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Force characterisation of a laser impulse using differential evolution with a local interaction simulation algorithm

Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNConference contribution/Paper

Published
  • Andrew Spencer
  • Keith Worden
  • Gareth Pierce
  • James Hensman
  • Daley Chetwynd
  • Wieslaw Staszewski
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Abstract

One approach to health monitoring of plate-like sections of structures is to look for changes in the way ultrasonic waves propagate through metal and composite panels when damaged. Waves travelling through thin plate-like structures are affected by reflections at the surfaces giving rise to Lamb waves which are highly dispersive. To simulate such waves, a Local Interaction Simulation Approach (LISA) algorithm has been implemented and this paper deals with the validation of this code for wave propagation in undamaged aluminium plates. In order to minimise unknown factors, experiments are carried out using a high power laser pulse for actuation and a laser vibrometer for sensing. However, the forces imparted by the ablative and heating effects of the laser pulse are still unknown. Differential Evolution (DE) is used to find the optimal profile of forcing to match the simulation with experiment. The accuracy of the simulation method is then verified by comparing the predicted and experimental results for tests using a similar laser pulse but with displacement measured at a different distance or with a different plate thickness.