Theoretical analysis and finite element (FE) simulation have been carried out for a constant specific load rate (CSLR) indentation creep test. Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover, the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate u...

Electronic power modules devices are paramount components in the aeronautical, automotive and military applications. The solder layers are the most critical parts of the module and are usually subjected in their whole life to complex loading conditions. To improve the design task, realistic thermoelastoviscoplastic and lifetime prediction models which can describe efficiently the deformation-da...

Nickel-rich NiAl foams, consisting of open cells with hollow struts and exhibiting two relative densities (5.0 and 6.6 pct) and average cell sizes (1.27 and 0.85 mm), were creep tested between 800 °C and 1100 °C under compressive stresses between 0.10 and 1.50 MPa. For stresses lower than 0.50 MPa, the foams exhibit secondary creep with power-law behavior characterized by creep exponents and ac...

Experimental data (Thornton et al., 1997) show that relaxation proceeds more rapidly (a greater slope on a log-log scale) than creep in ligament, a fact not explained by linear viscoelasticity. An interrelation between creep and relaxation is therefore developed for ligaments based on a single-integral nonlinear superposition model. This interrelation differs from the convolution relation obtai...

This paper discusses recent theoretical developments on fracture at elevated temperature in the presence of overall plastic (dislocation) creep. Two topics are considered: 1. Stress fields at tips of macroscopic cracks in creeping solids: Here consideration is given to the transient development of an effectively steady state of creep in a cracked body, following sudden load application for whic...

This paper describes a new approach which can be used to interpret the experimental creep deformation data obtained from miniaturized thin plate bending specimen test to the corresponding uniaxial data based on an inversed application of the reference stress method. The geometry of the thin plate is fully defined by the span of the support, l, the width, b, and the thickness, d. Firstly, analyt...

The slow motion of a crack line is studied via an experiment in which sheets of paper are split into two halves in a "peel-in-nip" (PIN) geometry under a constant load, in creep. The velocity-force relation is exponential. The dynamics of the fracture line exhibits intermittency, or avalanches, which are studied using acoustic emission. The energy statistics is a power law, with the exponent be...

This study investigated the time-dependent crack propagation of rock–concrete interface under sustained loading. First, loading tests were performed on composite beams three-point bending with respect to three roughness degrees, i.e., natural, 4×4, and 7×7 interfaces, load levels, 80% maximum load, initial cracking 97% load. Then, by employing Norton-Bailey model fictitious model, constitutive ...

Stimulated by the excessive deflections and collapse of the KB Bridge of world-rercord span, the deflection histories of 56 similar bridges, most of them excessive, have been collected by RILEM TC-MDC. They amount to a wake-up call: The standard creep recommendations of engineering societies have been misleading, and thus their revision is imperative. They also confirm a simple feature: The mul...

A large number of cyclic torsional shear tests on saturated soft clay under unconsolidated undrained condition have been carried out. The changing law between accumulative generalized shear strains vs. failure numbers has been analyzed and a cyclic shear strength curve has been received based on cyclic torsional shear tests. According to the test results, the criterion of saturated soft clay is...