Failure Criteria for Brittle Notched Specimens

Author(s):  
Young W. Kwon ◽  
Carlos Diaz-Colon ◽  
Stanley Defisher

Abstract Recently, new failure criteria were proposed for brittle materials to predict their failure loads regardless of the shapes of a notch or a crack in the material. This paper is to further evaluate the failure criteria for different shapes of notches and different materials. A circular hole, elliptical hole or crack-like slit with a different angle with respect to the loading direction was considered. Double circular holes were also studied. The materials studied were an isotropic material like polymethyl methacrylate (PMMA) as well as laminated carbon fiber composites. Both cross-ply and quasi-isotropic layup orientations were examined. The lamination theory was used for the composite materials so that they can be modelled as an anisotropic and homogeneous material. The test results were compared to the theoretical predictions using the finite element analysis with 2-D plane stress models. Both theoretical failure stresses agreed well with the experimental data for the materials and notch geometries studied herein.

2018 ◽  
Vol 7 (3.11) ◽  
pp. 62
Author(s):  
Nor Fazli Adull Manan ◽  
Mohammad Firdaus Mohd Jam ◽  
Shishir Kumar Sahu ◽  
Jamaluddin Mahmud

Composite material become interest on various applications in wide industry globally. The selection of composite material due to its versatile properties for instance high specific strength. Besides, the properties of composite material also tailorable for various application including automotive, aerospace and marine industry. The objective of this study is to perform the failure analysis of composite material under transverse sinusoidal load. Both failure criteria, Maximum Stress and Tsai-Wu Failure Criteria that provided in ANSYS used to carry out the analysis. Various aspect ratios will be used which are 5, 10, 20, 50 and 100 to perform the analysis with different thickness of laminate. Next, the boundary condition of the plate was set to simply and clamp supported. The finite element analysis of graphite/epoxy laminate with layup of (0/90/90/0) performed to determine the failure loads (First Ply Failure, FPF and Last Ply Failure, LPF loads). The un-normalized load obtained from the analysis is converted to normalized load using equation given. Finally, normalized load is plotted against aspect ratio for both failure criteria and boundary conditions.  


2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Roman Kvasov ◽  
Lev Steinberg

This paper presents the numerical study of Cosserat elastic plate deformation based on the parametric theory of Cosserat plates, recently developed by the authors. The numerical results are obtained using the Finite Element Method used to solve the parametric system of 9 kinematic equations. We discuss the existence and uniqueness of the weak solution and the convergence of the proposed FEM. The Finite Element analysis of clamped Cosserat plates of different shapes under different loads is provided. We present the numerical validation of the proposed FEM by estimating the order of convergence, when comparing the main kinematic variables with an analytical solution. We also consider the numerical analysis of plates with circular holes. We show that the stress concentration factor around the hole is less than the classical value, and smaller holes exhibit less stress concentration as would be expected on the basis of the classical elasticity.


2017 ◽  
Vol 27 (7) ◽  
pp. 963-978 ◽  
Author(s):  
Hadi Bakhshan ◽  
Ali Afrouzian ◽  
Hamed Ahmadi ◽  
Mehrnoosh Taghavimehr

The present work aims to obtain failure loads for open-hole unidirectional composite plates under tensile loading. For this purpose, a user-defined material model in the finite element analysis package, ABAQUS, was developed to predict the failure load of the open-hole composite laminates using progressive failure analysis. Hashin and modified Yamanda-Sun’s failure criteria with complete and Camanho’s material degradation model are studied. In order to achieve the most accurate predictions, the influence of failure criteria and property degradation rules are investigated and failure loads and failure modes of the composites are compared with the same experimental test results from literature. A good agreement between experimental results and numerical predictions was observed.


1987 ◽  
Vol 14 (5) ◽  
pp. 621-630 ◽  
Author(s):  
Erol Karacabeyli ◽  
Ricardo O. Foschi

Results from theoretical and experimental studies on the strength of glulam rivet connections under eccentric loading are presented. Two failure modes are studied: (1) rivet yielding in bending with simultaneous bearing failure of the wood under the rivet's shank and (2) wood failure around the rivet cluster. The latter is studied using brittle fracture theory and a finite element analysis of the stress distribution in the wood around the rivets.Experimental results are shown to compare well with theoretical predictions for failure loads and type of failure, and design guidelines are proposed. Key words: fasteners, wood connectors, glued-laminated, nails, timber engineering.


2007 ◽  
Vol 344 ◽  
pp. 663-668 ◽  
Author(s):  
Xiao Cong He ◽  
Ian Pearson ◽  
Ken W. Young

Self-pierce riveting (SPR) is a sheet material joining technique which is suitable for joining dissimilar materials, as well as coated and pre-painted materials. Published work relating to finite element analysis of SPR joints is reviewed in this paper, in terms of process, static strength, fatigue strength, vibration characteristics and assembly dimensional prediction of the SPR joints. A few important numerical issues are discussed, including material modelling, meshing procedure, failure criteria and friction between substrates and between rivet and substrate. It is concluded that the finite element analysis of SPR joints will help future applications of SPR by allowing system parameters to be selected to give as large a process window as possible for successful joint manufacture. This will allow many tests to be simulated that would currently take too long to perform or be prohibitively expensive in practice, such as modifications to rivet geometry, die geometry or material properties. The main goal of the paper is to review recent progress in finite element analysis of SPR joints and to provide a basis for further research.


Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1454
Author(s):  
Juan Enrique Martínez-Martínez ◽  
Mar Alonso-Martínez ◽  
Felipe Pedro Álvarez Rabanal ◽  
Juan José del Coz Díaz

In the research for sustainable construction, cross-laminated timber (CLT) has gained popularity and become a widely used engineered timber product. However, there are few numerical studies of the structural behaviour of CLT. Among other issues, the orthotropic properties of CLT complicate finite element analysis (FEA). This paper presents a finite element model (FEM) to predict the structural behaviour of CLT beams subjected to sustained flexural loading. This numerical model includes a material model based on the orthotropic material properties of different timber species. Furthermore, the orientation and the properties of each layer are considered. Most of the previous studies simulate CLT beams as a homogeneous material. However, in this work the CLT beam is modelled as a composite material made up of five layers with different orientations and properties. Bonded contacts are used to define the interaction between layers. In addition, nonlinearities, such as large displacement, are used to simulate the behaviour of CLT beams. The model provides the load-displacement relationship and stress concentration. Tsai-Wu failure criteria is used in the simulation to predict the failure modes of the CLT beams studied.


2019 ◽  
Vol 86 (6) ◽  
Author(s):  
Huaidong Yang ◽  
Itzhak Green

This is the first study to develop an empirical formulation to predict fretting wear (volume removal) under frictional conditions for plane-strain line contacts as borne out by the finite element analysis (FEA). The contact is between a deformable half-cylinder rubbing against a deformable flat block. The FEA is guided by detailed physical conceptions, with results that subsequently lead to the methodical modeling of fretting wear. The materials in contact are first set to steel/steel, then to Alloy617/Alloy617, and finally to copper/copper. Various coefficients of friction (COFs) and the Archard Wear Model are applied to the interface. Initially, pure elastic conditions are investigated. The theoretical predictions for the wear volume at the end of the partial slip condition in unidirectional sliding contact agree very well with the FEA results. The empirical formulation for the initial gross slip distance is constructed, again revealing results that are in good agreement with those obtained from the FEA for different materials and for various scales. The Timoshenko beam theory and the tangential loading analysis of a half elastic space are used to approximate the deflection of the half-cylinder and the flat block, respectively. That theory supports well the empirical formulation, matching closely the corresponding FEA results. The empirical formulation of the wear volume for a general cycle under fretting motion is then established. The results are shown to be valid for different materials and various COFs when compared with the FEA results. Finally, plasticity is introduced to the model, shown to cause two phenomena, namely junction growth and larger tangential deformations. Wear is shown to either increase or decrease depending on the combined influences of these two phenomena.


2002 ◽  
Vol 124 (4) ◽  
pp. 434-439
Author(s):  
Fuh-Kuo Chen ◽  
Yi-Che Lee

For a perforated sheet with circular holes, used in shadow masks, the diameter of the circular hole varies through the thickness, and the nonuniform circular holes are arranged in a triangular pattern. In order to simplify the analysis, a perforated sheet with equivalent circular holes of uniform diameter is proposed such that its plastic behavior is similar to that with the given nonuniform circular holes. In this study, a yield criterion is discussed for the perforated sheet with uniform circular holes by employing an equivalent continuum approach, which is then applied to examine the plastic deformation of the perforated sheet with nonuniform circular holes. The analytical results predicted by the theory, including those for the apparent yield stresses and strain ratios, are verified by the results obtained from the finite element analysis and also from experiments.


2019 ◽  
Vol 21 (5) ◽  
pp. 1683-1699
Author(s):  
Magnus Burman ◽  
Fredrik Stig ◽  
Dan Zenkert

This paper deals with the problem of face/core interfacial disbonds in sandwich panels that are pressurised, i.e. the disbond has an initial fluid pressure that causes the disbond to deform. The problem is often referred to as a blister. The panel with a blister is then subjected to an in-plane compressive load. Four different panels are analysed and tested, having different size disbonds and different initial internal pressure. The cases are analysed using a finite element approach where the blister is modelled using fluid elements enabling the pressure inside the blister to vary as the in-plane load is applied. The analysis uses non-linear kinematics, and in each load step, the energy release rate is calculated along the disbond crack front. This model is used for failure load predictions. The four cases are then tested experimentally by filling a pre-manufactured disbond cavity with a prescribed volume of air. This air volume is then entrapped, and the panel is subjected to an in-plane compressive load. The load and blister pressures are measured throughout the test and compared with the finite element analysis. Surface strains and blister deformations are also measured using digital correlation measurements. The predicted failure loads compare well with the experimental results, and so does the blister pressures, the latter at least qualitatively.


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