Search results for "Constant stress"
showing 2 items of 2 documents
Piezoelectric coefficients by molecular dynamics simulations in the constant stress ensemble: A case study of quartz
2006
Piezoelectric (strain) coefficients dij of quartz are calculated in terms of molecular dynamics as a function of pressure and temperature. We review the necessary formulas for the computation of electromechanical materials coefficients obtained at constant stress and temperature, and discuss how to overcome complications of the definition of polarization variations due to fluctuating box geometries. A method is employed suppressing significantly stochastic fluctuations of the estimators for piezoelectric coefficients. A recently suggested force field for the simulation of SiO2 reproduces available experimental data quite accurately. Predictions are made for the pressure dependence of dij of…
The Partial Discharge Behavior of Different Materials under DC Periodic Stress
2019
The aim of the present work is to evaluate the PDs behavior by stressing a specimen with a new type of waveform named DCP. This waveform was proposed by the authors in a previous work with the aim to overcome the main issues of PDs under DC stress. In the previous work PDs test on Kapton specimen was performed. In this paper, we propose a new DCP test on a different insulating material, such as the XLPE. The obtained patterns and the acquired data have been evaluated in order to validate the DCP approach as a new method for PDs measure under constant stress. The behavior of the XLPE material has been reported and compared with the former measures obtained for Kapton material.