Reliability Analysis for Inserts in Sandwich Composites

Inserts are used to transfer localized loads to structures made of sandwich composites. Stress concentrations near inserts are known to cause failures in sandwich panels. Experimental insert pull-out tests show that the load to failure can vary by 20% between batches of sandwich panels. Clearly, uncertainties in the mechanical properties of core and adhesive potting materials have to be accounted for in the optimal design of inserts in sandwich composites. In this paper, we use an one-dimensional computational model of an insert in a homogenized honeycomb sandwich panel to explore the utility of reliability methods in design. We show that the first-order reliability method (FORM) produces accurate estimates of loads that lead to low failure probabilities. We also observe that FORM is sensitive to the failure criteria and may not converge if the failure surface is not smooth and convex.

嵌件用于将局部载荷传递到由夹芯复合材料制成的结构上。已知嵌件附近的应力集中会导致夹芯板失效。嵌件拉拔试验表明，不同批次夹芯板的破坏载荷可能会有20%的差异。显然，在夹芯复合材料嵌件的优化设计中，必须考虑芯材和灌封胶材料力学性能的不确定性。在本文中，我们使用均匀化蜂窝夹芯板中嵌件的一维计算模型来探索可靠性方法在设计中的应用。我们表明，一阶可靠性方法（FORM）能对导致低失效概率的载荷进行准确估算。我们还观察到，FORM对失效准则敏感，如果失效面不光滑且非凸面，可能不收敛。