taking into account the microstructure of the material and the residual stresses, this method allows the determination of a stress intensity factor corresponding to the shakedown state. This factor is comparable to the fatigue threshold and can be used in the crack admissibility criteria.