ANALYSIS OF DAMAGE PREDICTION IN LAMINATED COMPOSITES SUBJECTED TO IMPACT LOADING

Fibre-reinforced laminated composites are susceptible to transverse impact, at low velocities causing significant damage, in terms of matrix cracks and delamination’s, which are very difficult to detect with the naked eye and can cause significant reductions in the strength and stiffness of the materials. This study aimed at analysing the transient dynamic response of laminated composites due to impact. The effect of fiber volume fraction, laminate thickness, plate boundary conditions, velocity and mass of impactor on the behaviour of composites during low velocity impact is analysed using ABAQUS software. For the analysis, a laminated composite panel made of graphite/epoxy fiber-reinforced laminates is subjected to transverse impact by projectile with a spherical nose. Hashin failure model was adopted for the analysis. The optimal fiber capacity fraction for extreme impact energy for T300/976 type of composite was determined. The velocity required to cause damage initiation was found out for different fiber volume fractions. The variation of contact force and central deflection with velocity and mass of impactor was determined and appropriate empirical models were developed to predict the maximum contact force and central deflection for particular values of impactor velocity and mass. The variation of resistance to failure with laminate thickness was found out and suitable boundary conditions of the plate were identified for different types of impact loading INDEX TERMS—Fiber Reinforced laminated Composite, impactor mass, contact force central deflection

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Implementation of the ultrasonic through-transmission technique for the elastic characterization of fiber-reinforced laminated composite

DYNA ◽

10.15446/dyna.v86n208.70279 ◽

2019 ◽

Vol 86 (208) ◽

pp. 153-161

Author(s):

Carlos A. Meza ◽

Ediguer E. Franco ◽

Joao L. Ealo

Keyword(s):

Laminated Composites ◽

Weight Ratio ◽

Laminated Composite ◽

High Strength ◽

Mechanical Tests ◽

Fiber Reinforced ◽

Transmission Technique ◽

Laminated Materials

Laminated composites are widely used in applications when a high strength-to-weight ratio is required. Aeronautic, naval and automotive industries use these materials to reduce the weight of the vehicles and, consequently, fuel consumption. However, the fiber-reinforced laminated materials are anisotropic and the elastic properties can vary widely due to non-standardized manufacturing processes. The elastic characterization using mechanical tests is not easy, destructive and, in most cases, not all the elastic constants can be obtained. Therefore, alternative techniques are required to assure the quality of the mechanical parts and the evaluation of new materials. In this work, the implementation of the ultrasonic through-transmission technique and the characterization of some engineering materials is reported. Isotropic materials and laminated composites of carbon fiber and glass fiber in a polymer matrix were characterized by ultrasound and mechanical tests. An improved methodology for the transit time delay calculation is reported.

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Fabrication and Characterization of Nanofiber Enhanced Prepregs

MRS Advances ◽

10.1557/adv.2017.142 ◽

2017 ◽

Vol 2 (17) ◽

pp. 951-956 ◽

Cited By ~ 4

Author(s):

ABM Iftekharul Islam ◽

Ajit D. Kelkar

Keyword(s):

Mechanical Properties ◽

Transverse Direction ◽

Volume Fraction ◽

Polymer Matrix Composites ◽

Laminated Composites ◽

Electrospun Nanofibers ◽

Woven Fabric ◽

Electrospun Nanofiber ◽

Transverse Impact ◽

Fiber Volume

ABSTRACTTypically, composites are lightweight, and high strength and hence are attractive for use in aerospace, automotive applications. For most of the aerospace applications, laminated composites serve as a primary load carrying structure and are subjected to a variety of loadings including transverse impact and fatigue loadings. The typical laminated composites are weak in the transverse direction. Since laminated composites are weak in the transverse direction, when these laminates are subjected to transverse loading, most of the time interlaminar failure occurs in the form of delaminations. Conventional methods of preventing delaminations include improving the design and improving the matrix properties. Although, improving the composite design suppress delaminations to some extent, a substantial amount of compromise with other properties like increase of resin volume fraction, degradation of inplane properties, voids, distortion in fibers and laminate, an increase of cost or process complexities are common. The present day researchers are more focused on improving matrix by nanomaterials such as Carbon Nano Tube(CNT), though the cost is hampering its potential for an industrial prospect. Electrospun nanofibers are being considered as a cheap alternative for vapor grown CNTs and other nanomaterials which involve complex fabrication and application methods in the field of interlaminar reinforcement for polymer matrix composites. Most of the aerospace quality composites are manufactured using prepreg due to the higher percentage of fiber volume fraction and hence higher mechanical properties. Although, nanomaterials have been recognized as a major advancement for improvement of composite material properties, there has been very little effort to fabricate prepregs using nanofibers. The current research focuses on the challenges involved in the fabrication of nanofiber enhanced prepregs and process difficulties and possible solutions for fabricating electrospun nanofiber overlaid prepregs. The effects of heat treatment on electrospun nanofiber overlaid woven fabric on the mechanical properties of both glass and carbon are investigated. A novel technique is proposed for manufacturing of nanofiber engineered prepregs.

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Behavior of Uniform Anisotropic Beams of Rectangular Section under Transverse Impact of a Mass

Shock and Vibration ◽

10.1155/1997/187215 ◽

1997 ◽

Vol 4 (2) ◽

pp. 125-141 ◽

Cited By ~ 2

Author(s):

Lu Chun ◽

K. Y. Lam

Keyword(s):

Boundary Conditions ◽

Equations Of Motion ◽

Laminated Composite ◽

Solution Procedure ◽

Beam Deflection ◽

Transverse Impact ◽

Lagrange Principle ◽

Arbitrary Boundary ◽

Force Contact ◽

Laminated Composite Beam

A numerical method is presented to investigate the dynamic response of uniform orthotropic beams subjected to an impact of a mass. Higher order shear deformation and rotary inertia are included in the analysis of the beams. The impactor and laminated composite beam are treated as a system. The nonlinear differential governing equations of motion are then derived based on the Lagrange principle and modified nonlinear contact law, and solved numerically. The solution procedure is applicable to arbitrary boundary conditions. Numerical results are compared with those available in the literature to demonstrate the validity of the method, and very good agreement is achieved. The effects of boundary conditions on the contact force, contact duration, stress distributions, and beam deflection are discussed.

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Mode count and modal density of nonsymmetric cross-ply laminated composite beams

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/14644207211008571 ◽

2021 ◽

pp. 146442072110085

Author(s):

Richard Bachoo

Keyword(s):

Finite Element ◽

Boundary Conditions ◽

Laminated Composite ◽

Composite Beams ◽

Fiber Reinforced Composites ◽

Reinforced Composites ◽

Fiber Reinforced ◽

Modal Density ◽

Laminated Composite Beams ◽

Count Function

Fiber-reinforced composites are used in many weight critical applications owing to their high strength-to-weight and stiffness-to-weight ratios. In certain applications, fiber-reinforced composites are subjected to broadband excitation sources that act over a significant portion of the audible frequency range leading to the response of a large number of higher order structural modes. In predicting the response levels of such systems, regardless of whether it is modeled in isolation or using a statistical energy analysis framework, it becomes necessary to quantify the number of resonant modes available to receive and store energy within a frequency band. Conventionally, the mode count and modal density are two parameters used for this purpose. Generally, the analysis of the mode count and modal density of anisotropic fiber-reinforced composite structures have received considerably less attention compared to their isotropic metallic counterparts, and as a result a number of key analytical formulations are yet to be derived and investigated. In this work, the modal distribution and density of nonsymmetric cross-ply laminated composite beams coupled in bending and longitudinal extension are analyzed. A wave approach is used to derive an expression for the mode count of the beam having generalized boundary conditions. Using numerical examples and nonlinear regression analysis, simplified expressions are then obtained for the average mode count function of the beam for different boundary conditions. An analytical expression for the modal density is obtained by taking the differential of the average mode count function with respect to frequency. The wave approach employed in this study is validated based on comparison with results from past literature in addition to finite element simulations. The expression for the modal density is also validated using a finite element model and is shown to be independent of boundary conditions.

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Fiber reinforced round panels subjected to impact loading

International RILEM Symposium on Concrete Science and Engineering: A Tribute to Arnon Bentur ◽

10.1617/2912143586.015 ◽

2004 ◽

Cited By ~ 3

Author(s):

S. Mindess

Keyword(s):

Impact Loading ◽

Fiber Reinforced

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Comparative study of elastic properties and mode I fracture energy of carbon nanotube/epoxy and carbon fibre/epoxy laminated composites

Micro and Nano Systems Letters ◽

10.1186/s40486-020-00120-1 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Jyotikalpa Bora ◽

Sushen Kirtania

Keyword(s):

Carbon Nanotube ◽

Carbon Fibre ◽

Fracture Energy ◽

Elastic Properties ◽

Volume Fraction ◽

Laminated Composites ◽

Laminated Composite ◽

Fe Analysis ◽

Mode I ◽

Mode I Fracture

Abstract A comparative study of elastic properties and mode I fracture energy has been presented between conventional carbon fibre (CF)/epoxy and advanced carbon nanotube (CNT)/epoxy laminated composite materials. The volume fraction of CNT fibres has been considered as 15%, 30%, and 60% whereas; the volume fraction of CF has been kept constant at 60%. Three stacking sequences of the laminates viz.[0/0/0/0], [0/90/0/90] and [0/30/–30/90] have been considered in the present analysis. Periodic microstructure model has been used to calculate the elastic properties of the laminated composites. It has been observed analytically that the addition of only 15% CNT in epoxy will give almost the same value of longitudinal Young’s modulus as compared to the addition of 60% CF in epoxy. Finite element (FE) analysis of double cantilever beam specimens made from laminated composite has also been performed. It has been observed from FE analysis that the addition of 15% CNT in epoxy will also give almost the same value of mode I fracture energy as compared to the addition of 60% CF in epoxy. The value of mode I fracture energy for [0/0/0/0] laminated composite is two times higher than the other two types of laminated composites.

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Effects of hostile solutions on the static and dynamic behavior of carbon/epoxy composites

Journal of Composite Materials ◽

10.1177/00219983211020094 ◽

2021 ◽

pp. 002199832110200

Author(s):

H Ersen Balcıoğlu ◽

Raif Sakin ◽

Halit Gün

Keyword(s):

Bending Strength ◽

Laminated Composites ◽

Fatigue Behavior ◽

Laminated Composite ◽

Test Sample ◽

Solution Concentration ◽

Static Stability ◽

Three Point Bending ◽

Sem Image ◽

Solution Type

Fiber-reinforced laminated composite is often used in harsh environments that may affect their static stability and long-term durability as well as residual strength. In this study, the effect of heavy chemical environments such as acid and alkaline and retaining time for these environments on flexural strength and flexural fatigue behavior of carbon/epoxy laminated composites were investigated. In this context, carbon/epoxy was retained into an acidic and alkaline solution having 5%, 15%, and 25% concentration by weight for 1–4 months. Fatigue behavior of carbon/epoxy was determined under dynamic flexural load, which corresponds to 80%, 70%, 60%, 50%, and 40% of static three-point bending strength of the test sample. SEM image of damaged specimens was taken to describe the failure mechanism of damage which occurs after fatigue. Also, to better understand environmental condition on the fatigue life, results were compared with results of carbon/epoxy laminated composites, which were not retained into any environments (unretained). The test results showed that the solution type, solution concentration, and retaining time caused noticeable changes in the static and dynamic strengths of carbon/epoxy laminated composites.

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The study of the nonlinear vibration of S-S and C-C laminated composite conical shells on elastic foundations through an approximate method

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211021439 ◽

2021 ◽

pp. 095440622110214

Author(s):

Shahin Mohammadrezazadeh ◽

Ali Asghar Jafari

Keyword(s):

Boundary Conditions ◽

Nonlinear Vibration ◽

Approximate Method ◽

Laminated Composite ◽

Vertex Angle ◽

Nonlinear Frequency ◽

Conical Shells ◽

Elastic Foundations ◽

Vibration Responses ◽

Comparison Of The Results

This paper investigates the nonlinear vibration responses of laminated composite conical shells surrounded by elastic foundations under S-S and C-C boundary conditions via an approximate approach. The laminated composite conical shells are modeled based on classical shell theory of Love employing von Karman nonlinear theory. Nonlinear vibration equation of the conical shells is extracted by handling Lagrange method. The linear and nonlinear vibration responses are obtained via an approximate method which combines Lindstedt-Poincare method with modal analysis. The validation of this study is carried out through the comparison of the results of this study with results of published literature. The effects of several parameters including the constants of elastic foundations, boundary conditions, total thickness, length, large edge radius and semi-vertex angle on the values of fundamental linear frequency and curves of amplitude parameter versus nonlinear frequency ratio for laminated composite conical shells with both S-S and C-C boundary conditions are investigated.

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