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中南大学学报(自然科学版)

Journal of Central South University

第51卷    第2期    总第306期    2020年2月

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文章编号:1672-7207(2020)02-0359-08
声弹性螺栓应力测量影响因素
韩玉强1,吴付岗1,李明海1,梅军2,王小龙1

(1. 中国工程物理研究院 总体工程研究所,四川 绵阳,621900;
2. 中国工程物理研究院 成都科学技术发展中心,四川 成都,610200
)

摘 要: 为了分析声弹性法螺栓应力测量中的影响因素,从固体质点声弹性理论入手,在模型中加入质点受力形变因素,建立质点时差法应力测量模型;针对螺栓结构建立不同轴向预紧力下应力分布,获得超声传播路径上的应力分布表达式,建立不均匀应力下的螺栓声弹性测量模型;设计应力不均匀区占超声路径比例不同的实验,采用基于ZnO压电薄膜的方式激发超声,压电薄膜溅射于螺栓表面,避免使用超声耦合层引入的测量误差,得到应力不均匀区与测试误差的关系;进行螺栓反复拉伸后声弹性测量的重复性实验,验证材料性质与螺栓应力测量的关系。研究结果表明,超声时差与应力呈线性关系;声弹性系数由螺栓的弹性模量、泊松比以及螺栓长度决定;不同应力非均匀区占比的螺栓应力测量误差相同,初始误差小于2%;螺栓反复拉伸后,声弹性螺栓应力测量误差变大;应力分布不会产生测量误差,测量误差来源于材料的非均匀性;经过拉伸后的螺栓,材料中的缺陷和错位增大,增强高频超声的散射,引起应力测量误差变大。

 

关键词: 声弹性;应力分布;压电薄膜;误差

Factors influencing measurement of bolt stress based on acoustoelastic effect
HAN Yuqiang1, WU Fugang1, LI Minghai1, MEI Jun2, WANG Xiaolong1

1. Institute of System Engineering, China Academy of Engineering Physics, Mianyang, 621900, China;
2. Chengdu Development Center of Science and Technology, China Academy of Engineering Physics,Chengdu, 610200, China

Abstract:In order to analyze the influence of various factors on the measurement of bolt stress by acoustoelastic effect, the theory of acoustoelastic of solid particles was analyzed. The stress and deformation factors of particles were introduced into the model and the stress measurement model of particles was established. The stress distributions under different axial preloads was established with the structure of bolt, the stress distribution expression on the ultrasonic propagation path was obtained and the acoustoelastic measurement model of bolt under uneven stress was established. ZnO piezoelectric film, which was sputtered on the bolt surface, was used to generate ultrasonic and could avoid the measurement error caused by the application of the ultrasonic coupling layer. The relationship between the uneven stress area and the measurement error was obtained. The relationship between the properties of materials and the stress measurement of bolts was verified by the repeated experiments of acoustoelastic measurement after repeated stretching of bolts. The results show that the ultrasonic time difference is linear with the stress. The acoustoelastic coefficient is determined by the elastic modulus, Poisson''''s ratio and length of bolt. The error of the different ratios of uneven stress area is the same and the initial error is less than 2%. The error of measurement increases after the bolt is repeatedly stretched. The stress distribution can not produce measurement errors while measurement error comes from the non-uniformity of the material. After stretching the bolt, the defects and dislocation in the material increase which may enhance the scatter of high-frequence ultrasonic and amplify the error.

 

Key words: acoustoelastic; stress distribution; piezoelectric film; error

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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