This Small Business Innovation Research Phase I project will investigate the feasibility of a novel non-destructive testing (NDT) technique/apparatus. The objective of this research is to develop a new capability for detecting minute cracks on the surface of structural components. Economic losses in the U.S. due to crack induced failure is estimated to exceed one billion dollars annually. A key step in reducing these losses is identifying cracks prior to catastrophic failure. This SBIR project will develop an NDT apparatus based on microwave heating and thermographic detection of cracks. The experimental apparatus consists of a rectangular waveguide which is open on one end. The open end may be pressed against a metal surface, thereby forming a microwave resonant cavity. With this arrangement the component being inspected forms one wall of the resonant cavity. The normal boundary condition for electromagnetic fields within the cavity requires that electric field components diminish to zero at the cavity walls. In the presence of a crack, however, this boundarv condition no longer applies and microwaves will be emitted from eddies of the crack. NDT is widely used for evaluating infrastructure such as bridges, pipeline, boilers, and transportation equipment. Immediate applications exist for new NDT methods which offer functional/economic benefit.
