高强钢冲压模具的疲劳寿命分析与结构拓扑优化

发布时间：2018-01-06 01:34

本文关键词：高强钢冲压模具的疲劳寿命分析与结构拓扑优化　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着汽车的大量普及,由汽车工业及相关配套产业所带来的社会问题成为人们关注的焦点。为实现可持续发展的目标,汽车企业纷纷推出节能环保战略,大力研发低油耗、低排放的产品。高强度钢以其较高的机械强度、良好的成形性能和成熟的制造加工工艺,在车身轻量化以及提高车身强度方面实现了广泛的应用,成为目前实现汽车节能减排的主要方法,但同时也给模具的材料选用和结构设计带来了新的挑战。相比于传统低强度钢板,高强钢在冲压过程中需要更高的成形力,冲压模具长期处于循环加载的大载荷和高冲击力环境下,很容易发生磨损、破裂等疲劳破坏失效。为避免疲劳现象的产生,很多模具企业通过进一步加大安全系数来提高模具的疲劳寿命,可结果往往是增加了生产成本,却没能改善模具的性能。因此,研究高强钢冲压模具的疲劳寿命和结构优化具有重要的意义。本文以高强钢冲压模具中受力最为恶劣的凸模作为研究对象,通过结构受力分析、疲劳寿命估算和结构拓扑优化三方面对凸模的疲劳性能和拓扑结构进行了研究。由结构受力有限元分析结果可知,在冲压过程中的不同时刻,凸模的等效应力分布并不均匀,大部分集中在圆角和起伏相对明显的凹凸特征处,这些部位也是容易发生疲劳破坏的危险位置。选择应力最大位置作为疲劳分析对象,通过疲劳寿命估算发现凸模的理论寿命远大于设计使用寿命,所以凸模的结构存在优化空间。再利用拓扑优化技术对凸模结构进行了优化设计,获得了更为合理的凸模拓扑结构。通过一系列的分析优化,重新设计的凸模质量降幅超过20%,对其进行结构受力分析和疲劳寿命估算,在整个冲压过程中,虽然凸模的最大等效应力平均值略有增大,但整体与优化前相比仍处于同一水平。同时,凸模的峰值应力得到了降低,使其理论疲劳寿命有所增加。基于以上研究分析结果,提出了针对小型高强钢冲压模具凸模结构的优化设计方法与部分关键参数的设计标准,为高强钢冲压模具的设计开发提供了可借鉴的参考依据。
[Abstract]:With the popularity of automobile, the social problems brought by automobile industry and related industries have become the focus of attention. In order to achieve the goal of sustainable development, automobile enterprises have launched energy-saving and environmental protection strategy. Research and development of low fuel consumption, low emissions products. High strength steel with its high mechanical strength, good formability and mature manufacturing and processing technology. In the body lightweight and improve the strength of the body to achieve a wide range of applications, become the main way to achieve energy saving and emission reduction. But at the same time, it also brings new challenges to the material selection and structure design of die. Compared with traditional low strength steel plate, high strength steel requires higher forming force in stamping process. For a long time, the stamping die is in the environment of high cyclic load and high impact force, so it is easy to cause fatigue failure, such as wear and tear, etc. In order to avoid the occurrence of fatigue phenomenon. Many die enterprises increase the safety factor to improve the fatigue life of the mould, but the result is that the production cost is increased, but the performance of the die is not improved. It is of great significance to study the fatigue life and structural optimization of high strength steel stamping die. Fatigue performance and topology of punch are studied in three aspects of fatigue life estimation and structural topology optimization. The equivalent stress distribution of the punch is not uniform, and most of them are concentrated in the convex and concave features, which are relatively obvious in angle and undulation. These parts are also dangerous places where fatigue failure is easy to occur. Selecting the maximum stress position as the fatigue analysis object, it is found that the theoretical life of the punch is much longer than the designed service life through the fatigue life estimation. Therefore, there is an optimization space in the structure of the convex module. Then the optimization design of the convex module structure is carried out by using the topology optimization technology, and a more reasonable topological structure of the convex module is obtained. Through a series of analysis and optimization, the structure of the convex module is optimized. The mass reduction of the redesigned punch is more than 20. The structural stress analysis and fatigue life estimation are carried out, although the average maximum equivalent stress of the punch increases slightly during the whole stamping process. However, the whole is still at the same level as before optimization. At the same time, the peak stress of the punch is reduced, and the theoretical fatigue life is increased. The optimization design method of punching die structure of small high strength steel and the design standard of some key parameters are put forward, which can be used as reference for the design and development of high strength steel stamping die.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U466;TG385.2

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