由气水流场耦合求解圆板的垂直等速入水

为探讨气流对入水空泡的影响以及计算非定常空泡面上的压力分布，本文提出了一个用自由面和物面上的边值同时求解气、水流场的方法，对圆板垂直等速入水算例，获得了空泡深闭合的结果。空泡内压力在深闭合时的骤增趋势与实验一致。表明本方法用于计算存在自由面的二层不掺混不可压势流问题是有效的。     

设置垫板的形件螺栓连接滞回性能试验研究

该文综述了对称和非对称型摩擦耗能连接40多年以来的发展历史和研究现状。摩擦耗能连接可用于结构的减震耗能,通过合理设计可实现地震作用下带摩擦耗能连接结构的低损伤,提高结构的韧性。研发滞回性能稳定、重复性好的摩擦耗能连接是相关研究的主要目标之一。该文从微观和宏观两个方面介绍了金属滑移面之间的摩擦磨损机理,从摩擦磨损的角度讨论了不同摩擦片材料对摩擦连接减震性能的影响。描述了螺栓预紧力大小对摩擦连接减震性能的影响,也总结了摩擦连接的抗腐蚀和抗火性能。阐述了摩擦耗能连接在钢结构支撑、梁柱节点和柱脚节点的应用,并介绍了相关节点的设计方法。对此类连接的关键技术进行了总结,并对该技术的后续研究进行了展望。     

An apparatus and a method for determining the slip resistance of shoes and floors by simulation of human foot motions

An apparatus to measure the coefficient of kinetic friction (μ_k) between the shoe sole and the underfoot surface was constructed, and a method including criteria to evaluate the risk of slipping during walking was developed. The apparatus is a prototype stationary step simulator capable of simulating the movements of a human foot and the forces applied to the underfoot surface during an actual slip, and the drainage capability of the contact surface between the shoe sole and the flooring when different lubricants or contaminants are used.

The apparatus consists of a movable artificial foot controlled by a computer with the aid of three hydraulic cylinders. The frictional force (F_μ), the normal force (F_N) and their ratio (μ_k = F_μ/F_N) are measured with a two-way force platform when the foot slides along its surface. Two separate gait patterns, heel-slide (μ_k1) and sole-slide (μ_k2) gait pattern, are used for the evaluations. The method classifies studied shoe, lubricant and underfoot surface combinations into five slip resistance classes according to the measured μ_k1 The slip resistance assessments are specified with some complementary safety criteria, e.g., the ratio μ_k1/ μ_k2 The reliability of the developed measurement method was assessed in an international comparison test. According to available results discussed in this paper, our method seems to be valid and the slip resistance measurements seem to be repeatable.     

Available friction of ladder shoes and slip potential for climbing on a straight ladder

Straight ladder accidents are a major safety problem. As a leading cause of injuries involving straight ladders, slips at the ladder base occur when the required friction exceeds the available friction at the ladder shoe and floor interface. The objectives of this experiment were to measure the available friction at the base of a portable straight ladder in contact with a floor and to estimate the slip potential of the ladder. The results of friction measurements indicated that the measured friction coefficient on the oily surfaces differed among the six commercially available ladder shoes evaluated. A statistical model was used to compare the available friction results from the current study with the friction requirements under different climbing conditions from a previous study based on their stochastic distributions to estimate the slip potential at the base of the ladder. The results showed that different climbing conditions used in the previous study could be supported by available friction on dry surfaces. However, when the ladder was put onto oily surfaces, resulting in a significant reduction in the available friction due to contamination, slip potential was significantly increased.     

Balance control during lateral load transfers over a slippery surface

Few studies have measured balance control during manual material handling, and even fewer with environmental cofactors. This study examined the effect of different surface frictions during a stationary manual material handling task. Thirty-six healthy participants completed 180° lateral transfer tasks of a load over high- and low-friction surfaces (μ = 0.86 and μ = 0.16, respectively). Balance measures, stance kinematics and lower extremity muscle activities were measured. Success during the novel slippery surface dichotomised our population, allowing us to investigate beneficial techniques to lateral load transfers over the slippery surface. Stance width reduction by 8 cm and 15° of additional external foot rotation towards the load were used to counter the imbalance created by the slippery surface. There was no clear alteration to lower extremity muscular control to adapt to a slippery surface. Changes in stance seemed to be used successfully to counter a slippery surface during lateral load transfers.

Statement of Relevance: Industries requiring manual material handling where slippery conditions are potentially present have a noticeable increase in injuries. This study suggests stance configuration, more so than any other measure of balance control, differentiates vulnerability to imbalance during material handling over a slippery surface.     

塑料材料的摩擦学性能研究综述

述了塑料材料摩擦、磨损的研究概况,详细阐述了摩擦因数、载荷、温度、速度、润滑、表面粗糙度pv值和热性能等因素对塑料材料摩擦性能的影响,介绍了磨损的衡量标准和测量方法.     

摩擦试验机数据采集与处理系统设计

基于摩擦试验机对计算机采集与处理数据功能的要求,采用串口通信方法,结合VB语言编程,设计了试验机的数据采集卡和数据处理系统。实验测试表明,该数据采集和处理系统能完成摩擦信号的实时动态采集、实时数据处理和数据动态显示。系统工作可靠,测试数据准确。     

摩擦对电动直线负载模拟器的影响及其抑制研究

为抑制摩擦非线性因素对电动直线负载模拟器（ELLS）的影响,采用仿真与实验结合的方法分析摩擦对ELLS的影响。利用遗传算法对系统中的摩擦模型进行辨识,并得出了系统摩擦力与速度的关系;提出了一种摩擦前馈加变增益PID的混合控制方法,摩擦前馈用于消除摩擦对系统的影响,变增益PID用于进一步抑制系统在低速时的相位滞后;进行了对比仿真与实验。仿真分析与实验结果表明：与传统PID控制相比,采用摩擦前馈加变增益PID控制的ELLS加载波形畸变被抑制、加载误差与相位滞后均明显减少;所提出控制方法能够较好地抑制摩擦对ELLS的影响,提高加载精度。     

发射药颗粒间摩擦系数测定及其对装填密度的影响

为测量发射药颗粒间的摩擦系数并探究其对装填密度的影响,以表面涂有石墨的发射药颗粒为研究对象,采用传统的斜面仪来测量静摩擦系数; 对于滚动摩擦系数的测定,基于离散单元法,模拟发射药颗粒堆积过程,得到模拟堆积角与滚动摩擦系数间的线性拟合方程,再基于实验所测堆积角进行参数标定获取参数值,二次拟合结果说明该参数测定方法可行。模拟结果表明,堆积角随着滚动摩擦系数的增大而增大。通过模块装填模拟,探究摩擦系数对装填密度的影响,结果表明,随着摩擦系数的增大,模块所装发射药的颗粒数越小,装填密度越小,说明摩擦系数对模块装填密度的影响是一个不可忽略的因素。     

基于响应面中心复合设计的固体推进剂摩擦感度理论

为了确定固体推进剂生产过程中的各因素对摩擦感度的影响,采用响应面法(RSM)与中心复合试验设计(CCD)相结合,以摆锤角度、滑柱压力、试样温度为影响因素,以固体推进剂摩擦感度值为响应值设计试验,采用摩擦感度测试仪进行试验,并分析试验结果拟合了响应面模型。结果表明,在三个响应面评价精度指标中,相对均方根误差为0.14、决定系数R~2为0.9309、校正拟合度R_(adj)~2为0.8686,说明方程拟合精度高且误差小;由模型方差分析得方差比值F为14.96,表明模型对响应面的影响程度较高;概率值p为0.0001,表明模型有0.01%的概率对响应面无影响;响应曲面图表明了各因素之间的相互作用;优化模型得到最小摩擦感度值所对应的三因素范围为角度小于45°,压力小于2 MPa,温度小于45℃。