摘要：A method for optimizing automotive doors under multiple criteria involving the side impact, stiffness, natural frequency, and structure weight is presented. Metamodeling technique is employed to construct approximations to replace the high computational simulation models. The approximating functions for stiffness and natural frequency are constructed using Taylor series approximation. Three popular approximation techniques,*** response surface (PRS), stepwise regression (SR), and Kriging are studied on their accuracy in the construction of side impact functions. Uniform design is employed to sample the design space of the door impact analysis. The optimization problem is solved by a multi-objective genetic algorithm. It is found that SR technique is superior to PRS and Kriging techniques in terms of accuracy in this study. The numerical results demonstrate that the method successfully generates a well-spread Pareto optimal set. From this Pareto optimal set, decision makers can select the most suitable design according to the vehicle program and its application.

摘要：The design methods of anode and cathode are proposed for precision profile grinding. Based on the electrolytic machining theory, electrolytic equilibrium condition and Faraday′s law of electrolysis are applied to establishing the mathematical model of profile diamond dressing process- es. A finite element method (FEM) program is developed to solve the inverse boundary problem of Laplace′s equation. Desired anode contour or cathode shape is determined by computing the distribution of electric potential layer by layer. Electrolytic machining experiment is carried out to verify the simulated anode shape. The research result shows that shape deviation between designed cathode and profile wheel increases with the value of angle between feed rate and the normal to anode surface. The shape of simulated anode is consistent with the contour of metal-bonded diamond profile wheel for a given cathode. Based on the anode contour, cathode shape can also be designed accurately.

摘要：7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical *** the process of deep hole boring,the boring bar is prone to vibrate because of its limited machining space,bad environment and large elongation induced low *** reduce vibration and improve machined surface quality,a particle damping boring bar,filled with particles in its inside damping block,is designed based on the theory of vibration *** theoretical damping coefficient is determined,then the boring bar structure is designed and *** studies through impact testing show that cemented carbide particles with a diameter of 5 mm and a filling rate of 70% achieve a damping ratio of 19.386%,providing excellent vibration reduction capabilities,which may reduce the possibility of boring ***,experiments are setup to investigate its vibration reduction performance during deep hole boring of 7075 aluminum *** observe more obviously,severe working conditions are adopted and carried out to acquire the time domain vibration signal of the head of the boring bar and the surface morphologies and roughness values of the *** comparing different experimental results,it is found that the designed boring bar could reduce the maximum vibration amplitude by up to 81.01% and the surface roughness value by up to 47.09% compared with the ordinary boring bar in two sets of experiments,proving that the designed boring bar can effectively reduce *** study can offer certain valuable insights for the machining of this material.

摘要：The nonlinear governing equations of the liquid sloshing modals in a cylindrical storage tank are established. Through analytical analysis, the analytical expressions of the solutions of this kind of system are obtained. With different parameters, the dynamical behaviors of the solutions are different from the trivial ones. To prevent system instability, two selection principles that the stiffness equations are positive-definite and the nonlinear terms of the system are not regenerative elements are given. Meanwhile, numerical simulations are also given, which confirm the analytical results.

摘要：A novel approach,which can be used for dynamic characteristics analysis of machine tools based on unit structure(US),is reported in this *** concepts of unit structures for design of machine tools are *** order to satisfy the dynamic characteristics requirement of high natural frequency and light-weight of US,a design method of multi-disciplinary optimization of NSGA-II about unit structures driven by natural frequency and mass is *** analyzing the unit structures,key factors affecting the natural frequency and mass are extracted,and the mathematical models of natural frequency and mass about unit structures are also established by using central composite design and response surface *** goal of high natural frequency and light-weight is reached by using the multi-objective genetic *** Pareto optimal set is also *** dynamic behavior of US is investigated by the experimental modal *** show the efficiency of the proposed novel method,the example of YKW51250 gear shaping machine bed is *** optimization of NSGA-II about US of YKW51250 machine bed,the natural frequency of YKW51250 gear shaping machine bed is increased by 30.4%and its mass decreased by 5.2%comparing with the original *** studying the dynamic characteristics of the simplified machine tools bed,useful laws are obtained,and these laws can be used in primary design of NC machine tools *** optimal method based on US can be also applied to the dynamic optimal design of machine tools and other similar equipments.

摘要：Flexure mechanisms with decoupled characteristics have been widely utilized in precision positioning ***,these mechanisms suffer from either slow response or low load ***,asymmetric design always leads to thermal *** order to solve these issues,a novel 2-DOF decoupled mechanism is developed by monolithically manufacturing sets of statically indeterminate symmetric（SIS） flexure structures in *** design helps to eliminate the thermal error and Finite Element Analysis（FEA） results show that the maximum coupling ratio between X and Y axes is below 0.25% when a maximum pretension force of 200 N is *** ignoring the mass effect,all the SIS flexure structures are simplified to ＂spring-damper＂ components,from which the static and dynamics model are *** relation between the first resonant frequency of the mechanism and the load is investigated by incorporating the load mass into the proposed dynamics *** results show that even with a load of 0.5 kg,the first resonant frequency is still higher than 300 Hz,indicating a high load *** mechanism＇s static and dynamic performances are experimentally *** linear stiffnesses of the mechanism at the working platform and at the driving point are measured to be 3.563 0 N·μm-1 and 3.362 1 N·μm-1,*** corresponding estimation values from analytical models are 3.405 7 N·μm-1 and 3.381 7 N·μm-1,which correspond to estimation errors of-4.41% and 0.6%,*** an additional load of 0.16 kg,the measured and estimated first resonant frequencies are 362 Hz and 365 Hz,*** estimation error is only 0.55%.The analytical and experimental results show that the developed mechanism has good performances in both decoupling ability and load capability;its static and dynamic performance can be precisely estimated from corresponding analytical *** proposed mechanism has wide potentials in precision positioning applic

摘要：A patented double-ring-plate gear reducer was designed and its dynamic performance was simulated. One unique characteristic of this novel drive is that the phase angle difference between two parallelogram mechanisms is a little less than 180 degree and four counterweights on two crankshafts are designed to balance inertia forces and inertia moments of the mechanisms. Its operating principle, advantages, and design issues were discussed. An elasto-dynamics model was presented to acquire its dynamic response by considering the elastic deformations of ring-plates, gears, bearings, etc. The simulation results reveal that compared with housing bearings, planetary bearings work in more severe conditions. The fluctuation of loads on gears and bearings indicates that the main reason for reducer vibration is elastic deformations of the system rather than inertia forces and inertia moments of the mechanisms.

摘要：Cutterhead loads are the key mechanical parameters for the strength design of the full face hard rock tunnel boring machine(TBM).Due to the brittle rock-breaking mechanism,the excavation loads acting on cutters fluctuate strongly and show some *** conventional method that using combinations of some special static loads to perform the strength design of TBM cutterhead may lead to strength failure during working *** this paper,a three-dimensional finite element model for coupled Cutterhead–Rock is developed to determine the cutterhead *** the distribution characteristics and the influence factors of cutterhead loads are analyzed based on the numerical *** is found that,as time changes,the normal and tangential forces acting on cutters and the total torque acting on the cutterhead approximately distribute log normally,while the total thrusts acting on the cutterhead approximately show a normal ***,the statistical average values of cutterhead loads are proportional to the uniaxial compressive strength(UCS)of cutting *** values also change with the penetration and the diameter of cutterhead following a power *** on these findings,we propose a three-parameter model for the mean of cutterhead loads and a method of generating the random cutter *** the strength properties of a typical cutterhead are analyzed in detail using loads generated by the new *** optimized cutterhead has been successfully applied in *** method in this paper may provide a useful reference for the strength design of TBM cutterhead.

摘要：Increasing demand for downsizing of engines to improve CO2 emissions has resulted in renewed efforts to improve the efficiency and expend the stable operating range of the centrifugal compressors used in petro-chemical equipment and turbochargers. The losses in these compressors are dominated by tip clearance flow. In this paper, the tip clearance flow in the subsonic impeller is numerically investigated. The nature of the tip clearance in inducer, axial to radial bend and exducer are studied in detail at design and off-design conditions by examining the detailed flow field through the clearance and the interaction of the clearance flow with the shear effect with the endwalls. The correlation between blade loading and span wise geometry and clearance flow at different locations are presented.

摘要：To implant radioactive seeds through a needle precisely and safely, a novel multi-DOF surgical robotic system is presented in this paper for percutaneous prostate intervention through the patient’s perineum under real-time ultrasound image guidance. The proposed robot, which is designed with 9-DOF, consists of a 3-DOF automatic location platform for position adjustment, 2-DOF for automatic ultrasonic probe adjustment mounted with electromagnetic trackers, and 4-DOF for manually adjusting the guided template. Meanwhile, a new registration method based on the quaternion algorithm and least square method is developed, and the needle insertion is performed under the real-time guidance of a navigation system. Furthermore, the robot system has undergone some preliminary experiments with a laser tracker to evaluate the repeatability and accuracy of the robot system. The location error of the puncture needle tip can be controlled under 0.7 mm in air for the whole robotic system. The acquired results endorse the precision of the robot system for prostate seed implantation brachytherapy. © 2017, tianjin university and Springer-Verlag GmbH Germany.