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实心圆柱镦粗(锻造)时产生的声发射(AE)所包含的信息有可能用于把镦粗过程区分为塑性变形区和塑性变形与裂纹并存区。本研究监测了圆柱形7075-T6铝试件镦粗时,从塑性变形的开始直到破裂整个过程所产生的AE信号。确定了作为有效应变的函数的计数率(N)和累积计数(N)。计数率数据的特点是具有三个明显不同的区域,即材料屈服时出现初始峰值的区域,塑性变形和同时发生试件几何形状变化时N逐步增加的阶段;以及随着裂纹开始产生而N迅速增加的最后阶段。累积计数和均方根(RMS)数据具有类似的图形。对应变范围内的累积计数数据的振幅分布作了分析,在振幅较高的发射区,可以看到塑性变形并产生表面裂纹时所得到的数据与只有单纯塑性变形时相比较,振幅分布变化高达二个数量级。如果作出对数计数(N)对信号振幅的图形,则结果是用最小二乘法得到的一条图线,提供了一个对变形程度敏感的乘方律关系。
The information contained in acoustic emission (AE) generated during upsetting of solid cylinders (forging) is likely to be used to differentiate upsetting into plastic deformation zones and plastic deformation and crack coexistence zones. This study monitored the AE signal generated from the beginning of plastic deformation until the rupture of the cylindrical 7075-T6 aluminum specimen during upsetting. The count rate (N) and cumulative count (N) were determined as a function of effective strain. Counting rate data are characterized by three distinct regions, namely, the area where initial peak occurs during material yielding, the stage of plastic deformation and the gradual increase of N as the geometry of the specimen changes at the same time, and the rapid increase of N as the crack begins to occur Increase the final stage. Cumulative counts and root mean square (RMS) data have similar graphs. The amplitude distribution of the cumulative count data in the strain range was analyzed. In the high-amplitude launch area, the plastic deformation and the surface cracked data were compared with those obtained by simple plastic deformation. The amplitude distribution changed up to Two orders of magnitude. If a graph of logarithm count (N) versus signal amplitude is made, the result is a line drawn by least squares that provides a power law relationship that is susceptible to deformation.