Advanced Materials Research Vols. 591-593

Abstract: The objective of this paper is to derive and verify a formula for calculating safety inventory that satisfies a desired cycle service level in a periodic review system. Stochastic variables, including customer demand and supplier’s lead time, are assumed to be normally distributed. Independent demand items are considered and backorders are not allowed. After deriving the formula, a computerized model simulating a periodic review system is developed by utilizing Microsoft Excel. Hypothesis testing is employed to compare the desired cycle service level with the simulated cycle service level. The result of this paper shows that there is strong agreement between the derived formula and the simulation model. In other words, the derived formula is verified. Furthermore, this simulation model also allows prompt identification of the impact of changes in inventory policy on cycle service level and inventory cost.

Abstract: Roller is a main tool and consumption parts for steel rolling. With analysis test on the fatigue property of roller, the development incentives of crack propagation were realized, the service life of roller was improved and the cost of Production was reduced in a large extent. Roller is a circular column, which do fixed-axis rotation under combined action of roll pressure, bearing reaction, Support roller reaction force and torsion. The failure types of roll such as flaking, fracture and crack. Simulate and analysis on damage of the roller crack by the fracture mechanics of knowledge and ANSYS, which shown that compressive was large with the ring and axial and compressive was small with the radial direction, so the compressive of radial direction the analysis had little effect on roll surface.

Abstract: Simulation is one of the most powerful tools available for decision makers to study, analyze and evaluate any design and operation particularly for complex processes and systems. One of the largest application areas for simulation modelling is the manufacturing systems. As such, it is widely applied in manufacturing as a representation of the industrial operation systems allowing the systems to be observed, learnt and tested in a more holistic manner. This paper is based on a preliminary study that demonstrates the application of computer simulation modelling, which is a branch of Operations Research techniques, as a means to identify bottlenecks in order to determine the ideal operating conditions for large scale aircraft composite parts production plant in Malaysia. The model development of the plant under study was built using Arena software.

Abstract: Now, the energy buffer device which seals up part of the oil and makes it into the throttle or the gap outflow to achieve the purpose of the piston’s slowing down at the end of the stroke is widely used. At the same time, the inside pressure produced by the oil of the buffer cavity resists the inertia and other external force to achieve the buffering. The cylindrical ring gap buffer device is analyzed in detail in this paper. The model of hydraulic buffer was built based on the MATLAB/SIMULINK, the dynamic characteristics of the buffer pressure and the buffer velocity were simulated, and the influencing factor of hydraulic buffer was compared and analyzed.

Abstract: The details of the process with respect to tool wear mechanisms in diamond cutting of ferrous metals are still not clear. For the sake of further studying on diffusion wear of diamond tool, as a consequence, the numerical simulation of diffusion process at interface of diamond and workpiece is presented based on Fick’s second law in this paper. The diffusion model of carbon atoms diffusion into γ-Fe has been established in terms of materials science theory. In addition, the distribution of carbon atoms concentration in regard to the variable of diffusion distance and diffusion time is calculated by numerical simulation, the tendency of concentration distribution is consistent with the results of previous studies. This work provides a basis research for diffusion wear in diamond cutting of ferrous metals.

Abstract: Taking double-row tapered roller bearings of a rail passenger coach as research object, the analysis on convexity for tapered roller bearings has been carried out. The comparison of contact stresses at different convexity values with the ANSYS has been done, the optimal range of convexity value under a certain load has been obtained. The results show that the reasonably design of convexity can avoid or reduce the border contact stress concentration occurred between rollers and inner, outer ring raceways under certain condition. But the approximate theoretic convexity and the results obtained by Finite element analysis have a certain margin of error.

Abstract: Adopt software Proe 5.0 to create model and processing technology planning of integral impeller, This paper is to establish an NC processing plan integrated with modeling, programming, simulation and optimization, taking the integral impeller as an example and combining the CAM system of software Proe 5.0 and 5-axis simulation module Vericut7.15. By the above plan, the more proper NC processing method can be got, the processing technology will be improved, and processing cost will decrease. By this plan, users can prolong the service life of the cutter, improve the surface quality, shorten the production cycle and enhance the utilization rate and productivity of the lathe. establish detailed machining plan, perform 5-axis linkage CNC programming and generate NC program for integral impeller. Modify and optimize the error existed in the NC program generated by Proe 5.0 under Vericut 7.15 environment. Achieve virtual machining of impeller parts and provide method and basis for actual machining on machine by combination of Vericut 7.15 and Proe 5.0.

Abstract: As a popular topic, robust stability for uncertain systems with time delay have been widely studied in various engineering, biological, economical, electronic and dynamical systems, nerve network and so on. Recently, many researchers have paid a lot of attentions on the problem of robust stability for uncertain nonlinear systems with time delay. In this paper, a type of uncertain nonlinear delay systems has been considered in robust stability analysis. A novel robust stability criterion of the system is derived by using Lyapunov method and quadratic stability theory. A new upper bound with high-level infinite small on time delay based on Hariwity matrix and a solvable algebraic Riccati equation is presented. The main results are as follows: Through Lyapunov function and a solvable algebraic Riccati equation, we obtain the criterion of robust stability (exponential stability) for uncertain nonlinear systems with time delay.

Abstract: The clamping force and clamping sequence in the process of thin-walled parts is an important factor affecting the quality of the workpiece. This article focused on solving the parts clamping force of the locating point and clamping sequence, according to the process of clamping force on the workpiece, by the means of screw theory and the minimum modulus principle, taking the contact friction into account, the article established a mathematical model. Furthermore, a new approach to optimize clamping and clamping sequence has been put forward combining Matlab optimization toolbox, which provided guidance basic theory for the preload design of the clamping process and flexible clamping. Finally a detailed discussion was conducted to the calculation of clamping force and clamping sequence by using some practical examples.

Abstract: A two degree of freedom input vehicle model is set up. Based on driver modeling analytical method of error analysis, step signal is taken as the input of steering angle to complex vehicle model based on CarSim, vehicle lateral acceleration is taken as as output. Meanwhile, the same steering wheel angle is taken as input as equivalent two degrees of freedom vehicle model, vehicle model parameters are optimized based on the minimum objective function. The results show that, in the same kind of speed, for steering wheel angle step input and sinusoidal input , when the input amplitude increases, the equivalent accuracy of the complex vehicle model and two degrees of freedom vehicle model will be reduced.