Simple Tests as Critical Indicator of Intra-Ply Shear Locking

2013 ◽  
Vol 554-557 ◽  
pp. 512-520 ◽  
Author(s):  
D.J. Wolthuizen ◽  
R.H.W. Ten Thije ◽  
R. Akkerman
Keyword(s):  
Finite Elements ◽  
Single Element ◽  
Shear Locking ◽  
Displacement Fields ◽  
Shear Field ◽  
Pull Out ◽  
Forming Simulations ◽  
Piecewise Continuous ◽  
Bias Extension

Standard finite elements can exhibit the numerical artifact of intra-plyshear locking during forming simulations. The displacement fields of elementsare piecewise continuous and cannot correctly capturediscontinuities in the shear field. This shear locking is illustrated insimulations of bias-extension experiments with an unaligned mesh. Two simpletests were developed as a critical indicator of intra-ply shear locking intriangular elements. A single-element-test shows the origin of the locking anda pull-out test indicates locking caused by small misalignments of theelements.

scholarly journals Special Finite Elements with Adaptive Strain Field on the Example of One-Dimensional Elements

2021 ◽  
Vol 11 (2) ◽  
pp. 609
Author(s):  
Tadeusz Chyży ◽  
Monika Mackiewicz
Keyword(s):  
Finite Elements ◽  
Strain Field ◽  
Main Idea ◽  
Deformation Field ◽  
Geometrical Parameters ◽  
Single Element ◽  
One Dimensional ◽  
New Type ◽  
Self Adaptation ◽  
Adaptation Method

The conception of special finite elements called multi-area elements for the analysis of structures with different stiffness areas has been presented in the paper. A new type of finite element has been determined in order to perform analyses and calculations of heterogeneous, multi-coherent, and layered structures using fewer finite elements and it provides proper accuracy of the results. The main advantage of the presented special multi-area elements is the possibility that areas of the structure with different stiffness and geometrical parameters can be described by single element integrated in subdivisions (sub-areas). The formulation of such elements has been presented with the example of one-dimensional elements. The main idea of developed elements is the assumption that the deformation field inside the element is dependent on its geometry and stiffness distribution. The deformation field can be changed and adjusted during the calculation process that is why such elements can be treated as self-adaptive. The application of the self-adaptation method on strain field should simplify the analysis of complex non-linear problems and increase their accuracy. In order to confirm the correctness of the established assumptions, comparative analyses have been carried out and potential areas of application have been indicated.

Macro Finite Element for Analysis of Textile Composites

1994 ◽  
Vol 28 (7) ◽  
pp. 607-618 ◽  
Author(s):  
John Whitcomb ◽  
Kyeongsik Woo ◽  
Sitaram Gundapaneni
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Textile Composites ◽  
Single Element ◽  
Micro Structure ◽  
Macro Elements ◽  
New Type

The analysis of textile composites is complicated by the complex micro-structure. It is not practical to account for this microstructure directly using traditional finite elements. A new type of finite element was developed to efficiently account for microstructure within a single element. These new elements, which are referred to herein as macro elements, performed well in initial tests.

Three-Dimensional Solutions for Rotor Blades Using High-Order Geometrical Nonlinear Beam Finite Elements

2019 ◽  
Vol 64 (3) ◽  
pp. 1-10
Author(s):  
Matteo Filippi ◽  
Alfonso Pagani ◽  
Erasmo Carrera
Keyword(s):  
Finite Elements ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Shear Deformation Theory ◽  
High Order ◽  
Rotor Blades ◽  
Constitutive Law ◽  
Displacement Fields ◽  
Cross Sectional ◽  
The Cross

This paper proposes a geometrically nonlinear three-dimensional formalism for the static and dynamic study of rotor blades. The structures are modeled using high-order beam finite elements whose kinematics are input parameters of the analysis. The displacement fields are written using two-dimensional Taylor- and Lagrange-like expansions of the cross-sectional coordinates. As far as the Taylor-like polynomials are concerned, the linear case is similar to the first-order shear deformation theory, whereas the higher-order expansions include additional contributions that describe the warping of the cross section. The Lagrange-type kinematics instead utilizes the displacements of certain physical points as degrees of freedom. The inherent three-dimensional nature of the Carrera unified formulation enables one to include all Green–Lagrange strain components as well as all coupling effects due to the geometrical features and the three-dimensional constitutive law. A number of test cases are considered to compare the current solutions with experimental and theoretical results reported in terms of large deflections/rotations and frequencies related to small amplitude vibrations.

A unified approach for shear-locking-free triangular and rectangular shell finite elements

2000 ◽  
Vol 75 (3) ◽  
pp. 321-334 ◽  
Author(s):  
Kai-Uwe Bletzinger ◽  
Manfred Bischoff ◽  
Ekkehard Ramm
Keyword(s):  
Finite Elements ◽  
Shear Locking ◽  
Unified Approach ◽  
Rectangular Shell

scholarly journals Experimental and Finite Elements Analysis Study of Warming Effect on Deboned Force for Embedded NiTinol Wire into Linear Low Density Polyethylene

2018 ◽  
Vol 14 (4) ◽  
pp. 1-8
Author(s):  
Samir Ali Amin ◽  
Ali Yasser Hassan
Keyword(s):  
Shear Stress ◽  
Finite Elements ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Finite Elements Analysis ◽  
Pull Out ◽  
Nitinol Wire

This study presents the debonding propagation in single NiTi wire shape memory alloy into linear low-density polyethylene matrix composite the study of using the pull-out test. The aim of this study is to investigate the pull-out tests to check the interfacial strength of the polymer composite in two cases, with activation NiTinol wire and without activation. In this study, shape memory alloy NiTinol wire 2 mm diameter and linear fully annealed straight shape were used. The study involved experimental and finite element analysis and eventually comparison between them. This pull-out test is considered a substantial test because its results have a relation with behavior of smart composite materials. The pull-out test was carried out by a universal tensile test machine type (Laryee), load capacity (50 kN), and a test speed of 1mm/min. The finite elements modeling was performed by ANSYS V.15. The results of pull-out test showed that in the activation of NiTinol wire embedded in host matrix linear low-density polyethylene (LLDPE), the deboned force was about 74 N, but for the case without activation, it was about 106 N. Deboned shear stress for the case with activation was about 0.73 MPa, but for the case of without activation, it was about 1.05 MPa. ANSYS result for deboned shear stress in case with activation was about 0.8 MPa. As for the case of without activation, deboned shear stress was about 0.99 MPa. The activation of the ratio of deboned shear stress and deboned force decreased by 30.47% and 30.13%, respectively. The error ratio between experimental and ANSYS results was equal to 8% for the case with activation and 5.7% for the case without activation. 

A note on the optimal lower bound pull-out capacity of inclined strip anchors in sand

1992 ◽  
Vol 29 (5) ◽  
pp. 870-873 ◽  
Author(s):  
D. N. Singh ◽  
P. K. Basudhar
Keyword(s):  
Nonlinear Programming ◽  
Finite Elements ◽  
Lower Bound ◽  
Key Words ◽  
Excellent Agreement ◽  
Limit Analysis ◽  
Uplift Capacity ◽  
Pull Out ◽  
Predicted Values ◽  
Optimal Lower Bound

A generalized procedure based on finite elements and nonlinear programming has been presented in this paper for finding the optimal lower bound pull-out capacity of inclined strip anchors in sands. The results obtained are compared with the values reported in the literature to validate the suggested method of analysis. The predicted values are found to be in excellent agreement with that of Meyerhof. Key words : limit analysis, lower bound, nonlinear programming, inclined anchors, uplift capacity.

scholarly journals Numerical Modeling of Functionally Graded Coatings

2013 ◽  
Vol 829 ◽  
pp. 327-331 ◽  
Author(s):  
Maryam Heidari ◽  
Maria Kashtalyan
Keyword(s):  
Finite Elements ◽  
Three Dimensional ◽  
Functionally Graded ◽  
Contributing Factors ◽  
Displacement Fields ◽  
Graded Coatings ◽  
Graded Material ◽  
Heat Penetration ◽  
Functionally Graded Coatings ◽  
Coating Design

Coatings play an important role in a variety of engineering applications protecting metallic or ceramic substrates against oxidation, heat penetration, wear and corrosion. One of the contributing factors to structural or functional failure of coatings is a mismatch of material properties between the coating and substrate at the coating/substrate interface. The concept of Functionally Graded Material (FGM) is actively explored in coating design for the purpose of eliminating this mismatch and improving coating performance and integrity. This paper presents analysis of the mechanical behavior of functionally graded coatings using commercial finite elements software ABAQUS in which user implemented graded finite elements have been employed. The model is used to carry out a comparative study of three-dimensional stress and displacement fields in the coated plates with homogeneous and functionally graded coatings.

Extending Lagrange Interpolation to Develop a 4-Node Quadrilateral Element

2006 ◽  
Author(s):  
A. S. Pradeep Kumar ◽  
Shrinivasa Udipi
Keyword(s):  
Finite Elements ◽  
Lagrange Interpolation ◽  
Body Motion ◽  
Stress Fields ◽  
Single Element ◽  
Shape Functions ◽  
Field Equations ◽  
Quadrilateral Element ◽  
Analysis And Design ◽  
Interpolation Functions

Today finite element method is a well established tool in engineering analysis and design. Though there are many two and three dimensional finite elements available, it is rare that a single element performs satisfactorily in majority of practical problems. The present work deals with the development of 4-node quadrilateral element using extended Lagrange interpolation functions. The classical univariate Lagrange interpolation is well developed for 1-D and is used for obtaining shape functions. We propose a new approach to extend the Lagrange interpolation to several variables. When variables are more than one the method also gives the set of feasible bubble functions. We use the two to generate shape function for the 4-node arbitrary quadrilateral. It will require the incorporation of the condition of rigid body motion, constant strain and Navier equation by imposing necessary constraints. The procedure obviates the need for isoparametric transformation since interpolation functions are generated for arbitrary quadrilateral shapes. While generating the element stiffness matrix, integration can be carried out to the accuracy desired by dividing the quadrilateral into triangles. To validate the performance of the element which we call EXLQUAD4, we conduct several pathological tests available in the literature. EXLQUAD4 predicts both stresses and displacements accurately at every point in the element in all the constant stress fields. In tests involving higher order stress fields the element is assured to converge in the limit of discretisation. A method thus becomes available to generate shape functions directly for arbitrary quadrilateral. The method is applicable also for hexahedra. The approach should find use for development of finite elements for use with other field equations also.

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