A Three-Dimensional Ply Failure Model for Composite Structures

ABSTRACT A fully 3D failure model to predict damage in composite structures subjected to multiaxial loading is presented in this paper. The formulation incorporates shear nonlinearities effects, irreversible strains, damage and strain rate effects by using a viscoplastic damageable constitutive law. The proposed formulation enables the prediction of failure initiation and failure propagation by combining stress-based, damage mechanics and fracture mechanics approaches within an unified energy based context. An objectivity algorithm has been embedded into the formulation to avoid problems associated with strain localization and mesh dependence. The proposed model has been implemented into ABAQUS/Explicit FE code within brick elements as a userdefined material model. Numerical predictions for standard uniaxial tests at element and coupon levels are presented and discussed.

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    ABSTRACT: This paper presents a ballistic impact simulation of an armor-piercing projectile in hybrid ceramic/fiber reinforced composite armor. The armor is composed by an alumina plate and an ultra high molecular weight polyethylene composite. Three different constitutive models (ceramic, composite and adhesive) were formulated and implemented into ABAQUS/Explicit finite element code. Comparisons between numerical and experimental results are presented.
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    ABSTRACT: Recent improvements in manufacturing processes and materials properties associated with excellent mechanical characteristics and low weight have made composite materials very attractive for application on civil aircraft structures. However, even new designs are still very conservative, because the composite failure phenomenon is very complex. Several failure criteria and theories have been developed to describe the damage process and how it evolves, but the solution of the problem is still open. Moreover, modern filament winding techniques have been used to produce a wide variety of structural shapes not only cylindrical parts, but also “flat” laminates. Therefore, this work presents the development of a damage model and its application to simulate the progressive failure of flat composite laminates made using a filament winding process. The damage model was implemented as a UMAT (User Material Subroutine), in ABAQUSTM Finite Element (FE) framework. Progressive failure analyses were carried out using FE simulation in order to simulate the failure of flat filament wound composite structures under different loading conditions. In addition, experimental tests were performed in order to identify parameters related to the material model, as well as to evaluate both the potential and the limitations of the model. The difference between numerical and the average experimental results in a four point bending set-up is only 1.6 % at maximum load amplitude. Another important issue is that the model parameters are not so complicated to be identified. This characteristic makes this model very attractive to be applied in an industrial environment.
    Applied Composite Materials 10/2013; · 1.05 Impact Factor
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    ABSTRACT: Variation of shear stresses  xy on failure behavior of different composite materials was investigated for two types of composites; Boron-Epoxy Narmco-5505 and Carbon-Epoxy AS4 (3501-6). The effect of material nonlinearity on failure behavior of unidirectional fibrous composite laminates was considered for several fiber-orientation angles; ϴ=15, 30, 45, 60 and 75 degrees. An energy-based nonlinear material model was adopted to predict the mechanical properties of a unidirectional composite lamina. A compatible failure criterion for nonlinear composite materials was utilized which incorporates the material model into the failure criterion. The resulting failure envelopes were compared for all the cases. KEYWORDS: Shear stress, Failure envelope, Composite material, Nonlinear behavior, Fiber-orientation.
    Jordan Journal of Civil Engineering. 09/2013; EBSCO, AULRICH(Vol. 7, No. 4).

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May 28, 2014