Study on Novel Yaw Error Strategy for Wind Turbines Based on a Multi-Body Dynamics Method

At present, using structural dynamics models is the most commonly used and effective method to simulate the dynamic characteristics of large wind turbine. This paper used the multi-body dynamics method to construct the precise multi-flexible body dynamics model of a wind turbine coupled with aerodynamics/structure/control. The model can realize multi-disciplinary co-simulation interactions, and the accuracy was verified by comparing the numerical simulation data with the measured data. The allowable yaw error of a wind turbine is typically simplified to two or three fixed values according to the wind speed range, which cannot often adapt to the high and unsteady change characteristics of wind speed and direction under special conditions. In this paper, an accurate calculation method of allowable yaw error threshold based on measured wind speed and the corresponding optimization strategy of large yaw error are proposed, which not only avoid unnecessary shutdown and improve the availability, but also reduce the load of yaw bearing and improve the safety.

Structural Safety Assessment of Connection between Sloshing Tank and 6-DOF Platform Using Co-Simulation of Fluid and Multi-Flexible-Body Dynamics

Prediction of sloshing loads, which is one of the most important issues in the design of LNG carriers, has usually been carried out by experiments. When designing a 6-DOF platform equipment used for sloshing experiments, it should target a system containing a fluid, not a solid, thereby making it difficult to predict precisely the dynamic load due to the changes of a center of mass according to the tank’s movement. In the present study, two-way co-simulation technology between DualSPHysics and RecurDyn has been developed to analyze the mechanical behavior in multi-body system coupled with fluid motion; in which DualSPHysics is an open-source code based on particle method for fluid analysis and RecurDyn a commercial software for multi-flexible-body dynamics (MFBD). The developed technology was applied to the sloshing problem inside a tank connected to an upper plate on a 6-DOF platform. The simulation results were verified through comparison with the experiments conducted for this study independently, such as snapshots of flow motion, pressure on the cargo hold, and force applied to the tank-platform connection. Finally, to investigate the effects of fluid dynamic load on structural safety assessment, a two-way co-simulation between fluid-MFBD analysis was performed for two cases filling partially with fluid and solid. As a result, it was concluded that the sloshing experiment system used in this study was quite safe, and the feasibility of using the present co-simulation technology for structural safety assessment was confirmed.

Coupled simulation of elastohydrodynamics and multi-flexible body dynamics in piston-lubrication system

In this work, we propose a robust modeling and analysis technique of the piston-lubrication system considering fluid–structure interaction. The proposed schemes are based on combining the elastohydrodynamic analysis and multi-flexible body dynamics. In particular, multi-flexible body dynamics analysis can offer highly precise numerical results regarding nonlinear deformation of the piston skirt and cylinder bore, which can lead to more accurate results of film thickness for gaps filled with lubricant and of relative velocity of facing surfaces between the piston skirt and the cylinder block. These dynamic analysis results are also used in the elastohydrodynamic analysis to compute the oil film pressure and asperity contact pressure that are used as external forces to evaluate the dynamic motions of the flexible bodies. A series of processes are repeated to accurately predict the lubrication characteristics such as the clearance and oil film pressure. In addition, the Craig–Bampton modal reduction, which is a standard type of component mode synthesis, is employed to accelerate the computational speed. The performance of the proposed modeling schemes implemented in the RecurDyn™ multi-flexible body dynamics environment is demonstrated using a well-established numerical example, and the proposed simulation methods are also verified with the experimental results in a motor cycle engine (gasoline) which has a four cycle, single cylinder, overhead camshaft (OHC), air cooled.

Steering test of mid-size bus with flexible-body dynamics model

The object of this paper is to analyze the vehicle structural vibration responses during the step steering simulation test. With computer simulations, confirming the influence from the difference between configurations of components on mid-size electrical bus and tradition one could be possible. The difference of the vibration responses between flexible multi-body model and rigid one would be discussed. Since the wheel base of mid-size bus is longer than passenger car, the deformation of vehicle body more obviously influences the output of vibration response. The operating condition in practical driving can be expressed by flexible model, and the performance prediction of vehicle can be closer to the real vehicle behavior. The difference between the flexible body simulation and rigid body simulation is 1.17%, and the flexible body model is more practical.

Numerical Modeling and Analysis of Piston Lubrication for Flexible Bodies Through Elastohydrodynamics and Modal Reduction Method

An analysis for operating characteristics of piston lubrication system is performed based on the numerical model in the area of fluid-structure interaction. A numerical model with an integration of elastohydrodynamics and multi-flexible-body dynamics (MFBD) is developed to analyze lubrication characteristics such as oil film thickness and pressure. In particular, elastic deformation of components in piston lubrication system through modal reduction method is reflected on elastohydrodynamic analysis. The oil film pressure evaluated from elastohydrodynamic analysis is used as external force to calculate the elastic deformation of flexible bodies in multi-flexible-body dynamics (MFBD) again. A series of process proposed in this study is available for the analysis of realistic elastohydrodynamic lubrication phenomenon. Moreover, asperity contact effect is also implemented. Finally, a numerical example for the piston lubrication system is also demonstrated.

A Hybrid Scheme of Synthesized Sliding Mode/Strain Rate Feedback Control Design for Flexible Spacecraft Attitude Maneuver Using Time Scale Decomposition

Presented herein is a new control approach for large angle attitude maneuver of flexible spacecraft. The singular perturbation theory (SPT) provides a useful tool for two time rate scale separation (mapping) of rigid and flexible body dynamics. The resulting slow and fast subsystems, enabling the use of two control approach for attitude (Modified Sliding Mode) and vibration Strain Rate Feedback (SRF) control of flexible spacecraft, respectively. An attractive feature of the present control approach is that the global stability of the entire system has been guaranteed while the controllers accomplished their tasks in coupled rigid/flexible dynamic domain without parasitic parameter interactions. Numerical simulations show the effectiveness of the present approach.