基于转角传感器板材滚弯成形曲率半径的测量

将转角传感器测量曲率半径方法应用于板材滚弯加工过程的成形检测之中,论述了采用转角传感器测量板材曲率半径的原理及其测量方法,通过试验研究分析得出该测量方法的优越性及造成测量误差的主要原因．     

型材滚弯数值模拟及应力、应变分析

用通用显式动力分析软件ANSYS/LS-DYNA成功实现了对型材弯曲件滚弯及其回弹过程的数值模拟.模拟结果表明,型材滚弯成形过程中,型材腹板应力中性层和应变中性层内移,而且应力中性层内移量大于应变中性层内移量.回弹后,等效弹性应变和等效应力的峰值变小.分析了型材弹塑性弯曲卸载过程中腹板截面的切向应力变化,模拟结果与理论分析一致.     

工字形截面偏心钢压杆考虑残余应力时的弯扭屈曲

本文以理想弹塑性材料为基础求解弯扭屈曲荷载,取用制订TJ17-74规范所用典型截面,考虑了焰割边钢板焊接工字形截面构件残余应力的影响。应用分支屈曲理论进行分析,将截面分为若干单元,编制了稳定系数φ_1的计算程序,算出了稳定系数φ_1。并将所算得的φ_1值与既有的试验结果和按三角形残余应力分布图形以及无残余应力时所算得的1值进行了对照比较,提出了简化方案。     

厚壁型钢冷弯应力分析

以厚壁矩形钢管为研究对象,在冷作硬化实验的基础上,对厚壁型钢的塑性弯曲应力沿板厚方向的分布进行解析分析,对其冷弯回弹应力进行数值模拟,将弯曲应力和回弹应力叠加计算冷弯厚壁型钢沿板厚方向的残余应力分布。结果表明,变形外区拉应力由钢板外表面向中性层递减,变化幅度较大;变形内区压应力变化幅度较小;残余应力沿板厚方向近似线性分布;切向残余应力较大,最大值出现在板带的中性层附近。研究结果与相关文献给出的测量结果基本一致。     

残余应力对卷边槽钢局部相关屈曲的影响

用有限条法对受压和受弯的卷边槽钢进行了弹性相关屈曲分析，在此基础上进一步分析了残余应力对卷边槽钢相关屈曲的影响，并提出了考虑残余应力时计算受压和受弯的卷边槽钢临界应力的建议公式     

2000m~3球罐残余应力、工作应力对比分析

报道了某炼油厂２０００ｍ３液化气球罐实际运行一年后的应力状况,对球罐的残余应力及工作应力进行了现场测试．采用Ｘ射线法,用日本理学公司生产的ＰＳＦ－２ＭＸ射线应力仪对残余应力进行了测试．测试结果发现球罐组装时虽经过整体热处理,但运行１年后局部残余应力仍高达０．９０σｓ等问题．为此采取了了局部热处理等措施．结果表明：残余应力总体水平有所降低,但仍存在个别点应力较高问题,需监控运行．     

钻孔法测量残余应力时双向等应力下孔边塑性变形对残余应力分析的影响

本文根据弹塑性理论基本方程,导出了高水平均匀残余应力场由于钻孔引起的松弛应变与残余应力的关系公式。利用所得关系,研究了孔附近塑性区对残余应力分析的影响。所得结果可用以对基于线弹性理论的残余应力值进行修正。     

不同喷丸工艺下残余应力沿深度的分布规律

不同喷丸工艺下残余应力沿深度的分布规律利用X射线衍射法系统研究了16种不同喷丸工艺产生的残余应力。每个工件取4个不同位置测点,每测点在表面下250μm范围内取8个测试深度,采用电解抛光进行剥层,结果表明:国产弹丸最大残余压应力出现在表面下50μm处,影响层深150μm;进口弹丸最大应力出现在50⁷5μm处,影响层深为200μm;喷丸工艺中抛头转速与阿尔门值成正比,随阿尔门值增大残余应力略有增加,但残余应力最大值与阿尔门值之间没有定量对应关系;喷丸后残余应力的影响层深度与弹丸特性有直接关系,而与抛头转速无关。     

高载作用下的疲劳裂纹闭合与残余应力作用

工程结构经常受到变幅载荷的作用,施加的高载对结构中的疲劳裂纹扩展有明显影响,了解高载作用机理对于随机载荷谱下的裂纹扩展预测十分重要。基于塑性诱导裂纹闭合原理,运用弹塑性有限元法模拟疲劳裂纹扩展。阐述了所采用的裂纹扩展模拟方法及确定裂纹张开和闭合应力的原理,计算获得等K基本载荷循环下的裂纹闭合特性和残余应力分布规律。重点分析在基本循环中插入单个拉伸超载、单个压缩超载和单个拉伸超载后紧跟单个压缩超载等情况下裂纹的张开、闭合应力及残余应力分布随裂纹扩展的变化规律。结果表明,超载在裂尖前方和裂纹尾迹区引起的压缩残余应力是导致裂纹闭合应力水平升高和裂纹扩展迟滞的重要原因。裂纹闭合效应在拉伸超载后瞬时减弱,但会随着裂纹扩展快速上升至超过正常水平;单纯的压缩超载对裂纹闭合的削弱可以忽略不计,但紧跟在拉伸超载之后的压缩超载将导致裂纹闭合效应减弱,削弱拉伸超载下的裂纹扩展迟滞效应。     

基于弹塑性变形理论的船体面板滚弯成形作业时间估算方法

为了准确估算船体面板滚弯成形作业时间,通过分析在滚弯过程中船体面板的弹塑性变化和滚弯成形后的最终状态,建立了滚弯成形最终状态下船体面板滚弯成形作业时间估算模型.与实测数据对比分析结果表明,基于弹塑性变形理论的总进给距离与实测进给距离无显著性差异,通过作业时间估算模型得出的理论作业时间与实测作业时间也无显著性差异而且相对误差都在10%以内(平均相对误差为5%).因此,基于弹塑性变形理论的船体面板滚弯成形作业时间估算模型合理且符合作业实际状况.     

Gauge-meter model building based on the effect of elastic deformation of rolls in a plate mill

The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge-meter model.     

Effect of Grinding and Polishing on the Residual Stress and Bending Strength of a Silicon Nitride Ceramic

The residual stresses on the surface of the differently ground and polished silicon nitride ceramics were measured using X- ray diffraction and identified by SEM. The effect of the residual stress on the bending strength was investigcaed. The investigatious show that the grinding process can introduce subatantial teusile residual stresses up to 290 MPa on the surface of silicon nitride ceramics, which has a significant effect on reducing the bending strength of the ceramics after grinding. Thus, in comparison with the ceramics with a rongh surface, the ceramics with a mirror image surface may bave a lower strength. Polishing can smooth the residual stresses. When we evaluate the quality of the ceramic components after grinding, we must take residual stress into consideration. The grinding methods and grinding conditions must be carefully selected in order to get the favorite residual stress as well as the surface smoothness.     

厚板焊接残余应力的测试

运用条形切割法 ,对桥梁、建筑等结构设计中常用的厚板焊接箱形杆件等构件的残余应力分布进行实例测试 ,通过对测试数据的分析整理 ,得出厚板焊接箱形杆件和 T形杆件截面纵向残余应力分布情况 ,为进一步总结焊接结构的残余应力分布规律提供了基础 .     

Influence of heavy metal stress on morphology and physiology of Penicillium chrysogenum during bioleaching process

In order to improve the efficiency of bioleaching heavy metal from the contaminated soil using Penicillium chrysogenum （P chrysogenum）, experiment was conducted to evaluate the influence of heavy metal stress on P. chrysogenum during bioleaching. The morphology and physiology of P chrysogenum were observed. Assuming that the heavy metals are all leached out from the experiment soil, heavy metals are added into the agar medium by simulating the heavy metal content in the soil. It is concluded that the survivable heavy metal contaminated soil mass range for P. chrysogenum is 2.5-5.0 g. As for biomass determination, the contaminated soil is added into the liquid medium directly. The soil mass that P.. chrysogenum can be survivable is in the range of 2.5-8.75 g. In this mass range, the biomass of P. chrysogenum is bigger than that of the control sample. 10 g soil mass is the threshold of the growth ofP chrysogenum. 102.2 mg/L gluconic acid, 156.4 mg/L oxalic acid, 191.6 mg/L pyruvic acid, 0.02 mg/L citric acid, 0.03 mg/L malic acid and 70.6 mg/L succinic acid are determined after 15 d bioleaching. The mycelium is broken into fragments, and heavy metals are adsorbed on the cell wall or transported into the cytoplasm during bioleaching. The GOD activity declines from 1.08 U/mL to 0.2 U/mL under 400 mg/L of multi-metal stress. The influence of Pb on GOD activity is bigger than that of Cr and Cd, and the GOD activity is not influenced apparently by Mn, Zn and Cu.     

梁板类构件焊接残余应力测试的试验方法研究

针对焊接梁板类构件内部残余应力分布规律难以确定的问题,基于屈服及刚度衰减条件,提出了一种测定焊接残余应力分布的试验方法.该方法以对接焊钢板及焊接工字型梁为对象,进行了纵向焊接残余应力分布的试验测试研究,并将试验结果与有限元数值模拟结果进行了对比分析,二者吻合较好.研究结果表明,该方法能够很好地确定板类及梁类焊接构件的纵向焊接残余应力分布规律,为钢结构设计提供一定的依据.同时该方法简单、精确,具有很强的工程实用和推广价值.     

变壁厚弯管工艺加热温度的检测与控制

加热温度的监测与控制 ,对热推变壁厚弯管工艺具有十分重要的意义。根据辐射测温原理 ,以单片机为核心设计出了光电比色测温系统。该系统用被测物的亮温替代实际温度 ,用查表程序由单片机自动校准误差 ,在 5 0 0～10 0 0℃范围内 ,相对误差为± 1%。该光电比色测温系统为曲锥芯棒上热推变壁厚弯管提供了有效的温度检测与控制方法。