【作者】 查微微；

【导师】 苑世剑；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 镁合金管材常用挤压方法生产,为了评价由挤压过程导致的管材各向异性,需要对管材环向力学性能进行测试。但目前对管材环向力学性能的评价方法并没有统一的标准,因此研究镁合金管材环向力学性能的测试方法具有十分重要的意义。建立了一种管材力学性能环向拉伸测试方法,根据径向正压力线性假设和边界条件,推导出环向拉伸等宽试样径向正压力和环向拉力公式;分析了环向拉力与角度及摩擦系数的关系。对镁合金管材的环向拉伸过程进行了有限元分析。初步验证了由径向正压力线性假设推导得到的环向拉力公式;分析了摩擦系数、标距位置、温度对破裂点位置、应变分布和伸长率的影响。进行了挤压针挤压管材试样的环向拉伸实验,通过对等宽试样的环向拉伸实验,验证了环向拉力分布的公式和模拟结果;研究了摩擦系数、标距角度和温度对环向拉伸应变分布和伸长率的影响;进行了不同温度下分流模挤压管材试样的环向拉伸实验,得出了焊缝位置对应变分布的影响;对比了三种不同管材试样的变形分布及伸长率。设计了简易的管材自由胀形装置。进行了镁合金管材不同温度下自由胀形实验,得到了不同温度下管材的极限膨胀率,并与环向拉伸结果进行了对比。更多还原

【Abstract】 The Magnesium alloy tubes manufacting process by extruding have significant anisotropy, which leads to great difference between the transverse direction and the axial direction. To evaluate the anisotropy behavior resulting form the tube-making process, tube transverse tensile properties must be obtained. There is no convenient standard test method to measure transverse tube tensile properties without flattening the material.The ring hoop tension test was established to obtain the transverse tensile properties. Under the positive pressure linear transform assumed condition and the boundary condition, the relational expression of the positive pressure and the hoop tension about the angle and the friction coefficient were derived.The ring hoop tension test process of magnesium alloy tubes was simulated to proof the relational expression of the hoop tension obtained above. The influence of friction coefficient, the angle of gage section and temperature on the location of deformation zone, the distribution of deformation and the total deformation rate were researched.The ring hoop tension tests at different temperatures were carried out. The equal wide sample was adopted to prove the relational expression of the hoop tension. The influence of friction coefficient, the angle of gage section and temperature on the location of deformation zone, the distribution of deformation and the total deformation rate were researched. The influence of the welded seam, which was existed on the divergent die extruding tubes, was researched according to the test with divergent die extruding tubes samples. The distribution of deformation and the total deformation rate were considered comparing the three kind of samples.Warm hydroforming experiments of magnesium alloy tubes at different temperatures were carried out to study the trend curve of bulging rate, whose results were compared with that of the ring hoop tension test.更多还原