Design analysis of sandwiched structures experiencing differential thermal expansion and differential free-edge stretching

Abstract

Compared to the theory of elasticity solutions the strength of material solutions offer closed form solutions that is favoured by practising engineers for performing design analysis. However, the existing strength of material solutions for a sandwich structure experiencing differential thermal strains have principally ignored the free edge conditions; and for the very limited publications that have enforced the free edge conditions, the solutions have been inaccurate. Understandably, design analysis using such solutions is unreliable. This manuscript describe a solution technique that enforces the nil shear stress condition at the free edge using a high power exponential function resulting in a simple yet accurate closed form solutions for the interfacial shear stress. The interfacial peeling stress is made up of two components: the mean and the amplitude of variations of the transverse normal stress in the bonding layer; the latter is the dominant component whose magnitude is linearly proportional to the gradient of the interfacial shear stress. Following validation by finite element analysis, design analysis for debonding, fracturing, and out-of-plane deformation are performed using the concise closed form solutions.