• Title, Summary, Keyword: finite element model

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Verification of Finite Element Model Using the Almen Strip Test and Its Applications to Calculate Residual Stress Distribution (알멘 스트립 시험 모사를 이용한 유한요소모델의 유효성 검증 및 잔류응력분포 계산)

  • Yang, Z.R.;Park, S.H.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.21 no.3
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    • pp.172-178
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    • 2012
  • We performed a shot peening test and used a 2-D finite element model which predicts the compressive residual stress distribution below the material's surface. In this study, the concept of 'impact cycle' is introduced to account for the irregularity in the shot's impact position during testing. The impact cycle was imbedded in the finite element model. In the shot peening test, shot bombarded a type-A Almen strip surface with different impact velocities. To verify the proposed finite element model, we compared the deformed cross sectional shape of the Almen strips with the shapes computed by the proposed finite element model. Good agreement was noted between measurements and the finite element model predictions. With the verified finite element model, a series of finite element simulations was conducted to compute the residual stress distribution below the material's surface and the characteristics of these distributions are discussed.

Vibration Analysis of HDD Actuator with Equivalent Finite Element Model of VCM Coil

  • Kim, Dong-Woohn;Lee, Jin-Koo;Park, No-Cheol;Park, Young-Pil
    • Journal of Mechanical Science and Technology
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    • v.17 no.5
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    • pp.679-690
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    • 2003
  • As the rate of increase in areal density of the HDD has accelerated, dynamic characteristics of the HDD actuator need to be improved with respect to the performance of the tracking servo and shock transmission. Therefore, it is important to analyze the vibration characteristic of the HDD actuator that consists of the VCM part, E-block and pivot bearing. In this paper, vibration modes of the HDD actuator are investigated the using finite element and experimental modal analyses methods. To develop a detailed finite element model, finite element models of each components of the actuator assembly are constructed and tuned to the results of the EMA. The VCM coil is modeled as an equivalent finite element model that has an orthotropic material property using auto-model updating program. Auto-model updating program with improved sensitivity based iterative method is applied to build a detailed finite element model using the result of the EMA. A detailed finite element model of the HDD actuator is then constructed and analyzed.

Finite Element Modeling and Mechanical Analysis of Orthodontics (치아교정의 역학적 해석을 의한 유한요소 모델링 및 치아의 거동해석)

  • Heo, Gyeong-Heon;Cha, Gyeong-Seok;Ju, Jin-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4
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    • pp.907-915
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    • 2000
  • The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element models by considering the measuring factors such as angulation, crown inclination, rotation and translations. The finite element analysis for the wire activation with a T-loop arch wire was carried out. Mechanical behavior on the movement and the initial stress for the malocclusion finite element model was shown to agree with the objectives of the actual treatment. Finite element models and procedures of analysis developed in this study would be suitably utilized for the design of initial shape of the wire and determination of activation displacements.

Finite Element Model Updating of Simple Beam Considering Boundary Conditions (경계조건을 고려한 단순보의 유한요소모델개선)

  • Kim, Se-Hoon;Park, Young-Soo;Kim, Nam-Gyu;Lee, Jong-Jae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.2
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    • pp.76-82
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    • 2018
  • In this present study, in order to update the finite element model considering the boundary conditions, a method has been proposed. The conventional finite element model updating method, updates the finite element model by using the dynamic characteristics (natural frequency, mode shape) which can be estimated from the ambient vibration test. Therefore, prediction of the static response of an actual structure is difficult. Furthermore, accurate estimation of the physical properties is relatively hard. A novel method has been proposed to overcome the limitations of conventional method. Initially, the proposed method estimates the rotational spring constant of a finite element model using the deflection of structure and the rotational displacement of support measurements. The final updated finite element model is constructed by estimating the material properties of the structure using the finite element model with updated rotational spring constant and the dynamic characteristics of the structure. The proposed finite element model updating method is validated through numerical simulation and compared with the conventional finite element model updating method.

Verification of the Finite Element Model of an Automotive Exhaust System Using Modal Testing (Modal Testing을 이용한 자동차 배기계의 유한요소 모델 검증)

  • 조민호;정해일
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.665-670
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    • 2001
  • The purpose of this paper is to verify a finite element model of an automotive exhaust system using Modal testing. In general, a lot of finite element models are used in initial design step of automotive development. One of them is a finite element model of an exhaust system. Verification on the finite element model of an automotive exhaust system is indispensable. In this paper, a finite element analysis on the exhaust system using MSC/NASTRAN is carried out, and the results are compared with those obtained by modal testing. By comparing MAC values of the analytical modes with the experimental modes, the finite element model of the automotive exhaust system is verified.

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Updating of Finite Element Model and Joint Identification with Frequency Response Function (주파수응답함수를 이용한 유한요소모델의 개선 및 결합부 동정)

  • 서상훈;지태한;박영필
    • Journal of KSNVE
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    • v.7 no.1
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    • pp.61-69
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    • 1997
  • Despite of the development in the finite element method, it is difficult to get the finite element model describing the dynamic characteristics of the complex structure exactly. Therefore a number of different methods have been developed in order to update the finite element model of a structure using vibration test data. This paper outlines the basic formulation for the frequency response function based updating method. One important advantage of this method is that the intermediate step of performing an eigensolution extraction is unnecessary. Using simulated experimental data, studies are conducted in the case of 10 DOF discrete system. The solution of noisy and incomplete experimental data is discussed. True measured frequency response function data are used for updating the finite element model of a beam and a plate. Its applicability to the joint identification is also considered.

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The finite element model research of the pre-twisted thin-walled beam

  • Chen, Chang Hong;Zhu, Yan Fei;Yao, Yao;Huang, Ying
    • Structural Engineering and Mechanics
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    • v.57 no.3
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    • pp.389-402
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    • 2016
  • Based on the traditional mechanical model of thin-walled straight beam, the paper makes analysis and research on the pre-twisted thin-walled beam finite element numerical model. Firstly, based on the geometric deformation differential relationship, the Saint-Venant warping strain of pre-twisted thin-walled beam is deduced. According to the traditional thin-walled straight beam finite element mechanical model, the finite element stiffness matrix considering the Saint-Venant warping deformations is established. At the same time, the paper establishes the element stiffness matrix of the pre-twisted thin-walled beam based on the classic Vlasov Theory. Finally, by calculating the pre-twisted beam with elliptical section and I cross section and contrasting three-dimensional solid finite element using ANSYS, the comparison analysis results show that pre-twisted thin-walled beam element stiffness matrix has good accuracy.

Modal Test and Finite Element Model Update of Aircraft with High Aspect Ratio Wings (고세장비 항공기의 모드 시험 및 동특성 유한요소모델 개선)

  • Kim, Sang-Yong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.5
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    • pp.480-488
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    • 2012
  • The aircrafts with high aspect ratio wings made by a composite material have been developed, which enable high energy efficiency and long-term flight by reducing air resistance and structural weight. However, they have difficulties in securing the aeroelastic stability such as the flutter because of their long and flexible wings. The flutter is unstable self-excited-vibration caused by interaction between the structural dynamics and the aerodynamics. It should be verified analytically prior to first flight test that the flutter does not happen in the range of flight mission. Normally, the finite element model is used for the flutter analysis. So it is important to construct the finite element model representing dynamic characteristics similar to those of a real aircraft. Accordingly, in this research, to acquire dynamic characteristics experimentally the modal test of the aircraft with high aspect ratio composite wings was conducted. And then the modal parameters from the finite element analysis(FEA) were compared with those from the modal test. To make analysis results closer to test results, the finite element model was updated by means of the sensitivity analysis on variables and the optimization. Finally, it was proved that the updated finite element model is reliable as compared with the results of the modal test.

Analysis of composite steel-concrete beams using a refined high-order beam theory

  • Lezgy-Nazargah, M.;Kafi, L.
    • Steel and Composite Structures
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    • v.18 no.6
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    • pp.1353-1368
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    • 2015
  • A finite element model is presented for the analysis of composite steel-concrete beams based on a refined high-order theory. The employed theory satisfies all the kinematic and stress continuity conditions at the layer interfaces and considers effects of the transverse normal stress and transverse flexibility. The global displacement components, described by polynomial or combinations of polynomial and exponential expressions, are superposed on local ones chosen based on the layerwise or discrete-layer concepts. The present finite model does not need the incorporating any shear correction factor. Moreover, in the present $C^1$-continuous finite element model, the number of unknowns is independent of the number of layers. The proposed finite element model is validated by comparing the present results with those obtained from the three-dimensional (3D) finite element analysis. In addition to correctly predicting the distribution of all stress components of the composite steel-concrete beams, the proposed finite element model is computationally economic.

Numerical modelling and finite element analysis of stress wave propagation for ultrasonic pulse velocity testing of concrete

  • Yaman, Ismail Ozgur;Akbay, Zekai;Aktan, Haluk
    • Computers and Concrete
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    • v.3 no.6
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    • pp.423-437
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    • 2006
  • Stress wave propagation through concrete is simulated by finite element analysis. The concrete medium is modeled as a homogeneous material with smeared properties to investigate and establish the suitable finite element analysis method (explicit versus implicit) and analysis parameters (element size, and solution time increment) also suitable for rigorous investigation. In the next step, finite element analysis model of the medium is developed using a digital image processing technique, which distinguishes the mortar and aggregate phases of concrete. The mortar and aggregate phase topologies are, then, directly mapped to the finite element mesh to form a heterogeneous concrete model. The heterogeneous concrete model is then used to simulate wave propagation. The veracity of the model is demonstrated by evaluating the intrinsic parameters of nondestructive ultrasonic pulse velocity testing of concrete. Quantitative relationships between aggregate size and testing frequency for nondestructive testing are presented.