scholarly journals Reinforcement and resonance control of head cover of Francis turbine by finite element analysis and modal testing

2020 ◽  
Vol 560 ◽  
pp. 012051
Author(s):  
Jiemin Xie ◽  
Bo Huang ◽  
Liang Fu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Testing ◽  
Francis Turbine ◽  
Element Analysis ◽  
Resonance Control ◽  
Head Cover

Flow Induced Stresses in a Francis Turbine Runner Using Computer-Based Design Tools

2009 ◽  
Author(s):  
Jose´ Manuel Franco-Nava ◽  
Oscar Dorantes-Go´mez ◽  
Erik Rosado-Tamariz ◽  
Jose´ Manuel Ferna´ndez-Da´vila ◽  
Reynaldo Rangel-Espinosa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Francis Turbine ◽  
Computational Domain ◽  
Element Analysis ◽  
Coordinate Measurement ◽  
The Finite Element Analysis ◽  
Turbine Runner ◽  
Induced Stresses

The stress analysis of the runner due to different loading is one of the most important tools that contribute its structural integrity evaluation. Finite element method has shown to be a strong numerical technique to provide good engineering accuracy. In this paper, the flow induced stresses in a Francis turbine runner is presented by using the finite element analysis. The runner geometry considered within the computational domain was modelled by using a three-dimensional laser triangulation scanner coupled with a portable coordinate measurement system. The runner geometry was generated by a number of 3D sub models, one for each of the main components of the runner, crown, band and a blade. In order to obtain a blade geometry a portable coordinate measurement system based on optical digitalization technology (scanner technology) was used. Because of symmetry, only a section of the runner domain was used for the finite element analysis. The runner was modeled with twenty-node solid elements. Loads due to pressure on the blade were derived from CFD computations for the runner at different power conditions (100%, 85% and 75%) for a medium head hydro power plant. CFD computations were carried out using the Finite Volume Method implement within FINE™/Turbo by NUMECA. The turbulence mathematical model used for the CFD computation was the Sparlart-Allmaras. The mesh of the turbine runner included different computational domains. For the runner blades the computational domain (mesh block) was defined in order to capture the complete blade row. All mesh blocks were structured hexahedral. Centrifugal force based on the rotational speed was considered. Also, a combined type loading analysis was computed including both pressure and centrifugal force. Appropriate boundary conditions were set in order to obtain the results due to the different type of analysis. The number of finite elements included in the FEM model was able to capture the pressure gradients on the blade surfaces obtained from the CFD results, which were investigated by application of a three dimensional Navier-Stoke commercial turbomachinery oriented CFD code. Analysis of the flow through the spiral case and stay vanes was carried out so as to include appropriate flow effects induced by these components and boundary conditions at the inlet of the wicket. A CFD analysis for the wicket and runner was carried out to generate the so called CFD reference solution. The analysis presented in this paper represents an initial characterization in order to increase understanding about combined loads acting on blades and to establish a reference state of stresses further comparison after refurbishments or optimization of the runner blades for a medium head hydroelectric power station.

scholarly journals Vibration control analysis of vehicle steering system based on combination of finite-element analysis and modal testing

2019 ◽  
Vol 26 (1-2) ◽  
pp. 88-101
Author(s):  
Shuilong He ◽  
Tao Tang ◽  
Enyong Xu ◽  
Mingsong Ye ◽  
Weiguang Zheng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Vibration Frequency ◽  
Commercial Vehicle ◽  
Steering System ◽  
Modal Testing ◽  
Control Analysis ◽  
Element Analysis ◽  
Wheel Vibration

Determining the natural frequency distribution is of great importance in studying the vibration of the steering system in a commercial vehicle. A high-speed vibration frequency sweep experiment on an unladen commercial vehicle was conducted to determine the resonance frequency of the vehicle components. A vibration waterfall plot of the collected vibration data revealed that the cause of the vibration was frequency coupling resonance between the steering wheel vibration frequency and the second-order rotation frequency of the tire. Thus, a combined optimization of the structure of the rigid bearing parts of the steering fixed support and the steering column structure was proposed. A combination of finite-element analysis and modal testing method was undertaken to verify the effectiveness of the proposed combined structural improvement; the results demonstrated the consistency of the combined methods and showed that the natural frequency of the improved steering structures, together with the vibration amplitude, had changed. This study demonstrated the feasibility of the combined modal testing and finite-element analysis method, provided more information on the vibration transfer characteristics related to the vehicle subsystems, and provided a reference for the structural design of steering systems with reduced vibration.

Dynamic Characterization of Car Door and Hood Panels Using FEA and EMA

2013 ◽  
Vol 471 ◽  
pp. 89-96 ◽  
Author(s):  
Zahir Hanouf ◽  
Waleed F. Faris ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Properties ◽  
Experimental Modal Analysis ◽  
Modal Testing ◽  
Dynamic Characterization ◽  
Element Analysis ◽  
Structural Dynamic

The dynamic characterization of vehicle structures is a crucial step in NVH analysis and helps in refining the vibration and noise in new vehicles. This paper investigates the dynamic properties of two parts of the vehicle structure which are door and hood panels. Theoretical modal analysis which is referred to as Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA) or modal testing has been used as investigative tools. The paper investigates the structural dynamic properties of door and hood panels of a local car. ME'scope software was used to analyze the data obtained from Pulse to extract the dynamic properties of the panels. LS-DYNA software was used to analyze the dynamic behavior of the structure. The comparison between the results obtained from both analyses showed some similarity in frequencies and mode shapes. Finally the paper concludes that experimental modal analysis and finite element analysis can both be used to extract dynamic properties of structures.

Modal Testing and Finite Element Analysis of a Battery Rack for Seismic Applications

2005 ◽  
Vol 48 (1) ◽  
pp. 94-102 ◽  
Author(s):  
Elzbieta Berak
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Results ◽  
Test Method ◽  
Modal Testing ◽  
Test Results ◽  
Element Analysis ◽  
Resonance Search ◽  
Qualification Testing ◽  
Sine Sweep

One of the most challenging aspects of reliability testing in the telecommunication industry is earthquake resistance testing. Cabinet systems, battery racks, equipment racks, and distribution frames are considered compliant with Network Equipment-Building System (NEBSTM) criteria for surviving earthquake conditions if test results indicate (1) the maximum deflection of the top of the structure does not exceed 7.6 cm (3 in.), (2) there are no permanent deformations or structural damage, and (3) the equipment or batteries remain functional (as defined in NEBS Requirements: Physical Protection, Specification GR-73 Issue 2). Based on seismic test results of a large population of telecom enclosures, it is accepted that a system always passes the seismic test if its fundamental natural frequency is at least 6 Hz. It is costly to produce and configure enclosures and conduct seismic qualification testing. To minimize the risk of telecom system failure, a modal finite element analysis (FEA) of the system should first be performed. Numerical results of the FEA should then be verified with experimental resonance search data generated by modal testing or sine sweep testing, combined with static pull testing where applicable. The resonance search results will determine the need for seismic testing (seismic analysis) prior to seismic qualification testing. This paper elaborates on key aspects of the static pull test method supported by the test results for a cabinet framework and a configured cabinet relative to the seismic test results. The paper also discusses sine sweep testing of a battery cabinet and results of two modal test methods used on the corresponding battery rack. Finally, this paper describes modal FEA of the same battery rack anchored to a concrete pad supported by a polystyrene plastic foam sheet and explains the correlation of the numerical results with the experimental modal analysis results. The correlated model serves as the baseline model for analyzing other battery racks and equipment cabinets configured with batteries.

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