Study on development of fatigue life prediction system based on neutron strain scanning method

基于中子应变扫描法的疲劳寿命预测系统开发研究

• 批准号: 12555023
• 负责人: TANAKA Keisuke
• 金额: $ 8.32万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555023/
• 关键词: Neutron diffraction; Residual stress; Fatigue; X-ray stress measurement; Composite materials; Crack; Diffraction elastic constant; Synchrotron radiation; ショットピーニング

1. The loading stress in sample specimens was measured by the neutron diffraction method to check the accuracy of the measured stress value. The diffraction elastic constants can be estimated from the single crystal elastic constants by combining Kroner model with the self-consistent model. In the plastic range, plastic anisotropy should be taken into account for stress determination. A new method is proposed to determine the strain-free lattice spacing.2. The microstress and macrostress can be evaluated separately by the neutron method. Several applications of the method to composites showed those stresses which agreed with the theoretical predictions baed on Esheby inclusion mechanics.3. A scanning method was proved to be useful to measure the distribution of strain within the bulk samples. Because of a low intensity of neutron sources, the minimum volume that can be measured by the neutron method was 2mm cube. The improvement of the special resolution is necessary to determine steep stress gradients.4. The neutron diffraction system developed by the present method was successfully applied to measure the residual stress distributions in several engineering materials and components.5. To measure the stress very near the surface, "the surface effect" will cause the error of the measured stress. The small divergence of the beam is effective to reduce this effect.6. High energy X-rays from synchrotron radiation will be a useful method to measure the stress distribution near the surface. A combination of the neutron method with high-energy and laboratory X-rays will be a promising new toll for nondestructive measurements of residual stress distributions.

1.采用中子衍射法对试件中的载荷应力进行了测量，以检验测量应力值的准确性。将Kroner模型和自洽模型相结合，可由单晶弹性常数估算出单晶的衍射弹性常数。在塑性范围内，确定应力时应考虑塑性各向异性。提出了一种确定无应变晶格间距的新方法。微观应力和宏观应力可以用中子法分别计算。该方法在复合材料中的多次应用表明，这些应力与基于Esheby夹杂力学的理论预测相吻合。扫描方法被证明是测量大块样品中应变分布的有效方法。由于中子源强度低，中子法可以测量的最小体积为2 mm立方体。为了确定陡峭的应力梯度，需要提高空间分辨率。利用该方法研制的中子衍射仪成功地测量了几种工程材料和构件中的残余应力分布。在测量非常接近地表的应力时，“表面效应”会引起测量应力的误差。光束的小发散可以有效地减小这种影响。来自同步辐射的高能X射线将是测量表面附近应力分布的有用方法。将中子法与高能X射线和实验室X射线相结合，将是无损测量残余应力分布的一个有希望的新目标。

项目成果

Keisuke Tanaka: "Neutron Diffraction Measurements of Residual Stresses in Engineering Materials and Components"Materials Science Research International. 8・4. 19-21 (2002)

Keisuke Tanaka：“工程材料和部件中残余应力的中子衍射测量”材料科学研究国际 8・4（2002 年）。

秋庭義明: "中性子回折法によるセラミックス複合材料の熱残留応力測定"材料. 49・7. 742-747 (2000)

秋叶义明：“使用中子衍射法测量陶瓷复合材料的热残余应力”材料49・747（2000）。

皆川宣明: "IN718ショットピーニングの中性子回折法による残留応力測定"第36回X線材料強度に関するシンポジウム講演論文集. 36. 263-265 (2000)

Nobuaki Minakawa：“使用中子衍射法测量 IN718 喷丸中的残余应力”第 36 届 X 射线材料强度研讨会论文集 36. 263-265 (2000)。

Makoto Hayashi, Masayuki Ishiwata, Yukio Morii, Nobuaki Minagawa and John H.Root: "Residual Stress Distribution in Carbon Steel Pipe Welded Joint Measured by Neutron Diffraction"Materials Science Research International. Vol.6, No.4. 287-294 (2000)

Makoto Hayashi、Masayuki Ishiwata、Yukio Morii、Nobuaki Minakawa 和 John H.Root：“通过中子衍射测量碳钢管焊接接头的残余应力分布”材料科学研究国际。

皆川 宣明: "中性子回折法による試料端部の測定"第38回X線材料強度に関するシンポジウム講演論文集. 38. 202-205 (2002)

Nobuaki Minakawa：“使用中子衍射法测量样品边缘”第 38 届 X 射线材料强度研讨会论文集 38. 202-205 (2002)。