Three-dimensional Failure Criterion Research Articles

On the prediction of bolted single-lap composite joints

A new set of failure criteria to predict composite failure in single-lap bolted-joints is proposed. The present failure criteria are an extension of Chang–Lessard criteria considering a three-dimensional stress field and including out-of-plane failure modes. The advantage with respect to other three-dimensional failure criteria is the consideration of non-linear shear stress–strain relationship. The failure criteria were implemented in a finite element model and validated through comparison with experiments in literature. Stresses were calculated by a non-linear finite element model developed in ABAQUS/Standard which considers material and geometric nonlinearities. A progressive damage model was implemented in a USDFLD subroutine. The model predicted the effect of secondary bending and tightening torque showing an excellent agreement with experimental results. Moreover, results were compared with those reported in literature using Hashin failure criteria. In addition, a parametric study was carried out to analyse the influence of friction coefficient and tightening torque.

Progressive failure analysis of composite pi joint with 3D FE modeling

Aimed at the complex failure modes of composite pi joint, the material elastic modulus degradation method was applied to simulate the progressive failure procedure. A three-dimensional finite element model of one type composite pi joint was established based on the commercial finite element software Abaqus. Two progressive failure analysis subroutines considering both the composite laminates and adhesive failures were developed within Abaqus/Standard. One of them is based on Hashin three-dimensional failure criteria and Ye-delamination criterion to distinguish five failure modes of composite laminates: fiber breakage, fiber buckling, matrix tensile cracking, matrix compression, and delamination failure. The other is based on Tsai-Wu criterion to discriminate the composite failure. Additionally, an elastic-perfectly plastic material model was applied in the subroutines to simulate the adhesive failure. The established pi joint model was analyzed under given increasing tensile loads. The numerical results s...

Numerical Simulation of Glass-Fiber-Reinforced Aluminum Laminates with Diverse Impact Damage

This paper presents a finite element model used to simulate the impact response of a fiber metal laminate. The load-time history, maximum deflection, and damage progression caused by impact loading were examined using an explicit finite element model. Two- and three-dimensional failure criteria in the commercial finite element code ABAQUS are used to model stiffness degradation in the glass-fiber-reinforced composite layers of the laminates. The finite element results showed good agreement with experimental measurements.

Progressive damage analysis of composite bolted joints with liquid shim layers using constant and continuous degradation models

Abstract The structural behaviour of a single-lap, single-bolt composite joint is investigated using a three-dimensional finite element model. In contrast to previous investigations the influence of a liquid shim layer, added between the two laminates, on strength and structural behaviour of the joints is investigated by virtual testing. The finite element model is validated with experimental data. The experiments point out that the structural behaviour of these joints is dominated by progressive damage. Therefore, as a first approach, progressive damage is considered using Hashin’s three-dimensional failure criterion and a constant degradation model. It is shown that this combination yields very conservative results. As a second approach the model is improved by a continuous degradation model. Considering continuous degradation, the numerical results show very good correlation with the experimental data.

Matrix and Fibre Stiffness Degradation of a Quasi-isotrope Graphite Epoxy Laminate Under Flexural Bending Test

The permanent research of reliability and precision for failure criteria is a major concern for proper dimensioning of composite structures. Discrepancies are observed between theoretical results based on laminated theory or finite element analysis [Greif, R. and Chapon, E. (1993). Investigation of Successive Failure Modes in Graphite Epoxy Laminated Composites Beams, Journal of Reinforced Plastics and Composites, 29; Echaabi, J., Trochu, F., Pham, F. X. T. and Ouelette, M. (1996). Theroretical and Experimental Investigation of Failure and Damage Progression of Quasi-Isotropic Graphite Epoxy Composites in Flexural Bending Test, Journal of Reinforced Plastics and Composites, 15(7)] and experiments. In order to investigate these problems, numerical simulations were carried out to study the behavior of graphite-epoxy [[+45/-45/90/0]3] laminates subjected to three point bending tests. Two approaches were followed. The first one is based on laminate theory with transverse shear. The successive failures, failure modes, progression of failure and the effect of the geometrical characteristics of the specimens were analyzed during loading. Various failure criteria have been studied to predict the load when the weakest ply fails under flexural bending. Traditional failure criteria and new ones taking into account physical considerations were used. These criteria are tested with two models of stiffness reduction to account for ply failure. The second approach is based on a finite element analysis of laminate, in which three-dimensional failure criteria were implemented. Finally, the results obtained with these two approaches are compared with theoretical and experimental predictions of the scientific literature [Echaabi, J., Trochu, F., Pham, F. X. T. and Ouelette, M. (1996). Theroretical and Experimental Investigation of Failure and Damage Progression of Quasi-Isotropic Graphite Epoxy Composites in Flexural Bending Test, Journal of Reinforced Plastics and Composites, 15(7)].

A four-parameter criterion for failure of geomaterials

A three-dimensional failure criterion is proposed. The criterion relies on a maximum of four parameters, that can be interpreted geometrically in principal stress space. It relates in a natural way the Rankine, the Lade, the Matsuoka–Nakai criterion and the von-Mises criterion. Predictions based on this criterion exhibit very good agreement with experimental data for a variety of materials, in particular considering three-dimensional aspects.

Bearing Strength Analysis of Single Mechanically Fastened Joint in Stitched Laminates

Experimental investigation is carried out to understand the bearing strength of stitched and unstitched uniweave T300/QY9512 laminates with single-lap single-bolt joint configuration in this article. The objectives of the studies are to determine the effects of stitching node position, stacking sequence, and hygrothermal environment on the bearing strength and the load–displacement curves of stitched laminates. A three-dimensional finite element model is also developed to investigate the bearing properties of mechanically fastened joints in unstitched and stitched laminates. Hashin's three-dimensional failure criterion is used to predict the progressive ply failure. The stitching node position effect is of primary interest. A good agreement between experimental results and numerical predictions is observed. The results show that the bearing strength decreased when the stitching node position was close to the hole boundary.

Characterization of Failure in Cross-Anisotropic Soils

Drained true triaxial tests on dense Santa Monica Beach sand deposited with a cross-anisotropic fabric have been performed to study the failure condition in the principal stress space. The failure surface was assumed to be symmetric around the vertical axis (on the octahedral plane of the principal stress space), but varying as a function of the Lode angle. Data from previously performed consolidated-undrained true triaxial tests on San Francisco Bay Mud and data from triaxial compression, triaxial extension, and plane strain tests on Toyoura sand showed similar behavior in terms of effective stresses. A three-dimensional failure criterion is proposed for characterization of failure in cross-anisotropic soils, under commonly occurring conditions when loading and depositional directions coincide and no significant rotation of principal stresses occur. This cross-anisotropic criterion is developed using a coordinate rotation of the principal stress space and utilization of an existing isotropic failure formulation. Derivation of the three required parameters is explained and illustrated. The proposed criterion is compared with various experimental results; and it is demonstrated that the failure criterion for cross-anisotropic soils captures the experimental behavior with good accuracy.

Finite Element Analysis of Low-Velocity Impact Damage in Composite Laminates

This paper investigates the low-velocity impact behaviour and impact-induced damages in graphite/epoxy composite laminates. A three-dimensional finite element and transient dynamic analysis is performed to calculate the time-varying displacements, forces, strains and stresses throughout the laminate resulting from transverse impact. A layered version of an eight-noded isoparametric brick element with incompatible modes is used to model the laminate. Transient dynamic equilibrium equation is integrated step-by-step with respect to time using Newmark direct time integration method. Modified Hertzian contact law is used to model the local contact behaviour. Appropriate three-dimensional failure criteria are used for predicting the occurrence of matrix cracking and the extent of delamination after impact.

Tensile load-bearing capacity of co-cured double lap joints

The co-cured joining method has several advantages over the adhesively bonded joining method because both the curing and the joining processes for the composite structures are achieved simultaneously. In this study, the tensile load-bearing capacities of co-cured double lap joints were investigated experimentally and compared with the analytical results calculated by finite element analysis. Co-cured double lap joint specimens with several bond parameters such as bond length, surface roughness, and stacking sequence of the composite laminate were fabricated and tested. From the experimental results, it was found that the failure mechanism of the co-cured double lap joint was cohesive failure by delamination at the first ply of the composite laminate in the co-cured double lap joint. Finally, optimum values of several bond parameters were determined. Analytical tensile load-bearing capacities of the co-cured double lap joints were calculated by the three-dimensional Tsai-Wu failure criterion using stress distributions obtained from finite element analysis.

A Progressive Damage Model for Mechanically Fastened Joints in Composite Laminates

A three-dimensional finite element model is developed to predict damage progression and strength of mechanically fastened joints in carbon fibre-reinforced plastics that fail in the bearing, tension and shear-out modes. The model is based on a three-dimensional finite element model, on a three-dimensional failure criterion and on a constitutive equation that takes into account the effects of damage on the material elastic properties. This is accomplished using internal state variables that are functions of the type of damage. This formulation is used together with a global failure criterion to predict the ultimate strength of the joint. Experimental results concerning damage progression, joint stiffness and strength are obtained and compared with the predictions. A good agreement between experimental results and numerical predictions is obtained.

Failure Mechanisms in Bolted CFRP

An experimental investigation on the damage mechanisms of mechanically fastened joints in composite laminates is presented. This information concerning damage mechanisms is required before developing damage progression models. For doublelap joints with fingertight washers, specimens that fail in the bearing, tension and shearout modes are investigated. For fully failed specimens and for specimens loaded to several percentages of failure load, the damage mechanisms are investigated using Xradiography and sectioning. It is concluded that failure occurs by a process of damage accumulation, where the failure mechanisms present are fiber fracture, delamination at the laminate loaded hole, matrix cracks and related fiber microbuckling, and internal delamination. Modelling this interaction between failure mechanisms requires further analytical efforts. Due to the importance of the through-thickness stresses present at the hole boundary, delamination has a significant effect on the joint strength, so the use of a threedimensional failure criterion is suggested.

Modelling the strengths of engineering materials in three dimensions

A general, three-dimensional failure criterion is presented. This criterion is formulated in terms of the first and third stress invariants of the stress tensor, and it involves only three independent material parameters. Although these parameters interact with one another, each parameter corresponds to one of three failure characteristics of material behaviour. These material parameters may be determined from any type of strength test, including the simplest possible, such as uniaxial compression and tension tests or biaxial tests for materials with cohesion and tensile strength, and by triaxial compression tests for materials without tensile strength. The procedure for determination of the three material parameters is demonstrated and comparisons between the failure criterion and experimental results are presented for different types of engineering materials. © 1997 John Wiley & Sons, Ltd.

Modelling the strengths of engineering materials in three dimensions

A general, three-dimensional failure criterion is presented. This criterion is formulated in terms of the first and third stress invariants of the stress tensor, and it involves only three independent material parameters. Although these parameters interact with one another, each parameter corresponds to one of three failure characteristics of material behaviour. These material parameters may be determined from any type of strength test, including the simplest possible, such as uniaxial compression and tension tests or biaxial tests for materials with cohesion and tensile strength, and by triaxial compression tests for materials without tensile strength. The procedure for determination of the three material parameters is demonstrated and comparisons between the failure criterion and experimental results are presented for different types of engineering materials. © 1997 John Wiley & Sons, Ltd.

Stress analysis and strength prediction of mechanically fastened joints in FRP: a review

A review of the investigations that have been made on the stress and strength analysis of mechanically fastened joints in fibre-reinforced plastics (FRP) is presented. The experimental observations of the effects of joint geometry, ply-orientation, lay-up and through-thickness pressure on the joint behaviour are described briefly for both single and multi-fastener joints. The analytical and numerical methods of stress analysis required before trying to predict failure are discussed. The numerical approaches cover both two and three-dimensional models and the effects of clearance, friction and geometry are assessed. The several methods that have been used to predict failure in single or multi-fastener joints are described. It is concluded that there are some issues that require further investigation. There is no general agreement about the method that should be used to predict failure, but progressive damage models are quite promising since important aspects of the joint's behaviour can be modelled using this approach. In order to take into consideration several factors related to joint strength the use of three-dimensional models is suggested. These models require a three-dimensional failure criterion and an appropriate property degradation law.

Evaluation of First Ply Failure in a Three-Dimensional Load Space

Numerically generated failure envelopes for several three-dimensional failure criteria are presented and compared to experimental data. These envelopes are developed through finite element analysis and are based on first ply failure (FPF). The experimental data are based on ultimate failure of filament wound tubes constructed from Toray 1000/DER332-T403 and loaded in various combinations of axial traction (both tension and compression), internal pressure, and torsion. All tubes have a layup of [± 1.5, ± 45, ± 89] T. Five three-dimensional failure criteria are considered: max-stress, max-strain, one proposed by Tsai, and two recently proposed by Feng. In addition to the three-dimensional failure criteria evaluated, the finite element results are used in conjunction with classical lamination theory to test the predictive capability of some of the more common two-dimensional failure criteria (max-strain, Tsai-Hill, and Tsai-Wu). None of the predicted envelopes compares well with the experimental data; thereby illustrating the need for progressive failure analysis in structures subjected to complex stress states. It is shown that it is possible to improve the accuracy of at least one of the three-dimensional failure criteria through a very minor modification of the theory.

Development of an elastoplastic model for porous rock

An elastoplastic constitutive model is proposed to describe the behavior of porous rock. This model is developed from the concept of two plastic deformation mechanisms and the three-dimensional failure criterion for rock materials previously proposed by Lade. The model is formulated according to experimental observations on a porous chalk. Particular attention is paid to the determination of the material parameters. The validity of the model is examined by comparing its predictions and the experimental results for different trixial tests in drained or undrained conditions.

A new approach of three-dimensional strength theory for anisotropic materials

A three-dimensional failure criterion is developed in a form of quadratic tensor polynomial with the fundamental strength function expressed in a sine series. This criterion has the operational flexibility of any desired degree of accuracy. It can be shown that the present theory is a generalization of the Von Mises yield criterion. One of the main features of this criterion is that it does not require shear strength properties. The flexibility and accuracy of this theory are justified through its comparison with the experimental data for three material systems under uniaxial tension, uniaxial compression and biaxial loading. Comparisons are also made with several existing failure criteria.

A Comprehensive Technique for Determination of Safety Factors in Composites

A three-dimensional quadratic failure criterion is used [2] to determine if a particular strain vector can be applied to a given laminate. This criterion is represented by an ellipsoid using ∈1, ∈2 and ∈6 as its three axes. A strain vector is safe when its ex tremity lies within the ellipsoid's envelope.

A general failure criterion for plain concrete

A general three-dimensional failure criterion for plain concrete is proposed. The criterion has been formulated in terms of three normalized stress invariants and includes material parameters which may be obtained from experimental data. It has been shown that simple failure criteria such as the von Mises model, the Drucker-Prager model and the Bresler-Pister model are special cases of that proposed. The application of the criterion has been demonstrated by comparison with available experimental results. From the results of this comparison it can be seen that the criterion may be applied throughout the stress range from tensile stress to high compressive stress.