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Acoustoelastic Spectrum Method for Nondestructive Residual Stress Measurements

用于无损残余应力测量的声弹谱法

基本信息

批准号：
03650091
负责人：
IWASHIMIZU Yukio
金额：
$ 1.22万
依托单位：
Ritsumeikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

The spectrum method for acoustoelastic stress analysis was studied experimentally. In main experiments, this method was applied to analyze plane stress distributions in two notched aluminum specimens. In the measurement, ultrasonic transverse waves were sent in the thickness direction, and their echoes were analyzed by FFT. First, the amplitude spectrum was used to determine the difference of two transverse velocities, and polarization directions. Since the orthogonality of polarization directions thus determined was not so satisfactory in the stressed state as in the stress-free state, the use of averaged orthogonal directions was shown necessary in this stress analysis. Applying these results to the acoustoelastic law of slightly orthotropic materials, the normal stress difference and shear stress were obtained, and each normal stress was subsequently determined by the shear difference method. Secondly, the normal stress difference was determined from the phase spectrum, and this new approach was confirmed very significant for further development of the spectrum method. Finally the availability of a small size transducer in the spectrum method was also confirmed. Though the stresses treated in these experiments were not residual ones, the obtained results are useful for nondestructive mesurements of residual stresses. For residual stress analysis, another experiments were carried out by using weld, and shrink-fit specimens of steel, and it was confirmed that the shear stress and normal stress difference were nondestructively determined by the spectrum method.

实验研究了声弹性应力分析的谱法。在主要实验中，应用该方法对两个缺口铝试样进行了平面应力分布分析。在测量中，超声横波沿厚度方向发送，利用FFT对其回波进行分析。首先，利用振幅谱确定两个横向速度差和极化方向；由于这样确定的极化方向的正交性在应力状态下不如在无应力状态下令人满意，因此在应力分析中有必要使用平均正交方向。将所得结果应用于微正交各向异性材料的声弹规律，得到了正应力差和剪应力，并利用剪应力差法确定了每个正应力。其次，从相谱中确定了正应力差，这对进一步发展谱法具有重要意义。最后也证实了小尺寸换能器在光谱法中的有效性。虽然这些实验处理的应力不是残余应力，但所得结果对残余应力的无损测量是有用的。在残余应力分析方面，采用焊接试样和收缩配合试样进行了试验，证实了用谱法可以无损地确定剪切应力和正应力差。