Damage detection via embedded sensory particles – Effect of particle/matrix interphase properties

Abstract

Supported by recent studies, a crack interior to the host material will cause an especially strong stress concentration and thus can be detected by monitoring or sensing the localized changes in the magnetic properties of the particles in metallic composites. Using finite element analysis calibrated from the experiments, this work investigates the effects of material properties and thickness of the particle/matrix interphase on the phase transformation response of embedded sensory particles in the vicinity of a crack existing in the host matrix. Depending on the interphase elastic and cohesive properties, its thickness, and the operational temperature, which is known to delay or promote martensitic transformation, it is found that interphase damage may occur at stress levels lower than that needed to initiate phase transformation in MSMA particles. Such a response would mitigate the degree to which the particle transforms and reduces particle sensitivity. The effect of particle position relative to the crack tip on interphase damage and particle transformation response is studied via the full factorial design of experiments. To assess the true feasibility of the technique, the average change in magnetic permeability in the vicinity of the particle given constant applied magnetic and applied stress fields is evaluated.