| Summary: | The aim of this research work is to propose a damage characterisation method using acoustic emission technology. The research is broadly categorised in structural health monitoring (SHM) of CFRP composite structures. A number of tests were performed on twill-weave CFRP composite material in correlating the various damage types to their associated signal features. Recent developments in aircraft structural material lead to an increase use of CFRP composite structures. However, these materials are susceptible to different modes of failures such as matrix cracking, delamination, stringer debonding, and fibre fracture which affect the integrity of the structure. Determining the type of failure during service life of an aircraft structure is an important input in the SHM of materials. This can potentially reduce inspection time, and increases knowledge of the damage type propagating within the said structure. Acoustic emission (AE) is a phenomenon where a stress wave is generated due to stresses in a material. AE sensors can be placed on the surface of the structure to detect these waves while the material is in service. These waves have possess distinct signal features which can be attributed to a particular damage type. Therefore, AE based technology is potentially suitable for the SHM of composite structures. This thesis proposes an improved damage characterisation method for twill weave CFRP composite when subjected to various modes of failure. These failure modes were achieved using a variety of test setups namely cantilever bending, three point bending, stringer debonding, and tensile testing. The proposed method uses live digital microscope video recording of events along with AE events. Distinct signal features were identified for delamination initiation and propagation, matrix cracking, fibre fracture and skin-stringer debonding.
|
|---|
