We derive an effective medium theory that predicts the bulk and shear moduli of composite materials consisting of a matrix material with soft or hard ellipsoidal inclusions. The theory predicts that diskshaped inclusions are most effective for softening or hardening a composite material. The theory is applied to the design of materials with highly absorptive acoustical properties. DTIC TAB0 UJn...

The formation of helium cavities in coarse-grained materials produces hardening proportional to the number density and size due interaction dislocations with intragranular defects. In nanostructured metals containing a high interfacial sinks, preferential cavity grain boundaries instead softening that is often attributed enhanced plasticity. Employing two grades ultrafine-grained tungsten, we e...

A cusp catastrophe model is presented and the necessary and sufficient conditions leading to landslides are discussed. The sliding surface is assumed to be planar and is a combination of two media: medium 1 is elastic-brittle or strain-hardening and medium 2 is strain-softening. The shear stress-strain constitutive model for the strain-softening medium is described by the Weibull’s distribution...

Cam-Clay nonassociative plasticity exhibits both hardening and softening behaviour, depending on the loading. For many initial data the classical formulation of the quasistatic evolution problem has no smooth solution. We propose here a notion of generalized solution, based on a viscoplastic approximation. To study the limit of the viscoplastic evolutions we rescale time, in such a way that the...

The micro-electro-mechanical system (MEMS) resonator developed based on surface processing technology usually changes the section shape either due to excessive etching or insufficient etching. In this paper, a section parameter is proposed to describe the microbeam changes in the upper and lower sections. The effect of section change on the mechanical properties is studied analytically and veri...

in this research, softening and ratcheting behaviors of ck20 alloy steel cylindrical shells were studied under displacement-control and force-control cyclic axial loading and the behavior of hysteresis curves of specimens was also investigated. experimental tests were performed by a servo-hydraulic instron 8802 machine. the mechanical properties of specimens were determined according to astm e8...