Stress analysis of a plain orthogonally woven textile composite under tension along the warp direction

2019 ◽  
Vol 53 (20) ◽  
pp. 2809-2829
Author(s):  
M Keith Ballard ◽  
John D Whitcomb
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Normal Stress ◽  
Local Coordinate System ◽  
Mesh Refinement ◽  
Element Model ◽  
Stress Concentrations ◽  
Textile Composite ◽  
Volume Average ◽  
Woven Textile

A non-idealized finite element model of a plain orthogonally woven textile composite was subjected to tension along the warp direction, and the predicted stress state was investigated. The effect of refining the geometry and mesh on the volume average stresses and the percentage of each constituent at different stress levels was explored. For the particular textile architecture considered, which consisted of large reinforcement tows and complex tow cross sections, it was shown that the typical mesh refinement in the literature might suffice for volume average stresses, but a higher mesh refinement is needed to accurately capture stress concentrations. The locations of stress concentrations within each constituent were identified. For the three types of tows, [Formula: see text], transverse normal stress in the local coordinate system, in the wefts was predicted to be the most severe component of stress. For the layers of wefts that are crossed over or under by a binder, stress concentrations developed where the warps were the most distorted. Whereas, for the interior layer of wefts, stress concentrations developed where a binder came closest to the weft. In the matrix, [Formula: see text], the normal stress in the direction of the load, concentrations developed where a binder came close to a warp or weft. The locations of peak cross-sectionally averaged stresses along the tow paths were shown to match the locations of local stress concentrations. However, it was observed that many of the stress concentrations might be sensitive to the method used to create the finite element model, boundary conditions, or accounting for the variation of local fiber-volume fraction that results from a variation of cross-sectional area.

Finite element modeling of guyed back spars in cable logging

2004 ◽  
Vol 34 (4) ◽  
pp. 817-828 ◽  
Author(s):  
Albert Saravi ◽  
C Kevin Lyons
Keyword(s):  
Finite Element ◽  
Normal Stress ◽  
Cross Section ◽  
A Priori ◽  
Element Model ◽  
Transverse Cross Section ◽  
Stress Fields ◽  
Stress Concentrations ◽  
Maximum Normal Stress ◽  
Tree Method

In this study a finite element model of a back spar system was developed with three guylines opposing the skyline strap tension. In this paper the allowable skyline strap tension is the tension in the skyline strap that results in the maximum normal stress on a transverse cross section of the tree being equal to an assumed allowable stress. An iterative routine was developed to find the allowable skyline strap tension, and this routine was found to converge rapidly from initial values that were below and above the allowable skyline strap tension. Two algorithms were developed for finding the maximum normal stress on a transverse cross section of a tree, method 1 and method 2. If the plane that the tree displaced in was known a priori, then method 2 could be used, and it was found to be less sensitive to mesh coarseness. If the plane that the tree displaced in was not known a priori, then method 1 had to be used with a less coarse mesh. It was found that the stress concentrations due to simplified cable connections were not significant for rigging configurations that allowed a larger rigging point displacement. The rigging configurations that allowed larger rigging point displacements have stress fields that are dominated by bending, while for rigging configurations that allow only small rigging point displacements, the stress fields are dominated by axial compression.

scholarly journals On the Convergence of Nonlinear Modes of a Finite Element Model

2008 ◽  
Vol 15 (6) ◽  
pp. 655-664
Author(s):  
Ramesh Balagangadhar ◽  
Joseph C. Slater
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Complex Geometry ◽  
Linear Part ◽  
Mesh Refinement ◽  
Closed Form Solution ◽  
Element Model ◽  
Mesh Independence ◽  
Nonlinear Modal Analysis

Convergence of finite element models is generally realized via observation of mesh independence. In linear systems invariance of linear modes to further mesh refinement is often used to assess mesh independence. These linear models are, however, often coupled with nonlinear elements such as CFD models, nonlinear control systems, or joint dynamics. The introduction of a single nonlinear element can significantly alter the degree of mesh refinement necessary for sufficient model accuracy. Application of nonlinear modal analysis [1,2] illustrates that using linear modal convergence as a measure of mesh quality in the presence of nonlinearities is inadequate. The convergence of the nonlinear normal modes of a simply supported beam modeled using finite elements is examined. A comparison is made to the solution of Boivin, Pierre, and Shaw [3]. Both methods suffer from the need for convergence in power series approximations. However, the finite element modeling method introduces the additional concern of mesh independence, even when the meshing the linear part of the model unless p-type elements are used [4]. The importance of moving to a finite element approach for nonlinear modal analysis is the ability to solve problems of a more complex geometry for which no closed form solution exists. This case study demonstrates that a finite element model solution converges nearly as well as a continuous solution, and presents rough guidelines for the number of expansion terms and elements needed for various levels of solution accuracy. It also demonstrates that modal convergence occurs significantly more slowly in the nonlinear model than in the corresponding linear model. This illustrates that convergence of linear modes may be an inadequate measure of mesh independence when even a small part of a model is nonlinear.

Analysis and Results of an SCS-6/Ti-15-3 MMC Reinforced Ring Structure Under Internal Radial Loading

1993 ◽  
Author(s):  
Phillip W. Gravett ◽  
Robert E. deLaneuville
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Finite Element Model ◽  
Stress Analysis ◽  
Ultimate Strength ◽  
Element Model ◽  
Ring Structure ◽  
The State ◽  
Stress Concentrations ◽  
State Of Stress

Abstract This paper presents a stress analysis method and test results of a ring structure reinforced with SCS-6/Ti-15-3 MMC under an applied internal radial load. To assess the structural integrity of an MMC reinforced component, the state of stress within the component must be determined. Two major factors complicating the state of stress in the given MMC reinforced rings are the stress concentrations caused by the load fixture and the thermal residual stresses induced during processing. To model the stress concentrations, the ring and its load fixture were modeled as a 3-d solid finite element model. To calculate the processing residual stresses, a 2-d axisymetric finite element thermal stress analysis was completed. Plasticity was modeled with the 2-d axisymetric finite element model accounting for the nonlinear response of the MMC core and monolithic sheath. Testing of the rings at room and high temperature showed good correlation to load-deflection calculations while ultimate strength was far less than predicted. Subsequent post failure analysis revealed preexisting damage within the MMC which was not detected by pretest NDE inspections. This damage did not significantly affect the measured stiffness of the ring, but diminished the ultimate strength by reducing the capability of the MMC in a localized area.

Assessment of the locations of fatigue failure in a commercial vehicle cab using the virtual iteration method

2016 ◽  
Vol 231 (1) ◽  
pp. 84-98 ◽  
Author(s):  
Tao Wang ◽  
Liangmo Wang ◽  
Yuanlong Wang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Iteration Method ◽  
Commercial Vehicle ◽  
Element Model ◽  
Life Assessment ◽  
Stress Distributions ◽  
Stress Concentrations ◽  
Structural Improvement

In this paper, fatigue damage analysis and structural improvement of a commercial vehicle cab were carried out, in which a simulation technique and durability road tests were combined. A full-scale finite element model of the cab was established and then validated by means of physical testing and analysis of its stiffness and its modal performance. The loading spectra, in accordance with the durability road test, were obtained by adopting the virtual iteration method. With the established finite element model, the stress distributions in the cab under unit excitation were determined. The obtained stress distributions were then used to assess the total fatigue life of the cab by employing the strain–life ( ε–N) method; thus, the critical regions were determined. The results showed that some components near the pillars and mounts are easy to damage because of the stress concentrations. It was also demonstrated that the predicted regions are reliable, which was verified by comparison with the physical durability road tests. Finally, structural improvements in the critical structures were made; the fatigue life assessment of the improved cab showed an obvious improvement in its durability performance.

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