Papers by Keyword: Structural Dynamics

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Authors: Jie Kai Gong, Wen Lei Sun, An Wu
Abstract: In recent decades, the rapidly development of wind energy in China and the increasing of size and complexity of wind turbine have requested the improvement in wind turbine systematic design technology. A reasonable systematic dynamic model is an important part for systematic design of MW-class wind turbine. In structural dynamic model, the flexibility of blade and tower is represented by presumed mode shapes. In this paper, based on presumed mode shape method, the structural dynamic equations of wind turbine were constructed. Along with the wind field model, the wind turbine aeroelastic systematic dynamic model was constructed. Using the model, the deflections and load of blade, low speed shaft torque of a 1.5MW wind turbine have been calculated. Therefore, the construction of wind turbines systematic dynamic model has an important significance for the development of wind systematic design and manufacturing capacity.
Authors: Miao Yu Hai, Xiao Hui Su, Yao Cao, Yong Zhao, Jian Tao Zhang
Abstract: A novel procedure for calculating the dynamic response of elastic solid structures is presented. The ultimate aim of this study is to develop a consistent set of finite volume (FV) methods on unstructured meshes for the analysis of dynamic fluidstructure interaction (FSI). This paper describes a two-dimensional (2D) FV cell-vertex based method for dynamic solid mechanics. A novel matrix-free implicit scheme was developed using the Newmark method and dual time step algorithm and the model is validated with a 2D cantilever test case as well as a 2D plate one.
Authors: Xing Pei Liang
Abstract: A new numerical integration method for dynamic finite element analysis is proposed in the paper. In the proposed algorithm, the acceleration change in a particular time step is first assumed to be curved variation, and then the displacement vector, velocity vector and acceleration vector at the current instance can be expressed in terms of the results at last time instance. Because of the curvilinear property of the acceleration change in a particular time interval, the complicated dynamical responding such as high-oscillatory modes can be captured with the present method. The efficiency and accuracy of the proposed algorithm are validated by two numerical examples and numerical results show that the present formulation has better accuracy than the Wilson’s method and the Newmark’s method used in the conventional finite element method.
Authors: Ze Ying Guo
Abstract: Based on the coupled precise time integration method and basic assumptions of constant average acceleration method in Newmark family, implicit series solution of structural dynamic equation is put forward by introducing the Taylor series expansion. Relevant time step integration formulas were designed. Stability and accuracy of the method were analyzed. Stability analyses show that the coupling implicit method is stable when damping ratio is equal to 0, and is conditionally stable when damping ratio are other values. The results show that the accuracy of the algorithm can be controlled by choosing the number of truncation order of Taylor series expansion and is better than that of traditional scheme with the increase of time step. Number examples are given to demonstrate the validity of the proposed method.
Authors: Run Lin Yang, Shun Zhang, Lu Bo Bi
Abstract: With increase of terrorist blast, it is becoming more important for buildings to resist the blast load than before. This paper focuses on analysis of loss influence on key members of frame structures subjected to blast loading. The performance of a 5 storey frame structure with damage was evaluated on the assumption that whose key columns and beams had been lost after blast. By comparing the deformation and the internal force of the original frame with the corresponding items of the incomplete one, the impact of the key columns or beams on the performances of the whole frame structure was discussed. Numerical results show that the loss of either the key columns or the key beams will endanger the whole structure. Especially, the deformation and the internal force of the members adjacent to the missing key column have obvious increases. Consequently, the loss of the key column exerts a more serious impact on the building than that of the key beam.
Authors: Ileana Corbi, Ottavia Corbi
Abstract: Base Isolation systems have been implemented on civil engineering structures subject to earthquakes worldwide for a number of years because of their simplicity, reliability, and effectiveness; passive isolators usually consist of members located in between the foundations and the super-structure and characterised by high damping capacity and relatively low stiffness. Devices are available typically coupling elements endowed with large translating deformability, mainly aimed at shifting the structural frequency band, with components devoted to dissipate and/or absorb the filtered transmitted energy. Although characterized by stability and low energy demand, BI devices are limited in their ability to adapt themselves to changing demands for structure response reduction. The performance of such devices may fail expectations under special, like in case of soft soil, or unexpected conditions, and, in order to optimize the overall performance of the control system, the isolated system should be embedded in a more complex system able to possibly activate some corrective actions. In the paper, with reference to steel structures, a strategy is outlined to this purpose, devoted to existing, or not, isolated constructions.
Authors: Paul-Virgil Rosu, Mihai Mihaila, Radu Canarache, Eddy Dascotte
Abstract: With the increasing complexity of the products, engineers face a higher level of uncertainty in both simulation and test. Correlation between numerical and experimental analysis using model updating techniques helps engineers to asses uncertainty. Present research efforts focus to combine finite element analysis and testing in one common framework. Experimental and operational modal analysis and simulation make benefit from common databases. Some applications presented emphasize the advantages of these techniques.
Authors: M.F. Harper, M. Thompson
Abstract: Noise from a source such as an engine or gearbox can travel through a surrounding structure by many routes. It can be very difficult to reduce noise transmission to the environment or to operators or passengers, because many paths contribute to the transmission and it may not be clear which need to be treated. In order to apply effective control measures, it is very helpful to start with knowledge of the relative importance of the various possible paths. We report on a method that allows the strengths of the different paths to be quantified and ranked in order of importance, without having to dismantle or disconnect the system. Having measured these, and then having measured the levels of noise being injected into each path by the engine or gearbox, the contribution of each path to transmitted noise can then be estimated. Finally the noise reduction obtained by treating any desired combination of paths can be predicted. We refer to the method as “Transmission Path Audit” (TPA). The method was applied to an operating wind turbine that was giving noise problems. A TPA was carried out: it indicated that the problem was due to the turbine blades and tower, which between them radiated the bulk of the noise at three different tonal frequencies. Based on these results, damping treatments were applied to the blades and tower, and noise radiation was reduced to acceptable levels. The TPA method has very general applicability, and can be used to characterise noise transmission through a wide range of structures. It is likely to be particularly useful in tracing transmission paths through vehicles, from the power plant to the passenger space. Its novelty lies in its being entirely non-intrusive.
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