压力铸造工艺及模具技术的现代设计理论方法研究

概述压力铸造工艺及模具设计理论方法的发展现状.提出压铸现代设计理论方法的基础框架.根据该理论框架的内涵,分析现代设计体系的研究要点及其实施方式,阐述其在优化与智能意义下的实际应用价值.现代设计理论方法有效地提高压铸工艺及模具技术的自主创新水平.     

High cycle fatigue and fracture behavior of 2124-T851 aluminum alloy

The high cycle fatigue properties and fracture behavior of 2124-T851 aluminum alloy were investigated roundly, including the fatigue crack growth rate, fracture toughness and fatigue S--N curve. Furthermore, the fatigue crack growth rate was analyzed by fitting the curves. And the microstructure of the alloy was studied using by optical microscopy, transmission electron microscopy and X-ray diffractometry, scanning electron microscop1/2 The results show that the fatigue strength and the fracture toughness of 2124-T851 thick plate are 243 MPa and 29.6 MPa.m at room temperature and R=0. 1, respectively. At high cycle fatigue condition, the characteristics of fatigue facture were observed obviously. And the higher the stress amplitude, the wider the space between the fatigue striations, the faster the rate of fatigue crack developing and going into the intermittent fracture area and the greater the ratio between the intermittent fracture area and the whole fracture area.     

薄壁管的超声检测

目前在核电站的重要设备中 ,有相当一部分薄壁管需作超声检测 ,如蒸汽发生器传热管和ＣＡＮ ＤＵ堆压力管等 ,这类管子的壁厚大多 <5ｍｍ ,其中ＣＡＮＤＵ堆压力管的壁厚为 4 .2 9ｍｍ ,内径为10 3 38ｍｍ ,长度 >6ｍ (图 1) ,材料为锆铌合金 ,核燃料和冷却剂被包容在压力管内部 ,其工作温度大约 30 0℃。这里以压力管超声检测为例来描述薄壁管的超声检测方法。图 1　压力管样管1　原理由于压力管壁较薄 ,用常规的超声探头不能进行有效的检测。根据加拿大的检测规范 ,至少要检测出深 0 .15ｍｍ的缺陷。选用 >10ＭＨｚ的横波 4 5°斜探头。…     

数控加工中心ATC弧面分度凸轮运动学问题研究

推导了弧面凸轮压力角和诱导主曲率的计算公式，对数控加工中心凸轮式自动换刀机械手(ATC)弧面分度凸轮的压力角和曲率进行了详细的分析，为ATC的优化设计和研究提供了理论基础，有助于ATC机构产品系列化的完成。     

气体辅助挤出中影响气垫形成及稳定性因素分析

对一种新型挤出技术———气辅挤出中的气垫层形成及其稳定性影响因素进行了实验研究和分析,对气体压力的研究表明,当气体压力高于熔体压力时,气流就会影响到挤出口模内熔体的流动,使挤出物表面出现竹节状突起,但气体压力太低时(实验条件下低于0.2MPa)形成不了稳定的气垫膜层;气体流量的大小影响到气垫层的厚度和气垫层内气体的速度,并可通过调整气体流量控制挤出物的截面尺寸;气体温度影响到气垫层的稳定,为保持稳定的气垫层,气体温度应保持和口模温度一致。     

筒形件正旋旋压力有限元计算及分析

采用三维刚塑性有限元法计算了筒形件正旋时的旋压力，并对各工艺参数对旋压力的影响进行了系统研究。     

颗粒介质传压性能的数值模拟和试验研究

文章作者自行研制了测试颗粒介质传压性能测试装置,通过试验,测得了多种颗粒介质在各种试验参数下的压力分布规律和应力应变关系。通过将颗粒介质作为连续体介质来处理,建立了研究颗粒介质传压性能的有限元模型,对不同试验参数下的颗粒介质,在承压筒底面上垂直压力分布进行了模拟计算。模拟和实测结果对比表明,应用连续体材料模型的模拟结果和实测结果较为接近。     

Hot-compression constitutive relation of as-cast AZ31 magnesium alloy

In hot-compression process, the various factors have obvious effects on the deformation behavior of AZ31 magnesium alloy deformation behavior. To understand the hot-compression constitutive relation thoroughly, the stress-strain behavior of AZ31 magnesium alloy at various strain rates and different deformation temperatures were investigated under maximum strain of 60%. The microstructure of the experimental alloy was studied in the hot-compression procedure. The experimental results show that the relation of peak flow stress, strain rate and temperature can be described by Z parameter which contains Arrheniues item. The strain rate and the deformation temperature are the key parameters affecting deformation activation energy.     

轧制折缘异型断面型钢轧制压力计算

论述了折缘型钢轧制过程中开口、闭口槽中金属变形，并建立各自的变形量，接触面积计算公式。探索了按变形特点分块计算轧制压力的方法，其计算结果与实测相比，较为符合，因此有推广使用价值。