Optimization-Based Network Identification for Thermal Transient Measurements

Network identification by deconvolution is a proven method for determining the thermal structure function of a given device. The method allows to derive the thermal capacitances as well as the resistances of a one-dimensional thermal path from the thermal step response of the device. However, the results of this method are significantly affected by noise in the measured data, which is unavoidable to a certain extent. In this paper, a post-processing procedure for network identification from thermal transient measurements is presented. This so-called optimization-based network identification provides a much more accurate and robust result compared to approaches using Fourier or Bayesian deconvolution in combination with Foster-to-Cauer transformation. The thermal structure function obtained from network identification by deconvolution is improved by repeatedly solving the inverse problem in a multi-dimensional optimization process. The result is a non-diverging thermal structure function, which agrees well with the measured thermal impedance. In addition, the associated time constant spectrum can be calculated very accurately. This work shows the potential of inverse optimization approaches for network identification.

Numerical studies on damage of carbon/epoxy composites exposed to lightning strike

Lighter carbon fiber/epoxy composites are replacing metals in wind turbines blades, aircraft structures, marine structures, automotive skins & other applications. Lightning strike damage is a real threat to these materials during service life. Along with experimental studies, their damage predictions by numerical methods are being attempted by various researchers. The numerical simulation of this damage by coupled thermal–electric (transient) analysis and thermal transient analysis is presented in this article. In this study, damage predictions based on thermal profiles are carried out, and suitable validations with earlier published work are discussed.