共查询到20条相似文献,搜索用时 93 毫秒
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多疲劳裂纹扩展的声发射特性研究 总被引:1,自引:0,他引:1
用声发射对低强度材料LD31铝材和A3钢双疲劳裂纹扩展过程进行了监测,得到了声发射参数与裂纹扩展速率的对应关系。介绍利用后处理线定位参数调整及载荷滤波降低噪声的具体方法。 相似文献
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装甲车辆扭杆裂纹的声发射检测 总被引:1,自引:0,他引:1
采用常规的无损检测手段检测装甲车辆悬挂系统扭杆裂纹损伤比较困难。为了方便地检测扭力轴上的裂纹缺陷,提出了利用声发射技术在扭杆加载状态下,检测裂纹损伤的方法。为此基于虚拟仪器的原理,采用便携式工控机、高速数据采集卡、高灵敏传感器、手动液压加载装置构建了扭杆检测硬件系统,并编制了专用的检测定位软件。通过实际应用试验,成功地检测到了被测装备扭杆上的损伤。通过对比分析可得,基于声发射技术的动态检测方法是解决扭杆裂纹静态检测的有效办法。 相似文献
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基于LabVIEW软件平台,绘制了6063铝合金缺口试样低周疲劳试验的声发射特征参数统计图和累积图。通过与断口分析结果进行对比,划分出AE信号对应裂纹扩展的三个阶段,并且发现两次主裂纹合并对应着三个高强度脉冲信号。通过对裂纹扩展三个阶段的撞击数进行波形分析和频谱对比分析,得出6063铝合金低周疲劳的声发射信号特征频率为225~250kHz和350~500kHz. 相似文献
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Detection of fatigue crack propagation with acoustic emission 总被引:1,自引:0,他引:1
M.N. Bassim 《NDT & E International》1992,25(6):287-289
Since its inception, acoustic emission has held great promise as a tool for detection and evaluation of damage in structures. Of particular concern is the occureence of fatigue manifested by the processes of crack initiation followed by crack growth to failure. Early research related acoustic emission parameters to physical variables, including load, stress, pressure etc. causing damage. In this paper, relationships relating acoustic emission to fatigue crack growth are developed. Acoustic emission equations, similar to Paris' law, are derived which allow determination of the stress intensity factor and the crack growth rate. These principles are embodied in a second-generation system which automatically and continuously determines these parameters. The approach is applied in the laboratory as well as to structures including bridges, air frames and transmission towers for electrical power. 相似文献
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TC4ELI合金疲劳裂纹尖端塑性区对裂纹扩展的影响 总被引:1,自引:1,他引:1
研究了TC4ELI合金片层组织与短棒α组织中的疲劳裂纹尖端塑性区及裂纹扩展行为.首先通过SEM及TEM观察比较两种显微组织下的疲劳裂纹尖端塑性区,讨论两种显微组织中裂纹尖端塑性区对疲劳裂纹扩展路径及扩展断口的影响,分析裂纹扩展路径和裂纹尖端塑性区对裂纹闭合及裂纹扩展速率的影响.结果表明:与短棒α组织相比,片层组织中具有较大的裂纹尖端塑性区及曲折的裂纹扩展路径,并最终从疲劳裂纹闭合的角度,解释了片层组织具有较低的疲劳裂纹扩展速率的原因. 相似文献
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采用声发射(acoustic emission,AE)技术对7N01铝合金单边缺口三点弯曲试样不同应力比、不同峰值载荷下疲劳裂纹扩展过程中声发射信号进行了监测,建立了裂纹扩展速率、声发射计数(count)与应力强度因子之间的关系.结果表明,大部分的声发射信号主要产生于疲劳循环载荷的低应力阶段,这主要是低应力阶段的声发射活动主要与裂纹尖端的塑性变形和裂纹闭合现象有关,声发射计数与应力强度因子之间呈指数增长的关系.基于所建立的声发射计数率与裂纹扩展速率的关系,可以预测疲劳损伤结构的剩余寿命. 相似文献
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分别对裂纹尖端附近有塑性区和无塑性区的304不锈钢脉冲电流止裂试样进行了显微观察和纳米压痕试验。结果表明,有裂纹尖端塑性区的304不锈钢,在脉冲电流止裂后,止裂处发生了相变和再结晶,在温度场和应力场共同作用下分别形成了凝固区、细晶区和形变诱发马氏体区;而无裂纹尖端塑性区的304不锈钢,裂纹止裂处只有凝固区。纳米压痕试验表明304不锈钢的疲劳裂纹尖端处具有较大的残余应力,且残余应力随着远离裂纹尖端而迅速衰减;经过脉冲电流止裂后,裂纹尖端形变诱发马氏体的产生导致该处体积膨胀,产生相变应力,增大了裂纹止裂处周边的压应力值,这有利于抑制裂纹的二次扩展。 相似文献
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This paper describes two methods for calibration of the frequency response of transducers used in acoustic emission testing of concrete. The first uses two transducers to be calibrated coupled back-to-back. One of the transducers is excited by an input signal. The frequency response of the transducers is then deduced from analysis of the output signal. Two types of excitation may be used: sinusoidal excitation, which makes it possible to obtain the response point by point, and impulse excitation, which gives the frequency response directly. The second method uses the breaking of a pencil lead on the transducer face. The response obtained must then be corrected. Three types of transducers, used in specific applications for acoustic emission testing of concrete, are then characterized by these methods. 相似文献
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矿柱岩爆过程声发射的数值模拟 总被引:6,自引:1,他引:6
由损伤力学理论与微元强度统计理论,得到了岩石声发射参数与损伤参量的关系。应用自行开发的RFPA^2D程序对矿柱岩爆的物理过程进行了数值模拟,其结果再现了矿柱岩石微破裂诱致宏观破裂的演化过程以及和微破裂相关的声发射事件源的空间分布特征和事件序列特征。特别是考虑到材料非均匀性的影响,分析了不同粒度材料的模型产生不同岩爆模式的原因。同时研究了岩爆发生过程“平静期”和“损伤愈合”的特性以及在大的岩爆前有较小的声发射这种前兆出现的规律。 相似文献
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Determining the stress intensity factor of a material with an artificial neural network from acoustic emission measurements 总被引:1,自引:0,他引:1
An artificial neural (ANN) network was trained to recognize the stress intensity factor in the interval from microcrack to fracture from acoustic emission (AE) measurements on compact tension specimens. The specimens were made from structural steel SWS490B whilst the ANN had a 5-14-1 structure. The number of neurons in the input layers was five inputs of the AE parameters such as ring-down counts, rise time, energy, event duration and peak amplitude. The performance of the ANN was tested using a specific set of the AE data. The ANN is a promising tool for predicting the stress intensity factor of material using AE data. 相似文献