Qifeng Fan¹, Yaping Zhang², Leiting Dong^1,3, Shu Li¹, Satya N. Atluri⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.2, pp. 155-186, 2015, DOI:10.3970/cmes.2015.107.155

Abstract Although “higher-order” and layer-wise “higher-order” plate and shell theories for composite laminates are widely popularized in the current literature, they involve (1) postulating very complex assumptions of plate/shell kinematics in the thickness direction, (2) defining generalized variables of displacements, strains, and stresses, and (3) developing very complex governing equilibrium, compatibility, and constitutive equations in terms of newly-defined generalized kinemaic and generalized kinetic variables. Their industrial applications are thus hindered by their inherent complexity, and the fact that it is difficult for end-users (front-line structural engineers) to completely understand all the newly-defined FEM DOFs in higher-order… More >

Leiting Dong^1,2, Ahmed S. El-Gizawy³, Khalid A. Juhany³, Satya N. Atluri²

CMC-Computers, Materials & Continua, Vol.41, No.3, pp. 163-192, 2014, DOI:10.3970/cmc.2014.041.163

Abstract Following previous work of [Dong, El-Gizawy, Juhany, Atluri (2014)], a simple locking-alleviated 3D 8-node mixed-collocation C0 finite element (denoted as CEH8) is developed in this study, for the modeling of functionally-graded or laminated thick-section composite plates and shells, without using higher-order or layer-wise zig-zag plate and shell theories which are widely popularized in the current literature. The present C0 element independently assumes an 18-parameter linearly-varying Cartesian strain field. The independently assumed Cartesian strains are related to the Cartesian strains derived from mesh-based Cartesian displacement interpolations, by exactly enforcing 18 pre-defined constraints at 18 pre-selected collocation… More >

Leiting Dong¹, Ahmed S. El-Gizawy², Khalid A. Juhany², Satya N. Atluri³

CMC-Computers, Materials & Continua, Vol.40, No.1, pp. 49-78, 2014, DOI:10.3970/cmc.2014.040.049

Abstract In this study, a simple 4-node locking-alleviated mixed finite element (denoted as CEQ4) is developed, for the modeling of homogeneous or functionally graded or laminated thick-section composite beam structures, without using higher-order (in the thickness direction) or layer-wise zig-zag theories of composite laminates which are widely popularized in current literature. Following the work of [Dong and Atluri (2011)], the present element independently assumes a 5-parameter linearly-varying Cartesian strain field. The independently assumed Cartesian strains are related to the Cartesian strains derived from mesh-based Cartesian displacement interpolations, by exactly enforcing 5 pre-defined constraints at 5 pre-selected… More >

Chandra Veer Singh^1,*

CMC-Computers, Materials & Continua, Vol.34, No.3, pp. 227-249, 2013, DOI:10.3970/cmc.2013.034.227

Abstract A non-linear damage model is developed for the prediction of stiffness degradation in composite laminates due to transverse matrix cracking. The model follows the framework of a recently developed synergistic damage mechanics (SDM) approach which combines the strengths of micro-damage mechanics and continuum damage mechanics (CDM) through the so-called constraint parameters. A common limitation of the current CDM and SDM models has been the tendency to over-predict stiffness changes at high crack densities due to linearity inherent in their stiffness-damage relationships. The present paper extends this SDM approach by including higher order damage terms in More >

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 >