Determining impact damage in a composite member by processing measurements of an acoustic wave

摘要

A method and apparatus is disclosed for processing measurements of an acoustic wave within a member (12, Fig 2), such as an aircraft wing, made of a composite material and caused by an impact to the member by e.g. a bird or debris. The method comprises: analysing the measurements to detect an initial acoustic wave feature; analysing the measurements to detect the presence of further acoustic wave features, the further features occurring after the initial feature; if there are no further acoustic wave features, determining that the impact to the member has not changed the structure of the member; if there are further features, determining a value of a function of the further acoustic wave features; if the determined value satisfies certain criteria, determining that the impact has changed the structure of the member; and if the determined value does not satisfy the criteria, determining that the impact has not changed the structure of the member. The acoustic wave sensor is either a piezoelectric or fibre optic sensor either bonded to or embedded into the member.