Failure site location by acoustic emission for composites reliability assurance

Abstract

The failure of fiber filaments in a composite subjected to load produces a stress wave which can be detected using acoustic emission techniques. The spatial clustering of multiple fiber failure sites is known to cause catastrophic failure of the macro composite. Acoustic emission can be used to determine locations of these flaws, providing a useful tool for reliability assurance of composite structures. This investigation establishes the necessary foundation by categorically quantifying the methodology of determining flaw locations in a one dimensional solid. Homogeneous isotropic (steel) thin rods are subjected to repeatable wave events to quantify distance measurement, resolution and repeatability. This experimentation is then extended to a unidirectional carbon fiber composite rod with further investigation to quantify effects of dispersion and damping in this heterogeneous, anisotropic material.