Papers by Author: Wei Yuan Wang

Abstract: A new reinforcement distribution design method inspired by venation configuration is discussed in the paper. Learned from dicotyledonous venation, venation growing algorithm is proposed, minimization of strain energy and shear stress determine growth direction of the mainveins and subveins respectively. Vectorial equilibrium equation is used to calculate vein widths and adjust the orientation of vein cells slightly. Sensitivity number is used to measure the change in strain energy and shear stress when a vein cell grows, necessary equations are derived for bending Kirchhoffs plate. Several examples are design for venation-like rib distribution. The resultant rib layout by VGA is applicable and effective.

Abstract: This paper concerns a venation-like design method of rib layout and its application on some plates subjected to bending loads. Main topological characters of dicotyledonous venation and two determinative mechanical parameters in leaf venation morphogenesis theories are extracted, on the basis of those elicitations, a venation growing algorithm is proposed as an attempt at the proper layout of ribs in plate. Energy criterion and shear stress is specified as the factor orienting mainvein and subveins respectively. Vectorial equation equilibrium is used in reorganization to calculate widths and adjust vein cells slightly. Finite element method functions as background technique, under which several simple-shaped plates under bending loads are designed by venation growing algorithm. The resultant venation-like ribs offer multi-balanced improvements.

Abstract: Gearbox system, as the main component of the marine power plant, is the closed drive unit that connects the main engine to the shaft. The operation state of the gearbox system has great influence for the safety and reliability of the ship. Shock loading is one of the most common external excitation for the ship and often destroys the devices and structures. Then, according to a mass of numerical calculations, this investigation develops some parameterizations for shock responses of the marine gearbox. The system modeling procedure is based on 3D finite element method which considers the effects of transient dynamic, geometrical nonlinear and impact/contact problems. Typical shock loads, which have the shape of double peak and triangle wave, were applied alone the three perpendicular directions on the bottom surface of the gearbox system to simulate the process of base excitation. The load can be described by two parameters: amplitude and wave length. Responses of the system were calculated with different load parameters and the maximum deformations were taken out by using Von Mises yield criterion. The relationship between shock parameters and structure stress were finally expressed by simulation data curve.

Abstract: The main purpose of this paper is to solve the yawing problem of a single point mooring catamaran which designed for some special offshore operations. Dynamic characteristics of mooring system had been analyzed with the effect of wind, wave and current in early research. The results show that the yawing motion would be occurred for that system and can not be avoided without external control methods. These results are supported by sea tests of the real catamaran. Then, an azimuth thruster, set aft the ship, is used for a simple dynamic positioning (DP) system of the catamaran. The system is not a complete DP system because only one freedom can be controlled for the horizontal plane motions of the catamaran. The yawing angle is selected as control variable to meet the design requirement. The thrust is perpendicular to the longitudinal axis of the ship and can provide a maximizing yaw motion for DP system. Proportional-derivative control law is applied and the feedback variables can be obtained by global positioning system in further practices. The control effectiveness is validated by numerical results and comparisons with the non-controlled situations.

Abstract: The purpose of this paper is to solve the positioning problem of a double body working ship. Dynamic characteristics of mooring system are analyzed with the effect of wind, wave and current. According to the dynamic equations of the system in the horizontal plane, longitudinal force coefficient, lateral force coefficient and yawing moment coefficient are obtained by towing test. The wind lord, wave load, current load and chain force can be calculated by empirical formulas. The motions of a mooring system are simulated in MATLAB. The results show that yawing motion would be occurred for the mooring system with single anchor at one point. The motions of the system have similar forms under the same amplitude of external loads. The results are agreed well with the observation data from documents about this relation. It is also can be point out that single point mooring system has poor stability and can not control the motion accurately. Thus dynamic positioning/mooring system should be developed for anchored working ships. This research in this paper provides the theoretical support and the analysis foundation for the further studies.

Abstract: The purpose of this paper is to investigate the optimal placement of piezoelectric actuator for active vibration control of smart structure. The structures can be described in the modal space based on the independent modal space control method and dynamic equations derived from finite element model. The modal damping ratios are derived from modal equations and an optimal target is given by maximizing the modal damping ratios. Accumulation method is adopted to the optimization calculation. Simulations are carried out for active vibration control of a conical shell with distributed piezoelectric actuators. Control effects proved the validity of the optimal method above by compared with the non-optimal results. The optimal method in this paper gives a useful guide for quantity optimization of actuators to piezoelectric structures.