scholarly journals Efficient modelling of flexible cable-pulley systems

2020 ◽  
Author(s):  
Markus Spiegelhauer ◽  
Berthold Schlecht
Keyword(s):  
Finite Element ◽  
Stiffness Matrix ◽  
Spatial Configuration ◽  
Steel Structures ◽  
Element Model ◽  
Finite Element Models ◽  
Structural Components ◽  
Cable System ◽  
Stiffness Matrices ◽  
Universal Procedure

AbstractThis article proposes a universal procedure for efficiently modelling the flexible behaviour of pre-stressed cables, guided by multiple pulleys. Such cable-pulley systems usually connect various structural components, which often feature additional flexibility. One concern in holistic system analyses is to correctly describe the elasticity of the entire assembly for one particular spatial configuration. This can be achieved in terms of a linear stiffness matrix that accounts for the kinematics of the assembly. In this article, parametric stiffness matrices for arbitrary cable-pulley arrangements are derived. A reduction scheme is used to facilitate the integration of the derived stiffness matrix into superordinate finite element models. The method is validated with a non-linear finite element model and applied to a complex hoisting cable system connecting multiple large steel structures.

Application of a FRF Based Model Updating Technique for the Validation of Finite Element Models of Components of the Automotive Industry

1995 ◽  
Author(s):  
Stefan Lammens ◽  
Marc Brughmans ◽  
Jan Leuridan ◽  
Ward Heylen ◽  
Paul Sas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Automotive Industry ◽  
Stiffness Matrix ◽  
Model Updating ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Model Parameters ◽  
Finite Element Models ◽  
Analytical Dynamic

Abstract This paper presents two applications of the RADSER model updating technique (Lammens et al. (1995) and Larsson (1992)). The RADSER technique updates finite element model parameters by solution of a linearised set of equations that optimise the Reduced Analytical Dynamic Stiffness matrix based on Experimental Receptances. The first application deals with the identification of the dynamic characteristics of rubber mounts. The second application validates a coarse finite element model of a subframe of a Volvo 480.

scholarly journals A Symbolic Formulation for Analytical Compliance Analysis and Synthesis of Flexure Mechanisms

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Hai-Jun Su ◽  
Hongliang Shi ◽  
JingJun Yu
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Stiffness Matrix ◽  
Screw Theory ◽  
Element Model ◽  
Fe Model ◽  
Flexure Mechanism ◽  
Stiffness Matrices ◽  
Analysis And Synthesis ◽  
Flexure Joints

This paper presents a symbolic formulation for analytical compliance analysis and synthesis of flexure mechanisms with serial, parallel, or hybrid topologies. Our approach is based on the screw theory that characterizes flexure deformations with motion twists and loadings with force wrenches. In this work, we first derive a symbolic formulation of the compliance and stiffness matrices for commonly used flexure elements, flexure joints, and simple chains. Elements of these matrices are all explicit functions of flexure parameters. To analyze a general flexure mechanism, we subdivide it into multiple structural modules, which we identify as serial, parallel, or hybrid chains. We then analyze each module with the known flexure structures in the library. At last, we use a bottom-up approach to obtain the compliance/stiffness matrix for the overall mechanism. This is done by taking appropriate coordinate transformation of twists and wrenches in space. Four practical examples are provided to demonstrate the approach. A numerical example is employed to compare analytical compliance models against a finite element model. The results show that the errors are sufficiently small (2%, compared with finite element (FE) model), if the range of motion is limited to linear deformations. This work provides a systematical approach for compliance analysis and synthesis of general flexure mechanisms. The symbolic formulation enables subsequent design tasks, such as compliance synthesis or sensitivity analysis.

Matching Finite Element Models to Modal Data

1990 ◽  
Vol 112 (1) ◽  
pp. 84-92 ◽  
Author(s):  
C. Minas ◽  
D. J. Inman
Keyword(s):  
Finite Element ◽  
Control Algorithm ◽  
Natural Frequencies ◽  
Mass Matrix ◽  
Element Model ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Test Results ◽  
Stiffness Matrices ◽  
Stiffness And Damping

A technique is proposed which systematically adjusts a finite element model of a structure to produce an updated model in agreement with measured modal results. The approach suggested here is to consider the desired perturbations in stiffness and damping matrices as gain matrices in a feedback control algorithm designed to perform eigenstructure assignment. The improved stiffness and damping matrices combined with the analytical mass matrix, more closely predict the modal test results. The technique is applicable to undamped, proportionally damped, as well as non-proportionally damped models. The proposed method assumes that the analytical mass, damping and stiffness matrices are known and that vibration test data is available in the form of natural frequencies, damping ratios, and mode shapes.

Contrastive Study on Finite Element Models of High-Strength Pipelines Crossing Active Faults

2016 ◽  
Vol 850 ◽  
pp. 957-964
Author(s):  
Wei Zheng ◽  
Hong Zhang ◽  
Xiao Ben Liu ◽  
Le Cai Liang ◽  
Yin Shan Han
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Active Faults ◽  
Shell Element ◽  
High Strength ◽  
Element Model ◽  
Beam Element ◽  
Finite Element Models ◽  
Fixed Boundary ◽  
Equivalent Boundary

There is a potential for major damage to the pipelines crossing faults, therefore the strain-based design method is essential for the design of buried pipelines. Finite element models based on soil springs which are able to accurately predict pipelines’ responses to such faulting are recommended by some international guidelines. In this paper, a comparative analysis was carried out among four widely used models (beam element model; shell element model with fixed boundary; shell element model with beam coupled; shell element model with equivalent boundary) in two aspects: differences of results and the efficiency of calculation. The results show that the maximum and minimum strains of models coincided with each other under allowable strain and the calculation efficiency of beam element model was the highest. Besides, the shell element model with beam coupled or equivalent boundary provided the reasonable results and the calculation efficiency of them were higher than the one with fixed boundary. In addition, shell element model with beam coupled had a broader applicability.

Behavior of Structures Using Simple Plastic Hinge Theory

1994 ◽  
Author(s):  
Ramakrishnan Maruthayappan ◽  
Hamid M. Lankarani
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cantilever Beam ◽  
Reliable Method ◽  
Plastic Hinge ◽  
Element Model ◽  
Finite Element Models ◽  
Computational Program ◽  
Hinge Model ◽  
The Impact

Abstract The behavior of structures under the impact or crash situations demands an efficient modeling of the system for its behavior to be predicted close to practical situations. The various formulations that are possible to model such systems are spring mass models, finite element models and plastic hinge models. Of these three techniques, the plastic hinge theory offers a more accurate model compared to the spring mass formulation and is much simpler than the finite element models. Therefore, it is desired to model the structure using plastic hinges and to use a computational program to predict the behavior of structures. In this paper, the behavior of some simple structures, ranging from an elementary cantilever beam to a torque box are predicted. It is also shown that the plastic hinge theory is a reliable method by comparing the results obtained from a plastic hinge model of an aviation seat structure with that obtained from a finite element model.

scholarly journals Aspects of Uncertainty Analysis for Large Nonlinear Computational Models

2010 ◽  
Vol 24-25 ◽  
pp. 25-41 ◽  
Author(s):  
Keith Worden ◽  
W.E. Becker ◽  
Manuela Battipede ◽  
Cecilia Surace
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
Computational Models ◽  
Element Model ◽  
Finite Element Models ◽  
Bayesian Algorithm ◽  
Basic Principles ◽  
Structure Interaction ◽  
Output Uncertainty ◽  
Input Uncertainties

This paper concerns the analysis of how uncertainty propagates through large computational models like finite element models. If a model is expensive to run, a Monte Carlo approach based on sampling over the possible model inputs will not be feasible, because the large number of model runs will be prohibitively expensive. Fortunately, an alternative to Monte Carlo is available in the form of the established Bayesian algorithm discussed here; this algorithm can provide information about uncertainty with many less model runs than Monte Carlo requires. The algorithm also provides information regarding sensitivity to the inputs i.e. the extent to which input uncertainties are responsible for output uncertainty. After describing the basic principles of the Bayesian approach, it is illustrated via two case studies: the first concerns a finite element model of a human heart valve and the second, an airship model incorporating fluid structure interaction.

scholarly journals Biaxial estimation of biomechanical constitutive parameters of passive porcine sclera soft tissue

2021 ◽  
Author(s):  
Zwelihle Ndlovu ◽  
Dawood Desai ◽  
Thanyani Pandelani ◽  
Harry Ngwangwa ◽  
Fulufhelo Nemavhola
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Model ◽  
Test Data ◽  
Element Model ◽  
Finite Element Models ◽  
Anisotropic Model ◽  
Material Models ◽  
Material Parameters ◽  
Constitutive Parameters

This study assesses the modelling capabilities of four constitutive hyperplastic material models to fit the experimental data of the porcine sclera soft tissue. It further estimates the material parameters and discusses their applicability to a finite element model by examining the statistical dispersion measured through the standard deviation. Fifteen sclera tissues were harvested from porcine’ slaughtered at an abattoir and were subjected to equi-biaxial testing. The results show that all the four material models yielded very good correlations at correlations above 96 %. The polynomial (anisotropic) model gave the best correlation of 98 %. However, the estimated material parameters varied widely from one test to another such that there would be needed to normalise the test data to avoid long optimisation processes after applying the average material parameters to finite element models. However, for application of the estimated material parameters to finite element models, there would be needed to consider normalising the test data to reduce the search region for the optimisation algorithms. Although the polynomial (anisotropic) model yielded the best correlation, it was found that the Choi-Vito had the least variation in the estimated material parameters thereby making it an easier option for application of its material parameters to a finite element model and also requiring minimum effort in the optimisation procedure. For the porcine sclera tissue, it was found that the anisotropy more influenced by the fiber-related properties than the background material matrix related properties.

scholarly journals Reconstruction finite element model of cars

2021 ◽  
Vol 4 (1) ◽  
pp. first
Author(s):  
Lý Hùng Anh ◽  
Nguyễn Phụ Thượng Lưu ◽  
Nguyễn Thiên Phú ◽  
Trần Đình Nhật
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Finite Element Models ◽  
Crash Analysis ◽  
Inertia Moment ◽  
Frontal Crash ◽  
Analysis Center ◽  
Simulation Results ◽  
And Behavior

The experimental method used in a frontal crash of cars costs much time and expense. Therefore, numerical simulation in crashworthiness is widely applied in the world. The completed car models contain a lot of parts which provided complicated structure, especially the rear of car models do not contribute to behavior of frontal crash which usually evaluates injuries of pedestrian or motorcyclist. In order to save time and resources, a simplification of the car models for research simulations is essential with the goal of reducing approximately 50% of car model elements and nodes. This study aims to construct the finite element models of front structures of vehicle based on the original finite element models. Those new car models must be maintained important values such as mass and center of gravity position. By using condition boundaries, inertia moment is kept unchanged on new model. The original car models, which are provided by the National Crash Analysis Center (NCAC), validated by using results from experimental crash tests. The modified (simplistic) vehicle FE models are validated by comparing simulation results with experimental data and simulation results of the original vehicle finite element models. LS-Dyna software provides convenient tools and very strong to modify finite element model. There are six car models reconstructed in this research, including 1 Pick-up, 2 SUV and 3 Sedan. Because car models were not the main object to evaluate in a crash, energy and behavior of frontal part have the most important role. As a result, six simplified car models gave reasonable outcomes and reduced significantly the number of nodes and elements. Therefore, the simulation time is also reduced a lot. Simplified car models can be applied to the upcoming frontal simulations.

scholarly journals APPLICATION OF RIGID LINKS IN STRUCTURAL DESIGN MODELS

2017 ◽  
Vol 13 (3) ◽  
pp. 119-137 ◽  
Author(s):  
Sergey Yu. Fialko
Keyword(s):  
Finite Element ◽  
Structural Design ◽  
Stiffness Matrix ◽  
Sparse Matrix ◽  
Element Model ◽  
Rigid Bodies ◽  
Design Models ◽  
Adjacency Graph ◽  
Direct Solvers ◽  
The Finite Element Model

A special finite element modelling rigid links is proposed for the linear static and buckling analysis. Unlike the classical approach based on the theorems of rigid body kinematics, the proposed approach preserves the similarity between the adjacency graph for a sparse matrix and the adjacency graph for nodes of the finite element model, which allows applying sparse direct solvers more effectively. Besides, the proposed approach allows significantly reducing the number of nonzero entries in the factored stiffness matrix in comparison with the classical one, which greatly reduces the duration of the solution. For buckling problems of structures containing rigid bodies, this approach gives correct results. Several examples demonstrate its efficiency.

A Parallel Solution Strategy for Finite Element Models

1996 ◽  
Author(s):  
Jordan J. Cox ◽  
Jeffrey A. Talbert ◽  
Eric Mulkay
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Decomposition Methods ◽  
Finite Element Models ◽  
Unique Contribution ◽  
Matrix Equations ◽  
Parallel Solution ◽  
The Finite Element Model ◽  
Parallel Fashion

Abstract This paper presents a method for naturally decomposing finite element models into sub-models which can be solved in a parallel fashion. The unique contribution of this paper is that the decomposition strategy comes from the geometric features used to construct the solid model that the finite element model represents. Domain composition and domain decomposition methods are used to insure global compatibility. These techniques reduce the N2 behavior of traditional matrix solving techniques, where N is the number of degrees of freedom in the global set of matrix equations, to a sum of m matrices with n2 behavior, where n represents the number of degrees of freedom in the smaller sub-model matrix equations.

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