scholarly journals Energy-Based Prediction of the Displacement of DCFP Bearings

2020 ◽  
Vol 10 (15) ◽  
pp. 5259
Author(s):  
Jiaxi Li ◽  
Shoichi Kishiki ◽  
Satoshi Yamada ◽  
Shinsuke Yamazaki ◽  
Atsushi Watanabe ◽  
...  
Keyword(s):  
Prediction Method ◽  
Analysis Data ◽  
Simplified Model ◽  
Design Stage ◽  
Response Analysis ◽  
Isolation Layer ◽  
Constant Friction ◽  
Friction Models ◽  
Isolation Systems ◽  
Friction Pendulum

Isolation systems are currently being widely applied for earthquake resistance. During the design stage for such systems, the displacement response and input energy of the isolation layer are two of the main concerns. The prediction of these values is also of vital importance during the early stages of the structural design. In this study, the simple prediction method of double concave friction pendulum (DCFP) bearings is proposed, which can relate the response displacement of the isolation layer to the ground velocity through energy transfer with sufficient accuracy. Two friction models (the precise and simplified model) and a constant friction coefficient of double concave friction pendulum (DCFP) bearings are comprehensively validated by full-scale sinusoidal dynamic tests under various conditions. In addition, a response analysis, based on previous studies, was conducted using the friction models under selected unidirectional earthquake excitations, and the accuracy of using the simplified model in the response analysis was verified. Based on the response analysis data, this article verifies and optimizes the proposed prediction method by parameterizing the characteristics of earthquakes and combining the energy balance in order to gain a deeper understanding of the design of the isolation systems.

scholarly journals Performance Analysis and Comparison of Two Base Isolation Systems with Super-Large Displacement Friction Pendulum Bearings

2020 ◽  
Vol 10 (22) ◽  
pp. 8235
Author(s):  
Peisong Wu ◽  
Jinping Ou
Keyword(s):  
Seismic Performance ◽  
Base Isolation ◽  
Design Method ◽  
Horizontal Displacement ◽  
Large Displacement ◽  
Large Radius ◽  
Isolation Layer ◽  
Deformation Ability ◽  
Isolation Systems ◽  
Friction Pendulum

Isolation technology has been successfully applied in seismic migration. With increasing of seismic demand, seismic performance of isolation structures subjected to very-rare earthquakes need further improvement. However, the isolation layer generally lacks sufficient deformation ability under very-rare earthquakes due to the deformation limit of classical isolation bearing. In order to circumvent the difficulty, this paper develops two new isolation bearings, namely super-large displacement rotation friction pendulum bearing (SLDRFPB) and super-large displacement translation friction pendulum bearing (SLDTFPB). By setting spherical shells with large span and large radius, large horizontal displacement and small horizontal stiffness can be achieved. Safety of the isolation layer and the isolation effect of the superstructure can be greatly improved. SLDTFPB differs from SLDRFPB in the motion state of the superstructure and space utilization of the isolation layer, thus SLDRFPB and SLDTFPB are suitable for structures with different requirements. Due to rotation of the superstructure with SLDRFPB or sliding frames in SLDTFPB, the traditional design method of friction pendulum bearing is no longer suitable. We present a new procedure to accurately and conveniently evaluate seismic performance of two developed bearings. Numerical simulation shows that the seismic response of both the superstructure and isolation layer is small. Developed SLDRFPB and SLDTFPB have sufficient emergency capacity and isolation resilience when subjected to very-rare earthquakes.

Motion Analysis of Pendulum-Type Isolation Systems During Earthquakes: Dynamic Test and Response Analysis on a Three Story Steel Frame Model Supported by Four Friction Pendulum Bearings

2004 ◽  
Vol 126 (1) ◽  
pp. 34-45 ◽  
Author(s):  
Shigeki Okamura ◽  
Satoshi Fujita ◽  
Masayoshi Ikenaga
Keyword(s):  
Motion Analysis ◽  
Dynamic Test ◽  
Experimental Tests ◽  
Response Analysis ◽  
Industrial Facilities ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Friction Pendulum ◽  
Structural Engineers

After the Hanshin-Awaji Earthquake Disaster, the number of earthquake isolated buildings is increasing. Most of the base isolated buildings or structures are built on laminated rubber bearings in order to give them certain natural periods. This situation, however, also encourages structural engineers to research and develop nonrubber-type isolation systems such as linear motion bearing isolators and friction pendulum systems. It is considered that the nonrubber-type isolation systems can be applied to important industrial facilities, such as LNG tanks, boiler facilities and so on to refine their seismic reliabilities. In the device of the nonrubber-type isolation systems, the device which applied the sliding is especially noticed. However, when using nonrubber-type isolation systems with sliding in the open air circumstances, long term durability of the systems must be taken into account and it may be very difficult to maintain the friction coefficient of the system. In this study, the dynamic motion analysis and the experimental tests on the isolated structure mounted on four Friction Pendulum Bearing (FPB) Systems were carried out to investigate the performance of isolation due to the rotational motion which might be induced by the friction force difference in FPB system.

Simplified Modeling Research of Reinforced Concrete Based on the Dynamic Stiffness Equivalence

2012 ◽  
Vol 446-449 ◽  
pp. 458-462
Author(s):  
Jie Hu ◽  
Jia Quan Feng ◽  
Xi Nong Zhang
Keyword(s):  
Reinforced Concrete ◽  
Reference Model ◽  
Dynamic Stiffness ◽  
Optimization Method ◽  
Simplified Model ◽  
Response Analysis ◽  
Reinforced Concrete Structure ◽  
Optimization Function ◽  
Nature Frequency ◽  
Simplified Modeling

This paper proposed a simplified modeling method of reinforced concrete based on the equivalence of dynamic stiffness, the parameters of simplified model were modified to make the error of nature frequency between reference model and simplified model as small as possible, and an appropriate optimization function was designed. The essentiality of the proposed method is parameter optimization, with the advantages such as fewer elements and calculation assumption. The numerical simulation result indicated that this optimization method is suitable for the dynamic response analysis of complicated reinforced concrete structure.

Experimental validation of a simplified model for rolling isolation systems

2013 ◽  
Vol 43 (7) ◽  
pp. 1067-1088 ◽  
Author(s):  
P. Scott Harvey ◽  
Gérard-Philippe Zéhil ◽  
Henri P. Gavin
Keyword(s):  
Experimental Validation ◽  
Simplified Model ◽  
Isolation Systems

Research on Characteristics of Fluid Exciting Force of Reactor Internals

2021 ◽  
Author(s):  
Zhipeng Feng ◽  
Liwen Deng ◽  
Xuan Huang ◽  
Pingchuan Shen ◽  
Shuai Liu ◽  
...  
Keyword(s):  
Pressure Fluctuation ◽  
Nuclear Reactor ◽  
Wide Band ◽  
Exciting Force ◽  
Design Stage ◽  
Response Analysis ◽  
Flow Induced Vibration ◽  
Analysis And Evaluation ◽  
Safety And Reliability ◽  
Force Characteristics

Abstract Flow-induced vibration is an important issue related to the safety and reliability of nuclear reactor, which need to be analyzed and evaluated in the design stage. In order to obtain the input loads and key parameters used in the calculation of flow-induced vibration of reactor vessel internals (RVIs) that need to satisfy the engineering requirements. The typical RVIs are selected as the research object, and the fluid exciting force characteristics are studied based on the computational fluid dynamics methods. The results show that the fluid exciting force acting on the RVIs is a wide-band stochastic process. For upper internal, the largest pressure fluctuation occurs at the guide tubes and support columns located near the outlet. Therefore, it is necessary to pay more attention to these guide tubes and support columns in response analysis. As for core barrel, the root mean square value of the pressure fluctuation changes drastically at the inlet and outlet location. For lower internal, the lower flow field of RVIs is relatively disordered, and its pressure fluctuation possesses irregular characteristics. Each component of lower internal need to be considered in analysis and evaluation.

An Approximate Method for Cross Curves of Cargo Vessels

2001 ◽  
Vol 38 (02) ◽  
pp. 92-94
Author(s):  
Huseyin Yilmaz ◽  
Mesut Giiner
Keyword(s):  
Prediction Method ◽  
Design Stage ◽  
Series Data ◽  
Design Parameters ◽  
Preliminary Design ◽  
Hull Form ◽  
Beam Depth ◽  
Preliminary Design Stage ◽  
The Mathematical Model ◽  
Load Conditions

In this study, a formula is presented to estimate cross curves of cargo vessels and to predict statical stability at the preliminary design stage of the vessel. The predictive technique is obtained by regression analysis of systematically varied cargo vessel series data. In order to achieve this procedure, some cargo vessel forms are generated using Series-60. The mathematical model in this predictive technique is constructed as a function of design parameters such as length, beam, depth, draft, and block coefficient. The prediction method developed in this work can also be used to determine the effect of specific hull form parameters and the load conditions on stability of cargo vessels. The present method is applied to a cargo vessel and then the results of the actual ship are compared with those of regression values.

scholarly journals Frequency Domain Response of Jacket Platforms under Random Wave Loads

2019 ◽  
Vol 7 (10) ◽  
pp. 328
Author(s):  
Xiaoshuang Han ◽  
Weiliang Qiao ◽  
Bo Zhou
Keyword(s):  
Design Stage ◽  
Response Analysis ◽  
Random Wave ◽  
Preliminary Design ◽  
Wave Loads ◽  
Spectral Densities ◽  
Spectral Moments ◽  
Jacket Platform ◽  
Power Spectral ◽  
Power Spectral Densities

This article presents a procedure that simplifies an offshore jacket platform as a non-uniform cantilever beam subjected to an axial force. A Ritz method combined with a pseudo-excitation method is then used to analyze the responses of the jacket platform under random wave loads with the associated power spectral densities, variances and higher spectral moments. The theoretical basis and pertinent governing equations are derived. The proposed procedure not only eases the process of determining the pseudo wave loads, but also requires only the rudimentary structural details that are typically available at the preliminary design stage. Additionally, the merit of the proposed procedure is that the process does not require one to compute the normal modes, which saves time and is particularly convenient for the dynamic-response analysis of a complex structure (such as an offshore platform). An illustrative example based on a three-deck jacket platform is presented to demonstrate the procedure used to obtain the power spectral densities, variances and second spectral moments of jacket-top displacement and the bending moment of the jacket at the mud line. The results obtained are compared with those obtained using a Finite Element Mothed (FEM) model. Based on the findings of the study and good agreement shown in the comparison of results, it is concluded that the proposed method is effective, simple and convenient, and can be a useful tool for the preliminary design analysis of offshore platforms.

scholarly journals An Equivalent Damping Numerical Prediction Method for the Ring Damper Used in Gears under Axial Vibration

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1469 ◽  
Author(s):  
Shuai Wang ◽  
Xiaolei Wang ◽  
Yanrong Wang ◽  
Hang Ye
Keyword(s):  
Structural Parameters ◽  
Great Influence ◽  
Prediction Method ◽  
Forced Response ◽  
Numerical Prediction ◽  
Axial Stiffness ◽  
Response Analysis ◽  
Axial Vibration ◽  
Equivalent Damping ◽  
Vibration Loads

In aircraft gas turbine engines, gears in the transmission system are typically cyclic in structure and inevitably encounter large dynamic loads, such as meshing excitation, resulting in high vibration loads in resonance. To prevent gear resonance failure, a ring damper is employed to reduce the resonance response. As relative motion between the gear and the ring damper occurs, vibration loads can be reduced by friction energy dissipation. Moreover, the gears in the aircraft engine are thin-walled and their axial stiffness is much smaller than radial stiffness; thus, it is easier for axial vibration to cause resonance failure. This paper proposes an equivalent damping numerical prediction method for a ring damper under axial vibration, which greatly shortens the calculation time and prevents the forced response analysis of nonlinear structures. Via this method, the influence of ring damper structural parameters on friction damping in gears under axial vibration is investigated. The results indicate that the friction coefficient and mass of the ring damper have a great influence on damping performance.

Numerical Analysis of Thermal Error for a 4-Axises Horizontal Machining Center

2017 ◽  
Vol 868 ◽  
pp. 64-68
Author(s):  
Yu Bin Huang ◽  
Wei Sun ◽  
Qing Chao Sun ◽  
Yue Ma ◽  
Hong Fu Wang
Keyword(s):  
Machine Tool ◽  
Working Condition ◽  
Prediction Method ◽  
Thermal Error ◽  
Error Modeling ◽  
Model Verification ◽  
Design Stage ◽  
Thermal Errors ◽  
Machining Center ◽  
Machining Errors

Thermal deformations of machine tool are among the most significant error source of machining errors. Most of current thermal error modeling researches is about 3-axies machine tool, highly reliant on collected date, which could not predict thermal errors in design stage. In This paper, in order to estimate the thermal error of a 4-axise horizontal machining center. A thermal error prediction method in machine tool design stage is proposed. Thermal errors in workspace in different working condition are illustrated through numerical simulation and volumetric error model. Verification experiments shows the outcomes of this prediction method are basically correct.

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