Analysis of end point vibrations of a two-link manipulator by integrated CAD/CAE procedures

In this work, the effect of flexibility on the trajectory of a planar two-link manipulator is studied using integrated computer-aided design/analysis (CAD/CAE) procedures. The solid models and finite element models of the parts of the manipulator are created by using the CAD/CAE software I-DEAS. The assembly is defined, and knowing the payload and the end point trajectory, the velocities and accelerations of the parts, joint forces and driving torques are calculated using the rigid body dynamics. All the time dependent nodal forces acting on the parts including distributed gravity and inertia forces are created in files with the I-DEAS program file format. The finite element vibration analysis of the parts is performed by I-DEAS. The end point vibrations and the deviations from the rigid-body trajectory are analyzed for different types of end point acceleration curves. A circular trajectory is considered as an example. It is observed that the precision of the manipulator can be increased by testing different end point acceleration curves without changing the trajectory and the duration of the end point work. The procedure explained in this work can be used for this purpose successfully.     

CAE技术在井架设计中的应用

应用GAE技术，针对ZJ30／1700CZ钻机井架分别进行了静态分析及在自然状态和有钩载情况下的模态分析，为合理设计钻机井架结构提供了理论依据。通过分析计算，可以看出：所设计的井架的静态强度满足要求；经动力再设计后的井架固有频率与钻机的设计工作转速相差较大，达到工程要求，表明修改后的井架设计方案合理。     

The changing role of physical testing in vehicle development programmes

The role of physical testing in product development is changing due to the requirements for faster new product development, reduced tolerance of failures in the field and the emergence of computer aided engineering (CAE) technologies. To be used most effectively, testing must be seen as an integral part of the process for reducing risks associated with new product introductions. Quality function deployment (QFD) and failure modes and effects analysis (FMEA) can be used to establish effective test and development plans that integrate the use of virtual and physical testing. By effectively integrating virtual and physical test technologies significant improvements in product performance can be achieved within shorter times and with reduced development and manufacturing costs. The approach was illustrated by a process of reducing in-cab noise during the design of a new truck.     

非线性塑性材料内部空洞闭合模型的研究

基于典型体元(RVE)模型和Rayleigh-Ritz法,对材料内部空洞从球形闭合成裂纹的过程进行了定量研究.基体材料的本构关系采用幂次粘性方程.通过研究材料变形过程中内部球形空洞和圆形裂纹的演化规律,得到了各自的体积应变率的表达式.采用插值近似,建立了空洞闭合的解析模型,发现空洞变形的主要机理来自于空洞周围基体材料的塑性流动.空洞闭合模型反映了材料属性、远场应力三轴度、远场等效应变对空洞闭合的定量规律.空洞闭合模型的预测结果与文献中的数值结果和有限元计算结果相吻合.空洞闭合模型与CAE(computer-aided engineering)技术相结合可对材料加工工艺进行优化设计,为消除材料内部空洞提供了一条有应用前景的新途径.     

Quick Profile Die Balancing of Automotive Rubber Seal Extrusion by CAE Technology

The extrusion process of a type of automotive rubber seal was considered by using Computer Aided Engineering (CAE) technology. Based on the die balancing requirement, CAE technology was utilized to speed up the die development and balancing process. The rubber material was EPDM and unacceptable extrusion deformation was found by using a parallel die. More balancing dies were then designed following the procedures proposed by the die balancing method and the effect of them was evaluated with respect to CAE analytical results. It was found that the addition of an opening section in the die would provide a more uniform velocity distribution at the die exit than the parallel die. The length of opening section was also found to affect the die balancing and so an optimum length of the opening section was determined by CAE analysis. Further optimization of the die was carried out by adjusting the local length of the opening section. Finally, a real die was cut based on the optimization results and used for production. Ideal profile products were obtained and very small and acceptable deviation from the die was observed, which validated the advantage and accuracy of CAE technology combined with die balancing requirement.     

A novel collagenase-assisted extraction of active pharmaceutical ingredients from gelatin products for quantitative analysis by high performance liquid chromatography

High performance liquid chromatography (HPLC) is frequently used for quantifying drugs in gelatin capsules. Gelatin has a strong UV absorption that often overlaps with drug absorbances. Therefore, the gelatin capsules must be removed manually before analysis. This study describes a novel extraction method named collagenase-assisted extraction (CAE), which uses collagenase to degrade gelatin into fragments with reduced hydrophobicity, allowing gelatin-related peaks to elute immediately, eliminating interference with the drug peak and enabling use of whole gelatin capsules during drug quantification. Use of CAE eliminates powder loss when opening a gelatin capsule, allows extraction of drugs from the capsule, reduces analytical time, and extends HPLC column life.     

Construction of Pre-Deformed Shapes for Rapid Tooling in Injection Molding

The major issues in the development of injection molding technology include the progress in CAE and the developments in tool design methodology such as rapid tooling. The applicability of rapid tooling in injection molding was examined using unbalanced cooling to analyze the warpage and shrinkage. Moldflow Plastics Insight simulation software was used for the deformation calculations with different mold thermal conductivities. It can be concluded that the decreasing mold thermal conductivity will dramatically increase the volumetric shrinkage and the warpage as well. Because of these effects, it is of fundamental importance to compensate for the shrinkage and warpage, so in the paper a new design methodology is suggested for rapid tooling, which is based on the pre-deformed model.     

Capillary electrophoresis methods for microRNAs assays: A review

MicroRNAs (miRNAs) are short noncoding RNAs that conduct important roles in many cellular processes such as development, proliferation, differentiation, and apoptosis. In particular, circulating miRNAs have been proposed as biomarkers for cancer, diabetes, cardiovascular disease, and other illnesses. Therefore, determination of miRNA expression levels in various biofluids is important for the investigation of biological processes in health and disease and for discovering their potential as new biomarkers and drug targets. Capillary electrophoresis (CE) is emerging as a useful analytical tool for analyzing miRNA because of its simple sample preparation steps and efficient resolution of a diverse size range of compounds. In particular, CE with laser-induced fluorescence detection is a promising and relatively rapidly developing tool with the potential to provide high sensitivity and specificity in the analysis of miRNAs. This paper covers a short overview of the recent developments and applications of CE systems in miRNA studies in biological and biomedical areas.     

轻量化碳化硅反射镜支撑方案分析

讨论了轻量化碳化硅反射镜的支撑方案。利用有限元力学分析方法,对大口径轻量化主镜进行了在两种工况下的支撑方案分析和优化。通过运用最小二乘法对支撑后的镜面进行拟合,使两种工况下的主镜面形变化的均方差均在λ/60(λ=632 8nm)之内,满足了实际的工程要求。     

浅谈光电实验室的教学管理改革

实验教学是帮助学生将理论知识转化为实践技能的重要途径。因此在重视理论教学的同时,必须加强实验环节。针对光电实验室的现状,有必要进行教学方法和管理制度的改革。强化实验室仪器管理,创造好的硬件条件为实验教学服务;改革创新教学方法,使实验效果在传统实验教学的基础上更上一层楼;因材施教,满足各层次学生的不同需求;全方位展开改革实践,建立适合科技发展的教学新体系,培养理论知识扎实,实践技能过硬的复合型人才,以适应社会的发展。