抄録
The computer image processing system incorporated into the specially designed servo-hydraulic fatigue loading facilities operating in a scanning electron microscope (SEM) has been developed. The image processing system developed is composed of a micro-computer (NEC PC9801, memory capacity is 4 Mbytes) and a high-speed direct memory access type A/D converter (ELMEC EC-2390). The secondary electron signal of SEM was directly transferred to the memory of micro-computer through the converter at a digitizing rate of 5 to 50μsec per point. By using this system, the sampling of successive five flames of SEM image data during fatigue loading of 0.1Hz become possible.
Direct, real time observations of fatigue crack growth behavior under both constant amplitude and repeated two-step loadings were made. Both the crack profile and the contours of fine magnesium oxide particles, which were scattered on the specimen surface as location markers, were extracted from the original SEM image data by using the image processing technique, and this processed image data was used in quantitative analyses of crack opening displacement, deformation behavior near the crack tip and crack growth increment.
