AN INTERNATIONAL SURVEY OF SMALL-CRACK RESEARCH

A survey was conducted to determine the current state of international research on small cracks. The survey consisted of inquiries regarding the nature of the research, the materials studied, the applications o f the investigators' research, the smallest crack size monitored, the techniques used to monitor crack growth, the testing environment, the surface conditioning/preparation, and the models used to predict crack growth. Survey participants were also asked to identify problem areas they were addressing with their research and other important unresolv ed questions regarding small cracks. The results of the survey show th at a wide range of materials, including metallics composites. rock, an d bone, are currently under investigation for both basic research purp oses and for particular applications. Researchers are able to monitor cracks smaller than 1 mu m in length using one of or combinations of s everal different techniques. Many crack growth models are being used t o predict crack growth in these materials. The absence of a single uni fied crack growth model stems from the fact that the small-crack regim e encompasses several different classifications, including microstruct urally small cracks and mechanically smalt cracks. Each type of crack grows differently, thus requiring a different treatment.