A robust design strategy for thin-walled composite structures under compression load based on the assessment of the structural energy

It is presented in this paper a robust design criterion to evaluate thin-walled composite structures under compressive loading based on the assessment of the structural energy until the ultimate loading. This robust design criterion accounts for the reliability of the structure in terms of the ultimate load, and at the same time its reliability in terms of the structural energy. In order to perform the structural energy assessment, it is calculated the area under the load-shortening curve between several characteristics points of the curve such as local buckling, global buckling, onset of degradation, maximum and collapse load. In this context, a finite element solver with geometrical nonlinearity is used, in which the ply properties are selectively degraded by ply progressive failure technique. The methodology is presented and demonstrated with a case study of an unstiffened composite plate under compressive loading in two steps: the first step comprises of a deterministic design of experiments, in which candidate designs are selected based on a load requirement, and the second step comprises of a nondeterministic evaluation of those candidate designs. Concluding, it is demonstrated that a design criterion that takes into account both simultaneously the reliability in terms of the ultimate load and the energy reserves could be advantageous