高速進展き裂前縁のホログラフィ撮影

概要

論文の詳細を見る
Pulsed holography is applied to take an instantaneous photograph of a crack front propagating through a PMMA plate specimen at a speed of several hundred m/s. The cracks are in the opening mode and not interacting with any stress waves. A pulsed holographic optical system records and reconstructs a crack front observed through a side boundary of a specimen, and the reconstructed image is photographed. A method is developed to decrease an aberration introduced by inhomogeneity of refractive index in PMMA, where the inhomogenity results from manufacturing process of the PMMA. Also discussed are effects of changes of specimen thickness and refractive index in the strong stress field near a crack tip. From an obtained photograph one can know the shape of a crack front, which is not always symmetric. One can moreover measure the two angles between the crack front and the two specimen surfaces. The angles are important quantities to understand the three-dimensional structure of the stress field around the crack tip. The measured angles are similar to the numerical results given by Bazant and Estenssoro.
1990-05-25