Photoelastic Investigation of Bimaterial Interfacial Stresses Induced by Thermal Loading

Abstract

In this paper, the photoelastic technique and finite element method were employed to investigate the interfacial stresses induced by thermal loading in bimaterial structures. By observing the photoelastic fringe patterns, in comparison with those theories developed by other investigators, severe temperature and stress gradients were found across the specimens’ heights. The maximum fringe order near the interface was six times that near the top surface of the photoelastic material when the temperature was raised to 65 °C. Furthermore, for the bimaterial structures, differences were found between measured stress fields as a result of increasing and decreasing temperature differences.

Analytical elasto-creep model of interfacial thermal stresses and strains in trilayer assemblies

“…Although this simplification results in violation of the zero shear stress boundary conditions, the predictions are believed to be accurate except in the vanishingly small distance from x = ±l (Ghorbani and Spelt, 2005). This is confirmed by the experimental evidence of Mirman (1991), Wang and Lin (2003), and Wen and Basaran (2004), none of whom could capture the zero shear stress or very steep shear stress gradient close to the free ends of interfaces. Therefore, the shear stress maxima must indeed be extremely close to the free edges, particularly with creep deformation.…”

Transient thermal stress intensity factors of bimaterial interface cracks using refined three-fringe photoelasticity

“…where N p is the fringe order obtained for the neighbourhood pixel to the point under consideration, and N is the fringe order at the current checking point of the calibration table. The additional term assures fringe order continuity, and the multiplication factor K is used to have control on the performance of equation (2). The magnitude of K has to be selected iteratively, and a value of 100 is found to be suitable for this problem.…”

“…Bimaterial strips are the simplified models used in the literature for experimental and theoretical analysis of electronic packages and bimetal thermostats [1]. Photoelasticity [1][2][3] and moiré interferometry [4,5] have been used to analyse the steady state thermal stresses in bimaterial strips. During thermal cycling of bimaterial specimens, the induced thermal stresses are predominant near the edges of the interface, which may eventually cause fatigue failure by initiating interface edge cracks [6].…”