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学位論文 |
学位
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茂木, 健司
概要:
Thesis or Dissertation<br />修士論文
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論文 |
論文
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神宮, 利夫
概要:
application/pdf<br />Journal Article<br />The strength of unidirectionally reinforced carbon/epoxy composites (CFRP) subjected to the compressive impact load was measured by the Split Hopkinson Pressure Bar Method (S. H. P. B. M),
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then the effect of fiber orientation on the compressive impact strength was investigated. Stress of the specimen, caused by multiple reflected stress waves at its ends in contact with the incident bar and transmitter, was analysed based on one-dimensional stress wave theory. The resulting formulation can be used to evaluate either the linear or nonlinear stress-strain relation. The strength of a specimen of zero-degree fiber is the greatest. The strain of a specimen of 45-degree fiber is the largest. A split fracture parallel to the fiber appeared in the specimen of zero-degree fiber. Inclination of the fracture surface of specimens of 30-, 45- and 60- degree fiber is in alignment with the fiber orientation. Tat of 90 degrees is not. The impact strength is about 80 MPa larger than the static strength. In contrast, the dynamic elongation is smaller than the static elongation.
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| 3.
論文 |
論文
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神宮, 利夫 ; 永倉, 和郎 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />The crack propagation velocity in tensile fracture is determined by comparison of the unloading wave observed by the strain gage method with the theoretical analysis based on postulating the
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crack growth models which are backed by the fractographic analysis using the photograph taken by the scanning electron microscope (SEM). The effect of elongation, contraction of notch bottom and load rate just before rupture on the crack propagation velocity is investigated using the notched round bar specimens of annealed JIS-SS41, S45C and quenched SKS93 steel. The fracture surface of SS41 and S45C is a dimple and SKS93 a cleavage. The deformation of SS41 is largest and in turn S45C, SKS93. It is shown that the crack speed slightly decreases as elongation or contraction of notch bottom increases. Particuraly, the decrease of crack speed of quenched SKS93 is a very little. The reduction of crack speed attributes to softening of notch bottom.
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