To avoid the serious accidents caused by the failure fastening bolts on reciprocating compressor cylinder cover,a new nondestructive testing(NDT) technology,metal magnetic memory(MMM) testing,was applied to safety eva...To avoid the serious accidents caused by the failure fastening bolts on reciprocating compressor cylinder cover,a new nondestructive testing(NDT) technology,metal magnetic memory(MMM) testing,was applied to safety evaluating and failure analyzing for the fastening bolts.Based on the dynamic stress calculation of the failure bolts,MMM testing was carried out at workshop.Given are the MMM stress distribution characteristics of the failure bolts and fracture faces.It has been found that the MMM signal variation amplitude of the crack transition zone in the fracture surface is minimal,that of the crack initiation zone is in the middle,and that of the tear fracture zone is maximal.The failure reasons were analyzed with MMM effect.The results of the metallographic examination showed that the validity and feasibility of MMM testing and failure analysis.This means MMM technology is a new,fast and validity method of failure analysis.展开更多
溜井放矿过程中贮矿段井壁的磨损破坏程度与井壁动态应力的分布特征密切相关。以金山店铁矿主溜井为工程背景,基于Janssen公式,引入超压系数,推导贮矿段井壁动态应力的理论计算公式,计算不同高度处井壁动态应力的理论值;采用颗粒流程序...溜井放矿过程中贮矿段井壁的磨损破坏程度与井壁动态应力的分布特征密切相关。以金山店铁矿主溜井为工程背景,基于Janssen公式,引入超压系数,推导贮矿段井壁动态应力的理论计算公式,计算不同高度处井壁动态应力的理论值;采用颗粒流程序模拟主溜井放矿过程,分析贮矿段井壁动态应力的分布特征;基于自主研发的溜井放矿相似试验平台,配合应变仪,对放矿过程中贮矿段井壁不同高度处的应变值进行监测,通过应变仪的率定参数将其转换为对应的动态应力值。将理论计算、数值模拟所得结果与相似试验所得井壁动态应力及井壁磨损分区范围进行对比。研究表明:理论计算、数值模拟、相似试验所得井壁动态应力的最大相对误差率在19%以内,验证了理论计算公式的合理性;三者所得井壁动态应力的均值在放矿口以上(5.0 m,15.0 m)范围内均超过了228 k Pa,在(15.0 m,30.0 m)范围内均不足204 k Pa,分别对应于相似试验中井壁的重磨损区及轻磨损区;井壁动态应力越大则井壁磨损程度越重,从力学角度解释了贮矿段井壁磨损破坏程度差异的原因。展开更多
基金Sponsored by the National Natural Science Foundation of China (Grant No. 11072056)Natural Science Foundation of Heilongjiang Province of China(Grant No.A200907)Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20092322120001)
文摘To avoid the serious accidents caused by the failure fastening bolts on reciprocating compressor cylinder cover,a new nondestructive testing(NDT) technology,metal magnetic memory(MMM) testing,was applied to safety evaluating and failure analyzing for the fastening bolts.Based on the dynamic stress calculation of the failure bolts,MMM testing was carried out at workshop.Given are the MMM stress distribution characteristics of the failure bolts and fracture faces.It has been found that the MMM signal variation amplitude of the crack transition zone in the fracture surface is minimal,that of the crack initiation zone is in the middle,and that of the tear fracture zone is maximal.The failure reasons were analyzed with MMM effect.The results of the metallographic examination showed that the validity and feasibility of MMM testing and failure analysis.This means MMM technology is a new,fast and validity method of failure analysis.
文摘溜井放矿过程中贮矿段井壁的磨损破坏程度与井壁动态应力的分布特征密切相关。以金山店铁矿主溜井为工程背景,基于Janssen公式,引入超压系数,推导贮矿段井壁动态应力的理论计算公式,计算不同高度处井壁动态应力的理论值;采用颗粒流程序模拟主溜井放矿过程,分析贮矿段井壁动态应力的分布特征;基于自主研发的溜井放矿相似试验平台,配合应变仪,对放矿过程中贮矿段井壁不同高度处的应变值进行监测,通过应变仪的率定参数将其转换为对应的动态应力值。将理论计算、数值模拟所得结果与相似试验所得井壁动态应力及井壁磨损分区范围进行对比。研究表明:理论计算、数值模拟、相似试验所得井壁动态应力的最大相对误差率在19%以内,验证了理论计算公式的合理性;三者所得井壁动态应力的均值在放矿口以上(5.0 m,15.0 m)范围内均超过了228 k Pa,在(15.0 m,30.0 m)范围内均不足204 k Pa,分别对应于相似试验中井壁的重磨损区及轻磨损区;井壁动态应力越大则井壁磨损程度越重,从力学角度解释了贮矿段井壁磨损破坏程度差异的原因。
