Research Of Acoustic Emission Caused By Local Cracking

Damage caused by natural disasters, structural fatigue or metal corrosion to engineering structures in regular operation is just unavoidable, whereas accidents of large structural projects can result in tremendous losses of lives and properties to the people and the economy. Therefore, it is of great importance and urgency to monitor momently and diagnose on the structure. It is still a hot topic researched in domestic and foreign to simulate dynamic response on the surface caused by acoustic emission events inside the structure. This paper analyses characteristics of acoustic emission caused by crack propagation, using the boundary element method in elastic dynamics.The paper introduces the boundary element method in elastic dynamics in the first place, that method find out fundamental solution of elastic dynamics equation in the Laplace transform domain, using the Laplace integral transformation. And the method deduces the boundary integral equation of elastic dynamics in the Laplace transform domain, using the weighted surplus method, and eliminate integral singularity. After integral equation is established, the integral equation is scattered, using the boundary element discrete technology and a series linear equations are formed in the Laplace transform domain. Then the numerical solution in time domain will be got, using numerical Laplace inverse transform to transform the solution of equations.The paper analyses dynamic response on the surface caused by acoustic emission events in the two kinds of typical structures, according to the boundary element method. Fluctuation curves simulated will be changed accordingly as the features of acoustic emission source changes. This paper simulates different dynamic response fluctuation curves, mainly from units classification, different stress impacting on crack surface, size of ellipsoid crack, inclination of ellipsoid crack, and analyzes the influence of fluctuation curves when parameter changes.