BUCKLING BEHAVIOR OF COMPOSITE LAMINATES (WITH AND WITHOUT CUTOUTS) SUBJECTED TO NONUNIFORM IN-PLANE LOADS

2013 ◽  
Vol 13 (08) ◽  
pp. 1350044 ◽  
Author(s):  
GANESH SONI ◽  
RAMESH SINGH ◽  
MIRA MITRA
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Structural Instability ◽  
Shear Load ◽  
Premature Failure ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Nonuniform Load ◽  
Parametric Studies ◽  
Plate Aspect Ratio

Critical buckling loads of composite laminates are usually calculated using analytical solutions based on the assumption of uniform in-plane loads, despite of the fact that real structures are often subjected to various nonuniform loads. The present work is focused on the buckling behavior of composite laminates, with and without cutouts, subjected to various nonuniform in-plane loads. The effect of the size of the cutouts, on the buckling behavior, has been studied using finite element method. Furthermore, parametric studies on the effects of plate aspect ratio, location of the cutout and the application of a nonuniform load combined with a shear load have also been studied. Higher buckling loads were observed in pure in-plane bending compared to uniformly/nonuniformly distributed loads. Consequently, it is important to consider nonuniformly distributed loading whenever applicable, to utilize complete strength of the composite laminate and to avoid premature failure of the composite laminate due to structural instability.

AN ANALYTICAL APPROACH FOR BUCKLING BEHAVIOR OF TEMPERATURE-DEPENDENT LAMINATED PIEZOELECTRIC FUNCTIONALLY GRADED PLATES UNDER THERMO-ELECTRO-MECHANICAL LOADINGS AND DIFFERENT END SUPPORTS

2014 ◽  
Vol 11 (04) ◽  
pp. 1350099 ◽  
Author(s):  
ABDOLHOSSEIN FEREIDOON ◽  
HESSAMEDDIN YAGHOOBI ◽  
ALI DEHGHANIAN
Keyword(s):  
Analytical Approach ◽  
Volume Fraction ◽  
Plate Theory ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Graded Materials ◽  
Buckling Behavior ◽  
Parametric Studies ◽  
Plate Aspect Ratio ◽  
Fgm Layer

In this paper, we examine the buckling behavior of piezoelectric laminated plate made of two-layered functionally graded materials (FGMs) that are integrated with surface-bonded piezoelectric actuators and is subjected to a combined action of uniform temperature change, inplane forces, and applied actuator voltage. Temperature-dependent material properties are assumed for both the substrate FGM layer and piezoelectric layers. Employing an analytical approach, five coupled governing stability equations, which were derived based on the first-order shear deformation plate theory, are converted into a fourth-order and a second-order decoupled partial differential equations. Then, an accurate analytical solution is proposed to solve them. Parametric studies are also undertaken, and show the effects of applied actuator voltage, volume fraction exponents, plate aspect ratio, ratio of piezoelectric layer thickness to thickness of FGM layer and temperature dependency, on the buckling load of the plate.

scholarly journals Deformation of Composite Laminates Induced by Surface Bonded and Embedded Piezoelectric Actuators

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3201
Author(s):  
Shiuh-Chuan Her ◽  
Han-Yung Chen
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Plate Theory ◽  
Piezoelectric Actuators ◽  
Classical Plate Theory ◽  
Electric Voltage ◽  
Bending Effect ◽  
Parametric Studies ◽  
Composite Mechanics ◽  
And Control

In this work, piezoelectric (PZT) actuators were surface bonded on or embedded in a composite laminate and subjected to an electric voltage across the thickness, resulting in a bending effect on the composite laminate. An analytical expression of the deflection of a simply supported cross-ply composite laminate induced by distributed piezoelectric actuators was derived on the basis of classical plate theory and composite mechanics. The theoretical solution can be used to predict the deformation of the composite laminate. Series of parametric studies were performed to investigate the effects of location, size, and embedded depth of PZT actuators on the composite laminate deformation. The analytical predictions were verified with finite element results. A close agreement was achieved. It demonstrated that the present approach provided a simple solution to predict and control the deformed shape of a composite laminate induced by distributed PZT actuators.

scholarly journals Linear Buckling Behaviour of Composite Laminate [(Θ/-Θ)] with Various Shaped Cutout using Fem

2019 ◽  
Vol 9 (1S4) ◽  
pp. 18-22
Keyword(s):  
Uniaxial Compression ◽  
Composite Laminates ◽  
Composite Laminate ◽  
Buckling Load ◽  
Laminated Plate ◽  
Vertical Rectangle ◽  
Buckling Behavior ◽  
Linear Buckling ◽  
Polyester Composite ◽  
Layer Orientation

In this paper, the buckling behavior has been investigated on square laminate made of Woven-glass-polyester composite with various shaped cutouts (i.e., circle, square, vertical rectangle, horizontal rectangle, vertical ellipse, horizontal ellipse) numerically. The composite laminates have been arranged in asymmetrical order as [(θ/-θ)]. The laminated plate that is subjected to uniaxial compression has been emphasized on the laminate along with the effect of layer orientation, effect of cutout ratio and effect of cutout angle. The result shows that the minimum buckling load is obtained at 45° and the maximum buckling load attained at 0° and 90°for all laminates by increasing the layer orientation. For cutout ratio, the maximum and minimum load is obtained for the smallest and largest cutout ratio in all cutout shapes. Increasing the cutout angle, the square cutout exhibits the minimum load at 60°. In elliptical cutouts, the load is decreasing and increasing gradually while they are aligned in along and perpendicular to the loading directions. The rectangular cutouts positioned vertically and horizontally the load is decreasing up to 30° and 60°and then increasing up to 90°.

SELF-HEALING OF WOVEN COMPOSITE LAMINATES VIA IN SITU THERMAL REMENDING

2021 ◽  
Author(s):  
ALEXANDER D. SNYDER ◽  
ZACHARY J. PHILLIPS ◽  
JASON F. PATRICK
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Laminated Composites ◽  
Reaction Times ◽  
Carbon Fiber Composites ◽  
Self Healing ◽  
Damage Mode ◽  
Woven Composite ◽  
Internal Damage

Fiber-reinforced polymer composites are attractive structural materials due to their high specific strength/stiffness and excellent corrosion resistance. However, the lack of through-thickness reinforcement in laminated composites creates inherent susceptibility to fiber-matrix debonding, i.e., interlaminar delamination. This internal damage mode has proven difficult to detect and nearly impossible to repair via conventional methods, and therefore, remains a significant factor limiting the reliability of composite laminates in lightweight structures. Thus, novel approaches for mitigation (e.g., self-healing) of this incessant damage mode are of tremendous interest. Self-healing strategies involving sequestration of reactive liquids, i.e. microcapsule and microvascular systems, show promise for the extending service- life of laminated composites. However, limited heal cycles, long reaction times (hours/days), and variable stability of chemical agents under changing environmental conditions remain formidable research challenges. Intrinsic self- healing approaches that utilize reversible bonds in the host material circumvent many of these limitations and offer the potential for unlimited heal cycles. Here we detail the development of an intrinsic self-healing woven composite laminate based on thermally-induced dynamic bond re-association of 3D-printed polymer interlayers. In contrast to prior work, self-repair of the laminate occurs in situ and below the glass-transition temperature of the epoxy matrix, and maintains >85% of the elastic modulus during healing. This new platform has been deployed in both glass and carbon-fiber composites, demonstrating application versatility. Remarkably, up to 20 rapid (minute-scale) self-healing cycles have been achieved with healing efficiencies hovering 100% of the interlayer toughened (4-5x) composite laminate. This latest self-healing advancement exhibits unprecedented potential for perpetual in-service repair along with material multi-functionality (e.g., deicing ability) to meet modern application demands.

Damage Control in Composite Laminates

2001 ◽  
Author(s):  
Alexander P. Suvorov ◽  
George J. Dvorak
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Damage Control ◽  
Thermomechanical Loading ◽  
Interlaminar Stresses ◽  
Damage Resistance ◽  
Viscoelastic Composite ◽  
Mechanical Loads ◽  
Composite Damage ◽  
The Matrix

Abstract Several effects that fiber prestress may have on stress redistribution in the plies of composite laminates and in the phases of individual plies are illustrated. These include improvement of composite damage resistance under tensile mechanical loads, reduction/cancelation of interlaminar stresses at free edges of composite laminate subjected to thermomechanical loading, and stress relaxation in the matrix phase of viscoelastic composite laminates. Specific results are found for quasi-isotropic and cross-ply symmetric S-glass/epoxy and carbon/epoxy AS4/EPON 828 laminates.

THE EFFECT OF LAMINATION SCHEME AND ANGLE VARIATIONS TO THE DISPLACEMENTS AND FAILURE BEHAVIOUR OF COMPOSITE LAMINATE

2015 ◽  
Vol 76 (11) ◽  
Author(s):  
Azizul Hakim Samsudin ◽  
Jamaluddin Mahmud
Keyword(s):  
Fiber Orientation ◽  
Composite Laminates ◽  
Finite Element Modelling ◽  
Composite Laminate ◽  
Maximum Stress ◽  
Failure Load ◽  
Failure Criteria ◽  
Stress Theory ◽  
Failure Behaviour ◽  
Failure Index

This paper aims to investigate the effect of lamination scheme and angle variations to the displacements and failure behaviour of composite laminate. Finite element modelling and analysis of symmetric, anti-symmetric and angle-ply Graphite/ Epoxy laminate with various angles of fiber orientation subjected to uniaxial tension are performed. Maximum Stress Theory and Tsai-Wu Failure Criteria are employed to determine the failure load (failure index = 1). Prior to that, convergence analysis and numerical validation are carried out. Displacements and failure behaviour of the composite laminates (symmetric, anti-symmetric and angle ply) are analysed. The failure curves (FPF and LPF) for both theories (Maximum Stress Theory and Tsai-Wu) are plotted and found to be very close to each other. Therefore, it can be concluded that the current study is useful and significant to the displacements and failure behaviour of composite laminate.

Molecular Dynamics Simulation of the Buckling Behavior of Boron Nitride Nanotubes under Uniaxial Compressive Loading

2010 ◽  
Vol 297-301 ◽  
pp. 984-989 ◽  
Author(s):  
S. Ebrahimi-Nejad ◽  
Ali Shokuhfar ◽  
A. Zare-Shahabadi
Keyword(s):  
Boron Nitride ◽  
Compressive Loading ◽  
Pair Potential ◽  
Md Simulations ◽  
Boron Nitride Nanotubes ◽  
Dynamics Simulation ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Bond Stretching ◽  
Different Diameters

Boron Nitride nanotubes (BNNTs) together with carbon nanotubes (CNTs) have attracted the wide attention of the scientific community and have been considered as promising materials due to their unique structural and physical properties. In this paper, the behavior of BNNTs of different diameters under compressive loading has been studied through molecular dynamic (MD) simulations. We have used a Lennard-Jones pair potential to characterize the interactions between non-bonded atoms and harmonic potentials for bond stretching and bond angle vibrations. Results of the MD simulations determine the critical buckling loads of the BNNTs of various diameters under uniaxial compression, and indicate that for the simulated BNNTs of length L = 6 nm, the critical buckling loads increase by increasing the nanotube diameters.

Determination of the Residual Stresses in Composite Laminate Using the Compliance Method

2005 ◽  
Vol 490-491 ◽  
pp. 533-538 ◽  
Author(s):  
Guillaume Montay ◽  
Olivier Sicot ◽  
X.L. Gong ◽  
Abel Cherouat ◽  
Jian Lu
Keyword(s):  
Experimental Data ◽  
Residual Stresses ◽  
Composite Laminates ◽  
Composite Laminate ◽  
Constant Width ◽  
Strain Gages ◽  
New Methods ◽  
Structure Surface ◽  
Finite Elements Simulation

Residual stresses play an important role on the mechanical behavior of composite laminate. The development of new methods to determine the residual stresses gradient within the laminates is necessary. This article presents the adaptation of the compliance method in the case of composite laminates carbon/epoxy [02/902]s. The incremental drilling of a constant width groove allows for each increment to measure the strains (using strain gages) and displacements (using an optical device) of particularly points of the structure surface. These experimental data are compared with results given by a finite elements simulation. This comparison allows to raise the residual stresses in the composite laminate.

Effect of Matching Buckling Loads on Post-Buckling Behavior in Compliant Mechanisms

2021 ◽  
Author(s):  
A. Numić ◽  
T. W. A. Blad ◽  
F. van Keulen
Keyword(s):  
Compliant Mechanisms ◽  
Relative Length ◽  
Optimal Designs ◽  
Element Analysis ◽  
Buckling Loads ◽  
Actuation Force ◽  
Stepped Beam ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Novel Method

Abstract In this paper, a novel method for stiffness compensation in compliant mechanisms is investigated. This method involves tuning the ratio between the first two critical buckling loads. To this end, the relative length and width of flexures in two architectures, a stepped beam and parallel guidance, are adjusted. Using finite element analysis, it is shown that by maximizing this ratio, the actuation force for transversal deflection in post-buckling is reduced. These results were validated experimentally by identifying the optimal designs in a given space and capturing the force-deflection characteristics of these mechanisms.

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