William Eberts, Matthew T. Siniawski^*, Timothy Burdiak, Nick Polito

Journal of Renewable Materials, Vol.3, No.4, pp. 259-267, 2015, DOI:10.7569/JRM.2014.634137

Abstract Single-ply biocomposite laminates were fabricated with two different woven fabrics and a bio-based resin using a wet layup technique at room temperature. A highly elastic, stockinette weave bamboo fiber fabric and a thicker, inelastic plain weave bamboo fabric were both investigated. The elastic fabric was pre-strained at 25% intervals, ranging from 0–100% of its original length. Samples made with E-Glass and S-Glass, two common glass fiber reinforcements, were also fabricated using the bioresin as benchmarks. The ultimate strength and modulus of elasticity characteristics of the composites were determined using the ASTM D3039/ D3039M-08 standard test method for determining the tensile… More >

Jinghua Wang¹, Leian Zhang¹, Xuemei Huang^1,*, Jinfeng Zhang², Chengwei Yuan¹

Energy Engineering, Vol.119, No.1, pp. 407-418, 2022, DOI:10.32604/EE.2022.016439

Abstract Transverse crack often occurs in the trailing edge region of the blade when subjected to the excessive edgewise fatigue load. In this paper a refined model was established through local mesh refinement methods in order to investigate the initiation mechanism of crack and its extension in blade trailing edge. The material stress around the crack in trailing edge region under different thicknesses is calculated based on the fracture mechanics theory. The factors affecting the fatigue robustness of blade trailing edge are concluded by investigating the results of finite element analysis and coupons test. Compared with the laminate, the lower fatigue… More >

Ravi Joshi^*, P. Pal

Sound & Vibration, Vol.55, No.2, pp. 173-190, 2021, DOI:10.32604/sv.2021.011387

Abstract Ply-by-ply failure analysis of symmetric and anti-symmetric laminates under uniform sinusoidal transverse dynamic loading is performed for a specified duration. The study investigates the first ply failure load, followed by the detection of successive ply failures along with their failure modes using various failure theories. Some of the well-established failure theories, mostly used by the researchers, are considered for the failure prediction in laminates. The finite element computational model based on higher order shear deformation displacement field is used for the failure analysis and the complete methodology is computer coded using FORTRAN. The ply-discount stiffness reduction scheme is employed to… 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 optimization (based on a strain… 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 point by an electromechanical shaker. 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. Transient response of the samples… 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. The matrix behavior is described… 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 stress concentration was… More >

Mena E. Tawfik^{1, 2}, Peter L. Bishay^{3, *}, Edward A. Sadek¹

CMES-Computer Modeling in Engineering & Sciences, Vol.115, No.1, pp. 105-129, 2018, DOI:10.3970/cmes.2018.115.105

Abstract Monte Carlo Simulations (MCS), commonly used for reliability analysis, require a large amount of data points to obtain acceptable accuracy, even if the Subset Simulation with Importance Sampling (SS/IS) methods are used. The Second Order Reliability Method (SORM) has proved to be an excellent rapid tool in the stochastic analysis of laminated composite structures, when compared to the slower MCS techniques. However, SORM requires differentiating the performance function with respect to each of the random variables involved in the simulation. The most suitable approach to do this is to use a symbolic solver, which renders the simulations very slow, although… More >

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 and layer-wise theories. In an… More >