大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element...大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element,SE)将柔性构件离散为带有力元弹簧和阻尼器的旋转铰连接的有限个数的刚体。基于多体系统(Multi-body system,MBS)动力学理论和混合多体系统(Hybrid multi-body systems,HMBS)的建模方法,通过编制的仿真程序自动建立受约束的风力机多体系统动力学方程并进行数值求解。通过傅里叶谱分析方法,实现了系统动力学特性分析。算例分析美国可再生能源实验室(National renewable energy laboratory,NREL)公布的5 MW水平轴近海风力机的固有频率与振型,验证了程序的有效性和建模方法的正确性。基于叶素动量(Blade element momentum,BEM)理论,计算叶片变形状态下各刚体所受的气动力,在数值积分过程中实时实现流固之间的耦合。分析结果表明超级单元能用较少的自由度准确地描述风力机气动载荷、惯性力和弹性力三者之间的耦合。所开发的仿真程序能为风力机气弹耦合及稳定性分析和控制系统设计提供实用的分析平台。展开更多
Some numerical models such as central atoms model （CAM） and superelement model were used to simulate the thermodynamics of austenite decomposition in the Fe-C-Mn-Si TRIP （transformation induced plasticity） steels....Some numerical models such as central atoms model （CAM） and superelement model were used to simulate the thermodynamics of austenite decomposition in the Fe-C-Mn-Si TRIP （transformation induced plasticity） steels. Thermodynamic calculations were carried out under a para-equilibrium （PE） condition. The results show that certain silicon content can accelerate the polygonal ferritic transformation and increase the volume fraction and stability of retained austenite by retarding the precipitation of carbides during the bainitic transformation.展开更多
We present the СATEС software, which implements the solution to the problems of computational acoustics. The software is based on the use of the superelement method and finite element modeling algorithms, in-cluding...We present the СATEС software, which implements the solution to the problems of computational acoustics. The software is based on the use of the superelement method and finite element modeling algorithms, in-cluding hydrodynamic noise. The paper presents the main possibilities of software for solving acoustic design problems. .展开更多
In this paper, a new mathematical form, matrix, continued fraction (MCF) is introduced to describe the decay of effects of an equilibrant system of forces acting on a sphere of an elastic body. By this way, the famous...In this paper, a new mathematical form, matrix, continued fraction (MCF) is introduced to describe the decay of effects of an equilibrant system of forces acting on a sphere of an elastic body. By this way, the famous Saint-Venant's principle is proved often but not always valid in computational mechanics.展开更多
The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of free...The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of freedom(DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element(FE) model for structure. In proposed model, the Craig-Bampton(C-B) method, which is one of the component mode syntheses(CMS), is used to establish superelement modeling to reduce structure's DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures.展开更多
文摘大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element,SE)将柔性构件离散为带有力元弹簧和阻尼器的旋转铰连接的有限个数的刚体。基于多体系统(Multi-body system,MBS)动力学理论和混合多体系统(Hybrid multi-body systems,HMBS)的建模方法,通过编制的仿真程序自动建立受约束的风力机多体系统动力学方程并进行数值求解。通过傅里叶谱分析方法,实现了系统动力学特性分析。算例分析美国可再生能源实验室(National renewable energy laboratory,NREL)公布的5 MW水平轴近海风力机的固有频率与振型,验证了程序的有效性和建模方法的正确性。基于叶素动量(Blade element momentum,BEM)理论,计算叶片变形状态下各刚体所受的气动力,在数值积分过程中实时实现流固之间的耦合。分析结果表明超级单元能用较少的自由度准确地描述风力机气动载荷、惯性力和弹性力三者之间的耦合。所开发的仿真程序能为风力机气弹耦合及稳定性分析和控制系统设计提供实用的分析平台。
基金Item Sponsored by National Natural Science Foundation of China (50334010)
文摘Some numerical models such as central atoms model （CAM） and superelement model were used to simulate the thermodynamics of austenite decomposition in the Fe-C-Mn-Si TRIP （transformation induced plasticity） steels. Thermodynamic calculations were carried out under a para-equilibrium （PE） condition. The results show that certain silicon content can accelerate the polygonal ferritic transformation and increase the volume fraction and stability of retained austenite by retarding the precipitation of carbides during the bainitic transformation.
文摘We present the СATEС software, which implements the solution to the problems of computational acoustics. The software is based on the use of the superelement method and finite element modeling algorithms, in-cluding hydrodynamic noise. The paper presents the main possibilities of software for solving acoustic design problems. .
文摘In this paper, a new mathematical form, matrix, continued fraction (MCF) is introduced to describe the decay of effects of an equilibrant system of forces acting on a sphere of an elastic body. By this way, the famous Saint-Venant's principle is proved often but not always valid in computational mechanics.
基金Project(LZ2015022)supported by Educational Commission of Liaoning Province of ChinaProjects(51138001,51178081)supported by the National Natural Science Foundation of China+1 种基金Project(2013CB035905)supported by the Basic Research Program of ChinaProjects(DUT15LK34,DUT14QY10)supported by Fundamental Research Funds for the Central Universities,China
文摘The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of freedom(DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element(FE) model for structure. In proposed model, the Craig-Bampton(C-B) method, which is one of the component mode syntheses(CMS), is used to establish superelement modeling to reduce structure's DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures.
