M. Steffen¹, P.C. Wallstedt², J.E. Guilkey^2,3, R.M. Kirby¹, M. Berzins¹

CMES-Computer Modeling in Engineering & Sciences, Vol.31, No.2, pp. 107-128, 2008, DOI:10.3970/cmes.2008.031.107

Abstract The Material Point Method (MPM) has shown itself to be a powerful tool in the simulation of large deformation problems, especially those involving complex geometries and contact where typical finite element type methods frequently fail. While these large complex problems lead to some impressive simulations and solutions, there has been a lack of basic analysis characterizing the errors present in the method, even on the simplest of problems. The large number of choices one has when implementing the method, such as the choice of basis functions and boundary treatments, further complicates this error analysis.\newline In this paper we explore some… More >

E.V. González¹, P. Maimí¹, A. Turon¹, P.P. Camanho², J. Renart¹

CMC-Computers, Materials & Continua, Vol.9, No.1, pp. 51-92, 2009, DOI:10.3970/cmc.2009.009.051

Abstract This paper presents the formulation of a tri-dimensional cohesive element implemented in a user-written material subroutine for explicit finite element analysis. The cohesive element simulates the onset and propagation of the delamination in advanced composite materials. The delamination model is formulated by using a rigorous thermodynamic framework which takes into account the changes of mixed-mode loading conditions. The model is validated by comparing the finite element predictions with experimental data obtained in interlaminar fracture tests under quasi-static loading conditions. More >

Amar Prakash¹, Srinivasan, S. M.², Rama Mohan Rao, A.³

CMC-Computers, Materials & Continua, Vol.42, No.1, pp. 75-102, 2014, DOI:10.3970/cmc.2014.042.075

Abstract Behaviour of layered steel fibre reinforced cementitious composite (SFRCC) panels is studied under high velocity impact of short projectiles. The panels consist of slurry infiltrated fibre concrete (SIFCON) layers in external faces and an intermediate (core) layer of latex modified concrete (LMC) and steel wire mesh embedded in cement sand slurry. In order to minimize acoustic impedance mismatch at the interfaces, judiciously selected materials are provided in the layers with appropriate lay-up sequences. For relative evaluation of high velocity impact performances of these panels', impact experiments are conducted in controlled environment. Two most commonly used types of short projectiles having… More >

Jennifer D. Rhymer¹, Hyonny Kim¹

CMC-Computers, Materials & Continua, Vol.35, No.2, pp. 87-117, 2013, DOI:10.3970/cmc.2013.035.087

Abstract Polymer matrix composite structures are exposed to a variety of impact threats including hail ice. Internal delamination damage created by these impacts can exist in a form that is visually undetectable. This paper establishes an analysis methodology for predicting the onset of delamination damage in toughened carbon/epoxy composite laminates when impacted by high velocity ice spheres (hailstones). Experiments and analytical work focused on ice sphere impact onto composite panels have determined the failure threshold energy as a function of varying ice diameter and panel thickness, and have established the ability to predict the onset of delamination using cohesive elements in… More >

M. C. Song¹, B.V. Sankar¹, G. Subhash¹, C. F. Yen²

CMC-Computers, Materials & Continua, Vol.35, No.1, pp. 67-85, 2013, DOI:10.3970/cmc.2013.035.067

Abstract Delamination initiation and propagation in plain woven laminates and 3D orthogonal woven composites during short beam shear (SBS) test were analyzed using finite element (FE) analyses. Two kinds of 3D woven composites, containing single z-yarns and double z-yarns, were considered. The FE models were guided by experimental observations from SBS tests for the same material systems. A series of mechanisms including creation and evolution of matrix cracks and delaminations were modeled discretely. The force-displacement curves obtained from the FE simulations were compared with those from experiments. Further parametric studies were conducted to investigate the effects of z-yarns and interlaminar fracture… More >

A. T. Rhead¹, T. J. Dodwell¹, R. Butler^1,2

CMC-Computers, Materials & Continua, Vol.35, No.1, pp. 1-16, 2013, DOI:10.3970/cmc.2013.035.001

Abstract When (robotic) Automated Fibre Placement (AFP) is used to manufacture aerospace components with complex three dimensional geometries, gaps between fibre tows can occur. This paper explores the interaction under compressive load of these tow gaps with impact damage. Two coupons with different distributions of tow-gaps were impacted. Results indicated that the area of delamination is smaller for an impact directly over a tow gap where the tow gap is situated close to the non-impact face. Subsequent Compression After Impact (CAI) testing demonstrated that both the formation of sublaminate buckles and subsequent growth of delaminations is inhibited by the presence of… More >

I. Smojver¹, J. Sorić²

CMC-Computers, Materials & Continua, Vol.3, No.1, pp. 13-24, 2006, DOI:10.3970/cmc.2007.003.013

Abstract The paper addresses the problem of impact on layered fibre composites. The behaviour of composite laminates under impact loading is dependent not only on the velocity but also on the mass and geometry of the impactor. Using micromechanical Mori-Tanaka approach, mechanical properties of the laminate have been calculated utilizing the material constants of the fibre and matrix. General purpose FEM software ABAQUS has been modified by means of user written subroutines for modelling of composite laminate and rigid impactor. The kinematics of the impact has been simulated using transient dynamic analysis. Employing user defined multi point constraints, delamination zones have… More >

L. Chernin¹, K.Y. Volokh^1,2

CMC-Computers, Materials & Continua, Vol.1, No.3, pp. 259-274, 2004, DOI:10.3970/cmc.2004.001.259

Abstract The conventional approach to analysis of thin film delamination is based on the consideration of the film, which is subjected to residual stresses arising from the thermal mismatch between the film and the substrate, within the framework of the classical fracture mechanics and the structural buckling theories. Such concepts as the energy release rate and the stress intensity factors are crucial in this case.

A different approach to analysis of thin film delamination considers the effect of the compliant interface between the film and the substrate. This compliant interface is described by the traction-separation constitutive law.

… More >