ABSTRACT The ultrasonic nonlinear parameter is measured from the amplitudes of the harmonic frequency components generated during the propagation of ultrasonic waves in a material. There are two definitions for this parameter: absolute and relative. The absolute parameter is defined by the displacement amplitude; however, it is difficult to measure because of the very small displacement amplitude of the harmonic components. Conversely, the relative parameter is defined by the amplitude of the detected signal, regardless of displacement. Many researchers use the relative parameter because it is easier to measure, although it is only available for a relative comparison of different materials. However, it has not yet been verified that the ratio of the relative parameters between two materials is identical to that of the absolute parameters. In this study, we make it clear that the ratio of the relative parameters is inherently not identical to that of the absolute parameters, but that they can be identical to each other by compensating for material-dependent differences, such as detection-sensitivity and wavenumber. For verification, the absolute and relative parameters were measured for two different materials. The results showed that the ratios of absolute and relative parameters were in good agreement after compensation.

中文翻译：

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超声波非线性参数的绝对测量和相对测量

摘要 超声波非线性参数是根据超声波在材料中传播过程中产生的谐波频率分量的幅度来测量的。该参数有两个定义：绝对和相对。绝对参数由位移幅度定义；然而，由于谐波分量的位移幅度很小，因此很难测量。相反，相对参数由检测信号的幅度定义，与位移无关。许多研究人员使用相对参数是因为它更容易测量，尽管它仅适用于不同材料的相对比较。但是，尚未验证两种材料之间的相对参数的比值是否与绝对参数的比值相同。在本研究中，我们明确了相对参数的比率本质上与绝对参数的比率不同，但它们可以通过补偿材料相关的差异（例如检测灵敏度和波数）而彼此相同. 为了验证，测量了两种不同材料的绝对和相对参数。结果表明，补偿后绝对参数与相对参数的比值符合较好。测量了两种不同材料的绝对和相对参数。结果表明，补偿后绝对参数与相对参数的比值符合较好。测量了两种不同材料的绝对和相对参数。结果表明，补偿后绝对参数与相对参数的比值符合较好。