Dynamical Models Quality of Truss Supporting Structures (original) (raw)
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Finite Element Analysis of the Tower Crane
2010
In heavy industries, tower cranes are used to lift and carry heavy materials. This study focuses on the prevention of crane damage which occurs due to heavy loads. In this study, the strength of the tower crane parts has been calculated according to FEM and DIN standards .In order to accomplish finite element analysis method, the tower crane parts are modelled one by one. Afterwards, the stress analysis of the crane parts are accomplished with ANSYS software considering the crane's self weight, payload, hook weight, trolley weight and the dynamic loads. As a conclusion, the results obtained from finite element method and analytical calculation are compared.
Machine Design, 2019
This research deals with the analysis and comparison of the results obtained analytically and by using the finite element method on the box girder of a double-beam bridge crane with the rail in the middle of the girder, where an existing bridge crane, which is in use, was observed. Stress states in the girder were observed in this analysis, and the emphasis was placed on the local stress states which occur in the middle of the girder due to the wheel-rail pressure. The expressions used in the domestic literature and applied in the design of these types of structures were used for obtaining analytical values of the results. The software package SAP2000 and the software module Autodesk Nastran In-CAD of the software package Autodesk Inventor were used for the FME analysis, where the girder structure was modelled by shell finite elements in both cases. In the application of the software package SAP2000, the rail was modelled by beam finite elements, and the loads were applied on the nodes of the finite element mesh which connect beam and plate finite elements, while in the application of the software module Autodesk Nastran In-CAD the rail was modelled by 3D finite elements, and the loads were applied on the external rail surfaces which are in contact with the wheel. The aim of this research is to present the comparison between analytical and numerical results in order to justify the application of the proposed models of FEM analysis, their advantages and disadvantages, as well as the credibility of the obtained results in relation to the existing analytical model of calculation. In this way, it can be shown whether the FEM results are within those obtained analytically, so that in the design of these types of structures the proposed modelling methods could be reliably used.
2007
In this work paper we will study the dynamic behavior of the tower crane during the horizontaltranslational movement of the load hanging in the crane's boom. Using computer simulations of the crane's virtual model, we will study the influentia of this motion in the crane's construction when fully engaged with load. We will try to find how does the load swinging effect the carrying construction, what happens when load stops somewhere in the crane's boom and at the peak point, and how does this effects some main parts of crane. For this case we created virtually a whole Tower Crane using Finite Elements and model design application MSC.VisualNastran [4]. Dimensions are from standard manufacturers and using DIN 44 [1]. The results will give us a better view about the dynamic occurrences caused by the load horizontal movement.
Dynamics Analysis of a Truss System Modelled by the Finite Element Method in the Frequency Domain
2020
The dynamic analysis of a truss system modelled by the finite element method in the frequency domain is studied. The truss system is modelled by 22 elements and has 44 degrees of freedom. The stiffness matrix and mass matrix of the truss system are obtained by using the finite element method. Differential equations of the truss system are obtained by using the obtained stiffness and mass matrix. By applying the Laplace transformation, the displacements of each node are calculated, and the equation is arranged in the frequency domain. The obtained differential equations are solved by using MATLAB. Eigen values are calculated and represented depending on the frequencies. Thus, static displacements, dynamic displacements, static reaction forces and dynamic reaction forces for each frequency are graphically obtained. Additionally, dynamic amplification factors are calculated and simulated depending on the frequencies. Dynamic displacements increased near the eigenvalues, and the dynamic...
Tower cranes are used at construction site. Tower crane jib is suspended beam which carries load moving along the jib. While designing components need to design crane hook & snatch block assembly, wire ropes, moving trolley, tie rods, jib, counterweight side, mast, slewing ring. We selected jib for analysis since we wanted to validate the use of ANSYS (FEM method) for structural design of Tower Crane Jib. Jib model was generated in ANSYS 14.5 workbench and further analyzed in the same. Two models of Tower Crane jib were compared initially for axial force and deformation developed in members of the jib and the better model was selected for further analysis. Throughout the analysis, the load has been applied at the end of the jib of the tower crane to generate maximum moment and stresses in the jib. Initially the results of ANSYS 14.5 were validated using analytical method for the jib (Method of sections for trusses). Later, the results for static as well as dynamic analysis are obtained. In static analysis, crane’s self weight, payload, hook weight, trolley weight and wind loading are considered whereas acceleration, braking, and angular velocity are considered in dynamic analysis.
A Computational Model for Structural Vibration Problems
This paper deals with the development of a computational model in freeFEM++ for the analyzes of structural vibration problems in civil engineering structures during earth-quakes. freeFEM++ is an open source program, based on the finite element method, which could be helpful to study and improving the analyzes of the dynamic response of civil engineer-ing structures due to seismic loads. The most general approach for dynamic analyzes is the direct numerical integration of the dy-namic equilibrium equations on the weak formulation. The resolution of this dynamic problem must satisfy two steps: space integration and time integration. For the first step are approached the fundamentals of numerical methods of space integration and is used finite element method. For the second step is used a time-domain numerical method -Newmark's method -to determi-nate dynamic response of strutural systems. After the solution is defined at time "t − ∆t", the method determinate the solution...
Failure Analyses of Tower Crane Using Fem and Theoretical Studies
Yanbu Journal of Engineering and Science
This paper describes the technique to explicitly increase the tower crane’s stability during cyclones through modal analysis in FEM. For this, modal analyses of a boom, mast, and tower crane are carried out individually to minimize the tuning effect of natural frequencies. The study explains the methodology to increase the stiffness using bracings in the mast expressed in modal parameters. In FEM analysis, bracings are applied in fixed support along the vertical mast of the tower crane. For this purpose, a 1/10 scale model of “Potain MCi85 A/B” tower crane was modelled in Nx-Unigraphics. Theoretical analysis of the boom’s natural frequencies and its counterweight is assumed as cantilever beam and mast in form column. The values of natural frequencies of tower cranes under different boundary conditions are obtained through Galerkin and Dunkerley’s mathematical expressions. Theoretical and FEM results established similar trends of increasing stability as revealed in terms of natural f...
Chinese Journal of Mechanical Engineering (© CMES & Springer), 2015
Geometric or sub-scale modeling techniques are used for the evaluation of large and complex dynamic structures to ensure accurate reproduction of load path and thus leading to true dynamic characteristics of such structures. The sub-scale modeling technique is very effective in the prediction of vibration characteristics of original large structure when the experimental testing is not feasible due to the absence of a large testing facility. Previous researches were more focused on free and harmonic vibration case with little or no consideration for readily encountered random vibration. A sub-scale modeling technique is proposed for estimating the vibration characteristics of any large scale structure such as Launch vehicles, Mega structures, etc., under various vibration load cases by utilizing precise scaled-down model of that dynamic structure. In order to establish an analytical correlation between the original structure and its scaled models, different scale models of isotropic cantilever beam are selected and analyzed under various vibration conditions(i.e. free, harmonic and random) using finite element package ANSYS. The developed correlations are also validated through experimental testing. The prediction made from the vibratory response of the scaled-down beam through the established sets of correlation are found similar to the response measured from the testing of original beam structure. The established correlations are equally applicable in the prediction of dynamic characteristics of any complex structure through its scaled-down models. This paper presents modified sub-scale modeling technique that enables accurate prediction of vibration characteristics of large and complex structure under not only sinusoidal but also for random vibrations.
Applied Sciences, 2021
Large attachments can dramatically affect the dynamic response of an assembled structure. In various industrial sectors, e.g., the automotive, aircraft, and shipbuilding industries, it is often necessary to predict the dynamic response of assembled structures and large attachments in early-stage engineering design. To deal with this, it is often the finite element method (FEM) that is used in the vibrational analysis. Despite the advent of large-scale computer availability, it is still commonplace, and often necessary, to reduce the model-size with large attachments to acceptable levels for computer time-scale or memory-size limitations. This article discusses the simple methodology of replacing large and sometimes complicated attachments by using a simplified boundary condition. This methodology is well-known in certain sectors of computer-aided design, but here we are able to present a comprehensive discussion from laboratory measurements, finite element analysis and a simplified ...