Stress Distribution in Multiphase Systems: I, Composites with Planar Interfaces

Abstract

Calculated stress distributions within materials sealed together across planar interfaces and having subsequently undergone differential dimensional change were compared with values measured in glass composite pairs sealed together at high temperature and slowly cooled. Where interdiffusion had occurred, dramatic departures from simple theory were observed both in the magnitude and in the sign of the corresponding stresses.

Mechanical Properties of Non-Metallic Thin Films

“…Such distributions will be discussed later under origins of the intrinsic stress. However, we shall consider here the case where we initially have a large stress 0]1 = a that lies in the plane 22 of the film, is isotropic, and neally uniform throughout the thickness, and is uniform over most of the area of the film. If we look at the cross section of the film-substrate composite, we see that the film appears to be a rectangular plate attached along its long edge to what we shall assume to be a semi-infinite rigid substrate.…”

Piezo-spectroscopic characterization of alumina-aluminium titanate laminates

“…If these data are used to evaluate the residual stress state in the laminate, the expected sign of the residual stresses would be the opposite of that experimentally determined here, as the layers of pure Al 2 O 3 , with larger thermal expansion coefficient, would contract more on cooling than the composite layers and thus, the former layers would be in tension in the laminate. 19,20 This apparent contradiction is clarified looking at the cooling part of the dilatometry curves in Fig. 4.…”

Thermal residual stress analysis of epoxy bi-material laminates and bonded joints

“…According to this work [19], the thermal strain at a point separated by a distance x from the interface in layer i is given by:…”

“…The curvature in bi-material samples is commonly used as a simple measure of residual stress [18][19][20][21], however, the experimentally measured deflection has to be analysed in order to calculate the stresses and strains [22,23]. Yu et al [24] used steel-epoxy adhesive bi-material strip experiments to investigate residual due to shrinkage of the adhesive on curing (curing stresses), differential thermal contraction of adhesive and adherend on cooling from the curing temperature (thermal stresses) and expansion of the adhesive on absorption of atmospheric moisture (hygroscopic stresses).…”

“…The analytical methods used are those of Oel and Frechette [19] and Timoshenko [25]. Three different geometric approximations were investigated for the 2D analyses, namely, plane strain (PE), plane stress (PS) and generalised plane strain (GPE).…”