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针对304奥氏体不锈钢顺磁性材料的裂纹检测,提出一种基于盲源分离的弱磁信号处理方法。根据正交试验,设计制作4个304奥氏体不锈钢试件,利用弱磁检测仪器采集试件磁感应强度;针对预置人工凹槽裂纹磁异常彼此独立的特点,建立弱磁信号的混叠模型,开展基于主成分分析和盲源分离的数据处理,并与磁梯度法作对比;结合独立向量和峰度系数,对缺陷信号进行智能识别。结果表明:相比磁梯度法,采用主成分分析和盲源分离方法能有效提升弱磁技术检测效果,依据独立向量和峰度系数,可实现弱磁仪器对缺陷信号的智能识别,为具有类似磁学特征的材料检测和仪器开发提供了新的思路和方法。 相似文献
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奥氏体不锈钢具有良好的耐腐蚀性、高韧性和塑性,在石化特种装备和海洋结构中有着广泛应用。奥氏体不锈钢通常在高温、高压、强腐蚀介质中服役,结构表面可产生各种类型不规则裂纹缺陷,威胁结构安全服役。由于不导磁、弱导电、晶粒粗大的特性,传统无损检测对奥氏体不锈钢表面不规则裂纹检测和评估存在诸多挑战。提出基于交流电磁场检测(Alternating current field measurement,ACFM)技术的奥氏体不锈钢不规则裂纹可视化重构方法,建立奥氏体不锈钢不规则裂纹ACFM有限元仿真模型,分析不规则裂纹周围电磁场畸变规律,提出垂直方向磁场(垂直于试块方向磁场,称为Bz)图像梯度场的不规则裂纹表面轮廓可视化重构方法,利用不规则裂纹检测试验验证可视化重构方法的效果。结果表明,ACFM探头感应电流可在奥氏体不锈钢不规则裂纹端点聚集,聚集电流引起垂直方向磁场Bz畸变,Bz图像梯度场可反映电流聚集位置,Bz图像梯度场可视化重构方法能够实现奥氏体不锈钢不规则裂纹表面轮廓可视化成像显示及精确评估。 相似文献
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针对SUS304亚稳奥氏体不锈钢的摩擦问题,自制一台耦合摩擦与变形实验机,用来模拟SUS304亚稳奥氏体不锈钢的摩擦行为.利用PCL-812PG数据采集卡完成耦合摩擦实验机数据采集系统的硬件设计,整个系统由工控机、数据采集卡、力传感器、信号调理电路等几部分组成.采用VC++6.0作为测控系统的软件开发平台,结合DLL技术实现了在Windows环境下数据采集系统的实现.该数据采集系统能很好地采集实验中的耦合摩擦力,为进一步分析SUS304亚稳奥氏体不锈钢的摩擦行为提供了保证. 相似文献
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基于小波熵的微弱磁异常信号降噪处理 总被引:1,自引:0,他引:1
针对地下磁性掩埋物检测时,磁异常信号信噪比低的问题,提出基于小波熵的微弱磁异常信号降噪方法。小波变换对弱磁异常信号进行提取的关键在于确定小波系数的阈值。为此,引入反映信号能量分布特性的小波熵概念和一个调节因子,最终确定阈值,利用软阈值方法处理高频系数。通过计算机仿真对算法进行了检验。结果表明:该算法可以有效地提高信噪比,还原原始信号。 相似文献
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Taking electrolytic lapping stainless steel for example, the principle of electrolytic lapping with a magnetic field is described, the movement of charged particles in the magnetic field is analyzed in tems of theory. Using a computer, the motion loci of the charged particles in the magnetic field are simulated. The theory and the experiment show that the magnetic field can accelerate the diffusion and mobility of the charged particles, accelerate the electrochemical reaction and reduce the surface roughness of the work more quickly, which improves the lapping efficiency. 相似文献
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ABSTRACT Magnetic abrasive finishing (MAF) of alloy steel workpiece with unbounded magnetic abrasive particles (UMAPs) indicates that the surface finish in the range of nanometer can be achieved. Important controllable four process parameters have been identified which are as current to the electromagnet, machining gap, abrasive size (mesh number), and number of cycles. Experiments have been planned using design of experiments technique. Based upon the results of response surface methodology and analysis of variance (ANOVA), it is concluded that magnetic flux density that depends on current to the electromagnet and machining gap, is most influencing parameter followed by grain size and number of cycles. The surface roughness profile generated during the MAF process has been discussed. To understand the cutting mechanism of magnetic abrasive finishing process, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the machined surfaces have been carried out. The correlation between surface finish and material removal has also been established. 相似文献
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针对新近发展起来的降低钢铁工件中残余应力的脉冲磁处理方法作用规律较为复杂的现状,研究了磁处理降残余应力效果的外磁场方向这一关键因素。通过盲孔法在16Mn焊接应力试样上进行残余应力的研究,研究脉冲磁处理前后试样中的残余应力分布,并对不同外磁场方向导致的磁处理效果进行对比。试验结果表明,在其他处理参数相同的情形下,不同的外磁场方向可导致不同的磁处理效果:磁场沿最大主应力方向进行处理,残余应力变化不明显;而磁场与最大主应力方向垂直进行处理,可获得较为明显的残余应力降低效果。采用电阻应变片研究不同外磁场方向引起试样中的磁致伸缩,获得不同外磁场方向作用下试样中磁致伸缩的不同特征,分析认为,这与脉冲磁处理效果的方向敏感性密切相关。 相似文献
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Magnetic abrasive finishing (MAF) of alloy steel workpiece with unbounded magnetic abrasive particles (UMAPs) indicates that the surface finish in the range of nanometer can be achieved. Important controllable four process parameters have been identified which are as current to the electromagnet, machining gap, abrasive size (mesh number), and number of cycles. Experiments have been planned using design of experiments technique. Based upon the results of response surface methodology and analysis of variance (ANOVA), it is concluded that magnetic flux density that depends on current to the electromagnet and machining gap, is most influencing parameter followed by grain size and number of cycles. The surface roughness profile generated during the MAF process has been discussed. To understand the cutting mechanism of magnetic abrasive finishing process, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the machined surfaces have been carried out. The correlation between surface finish and material removal has also been established. 相似文献
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