812 Development of Neurosurgical Training System : 3rd report, Development of finite element model for computational time reduction

2010 ◽  
Vol 2010.85 (0) ◽  
pp. _8-12_
Author(s):  
Osuke KOBAYASHI ◽  
Kazuhiko ADACHI ◽  
Youhei AZUMA ◽  
Atsushi FUJITA ◽  
Eiji KOHMURA
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Training System ◽  
Computational Time ◽  
Neurosurgical Training ◽  
Time Reduction

Methods for Reducing a Thermal Finite Element Model Including the Advection Network Contribution

2006 ◽  
Author(s):  
Daniele Botto ◽  
Stefano Zucca ◽  
Muzio M. Gola
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Real Time ◽  
Residual Life ◽  
Mathematical Formulation ◽  
Time Integration ◽  
Element Model ◽  
Computational Time ◽  
Fatigue Damage Accumulation ◽  
Secondary Air

The life monitoring concept needs on-line calculation to evaluate stresses and temperatures on aircraft engine components, in order to asses fatigue damage accumulation and residual life. Due to the amount of computational time required it is not possible for a full finite element model to operate in real time using the on-board CPU. Stresses and temperatures are then evaluated by using simplified algorithms. In the present work Guyan reduction and component mode synthesis have been applied to a thermal finite element model, including the cooling stream flow — the so called advection network — in order to reduce the size of the solving equation system. The appropriate mathematical formulation for the advection network reduction has been developed. Two reduction methods have been performed, discussed and subsequently applied to a thermal finite element model of a real low pressure turbine disk. The reduced system includes both the disk and the correlated fluid network model, simulating turbine secondary air system. The finite element model is axi-symmetric, with constant convective coefficients. Results of time integration for the reduced and the complete models have been compared. Results show that the proposed techniques gives models with a reduced number of degrees of freedom and at the same time good accuracy in temperature calculation. The reduced models are then suitable for real time computation.

An H-Adaptive Finite Element Model for Constructing 3-D Wind Fields

2004 ◽  
Author(s):  
Xiuling Wang ◽  
Darrell W. Pepper ◽  
Yitung Chen ◽  
Hsuan-Tsung Hsieh
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wind Field ◽  
Compressible Flows ◽  
Element Model ◽  
Computational Time ◽  
Individual Element ◽  
Adaptive Finite Element ◽  
Wind Fields ◽  
Irregular Terrain

Calculating wind velocities accurately and efficiently is the key to successfully assessing wind fields over irregular terrain. In the finite element method, decreasing individual element size (increasing the mesh density) and increasing shape function interpolation order are known to improve accuracy. However, computational speed is typically impaired, along with tremendous increases in computational storage. This problem becomes acutely obvious when dealing with atmospheric flows. An h-adaptation scheme, which allows one to start with a coarse mesh that ultimately refines in high gradients regions, can obtain high accuracy at reduced computational time and storage. H-adaptation schemes have been shown to be very effective in compressible flows for capturing shocks [1], but have found limited use in atmospheric wind field simulations [2]. In this paper, an h-adaptive finite element model has been developed that refines and unrefines element regions based upon velocity gradients. An objective analysis technique is applied to generate a mass consistent 3-D flow field utilizing sparse meteorological data. Results obtained from the PSU/NCAR MM5 atmospheric model are used to establish the initial velocity field in lieu of available meteorological tower data. Wind field estimations for the northwest area of Nevada are currently being examined as potential locations for wind turbines.

Modal Analysis Method for Blisks Based on Three-Dimensional Blade and Two-Dimensional Axisymmetric Disk Finite Element Model

2016 ◽  
Vol 139 (5) ◽  
Author(s):  
Wangbai Pan ◽  
Guoan Tang ◽  
Meiyan Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Mechanical Energy ◽  
Three Dimensional ◽  
Element Model ◽  
Computational Time ◽  
Engineering Practice ◽  
Analysis Method

In this paper, a novel and efficient modal analysis method is raised to work on blisk structures based on mixed-dimension finite element model (MDFEM). The blade and the disk are modeled separately. The blade model is figured by 3D solid elements considering its complex configuration and its degrees-of-freedom (DOFs) are condensed by dynamic substructural method. Meanwhile, the disk is structured by 2D axisymmetric element developed specially in this paper. The DOFs of entire blisk are tremendously reduced by this modeling approach. The key idea of this method is derivation of displacement compatibility to different dimensional models. Mechanical energy equivalence and summation further contribute to the model synthesis and modal analysis of blade and disk. This method has been successfully applied on the modal analysis of blisk structures in turbine, which reveals its effectiveness and proves that this method reduces the computational time expenses while maintaining the precision performances of full 3D model. Though there is limitation that structure should have proper coverage of blades, this method is still feasible for most blisks in engineering practice.

Numerical Simulation of Tube-Plate Welding Structure with T-Shaped Sections

2014 ◽  
Vol 1061-1062 ◽  
pp. 475-480
Author(s):  
Rong Han ◽  
Yi Guo Song ◽  
Dian Tao Zhang ◽  
Ren Fu Wang ◽  
Yu Feng Zheng ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Axial Direction ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Computational Time ◽  
Tube Plate ◽  
Complex Shapes

At present, the finite element method (FEM) is used to predict the residual stress distribution of the welding structure. A long computational time is required for the multi-pass welding structure with complex shapes. Therefore, it is necessary to develop time-effective finite element model and computational approaches. In this study, the suitable finite element model is developed to perform the thermal and mechanical analyses for obtaining residual stress data of the tube-plate welding structure with T-shaped sections. The results of the finite element analyses show that the residual stress distribution and radial, hoop and axial direction stress distribution of the welding structure.

Reliability of SnAgCu Alloys for CMOS Image Sensor QFN Package under Thermal Cycling Loading

2008 ◽  
Vol 594 ◽  
pp. 175-180
Author(s):  
Hsiang Chen Hsu ◽  
Hui Yu Lee ◽  
Wen Lo Shieh
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Region Of Interest ◽  
Element Model ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Computational Time ◽  
Mesh Density ◽  
Good Agreement

A three-dimensional finite element model of CMOS image sensor QFN packaging using ANSYS codes is developed to investigate the solder joint reliability under thermal cycle test. The predicted thermal-induced displacements were found to be very good agreement with the Moiré interferometer experimental in-plane deformations. The developed finite element model is then applied to predict fatigue life of Sn4.0Ag0.5Cu, Sn3.5Ag0.5Cu and Sn3.9Ag0.6Cu alloys based on JEDEC standard JESD22-A104. In order to save computational time and produce satisfactory results in the region of interest, an independent more finely meshed so-called submodel scheme based on cut-boundary displacement method is generated. The mesh density for different area ratio of refinery/coarse model was verified and the results were found to be good agreement with previous researches. The modified Coffin-Manson equation and strain energy density based equation are applied to evaluate the reliability of SnAgCu alloys. A series of comprehensive parametric studies were conducted in this paper.

Finite Element Modeling for High Speed Machining of Ti-6Al-4V Using ALE Boundary Technology

2011 ◽  
Vol 66-68 ◽  
pp. 1509-1514
Author(s):  
Dong Lu ◽  
Ming Ming Yang ◽  
Hong Fu Huang ◽  
Xiao Hong Zhong
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Speed ◽  
Element Model ◽  
Machining Process ◽  
Computational Time ◽  
High Speed Machining ◽  
Tool Edge Radius ◽  
Edge Radius ◽  
Tool Edge

A finite element model of HSM (High Speed Machining) process of Ti6Al4V was developed with Abaqus 6.10. The flow stress of Ti6Al4V is taken as a function of strain, strain rate and temperature. Considering the fact that the tool edge radius is relatively large in HSM of Ti6Al4V and significantly influences the mechanical behaviour, thus a new Arbitrary Lagrangian-Eulerian (ALE) boundary technology was incorporated into the finite element model to simulate the flowing material around the tool edge.The adoption of ALE boundary technology could avoid using the traditional chip separation criterias and element deletion method in the model, which at the same time results in the less excessive element distortion and computational time in comparison with traditional finite element models of cutting process. The simulation results of Cutting force and temperature close to the experimental values in an acceptable range could be obtained and a stagnant zone in front of the tool edge was successfully observed in this new developed model with large tool edge radius.

scholarly journals Free vibration analysis of coupled sloshing-flexible membrane system in a liquid container

2018 ◽  
Vol 25 (1) ◽  
pp. 84-97 ◽  
Author(s):  
Amir Kolaei ◽  
Subhash Rakheja
Keyword(s):  
Finite Element ◽  
Free Surface ◽  
Free Vibration ◽  
Finite Element Model ◽  
Liquid Membrane ◽  
Free Vibration Analysis ◽  
Element Model ◽  
Computational Time ◽  
Flexible Membrane ◽  
Liquid Free Surface

A finite element model is developed to study free vibration of a liquid in a tank of arbitrary geometry with a flexible membrane constraining the liquid free-surface. A variational formulation is initially developed using the Galerkin method, assuming inviscid, incompressible and irrotational flow. The resulting generalized eigenvalue problem is then reduced by considering only the elements on the liquid free-surface, which significantly reduces the computational time. The proposed physical model is subsequently implemented into the FEniCS framework to obtain coupled hydroelastic liquid-membrane frequencies and modes. The coupled frequencies are compared with those reported for rectangular and upright cylindrical tanks using analytical methods in order to illustrate the validity of the finite element model. The results are subsequently presented for a horizontal cylindrical tank with an elastic free-surface membrane for different fill ratios and tank lengths. The effects of the membrane tension on the free vibration of the liquid in the tank are further investigated by comparing the coupled liquid-membrane frequencies with slosh frequencies of the liquid alone. It is shown that sloshing frequencies can be effectively shifted to higher values to prevent resonance in partially filled moving containers.

scholarly journals Optimization of surface-mounted permanent magnet brushless AC motor using analytical model and differential evolution algorithm

2019 ◽  
Vol 70 (3) ◽  
pp. 208-217 ◽  
Author(s):  
Mohd Rezal Mohamed ◽  
Dahaman Ishak
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Differential Evolution ◽  
Permanent Magnet ◽  
Differential Evolution Algorithm ◽  
Element Model ◽  
Torque Ripple ◽  
Domain Model ◽  
Computational Time ◽  
Evolution Algorithm

Abstract This paper discusses the optimization of surface-mounted permanent magnet brushless AC (PMBLAC) motor using Analytical Sub-domain model with Differential Evolution Algorithm (ASDEA). Only two regions were considered in this analytical sub-domain model, ie magnet and airgap regions, with assistance of Complex Relative Permeance Function (CRPF) to account for the stator slotting effect. Five machine parameters were chosen to be optimized, namely the magnet arc-pole-pitch ratio, slot opening width, magnet thickness, airgap length and stator inner radius. The optimization process has four objectives, ie minimum torque ripple, low cogging torque, high efficiency, and high output torque. The results from the optimized ASDEA were compared with the Analytical Sub-domain Genetic Algorithm (ASGA) and further validated against 2-D finite element model (FEM). Results show a good agreement between analytically optimized models and finite element model. The ASDEA has faster computational time compared to ASGA, and this provides benefit in terms of reducing the machine design parameterization time and less redundancy work required to achieve motor design specifications.

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