
A technique was developed to detect the onset, size, evolution, and anisotropy of surface microcracks in ceramic composite materials as a function of applied stress. The method is based on measuring the electrical resistance changes of a thin gold film sputtered on the surface of the composite as a function of stress. The technique was applied to the tensile surfaces of a 90/0/90, single crossply, 50 vol% SiC-LAS composite bars subjected to three-point bending. The resistance changes during the first loading cycle were found to be a strong function of the surface condition prior to testing. The onset of microcracking varied between 70 and 160 MPa. The anisotropy in the resistance changes in two orthogonal directions demonstrated that, for a given stress, the damage resulting from axial cracks was comparable to that of matrix cracks and occurred simultaneously. Furthermore, the matrix cracks were found to close more readily than the axial ones. The resistance changes were converted to crack lengths assuming that one large crack extended normal to the applied stress. The presence of such cracks was confirmed by SEM. How this method can be used nondestructively to assess the integrity of a finished surface is also discussed.
| citations This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 3 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
