Computation of transient-temperature profiles in objects exposed to simulated lightning currents

This paper presents a theoretical analysis of transient temperature distribution in metals and composites struck by different lightning currents to simulate objects of interest, especially aircrafts. A computer program based on the finite volume technique is written to compute the transient-temperature distributions in three dimensions due to both high-amplitude impulse currents (IC) and the relatively low-amplitude long-duration currents (LDC). Typical waveform of the discharge current during lightning strikes to objects near/on ground (negative downward flash), at high altitudes (negative upward flash) and in-flight (e.g. aircrafts) are simulated with different amplitudes and durations. The simulation considers the IC as first negative, or superimposed or subsequent return strokes with respect to the LDC. Different types of metals and carbon-fiber composites are also investigated to compare their thermal transient responses. Finally, the theoretical results are verified by using a sophisticated high-speed infrared camera to measure the rear-face temperature profiles of metals as a function of the coordinates and time due to both IC and LDC.