A. Ataş¹, C. Soutis²

CMC-Computers, Materials & Continua, Vol.34, No.3, pp. 199-226, 2013, DOI:10.3970/cmc.2013.034.199

Abstract A strength prediction method is presented for double-lap single fastener bolted joints of cross-ply carbon fibre reinforced plastic (CFRP) composite laminates using cohesive zone elements (CZEs). Three-dimensional finite element models were developed and CZEs were inserted into subcritical damage planes identified from X-ray radiographs. The method makes a compromise between the experimental correlation factors (dependant on lay-up, stacking sequence and joint geometry) and three material properties (fracture energy, interlaminar strength and nonlinear shear stress-strain response). Strength of the joints was determined from the predicted load-displacement curves considering sub-laminate and plylevel scaling effects. The predictions are More >

Xiuqin Zhang¹, Simon Wang^2*, Yingshun Zhang³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 121-122, 2011, DOI:10.3970/icces.2011.017.121

Abstract A B-spline finite strip model is developed in the context of a layer-wise plate theory for analysing the geometrically non-linear transient response of laminated composite plates subjected to transverse low-velocity impact. To simplify the complicated contact analysis, a Hertz-type contact law has been incorporated into the finite strip (FS) model for accounting for the contact behaviour. The model includes the geometrical non-linearity through use of von Karman's non-linear strain-displacement relationship. The resulting non-linear dynamic problem is solved using the Newmark time-stepping scheme together with Newton-Raphson iteration. Several numerical applications are described and a close comparison More >

O. Allix¹, P. Kerfriden¹, P. Gosselet¹

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.3, pp. 271-292, 2010, DOI:10.3970/cmes.2010.055.271

Abstract We present numerical enhancements of a multiscale domain decomposition strategy based on a LaTIn solver and dedicated to the computation of the debounding in laminated composites. We show that the classical scale separation is irrelevant in the process zones, which results in a drop in the convergence rate of the strategy. We show that performing nonlinear subresolutions in the vicinity of the front of the crack at each prediction stage of the iterative solver permits to restore the effectiveness of the method. More >

G.M. Mota¹, P. Sollero¹, F.B. Batista¹, E.L. Albuquerque¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.2, pp. 95-100, 2008, DOI:10.3970/icces.2008.007.095

Abstract Nowadays, the experimental modal analysis in composite materials is an important tool in the structural analysis of new designs in aircraft structures. It supplies data on the behavior of these materials and, when associated with numerical methods, it can also be used to identify elastic properties. However, lightweight composite materials demand the use of appropriate techniques and devices. This paper describes an experimental modal analysis technique where the response is measured without physical contact in a large number of points using a Laser Doopler Vibrometer (LDV), and the excitation is carried out on a single More >

M.V. Hosur¹, F.H. Chowdhury¹, S. Jeelani¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.4, pp. 119-124, 2007, DOI:10.3970/icces.2007.002.119

Abstract In the present study, Nanomer® I-28E, organically modified montmorillonite nanoclay supplied by Nanocor Inc., was used to modify SC-15, a toughened epoxy system using sonication route. Different weight percentage ranging from 1-3% of nanoclay was used. The modified epoxy was then used to fabricate 15-layer plain weave carbon/epoxy composite laminates using vacuum assisted resin transfer molding (VARTM) method. Samples of size 100 x 100 mm were cut from the laminates and were subjected to low-velocity impact loading using an instrumented drop-weight system (Dynatup Model 8210) at three different energy levels of 10, 20 and 30J. More >

Tarun Kant¹, Sandeep S. Pendhari², Yogesh M. Desai³

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.2, pp. 135-162, 2007, DOI:10.3970/cmes.2007.017.135

Abstract A two-point boundary value problem (BVP) is formed in the present work governed by a set of first-order coupled ordinary differential equations (ODEs) in terms of displacements and the transverse stresses through the thickness of laminate (in domain -h/2 < z < h/2) by introducing partial discretization methodology only in the plan area of the three dimensional (3D) laminate. The primary dependent variables in the ODEs are those which occur naturally on a plane z=a constant. An effective numerical integration (NI) technique is utilized for tackling the two-point BVP in an efficient manner. Numerical studies on More >

F. Aymerich¹, M. Serra²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 49-66, 2006, DOI:10.3970/cmes.2006.013.049

Abstract The study reported in this paper explores the potential of Ant Colony Optimization (ACO) metaheuristic for stacking sequence optimization of composite laminates. ACO is a recently proposed population-based search approach able to deal with a wide range of optimization problems, especially of a combinatorial nature, and inspired by the natural foraging behavior of ant colonies. ACO search processes, in which the activities of real ants are simulated by means of artificial agents that communicate and cooperate through the modification of the local environment, were implemented in a specifically developed numerical algorithm aimed at the lay-up… More >

Yunfa Zhang¹, Zihui Xia^1,2

CMC-Computers, Materials & Continua, Vol.2, No.3, pp. 213-226, 2005, DOI:10.3970/cmc.2005.002.213

Abstract In the present study, the initiation and evolution of the interphase damage and their influences on the global stress-strain relation of composite laminates are predicted by finite element analysis on a micromechanical unit cell model. A thin layer of interphase elements is introduced and its stress-strain relation is derived based on a cohesive law which describes both normal and tangential separations at the interface between the fiber and matrix. In addition, a viscous term is added to the cohesive law to overcome the convergence difficulty induced by the so-called snap-back instability in the numerical analysis. More >

Kunigal Shivakumar¹, Anil Bhargava²

CMC-Computers, Materials & Continua, Vol.1, No.2, pp. 173-190, 2004, DOI:10.3970/cmc.2004.001.173

Abstract The fiber optic sensor (FOS) embedded perpendicular to reinforcing fibers causes an `Eye' shaped defect. The length is about 16 times fiber optic radius (R_Fos) and height is about 2R_Fos. The eye contains fiber optics in the center surrounded by an elongated resin pocket. Embedding FOS causes geometric distortion of the reinforcing fiber over a height equal to 6 to 8 R_Fos. This defect causes severe stress concentration at the root of the resin pocket, the interface (in the composite) between the optical fiber and the composite, and at 90° to load direction in the composite. The… More >

X. Han^1,2,3, G. R. Liu^1,2, G. Y. Li ¹

CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 39-50, 2004, DOI:10.3970/cmc.2004.001.039

Abstract An efficient hybrid numerical method is presented for investigating transient response of cross-ply laminated axisymmetric cylinders subjected to an impact load. In this hybrid numerical method, the laminated cylinder is divided into layered cylindrical elements in the thickness direction. The Hamilton principle is used to develop governing equations of the structure. The displacement response is determined by employing the Fourier transformations and the modal analysis. Numerical examples for analyzing transient waves have been provided in axisymmetric laminated cylindrical structures, both for thin cylindrical shells and thick cylinders.
A computational inverse technique is also presented for More >