Subsurface stress evaluation in steel plates and bars using the LCR ultrasonic wave
Subsurface stress evaluation in steel plates and bars using the LCR ultrasonic wave
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DOI：
10.1016/s0029-5493(01)00334-x
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发表时间：
2001-07-01
影响因子：
1.7
通讯作者：
Tang, W
中科院分区：
文献类型：
--
作者：
Bray, DE;Tang, W
焊接结构中的次表面应力增加了疲劳裂纹和环境引起的材料退化的可能性。评估焊接结构构件表面和内部应力的能力将大大提高结构寿命估计的准确性。临界折射纵波（L-CR）是一种在地表下有效深度内传播的体纵模。它可用于检测结构中的面内地下应力。过去，用L-CR波在冷轧钢板中进行的试验证明了它对近表面应力的评估能力。指定的L-CR波数据能够预测19 mm（0.75 in.）厚冷轧钢板。这种残余压应力通过盲孔钻孔法得到证实，并通过随后的热处理有效地消除。本文介绍了一种在长75 × 25 mm（2）（3 × 1 in. (3))钢筋四点弯曲。使用传统应变计和2.25或5 MHz L-CR探头组进行并排应力评估。在不同的应力水平下，5.0 MHz的数据几乎遵循表面应变计的数据，并显示出远大于2.25 MHz的数据所示的旅行时间的变化。这与计算的四点弯曲应力分布一致，其中高应力将分布在高频信号传播的外表面附近。对于每个频率，主动L-CR波将在限定的深度范围内与内部应力有效地相互作用，并在行进时间上产生可测量的变化。该技术在预测焊接结构和机械部件的内应力水平方面具有很高的潜力。(C)2001 Elsevier Science B. V.保留所有权利。
Subsurface stresses in welded structures increase the likelihood of fatigue cracks and environmental induced material degradation. The ability to evaluate stresses at the surface as well as in the interior of welded structural members would substantially increase the accuracy of structure life estimation. The critically refracted longitudinal (L-CR) wave is a bulk longitudinal mode that travels within an effective depth underneath the surface. It may be used to detect in-plane subsurface stresses in the structures. In the past, experiments of using the L-CR wave in the cold-rolled steel plates have proved its ability of evaluating near surface stresses. The designated L-CR wave data was able to predict the existence of surface compressive stress in a 19-mm (0.75-in.) thick cold-rolled steel plate. This residual compressive stress was confirmed by the blind-hole-drilling Method, and was effectively removed by a subsequent heat treatment. This paper presents a study of internal stress measurement in a long 75 x 25 mm(2) (3 x 1 in.(3)) steel bar under four-point bending. A side by side stress evaluation was conducted, using conventional strain gauge and 2.25 or 5 MHz L-CR probe set. At various stress levels the 5.0 MHz data almost followed the surface stain gage data and showed a far greater travel time change than that indicated by 2.25 MHz data. This is consistent with the calculated four-point bending stress distribution, in which high stress will be distributed near the outer surface where the high frequency signal is propagating. For each frequency, the active L-CR wave will effectively interact with the internal stress within a defined depth range and generate a measurable change on the travel time. This technique has high potential to predict internal stress level in welded structures and mechanical components. (C) 2001 Elsevier Science B.V. All rights reserved.