摘要：High-speed machine tool working table restrains the machining accuracy and machining efficiency,so lightweight design of the table is an important *** nature,leaf has developed a plate structure that maximizes the surface-to-volume *** can be seen as a plate structure stiffened by *** with a high-speed machine tool working table,leaf veins play a role of supporting part which is similar to that of stiffening ribs,and they can provide some new design ideas for lightweight design of the *** this paper,distribution rules of leaf veins were investigated,and a structural bionic design for the table was achieved based on regulation of leaf ***,statistical analysis on geometric structure of leaf veins was carried out,and four distribution rules were ***,relevant mechanical models were developed and analyzed in finite element *** on the results from mechanical analysis on those relevant models,the four distribution rules were translated into the design rules and a structural bionic design for the working table was *** simulation and experimental verifications were carried out,and results showed that the average displacement of the working table was reduced by about 33.9%.

摘要：超声振动铣削中分离-接触特征会影响钛合金的高效高质量加工,为了更深入的认识分离-接触特征对超声振动辅助铣削的影响,建立了接触率、平均切厚比的铣削模型,并提出基于平均切厚比的超声作用判别准则;通过开展铣削实验,讨论了周期性与持续性接触超声铣削中接触率与平均切厚比的作用机理;研究了不同铣削与超声参数对刀具磨损的影响规律。结果表明:在纵向超声振动辅助铣削钛合金时,分离效应与平均切厚效应共同作用使得超声加工相较于传统加工能改善加工质量,在周期性接触铣削中,刀具-工件周期性接触的间歇切削现象引起的分离效应是铣削力与表面质量改善的主要因素,在持续性接触铣削中(接触率为1),单位周期的平均切削厚度降低现象引起的平均切厚效应使得在一定范围内刀具-工件不分离也能降低铣削力,改善表面质量;Ti-6Al-4V钛合金存在临界切入速度值,约为42m/min,合理搭配主轴转速及超声振幅可改变切入速度以防止刀具磨损,这对钛合金的高效高质量加工与工艺控制具有重要的作用。

摘要：钛合金较差的耐磨性严重限制了其在航空航天领域的应用。为了研究Ti-6Al-4V(TC4)钛合金在超声冲击强化后耐磨性提高的机理,通过Ti-6Al-4V(TC4)钛合金超声冲击强化试验,探究超声冲击处理的工艺参数(刀具直径、气浮台压力、冲击道次、刀头形状、进给步距)对钛合金表面质量及性能的影响规律及敏感性,发现当采用球头刀具、气浮台压力为0.45MPa、进给步距为0.3mm时,超声冲击强化对钛合金耐磨性的提高最明显。通过对摩擦学试验中摩擦系数、球磨斑直径、盘磨损率、表面形貌图等试验结果的研究分析发现,经过超声冲击强化处理后钛合金材料的耐磨性能提高是压应力抑制裂纹机制、表面硬化强化机制和沟壑储油机制共同作用的结果,验证了超声冲击处理对钛合金耐磨性的实际强化效果。

摘要：Structural bionic design lacks mature and scientific theories, and the excellent structural characteristics of natural organisms sometimes cannot be transferred into engineering structures effectively. Aiming at overcoming the existing problems, this paper summarizes three related theories: similarity theory, fuzzy evaluation theory and optimization theory. Based on the related theories, a method of structural bionic design is introduced, which includes four steps: selecting the most useful structural characteristic of natural organism; analyzing the structural characteristic finally chosen for engineering problem; completing the structural bionic design for engineering structure; and verifying the structural bionic design. Similarity theory and fuzzy evaluation theory are employed to achieve Step 1. In Step 2 and Step 3, optimization theory is employed to analyze the parameters of structures. Together with the thoughts of simplification and grouping, optimization theory can reveal the relationship between organism structure and engineering structure, providing a way to structural bionic design. A general evaluation criterion is proposed in Step 4, which is feasible to evaluate the performance of different structures. Finally, based on the method, a structural bionic design of thin-walled cylindrical shell is introduced.