Dry three-body abrasive wear behavior of WC reinforced iron matrix surface composites produced by V-EPC infiltration casting process

This paper fabricated tungsten carbide (WC) particles reinforced iron matrix surface composites on gray cast iron substrate using vacuum evaporative pattern casting (V-EPC) infiltration process, investigated dry three-body abrasive wear resistance of the composites containing different volume fractions of WC particles, comparing with a high chromium cast iron. The fabricated composites contained WC particles of 5, 10, 19, 27, 36, and 52 vol.%, respectively. The results in abrasive wear tests showed that, with the increase in the volume fraction of WC particles, the wear resistance of the composites first increased until reached the maximum when the volume fraction of WC was 27%, then decreased, and was 1.5–5.2 times higher than that of the high chromium cast iron. The changes of the wear resistance of the composites with the volume fraction of WC particles and the mode of material removal in dry three-body abrasive wear condition were analyzed.     

汽车用超高强度钢的合金化方式及组织控制

超高强度钢因其优异的强度及塑韧性而在汽车行业得到广泛应用。针对汽车用超高强度钢,详细介绍了其合金化方式及强化机制,并详细阐述了奥氏体相及其相变所产生的组织增塑效应,以及对组织的调控方法。     

多孔储液介质自润滑机理研究进展

多孔储液介质是启发自关节软骨的仿生摩擦材料,因具有良好的自润滑性能,在工业生产中发挥着重要作用。早期多孔储液介质多是针对不同基体材料及骨架结构进行优化设计,或是根据单因素理想边界建立润滑数值模型,对多孔储液介质的润滑机理缺乏系统的理论描述,限制了其大规模的工业应用。根据不同的结构形式和润滑机理,将多孔储液介质分为有限直孔储液介质和随机多孔储液介质,总结了有限直孔储液介质中空化现象、流体运动、惯性效应、气-液耦合对润滑性能的影响,论述了基于渗流力学、流-固耦合作用的随机多孔储液介质自润滑理论的发展,以及多孔储液介质的应用现状。分析和讨论了多孔储液介质自润滑机理研究的难点问题,对推动多孔储液介质润滑机理的研究和工程实践应用具有重要的参考意义。     

[设备健康管理]深度置信网络在齿轮故障诊断中的应用

针对齿轮传动系统中齿轮等零部件易出现故障或失效等问题,提出了一种基于深度学习理论的齿轮传动系统故障诊断方法。首先利用深度置信网络强大的特征自提取能力,对齿轮传动系统的振动信号进行特征提取,然后通过DBNs的复杂映射表征能力对故障信号进行故障判别。诊断实例表明,若不对齿轮振动的原始时域信号进行特征提取,直接利用DBNs对其进行诊断时,故障识别正确率只能达到 60%左右;如果对时域信号进行简单的傅里叶变换后,再利用 DBNs 对处理后的振动信号频谱进行诊断分析,正确率能达到 99.7%,从而证明了所提故障诊断方法的简易性和有效性。     

Corrugated board bonding defect visualization and characterization

Adhesive bonding of fluted medium to linerboard is a fundamental process in manufacturing of wood-fiber based corrugated combined board for packaging. The quality of bonds requires frequent testing since production speed and container box stacking capacity are affected. Several different testing techniques are investigated in this paper that complement the standard tests commonly used: bond tensile strength “pin adhesion” (Technical Association of the Pulp and Paper Industry (TAPPI) method T 821), visual qualitative inspection of adhesive distribution by iodine stained separated components (TAPPI method T 610), and examination of manually peeled separated boards. A specially prepared corrugated board sample set was made on a pilot corrugating machine producing a range of bonding defects associated with common inadvertent improper corrugating operating conditions. A thermoelastic stress analysis using infrared image processing applied to the produced samples demonstrates a patterned localization of strains that is associated with adhesive distribution and bond strength. Analysis of load-displacement data of the pin adhesion test indicates significant measurable changes in the elastic properties of the corrugated board structure corresponding to bond quality. The experimental results supported by Finite Element Analysis indicate that increased bond strength arises from an increased localized modulus attributable to a combination of adhesive penetration into the substrate and formation of covalent bonds. Infra-red imaging of back-lighted board samples provides a complementary convenient means to assess the glue distribution.     

基于BITD和同态滤波解调的齿轮故障诊断方法

针对齿轮故障振动信号的非平稳特征以及本征时间尺度分解(ITD)方法的缺点,提出了B样条改进的本征时间尺度分解(BITD)和同态滤波解调相结合的故障诊断方法。首先采用BITD方法对齿轮振动信号进行分解,将其分解为若干个合理旋转分量之和,然后用相关系数筛选出最能表征故障信息的合理旋转分量进行同态滤波解调来提取故障特征。仿真信号与齿轮故障诊断工程实例分析验证了该方法的有效性。     

海洋拖曳绞车液压系统设计与仿真研究

针对海洋拖曳系统作业过程中缆长调整、拖曳及应急回收的特殊工况需求,进行海洋拖曳绞车液压系统设计与研究。结合不同工况特点和技术要求,提出了海洋拖曳绞车液压系统方案;运用AMESim软件进行建模仿真,验证了方案的可行性。在此基础上,以缆长调整工况为例,分析了机械等效转动惯量、可调节流阀开度、蓄能器以及考虑波浪因素对负载速度波动的影响。结果表明:适当增大机械等效转动惯量和可调节流阀开度、增加蓄能器可以提高负载运动的平稳性;波浪力幅值和频率对负载速度波动有较大的影响。     

结构拓扑优化参数的正交试验设计

基于正交试验设计方法,针对结构拓扑优化中体积系数、惩罚因子和控制半径等参数的组合问题,设计了9种不同的试验组合方案,利用MATLAB软件对这9种方案进行了仿真试验分析,采用极差分析法和方差分析法对仿真结果进行了分析,优选出了结构的刚度达到最大、目标函数的迭代步数最少的参数组合方案,该方案在结构拓扑优化设计中具有较强的泛用性。     

金属材料表面静摩擦学特性的预测研究——理论模型

对分形几何理论进行了改进,在此基础上建立了法向载荷、最大静摩擦力、静摩擦系数的改进分形模型。通过中间自变量实际接触面积,构建了金属材料结合面静摩擦学特性的预测模型。计算和分析表明：静摩擦系数随着法向载荷或材料特性的增大而微凹弧式增大,但随着分形粗糙度的增加而微凹弧式减小;当分形维数较小时,静摩擦系数随着分形维数的增加而增加;但当分形维数较大时,静摩擦系数随着分形维数的增加而减小;在双常用对数坐标系统下,最大静摩擦力与法向载荷大多呈现出线性正比的关系;分形几何理论适用于法向载荷极小的情况。