Applied Mechanics and Materials Vols. 66-68

Abstract: Considering the nonlinear and time-variable characteristics of the injection cylinder system of hydraulic injection molding machine (HIMM), a self-learning control method based on fuzzy neural network is proposed in this paper. A self-learning controller was designed based on the combination of PID controller, fuzzy neural network controller, and learning mechanism. It was applied to the position control of injection cylinder. The experimental results show that the controller has the property of higher position tracking accuracy under the high speed and variable track movement of injection cylinder, compared with PID controller. The conclusion of this research can provide the beneficial reference for designing high speed and high precision HIMM.

Abstract: This paper discusses recent nondestructive testing technology in the application of bridge structure, which focus on common rebound method and electromagnetic induction method. According to the actual measurement problems, the article explains the rebound method and electromagnetic induction method including their advantages and disadvantages, and puts forward the method of avoiding problems.

Abstract: Magnetorheological (MR) fluid is capable of changing its rheological characteristics under magnetic field. Controllability is one of the advantages of MR damper. Up to now, the dynamic characteristics of MR damper under impact loads have not been well known by researchers. In this paper, a new type of dynamic model for MR damper subject to impact load is derived. And in this novel model, it is pointed out that the square damping item and the inertia force item are two important factors which influence the total damping force in impact condition. The adding two items make the model more exactly describing its dynamic characteristics of MR damper in impact condition. This action makes the established model easier to do control analysis. Because of the polynomial form and a fixed coefficient, it is indicated that the optimization control method is a good choice for MR damper to track the demanded impact curves. Simulation analysis results prove that based on its controllability of damping force MR damper provide, its vibration-reduction and shock-resistant properties of MR damper under impact load will also be greatly improved.

Abstract: The aim of this work is the evaluation of the effects of PA6 content on the friction andwear properties of POM composite system. Friction andwear properties of PA6/POM composite were determined with the help of pin-on-disc tribometer in sliding contact with a steel-ball at room temperature without lubrication. The spectroscopic investigations reveal that the increasing concentration of PA6 has a drastic influence on crosslinking efficiency due to their interference with POM in curing process. As a result, POM filled PA6 with higher concentration showed remarkably enhanced friction and wear properties.

Abstract: This paper focuses on modified projective synchronization of uncertain unified chaotic systems via backstepping approach. A parameter observer is designed to identify the unknown parameter of unified chaotic systems and a novel backstepping control method is presented for synchronizing two identical unified chaotic systems with each other. Numerical simulations are shown to verify the feasibility and effectiveness of the proposed control technique.

Abstract: The dynamic analysis and control of flexible robot manipulators have been the main concerns of many recent studies in aeronautics and robotics. Moreover, the complexity of this problem increases when a flexible manipulator carries a payload. In this paper, we proposed a space two-link flexible manipulator with tip payload featuring surface-bonded piezoelectric torsional actuator and shear actuator. The equations of motion for the system are obtained using Hamilton’s principle. A Lyapunov-based controller is proposed to suppress the vibration of the system. Stability of the system is also investigated. The simulation results demonstrate the proposed control strategy is well suited for active control of vibration suppression on flexible manipulators.

Abstract: In this paper, a piezoelectric torsional actuator generating angular displacement from piezoelectric shear strain is proposed. The procedure for the design, and manufacture of the piezoelectric torsional actuator are presented. To evaluate the performance of the proposed piezoelectric torsional actuator, the torsional vibration suppression of a flexible manipulator system with the proposed actuator is studied. The experimental results show the piezoelectric torsional actuator is capable of producing large torque and angular displacement and is suited for vibration suppression on flexible torsional manipulator system.

Abstract: A large number of macroscopic pores were introduced into commercially pure aluminum (Al) and Zn-Al eutectoid alloy by air pressure infiltration process to comparatively study the influence of macroscopic pores on the damping behaviors of the materials. Macroscopic pores size are on the order of a millimetre (0.5~1.4mm) and in large proportions, typically high 76vol.%. The damping behavior of the materials is characterized by internal friction (IF). The IF was measured on a multifunction internal friction apparatus (MFIFA) at frequencies of 0.5, 1.0 and 3.0 Hz over the temperature range of 25 to 400 °C, while continuously changing temperature. The damping capacity of the metal materials is shown to increase with introducing macroscopic pores. Finally, the operative damping mechanisms in the metal materials with macroscopic pores were discussed in light of IF measurements.

Abstract: In automated manufacturing systems, one of the most important issues is the detection of tool wear during the machining process. The Hausdorff-Besicovitch (HB) dimension is used to analyze the feature of the surface texture of work-piece in this paper. The value of the fractal dimension of the work-piece surface texture tends to decrease with the machining process, due to the texture becoming more complex and irregular, and the tool wear is also becoming more and more serious. That can describe the inherent relationship between work-piece surface texture and tool wear. The experimental results demonstrate the probability of using the fractal dimension of work-piece surface texture to monitor the tool wear condition.

Abstract: As it is tough for the current energy absorb devices of urban vehicles to meet the crashworthiness requirements in the collision scenario of 25km/h, a methodology to improve the general crashworthiness is presented. A multi-criteria optimization, with the deformations and accelerations of all cars as the design functions and the force characteristics of end structures of cars as design variables, is defined and the Pareto Fonts are obtained. Then defining energy absorbed as design function, a single criteria optimization is made and the specific goal is achieved. No explicit relationship could be found between the design variables and the design functions, so a crash model of a train with velocity of 25km/h colliding to another train stopped is built and the genetic algorithm is chosen to solve the optimization problems. The results indicate that the crashworthiness performance of the trains is significantly improved and the crashworthiness requirements could be reached finally.