ホログラフィ二重露光法とフィゾー型干渉法による高速進展き裂先端応力場の同時測定

抄録

　　　Double exposure holography and Fizeau-type interferometry are simultaneously applied to measure the stress field in the vicinity of fast propagating cracks in PMMA plate specimens whose thickness is slightly non-uniform. The sensitivity of double exposure holography is about a quarter as high as that of Fizeau-type interferometry, however, it can measure only the change in specimen thickness caused by the stress concentration near the crack tip without distortion of interference fringes by the non-uniformity of specimen thickness. Measurement results say that the derivatives of fringe order with respect to the distance from the crack tip are proportional to the -3/2th power of the distance from the crack tip, which is in agreement with the theory of singular stress field of plane stress. The stress intensity factors are also obtained from the interference fringes. It is shown that double exposure holography can obtain true value of stress intensity factor even in the condition that Fizeau-type interferometry cannot give the true value being affected by the non-uniformity of specimen thickness.