Hydrostatic stress

About: Hydrostatic stress is a research topic. Over the lifetime, 1568 publications have been published within this topic receiving 37773 citations.

Thermodynamic Theory of Single-Crystal Lead Titanate with Consideration of Elastic Boundary Conditions

Abstract: A phenomenological free-energy function including the effects of elastic boundary conditions was presented and used to investigate the single-domain, single-crystal properties of the ferroelectric perovskite, PbTiO3. In particular, the effects of tensile and compressive hydrostatic stress on the spontaneous polarization, Curie point, dielectric susceptibility, and piezoelectric property coefficients were examined. The calculated shift of the Curie point with hydrostatic stress, along with the entropy and enthalpy of the ferroelectric-paraelectric phase transition, was found to be in good agreement with experimental measurements. The isothermal variation of the relative dielectric susceptibility and piezoelectric coefficients with hydrostatic stress exhibited the expected behavior near the ferroelectric-paraelectric phase transition.

The effect of heat treatment on plane strain fracture of glassy polymers

Abstract: The effect of annealing on the plane strain fracture of round-notched polycarbonate and poly(methyl methacrylate) bars has been investigated. Morphological observations of thin sections and fracture surfaces revealed that the fracture initiated from internal crazes which were nucleated at the tip of a local plastic zone. The critical hydrostatic stresses for internal craze nucleation were nearly constant regardless of annealing, while the shear yield stress increased with increasing annealing time. The reduction in toughness by annealing can be ascribed to the decrease of the maximum extent of the plastic zone which gives the critical hydrostatic stress for craze nucleation.

In situ measurement of reinforcement stress in an aluminum-alumina metal matrix composite under compressive loading

Abstract: The phenomena of stress partitioning between the matrix and the reinforcements in a loaded metal matrix composite dominate the mechanical behavior of these materials. Numerical models for estimating the stress in the matrix and the reinforcement under load are well developed. However, direct experimental measurements (e.g. measurement of reinforcement stress) are more difficult and have not been widely undertaken at present. The objective of the present work was to measure in situ the hydrostatic stress in the ceramic reinforcements in a continuously reinforced metal matrix composite loaded under transverse compression (i.e. loading perpendicular to the fiber axis). A single crystal sapphire reinforced AA6061 matrix model composite (reinforcement volume fraction ∼10%) was used for the measurements, which were undertaken at applied strains of 5, 10 and 20%. The stress measurements utilized the piezo-spectroscopic property of the Cr 3+ ions which were present as impurities in the sapphire reinforcements. The compressive deformation of the composite was simulated using an isotropic, plane strain finite element model. The reinforcement hydrostatic stress estimates from the isotropic FEM model were suitably modified to incorporate the effects of anisotropy in properties of the sapphire single crystal. The mean values of the experimental measurements of reinforcement hydrostatic stress matched well with the numerical estimates.