OS1208 高エネルギー放射光単色X線を用いた鉄鋼丸棒の内部疲労き裂のCTとひずみの同時測定(X線,放射光,中性子による材料・材料強度評価,オーガナイズドセッション)

概要

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Using high energy monochromatic X-rays of energy 66.4keV from the synchrotron radiation source, SPring-8, we have developed a system to perform the hybrid measurement of imaging of cracks and strain distribution around cracks. This system was applied to a fatigue crack made in a round bar made of carbon steel with the diameter of 4 mm. Computed tomography (CT) of the specimen gave the three-dimensional shape of a thumb-nail crack. Scanning of lattice strain along the loading axis around cracks was conducted under the zero and maximum applied stresses. High tensile strain ahead of the crack was measured at the maximum stress, while the strain on the crack face was low because of crack opening. The full width at half maximum (FWHM) increased near the crack tip under loading, and then decreased after unloading. This recoverable part of FWHM by unloading was caused by the steep distribution of the applied stress in the vicinity of the crack tip. The increase of FWHM due to plastic deformation did not change by unloading.
2009-07-24