• International Journal of Naval Architecture and Ocean Engineering
• /
• 제8권2호
• /
• pp.117-126
• /
• 2016

In this paper, a numerical procedure for the natural vibration analysis of plates with openings and carlings based on the assumed mode method is extended to assess their forced response. Firstly, natural response of plates with openings and carlings is calculated from the eigenvalue equation derived by using Lagrange's equation of motion. Secondly, the mode superposition method is applied to determine frequency response. Mindlin theory is adopted for plate modelling and the effect of openings is taken into account by subtracting their potential and kinetic energies from the corresponding plate energies. Natural and frequency response of plates with openings and carlings subjected to point excitation force and enforced acceleration at boundaries, respectively, is analysed by using developed in-house code. For the validation of the developed method and the code, extensive numerical results, related to plates with different opening shape, carlings and boundary conditions, are compared with numerical data from the relevant literature and with finite element solutions obtained by general finite element tool.

• 한국공간정보시스템학회:학술대회논문집
• /
• 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
• /
• pp.190-196
• /
• 2004

Thick composite laminated plates is considered in 3D finite-element. To consider continuity of transverse stresses and displacement field, mixed finite-element has been developed by using layerwise theory and the minimum potential energy principle. Mixed finite-element has been enforced through the thick direction, Z, of a laminated plate by considering six degree-of-freedoms per node. Six degree-of-freedoms are three displacement components in the coordinate axes directions and three transverse stress components ${\sigma}_z,\;{\tau}_{xz},\;{\tau}_{yz}$. The model maintain the fundamental elasticity relations that are stress-strain relation and displacement-strain relation, because the transverse stress components invoked as nodal degrees of freedom by using the fundamental elasticity relationship between th components of stress and displacement. Random vibration analysis of the model is performed by computing consistent mass matrix and computing covariance in frequency domain technique.

• 한국소음진동공학회논문집
• /
• 제15권4호
• /
• pp.395-403
• /
• 2005

The dynamic characteristics of delaminated smart composite laminates are studied using animproved layerwise laminate theory. The theory is capable of capturing interlaminar shear stresses that are critical to delamination. The presence of discrete delamination is modeled through the use of Heaviside unit step functions. Stress free boundary conditions are enforced at all free surfaces. Continuity in displacement field and transverse shear stresses are enforced at each ply level. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Numerical analysis is conducted to investigate the effect of nonlinearity in the transient vibration of bimodular behavior caused by the contact impact of delaminated interfaces. Composite plates with delamination, subject to external loads and voltage history from surface bonded sensors, are investigated and the results are compared with corresponding experimental results and plates without delamination.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.469-475
• /
• 2004

The transient analysis of delaminated smart composite laminates is studied using an improved layerwise laminate theory. The theory is capable of capturing interlaminar shear stresses that are critical to delamination. The presence of discrete delamination is modeled through the use of Heaviside unit step functions. Stress free boundary conditions are enforced at all fee surfaces. Continuity in displacement field and transverse shear stresses are enforced at each ply level. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Numerical analysis is conducted to investigate the effect of nonlinearity in the transient vibration of bimodular behavior caused by the contact impact of delaminated interfaces. Composite plates with delamination, subject to external loads and voltage history from surface bonded sensors, are investigated and the results are compared with corresponding experimental results and plates without delamination.

• Structural Engineering and Mechanics
• /
• 제54권4호
• /
• pp.741-754
• /
• 2015

This study evaluates prediction models for three EDPs (engineering demand parameters) using data from three symmetrical structures with RC walls designed according to the currently enforced Romanian seismic design code P100-1/2013. The three analyzed EDPs are: the maximum interstorey drift, the maximum top displacement and the maximum shear force at the base of the RC walls. The strong ground motions used in this study consist of three pairs of recordings from the Vrancea intermediate-depth earthquakes of 1977, 1986 and 1990, as well as two other pairs of recordings from significant earthquakes in Turkey and Greece (Erzincan and Aigion). The five pairs of recordings are rotated in a clockwise direction and the values of the EDPs are recorded. Finally, the relation between various IMs (intensity measures) of the strong ground motion records and the EDPs is studied and two prediction models for EDPs are also evaluated using the analysis of residuals.

• 농업과학연구
• /
• 제51권3호
• /
• pp.261-270
• /
• 2024

Starting from 2030, mandatory group housing for pregnant sows on pig farms has been enforced, requiring to secure the group housing spaces for pregnant sows. Additionally, six weeks after mating, pregnant sows are obligated to be raised in group housing spaces, and, the use of individual stalls is prohibited. This study analyzed the impact of mandatory group housing for pregnant sows on the pig industry using the equilibrium displacement model (EDM). The results showed a decrease in production due to the increase in space allocation per sow, but more significantly, consumers' willingness to pay, driven by animal welfare considerations, increased. This led to the increase in retail prices and farm prices by 13% and 25%, respectively. Analyzing the changes in social welfare, consumer surplus is increased by 5,887 billion won, and producer surplus is also increased by 10,655 billion won, contributing to the total increase in social welfare of 16,542 billion won. This suggests that the mandatory group housing for pregnant sows have positive impacts on both consumers and producers. However, this study did not consider the cost aspect, and, therefore future research is required to address the issue of cost.

• Journal of Mechanical Science and Technology
• /
• 제16권10호
• /
• pp.1276-1286
• /
• 2002

The numerical techniques are presented to solve the static and dynamic contact problems of deformable bodies having large rotations of the contact surfaces. The contact conditions on the possible contact surfaces are enforced by using the contact error vector, and an iterative scheme similar to augmented Lagrange multiplier method is employed to reduce the contact error vector monotonically. For dynamic contact problems using implicit time integration, a contact error vector is also defined by combining the displacement, velocity, and acceleration on the contact surface. The suggested iterative technique is implemented to ABAQUS by using the UEL subroutine UEL. In this work, after the computing procedures to solve the frictional contact problems are explained, the numerical examples are presented to compare the present solutions with those obtained by ABAQUS.

• Structural Engineering and Mechanics
• /
• 제58권2호
• /
• pp.231-242
• /
• 2016

To minimize the compliance of frame, a method to optimize the topology of bracing system in a frame is presented. The frame is first filled uniformly with a truss-like continuum, in which there are an infinite number of members. The frame and truss-like continuum are analysed by the finite element method altogether. By optimizing the distribution of members in the truss-like continuum over the whole design domain, the optimal bracing pattern is determined. As a result, the frame's lateral stiffness is enforced. Structural compliance and displacement are decreased greatly with a smaller increase in material volume. Since optimal bracing systems are described by the distribution field of members, rather than by elements, fewer elements are needed to establish the detailed structure. Furthermore, no numerical instability exists. Therefore it has high calculation effectiveness.

• Structural Engineering and Mechanics
• /
• 제6권8호
• /
• pp.883-899
• /
• 1998

The strength, deformation and buckling of a large engineering structure consisting of four ellipsoidal shells, two cylindrical shells with stiffening ribs and large holes, one conical shell and three pairs of large flanges under external pressure, self weight and heat sinks have been analysed by using two kinds of five different finite elements - four assumed displacement finite elements (shell element with curved surfaces, axisymmetric conical shell element with variable thickness, three dimensional eccentric beam element, axisymmetric solid revolutionary element) and an assumed stress hybrid element (a 3-dimensional special element developed by authors). The compatibility between different elements is enforced. The strength analyses of the top cover and the main vessel are described in the paper.

• Interaction and multiscale mechanics
• /
• 제2권4호
• /
• pp.353-374
• /
• 2009

A new seamless multiscale simulation was developed for coupling the continuum model with its molecular dynamics. Kriging-based Finite Element Method (K-FEM) is employed to model the continuum base of the entire domain, while the molecular dynamics (MD) is confined in a localized domain of interest. In the coupling zone, where the MD domain overlaps the continuum model, the overall Hamiltonian is postulated by contributions from the continuum and the molecular overlays, based on a quartic spline scaling parameter. The displacement compatibility in this coupling zone is then enforced by the Lagrange multiplier technique. A multiple-time-step velocity Verlet algorithm is adopted for its time integration. The validation of the present method is reported through numerical tests of one dimensional atomic lattice. The results reveal that at the continuum/MD interface, the commonly reported spurious waves in the literature are effectively eliminated in this study. In addition, the smoothness of the transition from MD to the continuum can be significantly improved by either increasing the size of the coupling zone or expanding the nodal domain of influence associated with K-FEM.