微米木纤维模压制品握钉结合部载荷分布及最佳分布条件

微米木纤维模压制品是一种新型高强度人造木基材料制品,其握钉力的计算及握钉结合部合理结构的设计均与握钉结合部的载荷分布情况有关。笔者以弹性力学为基础,分析了握钉结合部的受力和变形关系,运用数学手段,推导出微米木纤维模压制品握钉结合部载荷分布的一般计算公式,证明了载荷分布曲线是一条内凹曲线,并提出了最佳分布条件。     

微米木纤维模压制品螺钉连接强度可靠性优化设计

微米木纤维模压制品是通过木材细胞劈裂而成的微米木纤维模压成型的新型高强度人造木基材料制品,本文对其螺钉连接强度进行了可靠性优化设计,将优化设计与可靠性设计有机地结合起来。在满足一定可靠度的同时,迅速取得一组最佳结构参数,为微米木纤维模压制品螺钉连接提供了有效的设计方法,对该种新材料制品的推广具有重要的实际应用价值。     

车用微米木纤维模压制品设备的研究与实验

微米木纤维模压制品是一种新型人造木基复合材料制品,具有超高密度和超高强度,主要应用于汽车异型内饰零件,用来替代价格较贵的实木制品和强度较差的塑料制品,既有天然实木制品的外观又有优于实木制品的力学特性.文中研究了微米木纤维模压制品的制备方法,设计了专用模压设备,阐述了实验方法,介绍了模压工艺,获取了关键工艺参数,为产品产业化推广奠定了重要基础,将促进我国汽车装饰零件的发展.     

玻璃纤维增强不饱和聚酯基复合材料的力学性能

采用质量分数为20%的连续玻璃纤维和质量分数为10%的短切玻璃纤维以模压工艺制备不饱和聚酯基复合材料,研究了纤维类型对复合材料模压工艺以及力学性能的影响,并与质量分数为30%连续纤维增强的不饱和聚酯基复合材料进行了对比。结果表明:与连续纤维增强不饱和聚酯基复合材料相比,连续纤维与短切纤维混合增强复合材料的拉伸性能和弯曲性能略有下降,但模压工艺性能和压缩性能有所提高,纤维在基体中分布较为均匀,纤维相互交叉,散乱分布。     

废旧塑料材料模压制品的压制工艺探析

以废旧塑料为主要原材料,研究了影响塑料热压成型材料模压制品质量的因素,分析了塑料材料模压制品的压制工艺过程,期望找到塑料废弃物资源化的一种新技术和替代品。     

涂层长纤维复合材料应力场的等温解

用四层同心圆柱体模型对以由Ni涂层碳素纤维和金属Al基所构成的复合材料为例的涂层长纤维复合材料在恒温或绝热条件下承受机械载荷后的应力进行了计算,获得了其应力分布情况.     

树脂基复合材料内部离面位移场和应变场分布的动态测量

为了快速动态测量树脂基复合材料内部的受力变形情况,利用光学干涉谱域相位对照B扫描方法,对存在孔洞缺陷的树脂基复合材料样件内部的离面位移场和应变场进行了测量。分别对机械载荷和热载荷作用下的复合材料样件进行了弯曲变形和热变形实验,然后对实验中得到的相位差数据进行解卷绕,计算得出了材料内部的离面位移场分布和应变场分布。实验显示:得到的结果能够清晰反映复合材料内部缺陷周围受力变形的动态过程,观测到的材料应力集中区域的位移和应变明显大于完好部分,透视得到了测量材料表层以下1mm连续深度的变形情况。该方法能够实现亚微米级的位移场测量精度,并可对材料的变形过程进行动态测量,是一种进行材料力学特性分析的有效手段。     

纤维增强复合材料涡轮轴结构静强度计算与分析

基于适用于纤维增强复合材料的细观力学代表体积元(RVE)法和材料强度失效参数计算公式,计算体积分数为40%的SCS-ULTRA纤维增强TC17基复合材料的力学性能参数和强度失效参数,建立以实际某型号发动机低压涡轮轴为背景,并用SCS-ULTRA纤维增强TC17基复合材料代替原有高温合金材料,应用复合材料宏观强度准则中的蔡—吴张量失效准则,对其进行静强度计算与失效判定,总结作为衡量趋近失效程度的蔡—吴强度指数随轴结构复合材料铺层数的变化规律,同时对铺层总数为27层的轴结构进行给定载荷下的强度计算,得出轴结构内部每一铺层的强度指数及铺层强度指数随铺层位置、45°铺角不同的变化规律,并预测在极限载荷下轴结构铺层首先出现失效的情况。     

微米SiCp增强铝基复合材料摩擦磨损性能研究

以微米级(14μfm)SiCp和微米级Al粉(100～200目)为原料，采用冷压烧结和热挤压方法制备出不同体积分数的微米SiCp增强Al基复合材料，研究了它的耐磨性能。结果表明在较高载荷下，SiCp的体积分数为1．5％和5．0％的SiCp／Al基复合材料耐磨性比市售挤压态锡青铜QSn6．5—0．4和纯Al高得多，且随SiCp含量增加，复合材料的耐磨性能提高；磨损表面形成Al基体 弥散分布SiCp的理想耐磨组织。     

芳纶-预氧化丝混杂纤维增强橡胶基密封复合材料的配方设计及优化

选择橡胶粘结剂、增强纤维、增容组分作为试验因素，以芳纶-预氧化丝混杂纤维增强橡胶基密封复合材料（NAFC）高温时效处理后的残余横向抗拉强度为指标，采用3分量有下界约束的混料回归设计法对NAFC材料的配方进行了优选，得到了模压制备工艺下混杂纤维增强NAFC材料的最优配方。并对该材料的应力松弛率、压缩回弹率、泄漏率和耐油性等基本性能进行了测试，其基本性能达到了中国国家标准的要求，且部分指标已接近或超过了国外知名企业同类产品的水平。     

Distribution of loads in zone of contact between wooden insert and inner ring of radial-thrust self-lubricating sliding bearing

Regularities of load distribution in the zone of contact between the wooden insert and inner ring of the radial-thrust self-lubricating sliding bearing are considered. They are determined on the basis of the study of strength properties of the wooden-polymeric bearing material and the development of the calculation criteria of finding contact stresses and deformations in the bearing.     

内压载荷下复杂薄壁箱形结构承载能力的试验研究

薄壁装配式不锈钢水箱是近年来广泛使用的一种新型复杂薄壁箱形结构,文中对其承载能力进行试验研究,得到箱壳构件在冲压前后不同区域的各项力学性能指标,发现模压板球冠区域的屈服强度增加高达42%;获取内压载荷下箱体各控制部位的力学响应特性,箱体各模压板块中与加强槽毗邻的球冠边缘区域的应力始终占主导地位;发现这种薄壁结构存在底部模压板失稳、包角渗漏和斜拉筋拉脱等3种失效模式,模型箱体底板的屈曲临界载荷在0.050 MPa～0.055 MPa.     

Experimental and numerical analysis of the temperature distribution of injection molded products using protruding microprobes

Injection molding has been one of the most important polymer processing methods for manufacturing plastic parts. In the process, the temperature is an important parameter that influences process features such as cycle times, crystallization rates, degree of crystallinity, melt flow properties, and molded product qualities. This study aims to, experimentally and numerically, examine the three-dimensional temperature distribution along the melt flow path of injection molded parts. A special experimental set-up, which includes an injection mold equipped with protruding microprobes for guiding embedded thermocouples, was designed and built to measure the temperature field along the flow path, i.e., inside the runner and the cavity, of injection molded products. The experimental results suggested that the disturbance induced by the probes remained negligible and precise temperature profiles could be measured at various positions inside the cavity. A significant increase of melt temperature was found to result from the viscous dissipation of the polymeric materials in the runner. Additionally, a commercially available code was employed to simulate and predict the temperature variation in injection molded parts. It was shown that the numerical simulation predicted better the temperature distributions inside the cavity than those along the runner.     

Development of high gloss plastic for injection molding by utilizing wollastonite(CaSiO<Subscript>3</Subscript>) and talc fillers

The gloss of plastic products is an important factor with which customers rapidly and directly decide the value of product. In general, these high-gloss plastic molded parts are produced through the injection molding of glass fiber-added plastic resin using a high temperature mold with the fine surfaces like glass. However, making the mold temperature higher causes the cooling time of injection molding longer, and the prolongation of cooling time leads to the extension of whole cycle of injection molding process. In order to resolve this problem, we developed a resin which makes the high-gloss injection modeling possible at low mold temperature by replacing conventional glass fiber filler with wollastonite filler. The tensile strength, flexural strain, impact strength, flow rate, gloss level and so on of the developed resin were tested with respect to the content of wollastonite. The results show that most of the properties except for the flow rate and gloss level are reduced in the newly developed resin. However, the decline in these properties was not enough to limit the use of new resins. In the gloss level test, as for the equal gloss of injection molded parts, the mold temperature for the developed resin was 30 °C lower than the mold temperature for the conventional resin. The difference of gloss between two injection molded parts using two different resins has been confirmed from the surface inspection of injection molded parts by SEM (scanning electron microscope).     

基于Pro/E的电熨斗曲面造型设计

电熨斗产品是由非常复杂的曲面构成的,其造型设计比较困难。以普通蒸汽电熨斗产品为例,介绍了以Pro/E软件为开发平台进行其曲面造型设计。并对各零件进行虚拟装配,最后进行全局干涉检测。大大缩短了产品研发和模具设计周期,对同类产品的设计具有一定的参考价值。     

塑料托盘在卷烟企业自动化立库中的应用与分析

通过对塑料托盘和木托盘两者优缺点的具体论述,论证了塑料托盘必将取代木托盘大规模使用.论文以某卷烟厂自动化立体高架库上所用塑料托盘的设计为例,针对塑料托盘在高架库上运行必须具备的条件和所受的制约,重点就承重、尺寸、防滑、变形量、刚性等方面进行具体分析和设计,设计后经过均载强度试验,证明完全能制造出适应自动化立体高架库标准要求的塑料托盘.实际应用中也证明塑料托盘在卷烟企业自动化立体高架库上的运行是可行的.     

Applying ANN to predict the forming load and mechanical property of magnesium alloy under hot extrusion

This study establishes the database concerning magnesium alloy hot extrusion, and uses it to conduct various investigations. Firstly, artificial neural networks (ANN) analysis is used to determine the die shapes of various extrusion ratios. Secondly, the process parameters for the hot extrusion of magnesium alloy are determined, and thirdly, the tensile strength and maximum extrusion load of the finished product are predicted. The database includes 11 parameters, associated with 108 sets of experiment, determined by material type (AZ31 and AZ61), extrusion ratio (14.41, 35.9 and 55.85), product shape (tubular and sheet), semicone angle of the die (90° and 30°), extrusion speed, temperature to which the billet is heated, temperature to which the container is heated, lubricant, hold-time at a specified temperature, extrusion load and tensile strength. ANN is applied to learn from this database, and backward propagation analysis is conducted to find the mechanical properties of the products under various extrusion ratios. This study adopts the orthogonal array of the Taguchi method to hot extrusion experiments that involve dies with different extrusion ratios, and sets the tensile strength and extrusion load of the finished product as the quality characteristics, to acquire the optimal parameter condition. Then, based on the results obtained from the additive model, confirmatory experiments are performed. An Analysis of Variance (ANOVA) analysis is then performed to investigate and analyze the influence of factors on the hot extrusion process. The weight of important factors in the database is increased, and subsequently, the forming load and mechanical properties of magnesium alloy under extrusion are accurately predicted.     

广义模块化设计原理及方法

针对传统模块化设计的局限性,将参数化设计和变量化分析技术引入模块化设计,提出广义模块化设计方法,从而拓展模块化设计的应用领域,使其既可适用于系列分级特性比较明显的产品及其产品族的开发,又可满足工况复杂、大载荷,需要进行结构强度、刚度设计,系列分级特性不明显的机械产品的开发设计.对广义模块化设计原理、广义产品平台、基于广义模块组合和基于广义产品平台的产品族规划方法进行系统阐述.最后以液压机广义模块化设计和产品族规划为例,详细说明广义模块化设计的基本原理和方法.