Poisson’s ratio in viscoelastic solids is in general a time dependent (in the time domain) or a complex frequency dependent quantity (in the frequency domain). We show that the viscoelastic Poisson’s ratio has a different time dependence depending on the test modality chosen; interrelations are developed between Poisson’s ratios in creep and relaxation. The difference, for a moderate degree of ...

In this study, a real and significant industrial problem in a steam power plant was investigated. Reheater tubes in boilers are under the creep and the fireside corrosion mechanism that cause some of them to fail. Since the estimation of probability of failure (PoF) and remaining life (RL) is expensive and time consuming in the deterministic methods, in this work they were evaluated using struc...

Title of Dissertation: CREEP CORROSION OVER PLASTIC ENCAPSULATED MICROCIRCUIT PACKAGES WITH NOBLE METAL PREPLATED LEADFRAMES Ping Zhao, Doctor of Philosophy, 2005 Dissertation Directed By: Dr. Michael Pecht, Professor, Department of Mechanical Engineering Field failures were observed to be caused by the bridging of corrosion products across lead fingers. This phenomenon was identified as creep ...

The time dependence of the physical properties of ethylene/1-octene (EO)-copolymers after primary crystallization is investigated by calorimetry, density, and creep measurements. The temporal evolution of the multiple melting of EO-copolymers is monitored by differential scanning calorimetry. The low temperature endotherm displays an evolution similar to that observed for the enthalpy recovery ...

Grain-boundary (GB) diffusion creep (Coble creep) is the dominant deformation mechanism for the fine-grained materials under low stress and at elevated temperature [1]. From the classical Coble creep formula [1], the strain rate is proportional to the external stress, and inversely proportional to the cube of the grain size: 3 ~ − d σ ε& . During creep deformation the grains become elongated in...

The effect of molecular weight on the viscoelastic performance of an advanced polymer (LaRC-SI) was investigated through the use of creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of each material with different molec...

We remove the need for Laplace/inverse-Laplace transformations of experimental data, by presenting a direct and straightforward mathematical procedure for obtaining frequency-dependent storage and loss moduli [G'(omega) and G''(omega), respectively], from time-dependent experimental measurements. The procedure is applicable to ordinary rheological creep (stress-step) measurements, as well as al...

From soft polymeric gels to hardened cement paste, amorphous solids under constant load exhibit a pronounced time-dependent deformation called creep. The microscopic mechanism of such phenomenon is poorly understood in materials and constitutes an even greater challenge densely packed chemically reactive granular systems. Both features are prominently present hydrating pastes composed calcium s...

This paper presents the movement dynamic of the train and the relationship between the speed of wheel and train, as well as a discussion about the concept of wheel slip. There are two different operation regions designated as creep and wheelspin areas for wheel slip. Creep and wheelspin areas have stable and unstable characteristics, respectively. Wheels and rails are constructed from iron, and...