Indentation creep tests and finite element simulations were performed on a model material to show that the constitutive equation for conventional uniaxial creep can be derived using the instrumented indentation testing technique. When the indentation pressure and the indentation creep rate are maintained at constant values of ps and _ 3⁄4inðsÞ, respectively, the contours of the equivalent stres...

Indentation creep tests were performed on an Al-5.3mol% Mg solid-solution alloy to examine whether mechanical properties can be extracted accurately from a testpiece, as small as a rice grain. A conical diamond indenter was pressed into a test surface with a constant load F at temperatures ranging from 0.60 to 0.65 Tm (Tm: the absolute liquidus temperature). When the representative flow stress ...

Polypropylene is one of the most common, fastest growing and versatile thermoplastics currently used to produce tanks and chemical piping systems. Even at room temperature creep is considerable for polypropylene products. The creep behavior of strains, stresses, and displacement rates is investigated in a thick-walled cylinder made of polypropylene reinforced by functionally graded (FG) multi-w...

A microstructural model of steady-state creep that couples grain-boundary transport, micromechanics, and grain sliding is employed to investigate the grain-boundary diffusional creep response of an idealized microstructure with variable boundary diffusivities. Both numerical and analytical methods were used to determine the stress state and, in some cases, the strain rate associated with an app...

-The densification of a porous intermetallic alloy (Ti-14wt%AI-21wt%Nb) during the final stage of densification has been investigated under various states of stress and compared with the predictions of current models for densification by power-law creep. The experiments generally confirm the model predictions that the densification rate is a sensitive function of the stress state. Experimentall...

There is an increasing need to assess the service life of components containing defect which operate at high temperature. This paper describes the current fracture mechanics concepts that are employed to predict cracking of engineering materials at high temperatures under static and cyclic loading. The relationship between these concepts and those of high temperature life assessment methods is ...

A micromechanical finite element (FE) framework was developed to predict the viscoelastic properties (complex modulus and creep stiffness) of the asphalt mixtures. The two-dimensional (2D) microstructure of an asphalt mixture was obtained from the scanned image. In the mixture microstructure, irregular aggregates and sand mastic were divided into different subdomains. The FE mesh was generated ...

Reactive infiltration processing was used to fabricate bulk NiAl and fiber-reinforced NiAl composites. Homogenous, pore-free materials were obtained by chemical reaction between nickel and aluminum after complete infiltration with liquid aluminum of preforms of nickel wires (containing tungsten wires for the composites) with low surface-to-volume ratio, high permeability, and regular infiltrati...

Viscoelastic material behavior is often characterized using one of the three measurements: creep, stress-relaxation or dynamic sinusoidal tests. A two-stage numerical method was developed to allow representation of data from creep and stress-relaxation tests on the Fourier axis in the Laplace domain. The method assumes linear behavior and is theoretically applicable to any transient test which ...