Papers by Keyword: Dynamic Behavior

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Authors: Jae Hyun Kim, Jung Yup Kim, Bong Kyun Jang, Kyung Shik Kim, Byung Ik Choi, Sang Hyun Jun, Jun Ho Kim
Abstract: In this study, we propose a simplification scheme for modeling a complex bellows structure. Using 3-dimensional finite element analysis, vibration modes and natural frequencies are analyzed. The analysis results are compared with those measured by telemetry system of acceleration. It is found that bending mode of vibration can be activated even a low operation frequency and this leads to uneven distribution of stress. The uneven distribution of stress can be a possible cause for the early failure of a bellows with a large diameter.
Authors: Ming Yu, Ping Zhu
Abstract: Dynamic mechanical behaviors are critical to the engineering applications of hollow spheres filled syntactic foams. The potential of such composites cannot be fully realized unless the effects of strain rate on their mechanical properties are fully understood. In this study, both the compressive and the tensile behaviors of an epoxy syntactic foam filled by ceramic microspheres were experimentally investigated over the strain rate range from 0.001 to 2000 s-1. The compressive and tensile tests at high strain rates were carried out by means of split Hopkinson pressure bar (SHPB) and split Hopkinson tensile bar (SHTB), respectively. The stress-strain responses and failure mechanisms were examined quantitatively and qualitatively. The experimental results indicate that both the compressive and the tensile behaviors of syntactic foam are highly sensitive to strain rate. Moreover, a comparison of the stress-strain curves suggests that the compressive and tensile behaviors are dominated by different failure mechanisms, which consequently lead to distinct effects of strain rate on the compressive and tensile behaviors of syntactic foam.
Authors: Yi Lin, Tao Yang, Ting Ting Liu, Guang Yan Chen, Chao Wang
Abstract: This paper presents a micro-fluidic inertial switch with varying rectangular cross section, which employs the moving mercury droplet in the micro-channel to close a switch. Combining the Young-Laplace formula with the structure, the formula of the threshold g-value is derived. The influence of design parameters of microchannel on the threshold g-value is analyzed. Based on the VOF approach containing contact angle effects, the dynamic behavior of mercury droplet in the microchannel is simulated using Fluent. The response time is predicted through simulation with the contact angles ranging from 130° to 170°. In addition, the dynamic process of inertial switch is simulated, and the result indicates that the selected design parameters can achieve reliable switching under given threshold g-value.
Authors: Ting Fang Hung, Chia Che Chang, Fuh Kuo Chen
Abstract: The dynamic behavior of a radiator support frame impacted by a free-falling engine hood was studied with the use of the 3-D finite element simulations. The engine room including an engine hood, a radiator support frame, and a hood ledge was modeled first. Taking computing efficiency and accuracy into account, approaches for selecting element size, cleaning up complicated features of CAD files were then studied. In order to make the simulations more efficient, the contact spot weld model was adopted. To further reduce the computing time, a theoretical model was also proposed in the present study to calculate the instantaneous angular velocity of the engine hood at the incipient impact to the radiator support frame. The engine hood free-falling tests were also conducted to validate the finite element simulations. The consistency between the experimental data and the simulation results confirms the validity of the finite element model constructed in the present study.
Authors: Marin Guțu
Abstract: This paper presents the final design of glass-reinforced polyester (GRP) blade for 10 kW wind turbine developed at the Technical University of Moldova by finite element (FE) analysis techniques. This design was reached through an iterative analysis process following a previous design. The objective of this research is to maximize structural robustness of composite blade while reducing its mass and cost. Design optimization of the composite wind turbine blade was performed by checking the static and dynamic behavior. The design variables considered are related to the composite material parameters: fiber direction, layups direction and blade shell thickness based on number of composite layers. The constraints are tip deformations, allowable stresses and resonant vibration of the blade. According to FE analysis results the optimized blade will be stiff enough in storm conditions, will operate out of dangerous resonance frequencies and will weigh approximatively 20% less.
Authors: Xue Song Zhang, Ze Bing Dai, Zhi Cheng Lu, Cheng Chen Cui
Abstract: Dynamic behavior of the 1100kV porcelain arresters with and without the new type lead dampers and are investigated,based on theoretical analysis and finite element analysis. The results of theoretical analysis show that the dynamic response of 1100kv porcelain arrester can be decreased by damping measures, which can change the dynamic behavior of equipment. The results of finite element analysis show that the primary frequencies of these two structures are between 1Hz and 10Hz and the differences between them is not obvious, which indicated that the overall stiffness of the two structures is low and the frequency and vibration mode of these two structures have hardly been changed by the lead dampers. The level modes dominated the equipment, while vertical modes and torsional modes are not obvious. Owning to an effect of increment of damping device with the new type lead dampers, there is a reduction by 40% above in the maximum root stress of porcelain bushing. In the meantime, the new type lead dampers can also decrease the relative displacement at the top of equipment.
Authors: Geng Shun Chen, Yi Lv
Abstract: Article in the first quantitative analysis of milling process of material removal on the work piece model effects, using matrix perturbation theory gives the work piece modal approximation, fast algorithms. Major sources of uncertain factors analysis of milling process, based on the interval algebra, derivation of the work piece (or tool) interval characteristics of matrix, the use of interval finite element method for calculating the tool dynamic response of upper and lower bounds. Modal experimental results and theoretical predictions dovetailed.
Authors: Xiao Cong He
Abstract: The influence of adhesive layer thickness on the dynamic behaviour of the single-lap adhesive joints is investigated in this paper. The ABAQUS finite element analysis (FEA) software was used to predict the frequency response functions (FRFs) of the single-lap adhesive joints of different thickness of the adhesive layer. As a reference, the FRFs of a cantilevered beam without joint were investigated as well. It is clear that the FRFs of the four beams are close to each other within the frequency range 0~1000 Hz. It is also found that the composite damping of the single-lap adhesive joint increases as the thickness of the adhesive layer increases.
Authors: Gab Chul Jang, Kyong Ho Chang
Abstract: During welding process to make joints, residual stress is inevitably produced and weld metal should be used. These influence the static and dynamic behavior of steel structures with welded joints, such as steel piles. In steel structures, dynamic mechanical behavior is different to static mechanical behavior. Therefore, to accurately predict the behavior of steel piles with a welded joint under static-dynamic loading, the research on influence of a welded joint on the static and dynamic behavior of steel piles is necessary. For that purpose, a rate-dependent plasticity model was used, considering strain rate hardening and temperature rise. In this paper, the distribution of welding residual stress in a welded joint was computed by using three-dimensional heat conduction analysis and three-dimensional thermal elastic-plastic analysis. The behavior of steel piles with a welded joint under axial static and dynamic loading was investigated by using three-dimensional elastic-plastic finite element analysis, which employed a rate-dependent plasticity model and included residual stress and mechanical properties of weld metal in a welded joint. The rate-dependent plasticity model used in this paper is proposed by the authors based on the static-dynamic loading tests. Numerical analysis results of steel piles with a welded joint were compared to those without a welded joint. In comparison, the characteristics of static and dynamic behavior of steel piles with a welded joint were investigated.
Authors: Donato Cancellara, Fabio de Angelis, Vittorio Pasquino
Abstract: In the present work some characteristical features of autoclaved aerated concrete structures are illustrated in the seismic and nonseismic design for residential and industrial buildings. Besides the properties of this material with regards to fire resistance and thermal and acoustical insulation, the use of autoclaved aerated concrete for engineering structures may have the advantage of a confined structure with reinforced concrete bond elements that are disposed horizontally and vertically. In the present work the dynamical behavior of a building prototype realized with autoclaved aerated concrete is analyzed, a finite element modelling of the structure has been calibrated according to an experimental modal analysis carried by loading the structure with a vibrodyne located on top of the building and by monitoring the building outputs due to horizontal harmonic forces. The finite element modelling of the dynamical behavior of the autoclaved aerated concrete structure has been compared with a similar tuff masonry building whose characteristical behavior has already been the object of experimental and numerical analysis in a previous work.
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