摘要：For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism. In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces to improve the engine’s noise vibration and harshness performance.

摘要：The singular points of a 6-SPS Stewart platform are distributed on the multi-dimensional singularity hypersurface in the task-space, which divides the workspace of the manipulator into several singularity-free regions. Because of the motion un- certainty at singular points, while the manipulator traverses this kind of hypersurface from one singularity-free region to another, its motion cannot be predetermined. In this paper, a detailed approach for the manipulator to traverse the singularity hypersurface with its non-persistent configuration is presented. First, the singular point transfer disturbance and the pose disturbance, which make the perturbed singular point transfer horizontally and vertically, respectively, are constructed. Through applying these dis- turbances into the input parameters within the maximum loss control domain, the perturbed persistent configuration is transformed into its corresponding non-persistent one. Under the action of the disturbances, the manipulator can traverse the singularity hy- persurface from one singularity-free region to another with a desired configuration.

摘要：Fatigue crack propagation characteristics of a diesel engine crankshaft are studied by measuring the fatigue crack growth rate using a frequency sweep method on a resonant fatigue test rig. Based on the phenomenon that the system frequency will change when the crack becomes large, this method can be directly applied to a complex component or structure. Finite element analyses (FEAs) are performed to calibrate the relation between the frequency change and the crack size, and to obtain the natural frequency of the test rig and the stress intensity factor (SIF) of growing cracks. The crack growth rate i.e. da/dN-ΔK of each crack size is obtained by combining the testing-time monitored data and FEA results. The results show that the crack growth rate of engine crankshaft, which is a component with complex geometry and special surface treatment, is quite different from that of a pure material. There is an apparent turning point in the Paris's crack partition. The cause of the fatigue crack growth is also dis-cussed.

摘要：Negative Poisson's ratio(NPR) structure has outstanding performances in lightweight and energy absorption, and it can be widely applied in automotive industries. By combining the front anti-collision beam, crash box and NPR structure, a novel NPR bumper system for improving the crashworthiness is first proposed in the work. The performances of the NPR bumper system are detailed studied by comparing to traditional bumper system and aluminum foam filled bumper system. To achieve the rapid design while considering perturbation induced by parameter uncertainties, a multi-objective robust design optimization method of the NPR bumper system is also proposed. The parametric model of the bumper system is constructed by combining the full parametric model of the traditional bumper system and the parametric model of the NPR structure. Optimal Latin hypercube sampling technique and dual response surface method are combined to construct the surrogate models. The multi-objective robust optimization results of the NPR bumper system are then obtained by applying the multi-objective particle swarm optimization algorithm and six sigma criteria. The results yielded from the optimizations indicate that the energy absorption capacity is improved significantly by the NPR bumper system and its performances are further optimized efficiently by the multi-objective robust design optimization method.

摘要：A cylindrical negative Poisson's ratio(CNPR) structure based on two-dimensional double-arrow negative Poisson's ratio(NPR)structure was introduced in this paper. The CNPR structure has excellent stiffness, damping and energy absorption performances,and can be applied as spring, damper and energy absorbing components. In this study, the CNPR structure was used as a jounce bumper in vehicle suspension, and the load-displacement curve of NPR jounce bumper was discussed. Moreover, the influences of structural parameters and materials on the load-displacement curve of NPR jounce bumper were specifically researched. It came to the conclusion that only the numbers of cells and layers impact the hardening displacement of NPR jounce bumper. And all parameters significantly affect the structure stiffness at different displacement periods. On the other hand, the load-displacement curve of NPR jounce bumper should be in an ideal region which is difficult to be achieved applying mathematical optimization method. Therefore, a parametric design strategy of NPR jounce bumper was proposed according to the parametric analysis results. The design strategy had two main steps: design of hardening displacement and design of stiffness. The analysis results proved that the proposed method is reliable and is also meaningful for relevant structure design problem.

摘要：缩小的扁平的板的一个全面二维的数字模型毛状的抽的环( CPL )蒸发器被开发在多孔的灯芯结构描述液体和蒸汽流动，热转移和阶段变化，在赔偿洞的液体流动和热转移和在蒸汽沟和金属性的墙的热转移。全部蒸发器作为一个 conjugate 问题与简单算法被解决。缩小的扁平的板 CPL 蒸发器的表演上的金属性的方面墙的热传导的效果被分析，并且站在一起墙效果热转移限制被介绍估计蒸发器的表演。在灯芯内的蒸汽液体接口的形状和地点被计算，蒸发器表演上的应用的热流动，使过冷的液体，灯芯材料和金属性的墙材料的影响详细被调查。获得的数字结果为缩小的扁平的板蒸发器表演优化和 CPL 的设计是有用的。

摘要：This paper reports results of the authors’ studies on the virtual design method used in the development of low noise intake system of I.C. engine. The resulting high pass-by noise at level above the legislative target at full throttle when engine speed was around 5200 r/min necessitated a BEM-aided redesign task, following the typical process of design and development of an intake system. During the initial design, based on the acoustic theory and the requirements (1. The air flux of the redesigned should equal to or exceed the value of the original flux; 2. The filtering area must not be degraded), and considering the constraint of space in the engine compartment, total volume and rough internal dimensions were determined. During the detailed design, the exact internal dimensions of the air cleaner were determined, and an effective method was applied to improve the acoustic performance at low frequency. The predicted sound power of the intake system indicated that the objective of reducing the overall engine noise by minimizing intake system noise was achieved.

摘要：A kind of closed-loop Hall effect sensor is designed and fabricated by considering several factors such as iron core material,Hall device,as well as selected integrated *** studying the effect of the iron material and structures of current sensor,a kind of optimal Hall effect current sensor is *** experimental results show that the presented closed-loop Hall effect current sensor achieves 1 mA/A *** its linearity and accuracy are 0.1%and 0.35%FS,respectively,at currents ranging from 0 to 50 A.

摘要：由于在高效率和精确性之间的好平衡，元模型基于优化算法是一个重要全球优化范畴并且广泛地被使用了。更好解决高度非线性并且集中的工程优化问题，一个提高的混血儿和适应元模型基于的计算全球优化(电子火腿) 首先在这个工作被建议。重要区域更改方法(IRU ) 和不同采样尺寸策略在优化方法被建议提高表演。由使用自动、可伸缩的策略，重要区域将根据搜索结果适应地被更新改进产生精确和集中率。不平的采样策略和集中的采样策略在优化的不同阶段被使用高效地改进搜索并且避免过早地在一个小设计空格聚在一起的结果。新优化算法的有效性被与不同变量凳子标记优化问题作比较到六个优化方法验证。电子火腿优化方法然后被使用优化实际否定泊松比率(NPR ) 的设计参数在这个工作的碰撞盒子。结果显示建议电子火腿在优化计算有高精确性和效率集中的问题和罐头广泛地在设计工业被使用。

摘要：Biogas fermentation requires appropriate temperature,while the biogas fermentation can be affected by the low ambient temperature in *** order to overcome the negative effects of low temperature fermentation,a new type of solar heat pipe biogas fermentation heating system was designed and a preliminary experiment research on this system was conducted using cow manure as the raw material at 6%concentration and total fermentation volume of 175 *** experimental results showed that when the system was in normal operation,the fermentation temperature rose every day by *** gradient will gradually become smaller with the increase of fermentation liquid temperature,and the temperature can reach 38°C after *** this solar heat pipe heating system,the fermentation liquid temperature can be increased by 5°C every sunny *** solar heat pipe heating system plays a significant role in biogas *** results of economic analysis show that the system can realize the fermentation at constant temperatures of 25°C and 35°C respectively,and it can also save standard coal equivalent of 40 kg and 80 kg in winter and spring,respectively.