Search Results

A structural damage detection system has been used to sense the propagation of cracks in a metallic flight test specimen on board a Hawk jet trainer. The work has demonstrated that the growth of structural cracks can be successfully and automatically detected on board a fast jet while flying unrestricted flight profiles. The experiment was part of a European collaborative defense program designed to demonstrate a number of diverse structural health monitoring technologies during flight in a military jet environment. This paper focuses on the performance of an acoustic emission detection system that was able to detect the growth of cracks in an alloy cantilever specimen bolted to a structural bulkhead in a pod suspended beneath the aircraft's left hand wing.

An essential part of the SHM validation effort is to check the presence and adequacy of the methods required to validate the correct functionality of each SHM task, which can be targeted at detecting structural faults. The ultimate proof of the correct functionality is validation evidence, e.g. crack detection evidence, observed during the operation of the aircraft. However, the occurrences of structural faults such as cracks are infrequent, and hence, years of flight tests might be required to collect validation evidence; small numbers of flights would be only sufficient to prove the system's “fitness for flight” and would be insufficient to prove “fitness for purpose”. Validation evidence can be collected during laboratory tests by inducing faults in structural specimens and examining the SHM detection capability.