scholarly journals The choice of boundary conditions and mesh for scaffolding FEM model on the basis of natural vibrations measurements

2018 ◽  
Author(s):  
Patrycja Cyniak ◽  
Ewa Błazik-Borowa ◽  
Jacek Szer ◽  
Tomasz Lipecki ◽  
Iwona Szer
Keyword(s):  
Boundary Conditions ◽  
Natural Vibrations ◽  
Fem Model

Three-Dimensional FEM Simulation of the Ship-Bridge Collision

2013 ◽  
Vol 405-408 ◽  
pp. 3243-3247
Author(s):  
Wei Su ◽  
Ying Sun ◽  
Shi Qing Huang ◽  
Ren Huai Liu
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Reference Values ◽  
Large Scale ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Structural Safety ◽  
Fem Model ◽  
Finite Element Software

In this paper, the structural safety of the Niuwan Bridge subjected to vessel collision is investigated by the large-scale commercial finite element software ANSYS. A whole FEM model is built and a reasonable analysis and illustration for taking the value of vessel-collision forces is presented. Additionally, under the premise of reasonable simulation of the boundary conditions, the effects of the support abutments, the prestress and the carloads are considered. The analysis results have certain reference values for the anti-collision and reinforcement of bridges.

Vibration of a Simply Supported L-Shaped Plate

1997 ◽  
Vol 119 (3) ◽  
pp. 464-467 ◽  
Author(s):  
R. Solecki
Keyword(s):  
Boundary Conditions ◽  
Integral Equations ◽  
Natural Vibration ◽  
Boundary Integral Equations ◽  
Rectangular Domain ◽  
Boundary Integral ◽  
Theoretical Development ◽  
Natural Vibrations ◽  
Simply Supported ◽  
Discontinuous Functions

Recently Solecki (1996) has shown that a differential equation for vibration of a rectangular plate with a cutout can be reduced to boundary integral equations. This was accomplished by filling the cutout with a “patch” made of the same material as the rest of the plate and separated from it by an infinitesimal gap. Thanks to this procedure it was possible to apply finite Fourier transformation of discontinuous functions in a rectangular domain. Subsequent application of the available boundary conditions led to a system of boundary integral equations. A plate simply supported along the perimeter, and fixed along the cutout (an L-shaped plate), was analyzed as an example. The general solution obtained by Solecki (1996) serves here to determine the frequencies of natural vibration of a L-shaped plate simply supported all around its perimeter. This problem is, however, more complicated than the previous example: to satisfy the boundary conditions an infinite series depending on discontinuous functions must be differentiated. The theoretical development is illustrated by numerical values of the frequencies of the natural vibrations of a square plate with a square cutout. The results are compared with the results obtained using finite elements method.

scholarly journals Influence of boundary conditions in FEM model on structural behaviour of thin-walled steel beams strengthened by CFRP tapes

2020 ◽  
Vol 19 (2) ◽  
pp. 073-086
Author(s):  
Katarzyna Rzeszut ◽  
Ilona Szewczak ◽  
Patryk Rozylo
Keyword(s):  
Boundary Conditions ◽  
Laboratory Tests ◽  
Numerical Models ◽  
Load Capacity ◽  
Steel Beams ◽  
Structural Behaviour ◽  
Fem Model ◽  
Mesh Density ◽  
Newton Raphson ◽  
Thin Walled

The main aim of the study is verification and validation of FEM numerical model of beams made of thin-walled steel profiles retrofitted by CFRP tapes Sika CarboDur S. Validation is are carried out based on own laboratory tests conducted on “Blachy Pruszyński” S-type beams. The CFRP tape are bonded to the beam at compressed or tensioned flange. The most important part of this study is focused on investigation of boundary conditions influence in FEM model developed in Abaqus program. Moreover the numerical models are also tested in terms of different mesh density and types of finite elements. Numerical analyses are carried out using Newton-Raphson iterative method to solve non-linear equilibrium equation. In the paper special attention is paid to the evaluation of the possibility to increase the load capacity of the beams by appropriate localisation of CFRP tape.

scholarly journals Influence of Marine Main Engine Foundations on the Results of Vibration Calculations

2019 ◽  
Vol 26 (1) ◽  
pp. 95-101
Author(s):  
Lech Murawski
Keyword(s):  
Boundary Conditions ◽  
Ship Hull ◽  
Fem Model ◽  
Shaft Line ◽  
Marine Engines ◽  
Thermal Displacements ◽  
Engine Dynamic ◽  
Main Engine ◽  
Engine Power

Abstract The article presents an influence of foundations of slow-speed main engine body on the results of numerical analysis of the engine dynamic stiffnesses and thermal deformations. The engine body is much stiffer than its foundation pads and ship hull (double bottom) – boundary conditions of the engine. Especially for the high power, marine engines, the correct model of the boundary conditions plays a key role during the analyses. Therefore, modelling method of engine foundation (boundary conditions) of that kind of model is essential during the analyses. During shaft line alignment and crankshaft springing analyses, knowledge of dynamic stiffnesses characteristics and thermal displacements of radial (main) bearings is significant. Those data of marine main engine body are difficult to estimate because of lack of available documentation and complicated shape of the engine and ship hull. The article presents the methodology of the characteristics determination of the marine engine's body as well as the example of computations for a MAN B&W K98MC type engine (power: 40000 kW, revolutions: 94 rpm) mounted on a 3000 TEU (twenty-foot container equivalent unit) container ship (length: 250 m). Numerical analyses were performed with usage of Nastran software based on Finite Element Method. The FEM model of the engine body comprised over 800 thousand degree of freedom.

Natural Vibrations and Stability of Elliptical Cylindrical Shells Containing Fluid

2016 ◽  
Vol 16 (10) ◽  
pp. 1550076 ◽  
Author(s):  
Sergey A. Bochkarev ◽  
Sergey V. Lekomtsev ◽  
Valery P. Matveenko
Keyword(s):  
Boundary Conditions ◽  
Cross Sections ◽  
Cylindrical Shells ◽  
Mathematical Formulation ◽  
Three Dimensional ◽  
Natural Vibrations ◽  
Flowing Fluid ◽  
Thin Walled ◽  
Element Algorithm ◽  
Principle Of Virtual Displacements

The paper deals with a three-dimensional problem on natural vibrations and stability of thin-walled cylindrical shells with arbitrary cross sections, containing a quiescent or flowing ideal compressible fluid. The motion of compressible non-viscous fluid is described by a wave equation, which together with the impermeability condition and corresponding boundary conditions is transformed using the Bubnov–Galerkin method. A mathematical formulation of the problem of thin-walled structure dynamics has been developed based on the variational principle of virtual displacements. Simulation of shells with arbitrary cross sections is performed under the assumption that a curvilinear surface is approximated to sufficient accuracy by a set of plane rectangular elements. The strains are calculated using the relations of the theory of thin shells based on the Kirchhoff–Love hypothesis. The developed finite element algorithm has been employed to investigate the influence of the fluid level, the ratio of the ellipse semi-axes and types of boundary conditions on the eigenfrequencies, vibration modes and the boundary of hydroelastic stability of thin-walled circular and elliptical cylindrical shells interacting with a quiescent or flowing fluid.

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