• Title/Summary/Keyword: Angle-ply laminate

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Implementation of a micro-meso approach for progressive damage analysis of composite laminates

  • Hosseini-Toudeshky, H.;Farrokhabadi, A.;Mohammadi, B.
    • Structural Engineering and Mechanics
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    • v.43 no.5
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    • pp.657-678
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    • 2012
  • The mismatch of ply orientations in composite laminates can cause high interlaminar stress concentrations near the free edges. Evaluation of these interlaminar stresses and their role in the progressive damage analysis of laminates is desirable. Recently, the authors developed a new method to relate the physically based micromechanics approach with the meso-scale CDM considering matrix cracking and induced delamination. In this paper, the developed method is applied for the analysis of edge effects in various angle-ply laminates such as $[10/-10]_{2s}$, $[30/-30]_{2s}$ and $[45/-45]_{2s}$ and comparing the results with available traditional CDM and experimental results. It is shown that the obtained stress-strain behaviors of laminates are in good agreement with the available experimental results and even in better agreement than the traditional CDM results. Variations of the stresses and stiffness components through the laminate thickness and near the free edges are also computed and compared with the available CDM results.

Ant colony optimization for dynamic stability of laminated composite plates

  • Shafei, Erfan;Shirzad, Akbar
    • Steel and Composite Structures
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    • v.25 no.1
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    • pp.105-116
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    • 2017
  • This paper presents the dynamic stability study of laminated composite plates with different force combinations and aspect ratios. Optimum non-diverging stacking is obtained for certain loading combination and aspect ratio. In addition, the stability force is maximized for a definite operating frequency. A dynamic version of the principle of virtual work for laminated composites is used to obtain force-frequency relation. Since dynamic stiffness governs the divergence or flutter, an efficient optimization method is necessary for the response functional and the relevant constraints. In this way, a model based on the ant colony optimization (ACO) algorithm is proposed to search for the proper stacking. The ACO algorithm is used since it treats with large number of dynamic stability parameters. Governing equations are formulated using classic laminate theory (CLT) and von-Karman plate technique. Load-frequency relations are explicitly obtained for fundamental and secondary flutter modes of simply supported composite plate with arbitrary aspect ratio, stacking and boundary load, which are used in optimization process. Obtained results are compared with the finite element method results for validity and accuracy convince. Results revealed that the optimum stacking with stable dynamic response and maximum critical load is in angle-ply mode with almost near-unidirectional fiber orientations for fundamental flutter mode. In addition, short plates behave better than long plates in combined axial-shear load case regarding stable oscillation. The interaction of uniaxial and shear forces intensifies the instability in long plates than short ones which needs low-angle layup orientations to provide required dynamic stiffness. However, a combination of angle-ply and cross-ply stacking with a near-square aspect ratio is appropriate for the composite plate regarding secondary flutter mode.

ANALYSIS OF A LAMINATED COMPOSITE WIND TURBINE BLADE CHARACTERISTICS THROUGH MATHEMATICAL APPROACH

  • CHOI, YOUNG-DO;GO, JAEGWI;KIM, SEOKCHAN
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.23 no.4
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    • pp.367-380
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    • 2019
  • A 1kW-class horizontal axis wind turbine (HAWT) rotor blade is taken into account to investigate elastic characteristics in 2-D. The elastic blade field is composed of symmetric cross-ply laminated composite material. Blade element momentum theory is applied to obtain the boundary conditions pressuring the blade, and the plane stress elasticity problem is formulated in terms of two displacement parameters with mixed boundary conditions. For the elastic characteristics a fair of differential equations are derived based on the elastic theory. The domain is divided by triangular and rectangular elements due to the complexity of the blade configuration, and a finite element method is developed for the governing equations to search approximate solutions. The results describe that the elastic behavior is deeply influenced by the layered angle of the middle laminate and the stability of the blade can be improved by controlling the layered angle of laminates, which can be evaluated by the mathematical approach.

Thermal Buckling of Thick Laminated Composite Plates under Uniform Temperature Distribution (균일분포 온도하의 두꺼운 복합 재료 적층판의 열적 좌굴 해석)

  • Lee, Young-Shin;Lee, Yeol-Wha;Yang, Myung-Seog;Park, Bock-Sun;Lee, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7 s.94
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    • pp.1686-1699
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    • 1993
  • In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

Response of fiber reinforced plastic chimneys to wind loads

  • Awad, A.S.;El Damatty, A.A.;Vickery, B.J.
    • Wind and Structures
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    • v.3 no.2
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    • pp.83-96
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    • 2000
  • Due to their high corrosion and chemical resistance, fiber reinforced plastics (FRP) are becoming widely used as the main structural material for industrial chimneys. However, no national code currently exists for the design of such type of chimneys. The purpose of this study is to investigate analytically the response of FRP chimneys to wind loads. The classical lamination theory is used to substitute the angle-ply laminate of a FRP chimney with an equivalent orthotropic material that provides the same stiffness. Dynamic wind loads are applied to the equivalent chimney to evaluate its response to both along and across wind loads. A parametric study is then conducted to identify the material and geometric parameters affecting the response of FRP chimneys to wind loads. Unlike the across-wind response, the along-wind tip deflection is found to be highly dependent on the angle of orientation of the fibers. In general, the analysis shows that FRP chimneys are very vulnerable to across-wind oscillations resulting from the vortex shedding phenomenon.

Design Optimization of Double-array Bolted Joints in Cylindrical Composite Structures

  • Kim, Myungjun;Kim, Yongha;Kim, Pyeunghwa;Park, Jungsun
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.3
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    • pp.332-340
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    • 2016
  • A design optimization is performed for the double-bolted joint in cylindrical composite structures by using a simplified analytical method. This method uses failure criteria for the major failure modes of the bolted composite joint. For the double-bolted joint with a zigzag arrangement, it is necessary to consider an interaction effect between the bolt arrays. This paper proposes another failure mode which is determined by angle and distance between two bolts in different arrays and define a failure criterion for the failure mode. The optimal design for the double-bolted joint is carried out by considering the interactive net-tension failure mode. The genetic algorithm (GA) is adopted to determine the optimized parameters; bolt spacing, edge distance, and stacking sequence of the composite laminate. A purpose of the design optimization is to maximize the burst pressure of the cylindrical structures by ensuring structural integrity. Also, a progressive failure analysis (PFA) is performed to verify the results of the optimal design for the double-bolted joint. In PFA, Hashin 3D failure criterion is used to determine the ply that would fail. A stiffness reduction model is then used to reduce the stiffness of the failed ply for the corresponding failure mode.

Development of Compressive Failure Strength for Composite Laminate Using Regression Analysis Method (회귀분석법에 의한 복합재료 적층판의 압축파손강도 개발)

  • Lee, Myoung Keon;Lee, Jeong Won;Yoon, Dong Hyun;Kim, Jae Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.10
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    • pp.907-911
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    • 2016
  • This paper provides the compressive failure strength value of composite laminate developed by using regression analysis method. Composite material in this document is a Carbon/Epoxy unidirection(UD) tape prepreg(Cycom G40-800/5276-1) cured at $350^{\circ}F(177^{\circ}C$). The operating temperature is -$-60^{\circ}F{\sim}+200^{\circ}F$($-55^{\circ}C{\sim}+95^{\circ}C$). A total of 56 compression tests were conducted on specimens from eight (8) distinct laminates that were laid up by standard angle layers ($0^{\circ}$, $+45^{\circ}$, $-45^{\circ}$ and $90^{\circ}$). The ASTM-D-6484 standard was used for test method. The regression analysis was performed with the response variable being the laminate ultimate fracture strength and the regressor variables being two ply orientations ($0^{\circ}$ and ${\pm}45^{\circ}$).

Buckling load optimization of laminated composite stepped columns

  • Topal, Umut
    • Structural Engineering and Mechanics
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    • v.62 no.1
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    • pp.107-111
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    • 2017
  • This paper deals with critical buckling load optimization of symmetric angle-ply laminated stepped flat columns under axial compression load. The design objective is the maximization of the critical buckling load and the design variable is the fiber orientations in the layers of the laminates. The classical laminate plate theory is used for the finite element solution of the laminated stepped flat columns. The modified feasible direction (MFD) method is used for the optimization routine. For this purpose, a program based on FORTRAN is exploited. Finally, the optimization results are presented for width ratios (b/B), ratios of fillet radius ($r_1/r_2$), aspect ratios (L/B) and boundary conditions. The results are presented in graphical and tabular forms and the results are compared.

Numerical Study for the Estimation of Strengthening Effect of Concrete Column Strengthened with CFS (CFS 보강 콘크리트 기둥의 보강효과 산정을 위한 해석적 연구)

  • 이상호;허원석;박재우
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.709-714
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    • 1999
  • The objectives of this study are to estimate the strengthening effect of concrete column strengthened with CFS and to provide basic guideline for the strengthening design with laminated composite materials. Analysis stress-strain model of laminated CFS is presented based on laminate theory. This model has been implemented in the algorithm of evaluating confinement effect of CFS. From results of the algorithm, stress-strain relationship of confined concrete is obtained. Using this stress-strain relationship, section analyses of circular and rectangular concrete columns strengthened with CFS are carried our, and load-moment interaction and load-ductility curves of the columns are obtained. To evaluate the strengthening effects of CFS, parametric study is also conducted for the angle of ply, thickness of CFS, shape of section, and reinforcement ratio. Based on this investigation, design recommendations and basic guidelines for the strengthening design with CFS are proposed.

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A Study on the Inspection of Orthotropy Composite Laminate plates Using Ultrasonics (직교이방성 복합적층판의 초음파 탐사에 관한 연구)

  • 나승우;임광희;양인영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.583-586
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    • 2000
  • This work ethibits how susceptive the shear ultrasonic waves are to a little misoriented plies according to the angle variation of shear ultrasoic waves $0^\circ$ , $45^\circ$ and $90^\circ$. Also, it is shown that shear waves, particularly the transmission mode with the transmitter and receiver perpendicular to each other, have high sensitivity for detecting anomalies in fiber orientation and ply layup sequence that may occur in the manufacturing of composite laminates. Experimental results are agreed with modeling solutions which were based on decomposition of shear wave polarization vector as it propagates through the composite laminates. This wave appeared considerably to be sensitive to CFRP composites to the thickness direction along in-plane fibers.

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