The reasons for impact pressure are obtained by the research the hydraulic system of Hydraulic Rolling-Cut Shear. The impact pressure of hydraulic system is divided into direct impact and indirect impact. Based on analyzing the actual situation the measures should be taken to reduce the impact pressure when design hydraulic system. The suitable length of pipeline can improve the performance of the hydraulic system because the length is important for the impact pressure. The accumulator can absorb impact pressure and improve the work situation of servo valve. Therefore, the suitable accumulators should be set in the hydraulic system. The study provides theory basis for the pipe design of large hydraulic servo system.

Symmetric valve controlled asymmetric cylinder which is applied to force down system of hydraulic leveler. In this case, the flow metering-in is not equal with metering-out universally in proportional or servo control hydraulic system, "pressure jump" will appear at the time of symmetric valve changing direction[1,2]. To deal with this disadvantage well and improve the system, the disadvantage of symmetric valve controlled asymmetric cylinder is altered by the solution that asymmetric valve controlled asymmetric cylinder. In this paper, the mathematic model of the solution has been worked out actually and the transfer function has been constructed. Finally using simulink software of MATLAB to simulate the system and analyze the stability of closed-loop.

A flexplate is a mechanical component that couples the crankshaft to the torque converter of a car with automatic transmission. A higher axial stiffness is one of significant requirements for it in order to ensure its performance. In this paper an optimum design of the flexplate disk is described that maximizes the axial stiffness of the flexplate disk with weight and inertial moment constraints. The strategy for optimizing the layout of the disk is to perform topology optimization first then position optimization. The relation is presented which shows the variation of axial stiffness with respect to changes of the number, shape and position of the holes on the flexplate disk. The research shows that the shape of the hole punched on the disk does not affect the axial stiffness greatly. Thus, the manufacturing cost should be considered first in the optimum design of the flexplate disk

The efficiency of the element removal or addition is of significance for evolutionary structural optimization (ESO) process. The key is to find an appropriate rejection criterion (RC) which allows to assess the contribution of each element to the specified behavior（stress, stiffness, displacement, etc.）of the structure, and to subsequently remove elements with least contribution. This paper proposed a varying elements removal ratio (VERR) method which uses a larger ERR (Element Rejection Ratio) value at early iterations where exist a lot of redundant material, and decreases the value of ERR in the optimal process to lessen the number of elements removed at later iterations. Meanwhile, this paper proposed a strategy for element addition based on stress level and the contribution of elements to the structure in order to decide which elements should be added to the model and the sequence of the element addition. With the proposed VERR and the strategy, the optimization procedure of the structure evolves more quickly and smoothly.

The hydraulic bending roller system, as a kind of most effective shape control process, has already become the key technology that used in shape control of the leveller at present. For hydraulic bending roller system, a mathematical model of dynamic characteristics of electro-hydraulic system was built .According to analyze the system, the parameters effect the pressure fluctuation of the system was obtained. A more effective control strategy was proposed to decrease the effect of the pressure fluctuation to the system.