Transverse cracking based numerical analysis and its effects on cross-ply laminates strength under thermo-mechanical degradation

Berriah Abdelatif,Megueni Abdelkader,Lousdad Abdelkader 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.6

Components manufactured from composite materials are frequently subjected to superimposed mechanical and thermal loadings during their operating service. Both types of loadings may cause fracture and failure of composite structures. When composite cross-ply laminates of type [0m / 90n]s are subjected to uni-axial tensile loading, different types of damage are set-up and developed such as matrix cracking: transverse and longitudinal cracks, delamination between disoriented layers and broken fibers. The development of these modes of damage can be detrimental for the stiffness of the laminates. From the experimental point of view, transverse cracking is known as the first mode of damage. In this regard, the objective of the present paper is to investigate the effect of transverse cracking in cross-ply laminate under thermo-mechanical degradation. A Finite Element (FE) simulation of damage evolution in composite crossply laminates of type [0m / 90n]s subjected to uni-axial tensile loading is carried out. The effect of transverse cracking on the cross-ply laminate strength under thermo-mechanical degradation is investigated numerically. The results obtained by prediction of the numerical model developed in this investigation demonstrate the influence of the transverse cracking on the bearing capacity and resistance to damage as well as its effects on the variation of the mechanical properties such as Young’s modulus, Poisson’s ratio and coefficient of thermal expansion. The results obtained are in good agreement with those predicted by the Shear-lag analytical model as well as with the obtained experimental results available in the literature.

Rate-Dependence of Off-Axis Tensile Behavior of Cross-Ply CFRP Laminates at Elevated Temperature and Its Simulation

Takeuchi, Fumi,Kawai, Masamichi,Zhang, Jian-Qi,Matsuda, Tetsuya The Korean Society for Composite Materials 2008 Advanced composite materials Vol.17 No.1

The present paper focuses on experimental verification of the ply-by-ply basis inelastic analysis of multidirectional laminates. First of all, rate dependence of the tensile behavior of balanced symmetric cross-ply T800H/epoxy laminates with a $[0/90]_{3S}$ lay-up under off-axis loading conditions at $100^{\circ}C$ is examined. Uniaxial tension tests are performed on plain coupon specimens with various fiber orientations $[{\theta}/(90-{\theta})]_{3S}$ ($\theta$ = 0, 5, 15, 45 and $90^{\circ}C$) at two different strain rates (1.0 and 0.01%/min). The off-axis stress.strain curves exhibit marked nonlinearity for all the off-axis fiber orientations except for the on-axis fiber orientations $\theta$ = 0 and $90^{\circ}$, regardless of the strain rates. Strain rate has significant influences not only on the off-axis flow stress in the regime of nonlinear response but also on the apparent off-axis elastic modulus in the regime of initial linear response. A macromechanical constitutive model based on a ply viscoplasticity model and the classical laminated plate theory is applied to predictions of the rate-dependent off-axis nonlinear behavior of the cross-ply CFRP laminate. The material constants involved by the ply viscoplasticity model are identified on the basis of the experimental results on the unidirectional laminate of the same carbon/epoxy system. It is demonstrated that good agreements between the predicted and observed results are obtained by taking account of the fiber rotation induced by deformation as well as the rate dependence of the initial Young's moduli.

적층형 탄소섬유 복합재료의 기계적 성질에 미치는 수분환경의 영향

김원근(Won-Keun Kim),문창권(Chang-Kwon Moon) 한국해양공학회 1999 韓國海洋工學會誌 Vol.13 No.4

This study has been investigated about the influence of moisture environment on the mechanical properties in the carbon fiber cross laminates. And it has been also investigated the effect of unit ply thickness of the carbon fiber cross laminates on the mechanical properties in distilled water of 80℃ for a certain period of time.<br/> As a results, it was found that the weight gain of water was increased with the immersion time and the bending strength and fracture toughness were decreased with the weight gain of water. And it was also shown that the bending strength and fracture toughness were decreased with the increasing of the unit ply thickness of carbon fiber cross laminates through the immersion time.

응력장을 이용한 직교적층 탄소섬유/에폭시 복합재 적층판의 모드 I 균열 특성 연구

강민송,전민혁,김인걸,우경식 한국복합재료학회 2019 Composites research Vol.32 No.6

The delamination is a special mode of failure occurring in composite laminates. Several numerical studies with finite element analysis have been carried out on the delamination behavior of unidirectional composite laminates. On the other hand, the fracture for the multi-directional composite laminates may occur not only along the resin-fiber interface between plies known as interply or interlaminar fracture but also within a ply known as interyarn or intralaminar fracture accompanied by matrix cracking and fiber bridging. In addition, interlaminar and intralaminar cracks appear at irregular proportions and intralaminar cracks proceeded at arbitrary angle. The probabilistic analysis method for the prediction of crack growth behavior within a layer is more advantageous than the deterministic analysis method. In this paper, we analyze the crack path when the mode I load is applied to the cross-ply carbon/epoxy composite laminates and collect and analyze the probability data to be used as the basis of the probabilistic analysis in the future. Two criteria for the theoretical analysis of the crack growth direction were proposed by analyzing the stress field at the crack tip of orthotropic materials. Using the proposed method, the crack growth directions of the cross-ply carbon/epoxy laminates were analyzed qualitatively and quantitatively and compared with experimental results. 층간분리는 복합재 적층판에서 발생하는 특수한 파손 모드이다. 유한요소해석기법을 활용하여 균열 성장 방향이 확실히 예측되는 일방향 복합재 적층판의 층간분리 거동과 관련된 많은 수치적 연구가 수행되었다. 반면에 여러 방향으로 적층된 복합재 적층판의 층간분리는 층간 균열 뿐 만 아니라 기지재료 파손 및 섬유 브릿징을 수반하는 층내 균열이 발생한다. 또한 층간 균열과 층내 균열이 불규칙적인 비율로 나타나고 층내 균열도 임의의 각도로 성장한다. 이러한 직교적층 복합재 적층판의 균열 성장 방향에 대한 예측은 확정론적 해석 방법 보다는 확률론적 해석 방법이 유리하다. 본 논문에서는 직교적층 탄소섬유/에폭시 복합재 적층판에 모드 I 하중이 가해질 때 균열 경로를 분석하여 향후 확률론적 해석의 기반 자료로 사용할 수 있는 확률 데이터를 수집하고 분석하였다. 직교이방성 재료의 균열선단에서의 응력장 해석결과를 활용하여 균열 성장 방향을 분석할 수 있는 두 가지 기준을 제안하였다. 제안한 방법을 이용하여 직교적층 탄소섬유/에폭시 복합재 적층판의 균열 성장 방향을 정성적, 정량적으로 분석하고 실험값과 비교분석하였다.

유한 요소법에 의한 크로스-플라이 복합적층판의 해석

송석은,이원홍 진주산업대학교 1998 산업과학기술연구소보 Vol.- No.5

In general, cross-ply laminated compostie plates exhibit properties considerably different from those of the single-layer plate. The great difference in elastic properties between fiber and mtrix materials leads to a higher ratio of in-plane Young`s modulus to transverse shear modulus for laminated composite plates. Thus, to obtain the more accurate solutions to laminated composite plate problems, effcets of shear strain should be considered in analysis of them. The purpose si to expend the first-order shear deformation theory by Finite Element Analysis and to clarify the cross-ply laminated composite plates.

Thermo-elastic stability behavior of laminated cross-ply elliptical shells

Patel, B.P.,Shukla, K.K.,Nath, Y. Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.6

In this work, thermo-elastic stability behavior of laminated cross-ply elliptical cylindrical shells subjected to uniform temperature rise is studied employing the finite element approach based on higher-order theory that accounts for the transverse shear and transverse normal deformations, and nonlinear in-plane displacement approximations through the thickness with slope discontinuity at the layer interfaces. The combined influence of higher-order shear deformation, shell geometry and non-circularity on the prebuckling thermal stress distribution and critical temperature parameter of laminated elliptical cylindrical shells is examined.

Elastic stresses and failure of rotating cross-ply laminate disks

구교남 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.5

Centrifugal force acting on a rotating disk induces in-plane loads in the radial and circumferential directions. An application of fiber-reinforced composite materials to a rotating disk can satisfy the demand for increasing its rotating speed. However, previous researches have been confined to single lamina disks. In this paper, a stress analysis of rotating disks made of multidirectional laminates is performed. The Tsai-Wu failure criterion is applied to the strength analysis of the rotating laminate disks, from which the maximum allowable speeds are obtained. The cross-ply ratios providing the maximum allowable speeds are obtained for the glass/epoxy and carbon/epoxy cross-ply laminate disks with CD geometry.

A new refined hyperbolic shear deformation theory for laminated composite spherical shells

Kada Draiche,Abdelouahed Tounsi 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.6

In this study, a new refined hyperbolic shear deformation theory (RHSDT) is developed using an equivalent singlelayer shell displacement model for the static bending and free vibration response of cross-ply laminated composite spherical shells. It is based on a new kinematic in which the transverse displacement is approximated as a sum of the bending and shear components, leading to a reduction of the number of unknown functions and governing equations. The proposed theory uses the hyperbolic shape function to account for an appropriate distribution of the transverse shear strains through the thickness and satisfies the boundary conditions on the shell surfaces without requiring any shear correction factors. The shell governing equations for this study are derived in terms of displacement from Hamilton’s principle and solved via a Navier-type analytical procedure. The validity and high accuracy of the present theory are ascertained by comparing the obtained numerical results of displacements, stresses, and natural frequencies with their counterparts generated by some higher-order shear deformation theories. Further, a parametric study examines in detail the effect of both geometrical parameters (i.e., side-to-thickness ratio and curvature-radius-to-side ratio), on the bending and free vibration response of simply supported laminated spherical shells, which can be very useful for many modern engineering applications and their optimization design.

Buckling of symmetrically laminated plates using <i>n</i>th-order shear deformation theory with curvature effects

Tawfiq Becheri,Khaled Amara,Mokhtar Bouazza,Noureddine Benseddiq 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.6

In this article, an exact analytical solution for mechanical buckling analysis of symmetrically cross-ply laminated plates including curvature effects is presented. The equilibrium equations are derived according to the refined <i>n</i>th-order shear deformation theory. The present refined <i>n</i>th-order shear deformation theory is based on assumption that the in-plane and transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments The most interesting feature of this theory is that it accounts for a parabolic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Buckling of orthotropic laminates subjected to biaxial inplane is investigated. Using the Navier solution method, the differential equations have been solved analytically and the critical buckling loads presented in closed-form solutions. The sensitivity of critical buckling loads to the effects of curvature terms and other factors has been examined. The analysis is validated by comparing results with those in the literature.

Curvature tailoring of unsymmetric laminates with an initial curvature

Ryu, Junghyun,Kong, Jung-Pyo,Kim, Seung-Won,Koh, Je-Sung,Cho, Kyu-Jin,Cho, Maenghyo SAGE Publications 2013 Journal of composite materials Vol.47 No.25

<P>An unsymmetric laminated composite having bi-stability is interesting as a morphing structure because it can sustain large deformation without energy supply and the deformed state is stable. Especially, inducing different curvature values at each stable state is important for the practical application of unsymmetric laminates. In this study, we propose a method for tailoring the curvature of unsymmetric cross-ply laminates by curing the composite on a curved tool plate. The results show that the final normal curvature tensor of unsymmetric laminates is the summation of the tool plate curvature tensor and the normal curvature tensor of the laminates.</P>