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In this study, singularity fields at the interface corners of piezoelectric-brass unimorphs are investigated. Two models differing in side surface geometry (step and flat surfaces) are analyzed to study the singularity effect on mechanical (stress–strain) and electrical (electric potential and intensity) behavior. A mixed-mode mechanical boundary condition is applied for analyzing the realistic application of unimorphs, with normal force, shear force, and bending moment as internal forces. The conservative integral together with a three-dimensional finite element analysis is used to determine the intensity of singularity. There are three singularity terms at each vertex and singular line. All singularity terms are investigated in detail. Intensities of the singularities at the vertex and several points located on side surfaces (singular lines) are examined. Results show that the intensities of singularities for mixed-mode conditions differ from that of tensile load conditions. For mixed-mode conditions, the intensity of singularity must be calculated for all singularity terms. In addition, the stress singularity characteristics at the vertex may be described as a function of the singularities along the singular lines. These findings clarify the understanding of singularity at interface corners of piezoelectric-brass unimorphs and may be used as references for developing relevant piezoelectric devices.

In the present paper, surface Green functions in an anisotropic elastic half-domain subjected to a concentrated force and a line force are derived using Stroh's formalism considering surface stress and surface elasticity. Formulation of the boundary condition based on Stroh's formalism is presented and is used to derive the surface Green functions. The displacement field far from the surface is affected only slightly by the surface stress and elasticity. However, the stress field is influenced to a somewhat greater degree by the surface stress and elasticity. The influence of the mechanical properties of the surface on the distributions of displacement and stress near the surface is investigated for various values of surface elastic modulus and surface stress. The surface stress and surface elasticity affect the displacements and stresses, respectively, in different manners. Displacement fields in molecular dynamics are compared with those in the Green function, and it is shown that the results are in fair agreement. [DOI: 10.1115/1.2967893]

In the present paper, a deformation induced in a new bonding technology of chip-scale package (CSP) using resin encapsulation sheets is examined numerically and experimentally. Deflections after cooling from a bonding temperature are measured experimentally for various kinds of substrate and the thickness of an integrated circuit using a laser beam. In particular, a simple theory on the basis of a multilayered plate theory considering a viscoelastic property in the substrate is presented, and the thermo-viscoelastic analysis for the deflection of CSP is performed. Furthermore, the thermo-elastoplastic finite element method analysis is performed under the same temperature history. We could show that the simple formula for multilayered plates based on the thermo-viscoelastic theory can estimate fairly well the deflection of CSP in experiment. [DOI: 10.1115/1.1602705]

Arbitrary normal and shearing processes based on elasticity theory are applied to the three-phase bonded structure problem, which are defined by two interfaces and two free surfaces. Bonded wedge geometries displayed a direct relationship between material pairing and stress singularity order. Material bonding order also conditioned the singularity order for the given bonded structure.