자동차용 경량 샌드위치 판재의 제조 및 진동 감쇠 특성 평가

김기주,원시태 한국기계기술학회 2019 한국기계기술학회지 Vol.21 No.4

Damping and sound absorption not only reduce environmental pollution caused by vibration and noise, but also improves processing accuracy, resolution of precision measuring instruments and fatigue life of machine parts in various precision machines. The vibration-damping plate is largely divided into a constrained type in which the resin is confined by a plate and a non-constrained type in which a plate is made of a polymer material mainly composed of polymer. The external vibration energy is absorbed by the thermal energy required for friction, stretching and compression of resin, so that the noise and vibration generated by resonance are reduced. The vibration damping ability of the sandwich plate produced in this study was found to be somewhat superior, which may be due to the difference in adhesive force during the manufacture of the sandwich plate. In the experimental results, it was confirmed that the sandwich plate material is superior to the vibration damping ability than the 5182 aluminum single plate material, it can be seen that the sandwich plate is effective for vibration damping of the aluminum alloy plate material.

Free-vibration and buckling of Mindlin plates using SGN-FEM models and effects of parasitic shear in models performance

Leilson J. Araujo,João E. Abdalla Filho 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.3

Free-vibration and buckling analyses of plate problems are investigated with the aid of the strain gradient notation finite element method (SGN-FEM). As SGN-FEM employs physically interpretable polynomials in developing finite elements, parasitic shear sources, which are the cause of shear locking, can be precisely identified and subsequently eliminated. This allows two mutually complementary objectives to be defined in this work, namely, evaluate the efficiency of free-vibration and buckling results provided by corrected models, and study the severity of parasitic shear effects on plate models performance. Parasitic shear are flexural terms erroneously present in shear strain polynomials. It is reviewed here that six parasitic shear terms arise during the formulation of the four-node Mindlin plate element. Two parasitic shear terms have been identified in the in-plane shear strain polynomial while other two have been identified in each of the transverse shear strain polynomials. The element is corrected a-priori, i.e., during development, by simply removing the spurious terms from the shear strain polynomials. The computational implementation of the element in its two versions, namely, containing the parasitic shear terms (PS) and corrected for parasitic shear (SG), allows for assessments of the accuracy of results and of the deleterious effects of parasitic shear in free vibration and buckling analyses. This assessment of the parasitic shear effects is a novelty of this work. Validation of the SG model is done comparing its results with analytical results and results provided by other numerical procedures. Analyses are performed for square plates with different thickness-to-length ratios and boundary conditions. Results for thin plates provided by the PS model do not converge to the correct solutions, which indicates that parasitic shear must be eliminated. That is, analysts should not rely on refinement alone. For thick plates, PS model results can be considered acceptable as deleterious effects are really critical in thin plates. On the other hand, results provided by the SG model converge well for both thin and thick plates. The effectiveness of the SG model is established via high-accuracy results obtained in several examples. It is concluded that corrected SGN-FEM models are efficient alternatives for free-vibration and buckling analysis of Mindlin plate problems, and that precise elimination of parasitic shear is a requirement for sound analyses.

Improvement of Chromate Plating Characteristics Using Vibration

허우석(Woo Seok Heo),이종항(Jong Hang Lee),김덕기(Duck Gi Kim) Korean Society for Precision Engineering 2020 한국정밀공학회지 Vol.37 No.1

In the chemical plating of the randomly loaded workpiece, it is very important to promote the agitation of plating solution and secure the space for the chemical reaction. This study investigated the possibility of chemical plating using only vibration, as well as the plating characteristics for a combination of vibration and pressurized floating. The results of the study indicate that it is possible to perform chemical plating with only vibration, and the amount of plating increases as the vibrating frequency increases. Additionally, when combined with the vibration and pressurized floating, the probability of securing a chemical reaction space and the probability of stirring become high, resulting in highly effective plating.

Free Vibration Analysis of Graphene Platelets–Reinforced Composites Plates in Thermal Environment Based on Higher-Order Shear Deformation Plate Theory

Saeedeh Qaderi,Farzad Ebrahimi,Vinyas Mahesh 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.4

As a first endeavor, this article presents the free vibration of composite plates reinforced with graphene platelets (GPLs) based on the higher-order shear deformation plate theory. Moreover, it is assumed that the material properties are temperature dependent and are graded in the thickness direction. It is assumed that GPLs randomly spread out in each individual composite layer reinforced with graphene platelets. The theoretical formulation is derived based on higher-order shear deformation plate theory and the initial thermal stresses are evaluated by solving the thermo-elastic equilibrium equations. The Halpin–Tsai micromechanical model is used to evaluate the effective material properties of every layer of composite plates reinforced GPLs. Further, the Navier solution has been used to derive the governing equations of motion and evaluate the natural frequencies and dynamic response of simply supported graphene platelet reinforced composite plates. Four different GPL distribution pattern is modeled to find out its effect on the frequency of the plate and the other parameters. The result asserted that subjoining GPL to composite plates has a significant reinforcing effect on the free vibration of Graphene platelet reinforced composite (GPLRC) plates.

Free vibration analysis of functionally graded plates with temperature-dependent properties using various four variable refined plate theories

Amina Attia,Abdelouahed Tounsi,E.A. Adda Bedia,S. R. Mahmoud 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.1

In this paper, various four variable refined plate theories are presented to analyze vibration of temperature-dependent functionally graded (FG) plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations for the present model is reduced, significantly facilitating engineering analysis. These theories account for parabolic, sinusoidal, hyperbolic, and exponential distributions of the transverse shear strains and satisfy the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Uniform, linear, nonlinear and sinusoidal thermal conditions are imposed at the upper and lower surface for simply supported FG plates. Equations of motion are derived from Hamilton's principle. Analytical solutions for the free vibration analysis are obtained based on Fourier series that satisfy the boundary conditions (Navier's method). Non-dimensional results are compared for temperature-dependent and temperature-independent FG plates and validated with known results in the literature. Numerical investigation is conducted to show the effect of material composition, plate geometry, and temperature fields on the vibration characteristics. It can be concluded that the present theories are not only accurate but also simple in predicting the free vibration responses of temperature-dependent FG plates.

Free vibration analysis of pores functionally graded plates using new element based on Hellinger–Reissner functional

Majid Yaghoobi,Mohsen Sedaghatjo,Mohammad Karkon,Lazreg Hadji 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.49 No.6

This paper aims to investigate the free vibration analysis of FG plates, taking into account the effects of even and uneven porosity. The study employs the Hellinger-Reisner functional and obtains the element's bending stress and membrane stress fields from the analytical solution of the governing equations of the thick plate and plane problem, respectively. The displacement field serves as the second independent field. While few articles on free vibration analysis of circular plates exist, this paper investigates the free vibration of both rectangular and circular plates. After validating the proposed element, the paper investigates the effects of porosity distributions on the natural frequency of the FG porous plate. The study calculates the natural frequency of thin and thick bending plates with different aspect ratios and support conditions for various porosity and volume fraction index values. The study uses three types of porosity distributions, X, V, and O, for the uneven porosity distribution case. For O and V porosity distribution modes, porosity has a minor effect on the natural frequency for both circular and rectangular plates. However, in the case of even porosity distribution or X porosity distribution, the effect of porosity on the natural frequency of circular and rectangular plates increases with an increase in the volume fraction index.

Free Vibration Analysis of Eccentric and Concentric Isotropic Stiffened Plate with Orthogonal Stiffeners using ANSYS

Harun Rashid Siddiqui,Vaibhav Shivhare 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.12

This paper shows the study of free vibration analysis of stiffened isotropic plates with orthogonal stiffeners placed eccentrically and concentrically to the plates. In this paper finite element model is developed in ANSYS parametric design language code and discretized using 20 node structural element (SOLID 186) and convergence study of isotropic stiffened plates has been performed and compare the results with related published literature. Effects of various parameters such as boundary conditions, aspect ratios, position of stiffeners eccentrically and concentrically to the stiffened plates has been studied. The vibration analysis of stiffened plate have been studied using Block -Lanczos algorithm. The results of non dimensional frequency of eccentric and concentric isotropic stiffened plate have been compare at different mode shapes, aspect ratio’s, boundary conditions using ANSYS.

On vibration properties of functionally graded nano-plate using a new nonlocal refined four variable model

Ismahene Belkorissat,Abdelouahed Tounsi,Mohammed Sid Ahmed Houari,E. A. Adda Bedia,S. R. Mahmoud 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

In this paper, a new nonlocal hyperbolic refined plate model is presented for free vibration properties of functionally graded (FG) plates. This nonlocal nano-plate model incorporates the length scale parameter which can capture the small scale effect. The displacement field of the present theory is chosen based on a hyperbolic variation in the in-plane displacements through the thickness of the nano-plate. By dividing the transverse displacement into the bending and shear parts, the number of unknowns and equations of motion of the present theory is reduced, significantly facilitating structural analysis. The material properties are assumed to vary only in the thickness direction and the effective properties for the FG nano-plate are computed using Mori-Tanaka homogenization scheme. The governing equations of motion are derived based on the nonlocal differential constitutive relations of Eringen in conjunction with the refined four variable plate theory via Hamilton's principle. Analytical solution for the simply supported FG nano-plates is obtained to verify the theory by comparing its results with other available solutions in the open literature. The effects of nonlocal parameter, the plate thickness, the plate aspect ratio, and various material compositions on the dynamic response of the FG nano-plate are discussed.

Dynamic characterization of a CNT reinforced hybrid uniform and non-uniform composite plates

Jakkamputi Lakshmipathi,Rajamohan Vasudevan 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.1

In the present study, the various dynamic properties of MWCNT embedded fiber reinforced polymer uniform and tapered composite (MWCNT-FRP) plates are investigated. Various configurations of a tapered composite plate with ply-drop off and uniform composite plate have been considered for the development of the finite element formulation and experimental investigations. First order shear deformation theory (FSDT) has been used to derive the kinetic and potential energy equations of the hybrid composite plates by including the effect of rotary inertia, shear deformation and non-uniformity in thickness of the plate. The governing equations of motion of FRP composite plates without and with MWCNT reinforcement are derived by considering a nine- node rectangular element with five degrees of freedom (DOF) at each node. The effectiveness of the developed finite element formulation has been demonstrated by comparing the natural frequencies and damping ratio of FRP composite plates without and with MWCNT reinforcement obtained experimentally. Various parametric studies are also performed to study the effect of CNT volume fraction and CNT aspect ratio of the composite plate on the natural frequencies of different configurations of CNT reinforced hybrid composite plates. Further the forced vibration analysis is performed to compare the dynamic response of the various configurations of MWCNT-GFRP composite plate with GFRP composite plate under harmonic excitations. It was observed that the fundamental natural frequency and damping ratio of the GFRP composite plate increase approximately 8% and 37% respectively with 0.5wt% reinforcement of MWCNT under CFCF boundary condition. The natural frequencies of MWCNT-GFRP hybrid composite plates tend to decrease with the increase of MWCNT volume fraction beyond 2% due to agglomeration of CNT‘s. It is also observed that the aspect ratio of the CNT has negligible effect on the improvement of dynamics properties due to randomly orientation of CNT‘s.

Vibration and Buckling of Thick Plates using Isogeometric Approach

이상진,김하룡 대한건축학회 2013 Architectural research Vol.15 No.1

A study on the free vibration and linear buckling analyses of thick plates is described in this article. In order to determine the natural frequencies and buckling loads of plates, a plate element is developed by using isogeometric approach. The Non-uniform B-spline surface (NURBS) is used to represent both plate geometry and the unknown displacement field of plate. All terms required in isogeometric formulation are consistently derived by NURBS definition. The capability of the present plate element is demonstrated by using several numerical examples. From numerical results, it is found to be that the present isogeometric element can predict accurate natural frequencies and buckling loads of plates.