Evaluation of two models of a slipmeter

The aim of the study was to compare the performances of the Brungraber Mark II (BM II) and Mark III (BM III) slipmeters. Friction measurements with the two slipmeters were conducted in a laboratory using four footwear materials, four floor types, and three surface conditions. Both the coefficient of friction (COF) values obtained with the slipmeters and the force platform-based COF values were measured. The COF measured with the BM II was slightly higher than that measured with the BM III with a R² of 0.83. A comparison of the averaged normal force between the two slipmeters showed that the BM II generated a significantly higher normal force than the BM III at a low COF and the difference of the normal force between the two slipmeters decreased when the COF value was increased. The regression analysis results in this study showed that the force platform-based COF values were closer to the COF values obtained with the BM III than with the BM II. The R² values for the regression model between the COF values obtained from the slipmeter and the force platform were 0.90 and 0.79 for the BM II and BM III, respectively.     

后扣板冷挤压工艺及模具

此文分析了产品成形的特点,模具承载的负荷特点,从而在成形工艺上、润滑上、模具结构及选材上采取了相应的措施.用H-4水基高分子润滑剂和3Cr2W8V制作冷挤压模都取得了明显效果.     

一种特殊形状制件的成形工艺

对弹匣前口板这种特殊形状制件成形工艺进行了讨论,找到了一种具有较高材料利用率,较高生产效率及简便易行的成形方法.     

A comparison of required coefficient of friction for both feet in level walking

The required coefficient of friction (RCOF) is one of the critical elements in determining whether a slip incident might occur. Most researchers, when measuring RCOF, do not differentiate between the two feet of the same participant under the same walking condition. Results from a recent study (Chang et al., 2010) indicated that the stochastic distributions of the RCOF of both feet were different in 76% of the cases. Using the previous data (Chang et al., 2010), this paper presents a comparison of the RCOF for both feet of 50 participants under four level walking conditions resulting from two footwear types and two walking speeds using a t-test, commonly used by safety professionals to compare two pools of data. The current results indicated that 78% of the RCOF data showed a statistically significant difference between the RCOF from two feet for the same participant under each walking condition. The results of the logistic regression analysis used to identify factors that contributed to the outcome of the t-test indicated that the walking speed was the only factor with a statistical significance (p = 0.044).     

锚索拉断火花引爆瓦斯的实验研究

设计了锚索拉断火花引爆瓦斯实验装置 ,在瓦斯浓度为爆炸范围的环境中 ,对锚索拉断时产生火花规律及引起瓦斯爆炸的可能性进行了一系列实验研究。结果表明 :锚索拉断产生火花的概率为 5 0 % ,锚索钢绞线破断产生的火花不能引起瓦斯爆炸。采用红外热成象仪对锚索拉断火花温度的测试表明 ,锚索拉断产生的火花最高温度远小于瓦斯爆炸所需的最低点燃温度 6 5 0℃。     

摩擦压砖机缓冲逆动式安全装置

针对摩擦压砖机发生的伤害事故,研制出一种新型实用的摩擦压砖机安全装置,能有效地减少事故的发生。     

工业固废填埋场边坡防渗层环境安全分析

考虑了固废沉降的力学作用及坡角平台的影响机理,建立了尾矿渣、防渗膜及垫层相互作用的力学简化模型,应用平衡微分方程,结合边界条件,得到了防渗膜拉应力与位移的解析解及膜内最大拉力计算公式。最后,结合工程设计分析研究了重要参数对膜完整性的影响,并提出了相关解决机制。从力学机理上指导填埋场边坡防渗设计,具有很高的工程实际应用价值。     

Inertia welding for assembly of copper squirrel cages for electric motors

The automotive industry is developing designs and manufacturing processes for new generations of electric motors intended for use in hybrid and electric vehicles. There is interest in replacing the aluminum traditionally used in induction motor rotors with copper to improve motor capability. This paper focuses on solid-state welding to join copper end rings to copper spokes in the fabrication of copper rotors. Inertia friction welding was explored to examine weldability of these copper components. A better understanding of inertia welding characteristics will help the advancements in its application for induction rotors. The limitations of this application are discussed.     

不同物质组合摩擦火花引燃特性的研究

在本研究中,对碳钢、铍青铜和铜镍锰合金等三种金属与砂轮和45号钢轮摩擦时产生火花的能力和引燃能力作了对比实验。用于实验的可燃混合气为液化石油气/空气和氢/空气。实验表明,碳钢和砂轮摩擦产生的火花最强烈,但仍很难引燃液化石油气/空气混合气;铍青铜与砂轮摩擦时几乎看不到火花,铜镍锰合金在同样条件下产生火花的几率销大。在摩擦时间较长的条件下,两者均能引燃极易爆炸的氢/空气混合气,但爆炸却并不是在火花出现时立即发生的。可以推断:在上述条件下,摩擦造成的炽热表面是引燃的主要原因,而材料的引燃能力的强弱,不能只以是否产生火花为判断基准。     

拉延成形中拉延筋的摩擦分析

此文建立了一种用拉延筋单元模拟试验器测试拉延筋摩擦系数的方法,同时对成形中的摩擦润滑进行了试验研究和分析。