背压对超塑自由胀形影响的实验研究

本文实验研究了背压 P_b 对超塑性自由胀形宏观力学行为的影响。实验结果表明,背压 P_b 的施入,提高了胀形的成形速度而缩短了成形时间,胀形极限有所提高,厚度变薄趋于均匀,胀形件的几何形状趋于球面。

超塑性差压胀形m值的测量理论与方法

本文采用载荷跃变法建立了差压自由胀形应变速率敏感性指数 m 值的测量公式与测量方法。实验结果表明,测量方法简单,测量结果稳定可靠。

加压路径对超塑胀形m值曲线的影响

本文利用超塑胀形光电转换自动加压实验测量装置和超塑胀形m值的测量公式,给出恒压、恒速、恒应变速率和任意加载规律加压胀形对m-logε曲线影响的研究方法,并用ZnAl_(22)和ZnAl_(4Cu)两种典型的超塑合金板材进行了实验。就提高胀形速度和改善成形质量而言,实验结果表明,恒应变速率胀形最好,恒速胀形次之,恒压胀形最差。

原电池的常见考点聚焦

考点一:原电池的形成条件形成原电池一般需要四个条件:1.具有金属活动性不同的两个电极;2.具有电解质溶液;3.形成闭合回路;4.具有自发的氧化还原反应。该考点主要考查原电池形成条件的判断。例1在如图1所示的8个装置中,能形成原电池的是()。

高三有机化学复习策略

作为高中化学的重要组成部分,有机化学在高考中占有较大分值。在高三复习有机化学的过程中,教师应引导学生运用化学思维,遵循化学学习规律,进行循序渐进、按部就班的学习,以此确保在高考中发挥出最好水平。

机械压力机传动系统的优化设计

采用复合形法对 J31—400机械压力机齿轮传动系统进行优化设计,使总中心距由1796.3mm 降至1607.1mm,减少了11.8%。另外,还对算法本身进行了一些处理。

MATHEMATIC MODELS OF THINNING PATTERN FOR NON-SPHERE SUPERPLASTIC FREE BULGING(Ⅰ)

As clamping periphery is fixed during superplastic bulging, the thinning of thickness iscertainly inhomogeneous. There are large deviations between the mathematic model of athinning pattern established formerly for free bulging and the real deformation. In this paper,the mathematic model of a thinning pattern about non-spheric free bulging is establishedfor the first time by means of a function simulation method, and a simple and convenientmethod to determine the concrete form of this model in application is suggested. The agree-ment between the theoretical curve and the measured values proved to be perfect. Since themodel is established according to the experimental data of typical superplastic alloys, it canbe considered as a proper representation. This method is of general significance to bothnon-typical superplastic alloys and tough materials.

MODELS OF GEOMETRIC PROFILE FOR NONSPHERE SUPERPLASTIC FREE BULGING(Ⅱ)

It is one of the key problems in urgent need to establish mathematic models of geome-tric profile for non-sphere free bulging in order to develop and perfect the mechanicalanalysis theory for superplastic bulging. Although free bulging is of axial symmetry,the variation of the profile is very complex. This problem theoretically remains unsolvedtill now. In the present paper, based on the experiment data of free bulging for typicalsuperplastic alloys ZnAl_(22) and ZnAl_4Cu, the mathematic models of geometric profile fornon-sphere free bulging are established for the first time by means of function simulation,and it is proved that the theoretical models may agree with the real profile perfectly well.Though the establishment of the mathematic models is restricted to two kinds of typicalsuperplastic alloys in the paper, this research method kas general significance for non-typical superplastic alloys.

THE MECHANICAL FIELDS FOR SUPERPLASTIC FREE BULGING (Ⅲ)

Based on the fundamental theory of plastic mechanics for continuous media,the stress, strain and strain rate fields on non-spheric free bulging are established for the first time by utilizing the models of geometric profile and thinning pattern for non-spheric free bulging, the special case of sphere bulging and the general case of non-sphere bulging are also discussed.