Monitoring the failure states of a metal matrix syntactic foam by modal analysis

This paper presents a new non-destructive method applying modal analysis to determine the failure state of the AlSi12 matrix syntactic foam containing ceramic hollow spheres. The results proved that the decrease in natural frequencies of the first two modes and the calculated effective Young's modulus indicate the damage state of the syntactic foam's structure during compression. Both the natural frequencies and the elastic modulus start to change after the onset of fracture of hollow spheres, which is similar to 60 MPa, according to our previous work. A 5% decrease in these parameters are suggested as a practical limit of the deterioration of a load-bearing structure, which collides with the maximum in the acoustic emission activity. (C) 2019 Elsevier B.V. All rights reserved.