In this paper, the superposition method is used to investigate the complete temperature field of a lightemitting diode (LED) packaging substrate, based on the results of transient temperature rise measurements and the thermal resistance coupling matrix. The feasibility of use of the superposition method in an LED array with multiple packages has been proved first by temperature comparisons with...

Dielectric relaxation measurements on supercooled triphenyl phosphite show that time-temperature superposition (TTS) is obeyed for the primary relaxation process at low temperatures. Measurements on other molecular liquids close to the calorimetric glass transition indicate that TTS is linked to an omega(-1/2) high-frequency decay of the loss, while the loss peak width is nonuniversal.

We consider systems undergoing very-low-temperature solid-solid transitions, exhibiting the well-known "broken-ergodicity" problem that is often so severe that even the replica exchange method converges too slowly. We propose an improvement of the latter, which consists of coupling the lower-temperature random walks to analytically generated random walks corresponding to an auxiliary harmonic s...

The high strain rate compressive behaviour of a Silicone elastomer: Sylgard 184® is presented. Experiments were performed over strain rates between 3000 and 15,000 s -1 , and temperatures between -40 and +73 oC, corresponding to environmental conditions in many industrial applications. An Ogden strain energy density function was fit to the data, and the strain rate and temperature dependence of...

Failure models based on the Palmgren-Miner concept that material darnage is cumulative have been derived and used mainly for fatigue life predictions for metals and composite materials. Wexeview the principles underlying such models and suggest ways in which they may be best applied to polymeric materials in temperature environments. We first outline expectations when polymer degradation data c...

The use of thermoplastics in the automotive industry is continuously increasing. Design parts require characterization and numerical modelling thermo-mechanical behaviour those materials under wide strain rate (0–300 s−1) temperature ranges (−30 °C to +85 °C). Large costly experimental campaigns are therefore necessary identify all behaviour's sensitivities. Yet, time-temperature-superposition ...

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...