Applied Mechanics and Materials Vols. 26-28

Abstract: The maintenance tasks in present studies for the maintenance optimization of multi-component systems are mostly simplex, while the compound maintenance that integrates several kinds of maintenance types existing in practice are seldom studied. To optimize the compound maintenance intervals of multi-component systems, the group maintenance strategy was introduced in this paper, the maintenance cost structure and composition were analyzed from system point of view, and the mathematical models were established for expected maintenance cost per unit time. Finally, a numerical example was illustrated to prove the validity of the strategy and models above.

Abstract: Workflow technology is a key technology to improve business process efficiency and productivity. It can monitor, control and coordinate the business processes and programs and can track the flow of work and information as well as the utility and inputs of resource in advance. Through workflow systems have a significant impact on organizations in the past decade, how to rapidly and cost-effectively satisfy the various dynamic demands of the market adapt to an unpredictable business environment and increasing rates of new production methods are the major challenges for enterprises. A service-based dynamically reconfigurable system framework was proposed in the paper. In the framework, a service center represents an intelligent service broker that offers a self-managed and integrated service to respond to the requests from the workflow adaptively. A workflow engine in this framework coordinates these service agents to implement particular business functions. The structure of the service agent, including its plan model, the relevant reconfiguration method and a service optimization mechanism, were discussed in the paper. A case study and an implementation were also presented.

Abstract: An object-oriented modeling method was proposed to develop a simulation software package named GVDS which could be used to predict some aspects of dynamic behavior of railway vehicle. The package based on multi-body dynamics mainly consists of three parts, an interactive pre-processor, the solver and an interactive post-processor. With UML, demands and structure of the software package are represented. By modeling of the geometry and behavior of each object, virtual prototype of railway vehicle is formed and by the simulation, the critical speed of hunting stability, wheel-rail contact forces and so on can be determined and the hunting stability, curving behavior and ride comfort can be analyzed and evaluated. Finally, some cases are simulated. The simulation results show the effectiveness of the proposed method.

Abstract: This paper describes vibration suppression of the flexible cantilever beams using shunted electromagnetic transducer. The proposed system consists of a coil attached on a cantilever and a permanent magnet placed under the bottom of the coil, and both ends of the coil were connected to the parallel resonant RLC shunt circuit. The dynamic model of cantilever beam with shunted electromagnetic damper was theoretically formulated and used to compare the analytic predictions with the experimental results. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. Also, the effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. Presented results show that the electromagnet shunt damper has good vibration reduction effect, and it can be successfully applied to reduce the vibration of the flexible structures.

Abstract: A novel method of improved Dijkstra algorithm and particle swarm optimization is proposed to evaluate global path planning for mobile robot. The first step is to make the MAKLINK graph which is used to describe the working space of mobile robot. The limited length value of free linkage line is conducted to substitute the constant weights in the adjacent matrix, which is well correlated with the fact that the number of paths is drastically less than that using the conventional Dijkstra method. Then the particle swarm optimization is adopted to investigate the global path from the several possible paths. Therefore, the proposed method facilitates reducing the computing time which enhances the efficiency of particle swarm optimization when performs the global path planning for mobile robot. Furthermore, simulation result is provided to verify the effectiveness and practicability.

Abstract: On the basis of shortage existing in traditional ERP system, this paper puts forward a novel ERP framework based on Service-Oriented Architecture. Through publishing functional components into well packaged, reusable, easily maintained and cross-platform used services and using the WS-BPEL language to arrange those independent services, those business processes of ERP can be achieved to construct ERP system and integrate existing systems rapidly ultimately.

Abstract: Based on the combined toughening principle, pure Al2O3/AlB12/Al composite ceramic powders have been synthesized using pulsed Nd:YAG laser igniting method. This method starts from Al and B2O3 powder mixtures, after which Al2O3/AlB12/AlN composite ceramics were fabricated by hot-press sintering at 1600°C for 2h under the protection of a N2 atmosphere. XRD and SEM techniques were used to characterize the phases and morphologies of the powders and the ceramics. The bending strength and the fracture toughness of the ceramics were measured by the three-point bending method and the indentation fracture method, respectively. The results show that the pure Al2O3/AlB12/Al composite ceramic powders can be successfully synthesized by pulsed Nd:YAG laser igniting method because the adiabatic temperature of Al-B2O3 system is more than 1800K. Al2O3 and AlB12 phases were formed by the liquid-liquid reaction mechanism and the liquid-solid reaction mechanism, respectively. The bending strength and the fracture toughness of the Al2O3/AlB12/AlN composite ceramics were 525.86MPa and 5.68MPa.m1/2, respectively. These values are 50.25% and 42% greater than those of the pure Al2O3 ceramic (350MPa and 4MPa.m1/2) due to the reinforcing and toughening in-situ formation of small AlN particles.

Abstract: As a powerful tool for scientific research, Monte Carlo simulation has been utilized widely in mechanical engineering for a long time. The paper reviews the application in statistical tolerance analysis, reliability design and analysis, uncertainty analysis in mechanical measurement, robot error, position and attitude analysis, and optimum design. The implementation of Monte Carlo method is also discussed and classified into three types: using Monte Carlo simulation software directly, programming in the development environment with random number generator, and programming from the basic random number generation. Finally, the authors points out using Monte Carlo software directly is recommend because the engineer needn’t concern the detail of the complex computation and can pay more attention to the purpose of the mechanical application.

Abstract: This paper presents 3D modeling and simulation for a new type of globoidal indexing cam mechanism with steel ball. The characteristic of this mechanism is that cam raceway section is double circular arc section, and this characteristic is helpful to realize approximate rolling transmission. Profile surface equation of globoidal cam is established according to rotary transform tensor theory and meshing theory. Coordinate points of profile surface is obtained by MATLAB software. 3D model of parts of globoidal indexing cam mechanism with steel ball is built by Pro/E software. In Pro/E software these parts are assembled, and kinematics simulation is performed. Through kinematics simulation angular displacement, angular velocity and angular acceleration of indexing plate are obtained. Finally dynamic simulation of this mechanism is performed by ADMAS software, and contact force between cam and roller is obtained.

Abstract: In this paper, the poplar LVL was reinforced with multilayer fiberglass mesh. The reinforcing effect of adding position of fiberglass mesh on improving the static MOE was studied. And three different nondestructive testing (NDT) methods, such as the longitudinal transmission method, longitudinal vibration method and flexural vibration method (out-plane and in-plane), were used to test the dynamic properties of the reinforced poplar LVL. The correlation analysis was implemented between the dynamic Young’s modulus and the static MOE of the reinforced poplar LVL. It can be concluded that the three NDT methods are useful for predicting the MOE of reinforced LVL, but the flexural and longitudinal vibration methods had better accuracy to estimate the MOE.