摘要：A large number of experiments have been done for analyzing the two important indicators -compressive strength and flexural strength, which affect computer numerical control （CNC） engraving material physical properties. Using Matlab for simulation experiment, the processing quality of different intensity brick materials is analyzed by the theory of fracture toughness. The result show that porosity is an important factor for engraving, and the research also provide a reference for further study which can improve the quality of brick carving.

摘要：Optimization of the curing process can not control the deformation of composite part prepared in autoclave accurately. And traditional ＂trial-and-error＂ tool surface compensation approach is low efficiency, high cost and can not control part deformation quantificationally. In order to address these issues, tool compensation approach based on FEA is presented. Model of multi-field coupling relationship in autoclave is realized. And finite element analysis model of composite part＇s curing process is developed to analyze part deformation. According to displacement of the part surface nodes after deformation, tool surface which compensated by the displacement of composite part which analyzed by FEA is used to control part deformation. A cylindrical composite part is ana- lyzed to verify the approach, and the result proves the correctness and validity of the approach.

摘要：盘形滚刀地质适应性设计是隧道掘进机(TBM)刀盘设计的重要环节,直接影响TBM的整体掘进效率。滚刀匹配设计的关键是通过滚刀性能评价选择适宜的滚刀尺寸。本文提出一种基于多准则决策的新型评价方法用以确定滚刀尺寸,以不同型号滚刀为设计对象,建立滚刀性能评价递阶层次模型,采用层次分析和物元理论计算滚刀性能指标权重值,并通过模糊综合评价法和模糊TOPSIS决策法对不同型号滚刀性能进行综合评判与决策。将滚刀地质适应性设计方法应用于某水利工程TBM刀盘正面滚刀设计,结果表明该方法有效可靠,可为刀盘设计过程中滚刀性能评价和匹配设计提供一定理论依据。

摘要：为了求解滚珠丝杠副的接触热阻,提出了一种基于最小余能原理和MB分形理论的解析方法。该方法在求解接触热阻时可考虑接触面的微观分形特征。采用最小余能原理求解法向应力分布,进而采用MB分形理论求解接触热阻。通过自行设计实验验证了该方法的有效性。理论和实验的结果对比说明,该方法可准确获得滚珠丝杠副接触热阻。在此基础上,讨论了分形参数对滚珠丝杠副接触热阻的影响,分析了螺母轴向载荷对滚珠丝杠副的接触热阻的影响。结果表明,接触热阻随着分形参数D的增加而减小,随着尺度参数G的增加而增加。在右螺母预紧力变为零之前,滚珠丝杠副接触热阻随着轴向载荷的增加几乎保持不变。最后,开展了该建模方法在自行设计试验台的应用,开展了相应的温度测试,进一步验证了该方法的有效性。

摘要：In the process of generating assembly dimension chain automatically, there are many problems such as complex assembly relationship, variety of constraints of components and complex dimension and tolerance relations of components. These problems lead to many difficulties in search process and need lots of man-machine interaction. Because of these difficulties, this paper presents a method of automatic generation of assembly dimension chain based on tolerance cell. This method is realized through obtaining assembly tolerance cell and part tolerance cell first. These two types of tolerance cell are extracted and expressed in the form of linked list structure in computer further. Then assembly dimension chain is searched automatically based on obtained tolerance cell, and the correct assembly dimension chain is extracted finally. A system of generating assembly dimension chain automatically has been developed based on DELMIA and successfully deployed in aircraft assembly simulation in the engineerine practice.

摘要：As two promising biomaterials for bone implants,biomedical metals have favorable mechanical properties and good machinability but lack of bioactivity;while bioceramics are known for good biocompatibility or even bioactivity but limited by their high ***,a kind of composites composing of bioceramics and biomedical metals,have been developed as an effective solution by combining their complementary *** paper focused on the recently studied biocermets for bone implant ***,biocermets were divided into ceramic-based biocermets and metal-based biocermets according to the phase *** characteristics were systematically summarized,and the fabrication methods for biocermets were reviewed and *** were put on the interactions between bioceramics and biomedical metals,as well as the performance improvement *** importantly,the main methods for the interfacial reinforcing were summarized,and the corresponding interfacial reinforcing mechanisms were *** addition,the in vitro and in vivo biological performances of biocermets were also ***,future research directions were proposed on the advancement in component design,interfacial reinforcing and forming mechanisms for the fabrication of high-performance biocermets.

摘要：CAD model with nominal dimension is implemented in interference checking of assembly simulation of aircraft complex parts at present, which causes inadequate availability. In order to address this challenging issue, interference checking method with tolerance based on assembly dimension chain was proposed. Worst case and maximum error probability of tolerance of composing loop were used, and CAD models were respectively re-constructed and inserted into simulation system. Before dynamic interference checking, engineering semantic interference condition was set to assembly requirements. Finally, the interface checking result was a basis for reasonability of assembly process and tolerance. A prototype system was developed based on the above research.

摘要：为了实现常压换刀作业,提出了一种具有冻结功能的盾构机,并且提出了冷冻刀盘的改造方案和换刀维护方法。以环西电力隧道盾构施工为例,对该工程冷冻刀盘进行了数值分析。结果表明,当盐水温度为-25°C时,冻结30 d后,冻土的冻结壁厚可达0.67 m,冻土平均温度降至-9.9°C。当盐水温度为-30°C时,冻结50 d后,冻结壁厚可达1.01 m,平均温度降至-12.4°C以冻结壁厚度为0.5 m,平均温度为-10°C作为冻结壁设计指标时,盐水温度应低于-28°C,以满足30 d的开挖要求。通过对0.5 m厚、-10°C平均温度下的冻结壁进行应力分析得出:最危险位置的抗拉、抗压安全系数均大于2,满足盾构施工换刀要求。

摘要：本文利用第一性原理对类石墨烯GaN和WS_2/WSe_2构成的复合材料的结构,电学及光学性质进行了系统的研究.氮化镓和WS_2/WSe_2之间通过范德华力进行相互作用,且这两种纳米复合结构中最稳定的构型都显示出直接带隙的特征.同时,由于导带底和价带顶分别由WS_2(或WS e2)和GaN贡献,这两种复合结构形成了第二类异质结.我们对这两种异质结构的介电函数虚部和吸收光谱进行了计算并观察到由带间跃迁所引起的光学性质的增强.此外,能带偏移以及由电荷转移所产生的内建电场能够有效地抑制电荷-空穴对的复合,这对于光催化过程十分有利.通过施加双轴应变能有效地调节这两个异质结的带隙,甚至能在一定程度上使导带边远离H^+/H_2势能,从而进一步地提升异质结构的光催化性能.研究结果表明GaN/WS_2和GaN/WSe_2是优异的光催化和光电应用的候选材料.