Creep damage characterization using non-linear ultrasonic techniques
Creep damage characterization using non-linear ultrasonic techniques
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DOI：
10.1016/j.actamat.2009.11.050
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发表时间：
2010-04
期刊：
影响因子：
9.4
通讯作者：
Jitendra S. Valluri;K. Balasubramaniam;R. Prakash
中科院分区：
文献类型：
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作者：
Jitendra S. Valluri;K. Balasubramaniam;R. Prakash
本文介绍了使用非线性超声技术的表征材料退化的99.98%纯铜由于高温蠕变。在不同的应力和温度水平下，对扁平狗骨形试样进行恒定载荷蠕变试验。蠕变损伤的进展进行连续和中断模式蠕变试验监测。在连续加载的情况下，非线性超声（NLU）测量进行断裂后，在不同的位置沿着标距长度的样品。对于中断测试，通过蠕变测试的周期性中断，对不同的蠕变寿命分数进行NLU测量。在所有的情况下，通过传输NLU测量技术被采用。三种不同的非线性测量，即静态位移，二次谐波和三次谐波，并比较它们的响应。发现NLU测量对蠕变损伤的程度（基准水平的200-2500%）显著敏感，而线性超声测量（代表纵向速度的变化）对于可比的蠕变损伤水平仅在10-30%的范围内。对断裂样品进行的NLU测量表明，与其他位置相比，即使在试样的标距长度内，在蠕变损伤集中的位置处，NLU响应局部较高。这一点通过显微镜观察得到了证实。三个非线性测量，三次谐波数据是最敏感的蠕变损伤。
This paper describes the use of non-linear ultrasonic techniques for the characterization of material degradation in 99.98% pure copper due to high-temperature creep. Flat dog-bone-shaped specimens were subjected to constant load creep testing at different stress and temperature levels. Creep damage progression was monitored by conducting continuous and interrupted mode creep tests. In the case of continuous loading non-linear ultrasonic (NLU) measurements were conducted after fracture at different locations along the gage length of the sample. For interrupted tests the NLU measurements were conducted on different creep life fractions, through periodic interruption of the creep test. In all cases a through transmission NLU measurement technique was employed. Three different non-linear measurements, namely static displacement, second harmonic and third harmonic, were taken and their responses compared. The NLU measurements were found to be significantly sensitive to the extent of creep damage (∼200–2500% of base level), while the linear ultrasonic measurements, representing the change in longitudinal velocities, were only in the range 10–30% for a comparable creep damage level. NLU measurements carried out on fractured samples suggest that the NLU response was locally high at locations where the creep damage was concentrated, compared with other locations, even within the gage length of the specimen. This was confirmed using micrograph observations. Of the three non-linear measurements, the third harmonic data was most sensitive to creep damage.