Development of Crack Damage Evaluation Method for Utilizing High Frequency A.C.Potenial Method

高频交流电位法裂纹损伤评价方法的研制

• 批准号: 10650105
• 负责人: SAKANE Masao
• 金额: $ 2.05万
• 依托单位: Ritsumeikan University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650105/
• 关键词: Nontructive testing; potential method; crack detection; alternating current; skin effect; superalloy; multiple crack; coating; き裂検出; 複数き裂

Many cracks were initiated and propagated on the surface of gas turbine blades made by nickel base superalloys due to the thermal stresses during start up and shut down of turbines. Nondestructive crack detection method is necessary for the damage evaluation for blades. This study investigated the crack depth detection and the detection of the number of cracks simultaneously by a measurement using a.c.potential method.The material used was a solid bar with a rectangular cross section of 5 mm width, 10 mm height and 100 mm length. The artificial cracks with 50, 100, 150 200 200, 300 and 500 micron meter depth were made by a wire electric discharge machine. The number of artificial cracks was 1, 2, 3 and 5. The a.c.potentials were measured at the frequencies from 200 to 5000Hz using the four points probe method. The main conclusion obtained are as follows.1. A. c. potentials at all the frequencies increased with increasing the crack depth in all the specimens.2. For the same crack depth, a. c. potentials increased with increasing the number of cracks.3. The high frequency a. c. potentials were more sensitive to the shallow cracks while the low frequency a. c. potentials were sensitive to the deep cracks.4. By using the a. c. potentialst at many frequencies, the number of cracks and the crack depth are detectable at a measurement. The developed method in this study basically is extendable to the damage evaluation of actual gas turbine blades.5. The above experimental results agreed well with the finite element results of harmonic analysis of a.c.potentials.

镍基高温合金燃气涡轮机叶片在启停过程中，由于热应力的作用，叶片表面产生了大量裂纹并扩展。叶片裂纹的无损检测是叶片损伤评估的必要手段。本研究通过使用交流电位法的测量同时研究了裂纹深度检测和裂纹数量检测。所用材料是具有宽5 mm、高10 mm和长100 mm的矩形横截面的实心棒。用电火花线切割机加工出深度为50、100、150、200、200、300和500 μ m的人工裂纹。人工裂缝的数量为1、2、3和5。用四点探针法在200 ~ 5000 Hz频率范围内测量交流电位。主要结论如下：1. A. C.所有频率下的电位都随着裂纹深度的增加而增加.对于相同的裂纹深度，a。C.电位随裂纹数的增加而增加.高频率A。C.电位对浅裂纹更敏感，而低频a. C.电位对深裂纹敏感.通过使用A。C.在许多频率下，裂纹的数量和裂纹的深度在测量中是可检测的。该方法基本上可推广到实际燃气涡轮机叶片的损伤评估中.上述实验结果与交流电位谐波分析的有限元结果吻合较好。

项目成果

Lee Yeonkyeong and M.Sakane: "Multiple Crack Detection of Inconel 738LC by A.E.Potential Method"Proceedings of the 48th Annual Meeting of Japan Society of Materials Science. 111-112 (19699)

Lee Yeonkyeong 和 M.Sakane：“A.E.电位法检测 Inconel 738LC 的多重裂纹”第 48 届日本材料学会年会论文集。

李 年慶: "複数微小き裂に対する交流電位差法の評価"第48期 学術講演会講演論文集 (日本材料学会). 111-112 (1999)

李念庆：“多微裂纹的交流电位法的评估”第48届学术会议论文集（日本材料学会）111-112（1999）。

李 年慶: "複数微小き裂に対する交流電位差法の評価"第48期学術講演会講演論文集(日本材料学会). 111-112 (1999)

李念庆：“多微裂纹的交流电位法的评估”第48届学术会议论文集（日本材料学会）111-112（1999）。

李 年慶: "交流電位差法によるInconel738LCの複数き裂検出" 日本材料学会第48期学術講演会. (1999)

李念庆：“利用交流电位法检测Inconel738LC中的多重裂纹”，日本材料学会第48届学术会议（1999年）。