MEASUREMENT OF CRACK TIP STRESSES BY X-RAY DIFFRACTION.

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作者：

Allison, John E.

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来源：

| 1978年

关键词：

STRUCTURAL ANALYSIS - X-Ray Analysis;

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摘要：

Crack tip stresses were measured in specimens of 1020 and 1045 steel using a semi-automatic x-ray diffraction technique. Crack tip residual stresses were measured in the unloaded condition and crack tip ″applied″ stresses were measured under load. It was observed that a dependence exists for the maximum crack tip residual stress on the level of the previous stress intensity factor and also for the maximum crack tip ″applied″ stress on the level of the applied stress intensity. This is in sharp contrast to theoretical models of the crack tip stress fields which predict an independence between crack tip stresses and stress intensity levels. Crack tip stresses were observed relative to the fatigue crack growth retardation process. Limited studies indicated that crack growth, after an overload, had little or no effect on the overload-induced crack tip residual stress distribution. Measurements taken at applied loads indicated that portions of the material behind the tip of the extended crack were in compression while areas ahead of the extended crack were in tension.

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