A methodology for analyzing laser-induced structural damage

Abstract

The analysis of laser-induced structural damage requires the merging of a thermal analysis which includes the characterization of the laser damage with a structural analysis which enables the determination of the deformation and the residual load carrying ability. Three types of laser-induced damage are considered: loss of structure due to melting, change of material properties due to temperature changes, and addition of load due to thermal stress. The thermal solution is calculated from a set of finite difference equations obtained from heat balances performed at successive finite time increments on an array of finite cells. The structural analysis is performed by a re-analysis technique, applicable when changes in structural stiffness are small compared to the initial value. The combined procedure for evaluating laser damage is applied to two structures, representing two levels of complexity. The first was a simple two-dimensional plate and the second a three-dimensional wing structure. The displacement solutions were compared to results obtained from NASTRAN to determine the accuracy of the iterative solution technique. The procedure was found to be efficient, and permits the parametric studies needed for a-priori estimates of the effectiveness of potential laser weapons systems. 10 references.