Acoustic softening – Investigation of the volume effect and introduction of amplitude strain parameter
Acoustic softening – Investigation of the volume effect and introduction of amplitude strain parameter
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DOI：
10.1016/j.msea.2023.145437
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发表时间：
2023-07
期刊：
影响因子：
--
通讯作者：
Randy Cheng;S. Rose;A. Taub
中科院分区：
文献类型：
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作者：
Randy Cheng;S. Rose;A. Taub
声软化是一种现象，其中金属表现出较低的流动应力时，由振动在超声频率激发。这种软化效应在文献中已有很好的记载，但是，有两个方面需要进一步深入分析。第一个涉及到广泛的报告软化反应相同的合金。第二个涉及到使用系数和补偿因子时，在一个复杂的成形过程中的声学软化现象建模。本研究探讨在超音波辅助压缩试验中，当改变试件尺寸时，软化反应的变化。将2024-O和7075-O两种铝合金加工成不同尺寸，并在超声辅助下进行压缩，研究试样体积与软化响应之间的关系。发现软化幅度与试样体积成反比关系，当与声能密度和应力相关时，其值是不变的，因为标准声学方程不能解释试样高度的变化。振幅应变参数，振幅除以当前的试样高度，被引入，并示出占试样尺寸的变化。此外，软化效应相对于应变状态减小。结果表明，声软化是幅值应变参数和应变历史的函数。
Acoustic softening is a phenomenon where metals exhibit a lower flow stress when excited by a vibration at ultrasonic frequencies. This softening effect has been well documented in the literature, however, there are two areas that require further in-depth analysis. The first relates to the wide range of reported softening responses for the same alloy. The second relates to the use of coefficients and compensation factors when modeling the acoustic softening phenomenon in a complex forming processes. This study investigates the changes in softening response when altering specimen dimensions in ultrasonic assisted compression tests. Aluminum alloys (AA) 2024-O and AA7075-O were machined to different dimensions and compressed with ultrasonic assistance, to investigate the relationship between specimen volume and softening response. An inverse relationship between softening magnitude and sample volume was found. When relating this to acoustic energy density and stress, the values are invariant because the standard acoustic equations cannot account for changes in specimen height. The amplitude strain parameter, amplitude divided by the current specimen height, is introduced, and shown to account for changes in specimen dimensions. In addition, the softening effect diminishes relative to the state of strain. The results suggest acoustic softening is a function of the amplitude strain parameter and strain history.