Showing papers on "Composite laminates published in 2018"
TL;DR: In this paper, a finite element-based computational damage model was developed to predict the material response of hybrid unidirectional/woven laminates, using resin infusion, to assess their performance in low velocity impact tests.
Abstract: A woven five-harness satin (5HS) weave with AS4 carbon fibres, and unidirectional high strength IMS60 carbon fibres were used to manufacture hybrid laminates, using resin infusion, to assess their performance in low velocity impact tests. Load/energy-time curves and load-displacement curves were extracted from the experimental data, and non-destructive C-scanning was performed on all pre- and post-impacted specimens to quantify the extent of damage incurred. A finite element-based computational damage model was developed to predict the material response of these hybrid unidirectional/woven laminates. The intralaminar damage model formulation, by necessity, consists of two sub-models, a unidirectional constitutive model and a woven constitutive model. The built-in surface-based cohesive behaviour in Abaqus/Explicit was used to define the interlaminar damage model for capturing delamination. The reliability of this model was validated using in-house experimental data obtained from standard drop-weight impact tests. The simulated reaction-force and absorbed energy showed excellent agreement with experiment results. The post-impact delamination and permanent indentation deformation were also accurately captured. The accuracy of the damage model facilitated a quantitative comparison between the performance of a hybrid unidirectional/woven (U/W) laminates and a pure unidirectional (PU) carbon-fibre reinforced composite laminates of equivalent lay-up. The hybrid laminates were shown to yield better impact resistance.
130 citations
TL;DR: In this article, the influence of cutting parameters on the drilling process was studied for both CFRP and GFRP laminates, focusing the attention on the measurement of the forces acting on the laminate for several values of cutting speed and feed rate.
111 citations
TL;DR: In this article, the mechanical properties of carbon/basalt fiber reinforced epoxy hybrid composite were investigated through experimental, analytical and numerical methods, and a modified analytical model was derived for predicting flexural strength by comparing with the FEA and experimental results.
100 citations
TL;DR: In this article, composites with various fiber/matrix and interlaminar interfacial properties were fabricated using an autoclave under curing pressures ranging from 0 to 0.8 MPa.
Abstract: The development of the latest generation of wide-body passenger aircraft has heralded a new era in the utilisation of carbon-fibre composite materials. One of the primary challenges facing future development programmes is the desire to reduce the extent of physical testing, required as part of the certification process, by adopting a ‘certification by simulation’ approach. A hierarchical bottom-up multiscale simulation scheme can be an efficient approach that takes advantage of the natural separation of length scales between different entities (fibre/matrix, ply, laminate and component) in composite structures. In this work, composites with various fibre/matrix and interlaminar interfacial properties were fabricated using an autoclave under curing pressures ranging from 0 to 0.8 MPa. The microstructure (mainly void content and spatial distribution) and the mechanical properties of the matrix and fibre/matrix interface were measured, the latter by means of nanoindentation tests in matrix pockets, and fibre push-in tests. In addition, the macroscopic interlaminar shear strength was determined by means of three-points bend tests on short beams. To understand the influence of interfacial properties on the intralaminar failure behaviour, a high-fidelity microscale computational model is presented to predict homogenized ply properties under shear loading. Predicted ply material parameters are then transferred to a mesoscale composite damage model to reveal the interaction between intralaminar and interlaminar damage behaviour of composite laminates.
89 citations
TL;DR: A reliable virtual testing framework for unidirectionally laminated composites is presented that allows the prediction of failure loads and modes of general in-plane coupons with great realism and can be reliably used in for composite materials screening, design and certification.
85 citations
TL;DR: In this paper, a simulation of low velocity impact and compression after impact in thin ply fabric laminates is studied through numerical simulations in which special attention has been devoted towards the computational efficiency.
Abstract: Numerical simulations can help in the understanding of the damage sequence of polymer based composite laminates during an impact event, which is a difficult experimental task when dealing with a large number of plies. Low velocity impact and compression after impact in thin ply fabric laminates are studied through numerical simulations in which special attention has been devoted towards the computational efficiency. The impact results show the importance of delamination during the damage initiation, which takes place at few interfaces. After damage initiation, delamination and fiber breakage propagate until a last stage which is mainly governed by fiber breakage. Compression after impact shows a brittle behaviour with almost no damage propagation prior to failure. The numerical models indicate that matrix cracking effects can be assumed negligible for the studied thin ply laminates while delamination and especially the fiber constitutive law shape are important for accurate predictions.
84 citations
TL;DR: In this article, the authors presented a model for the numerical simulation of Compression-After-Impact (CAI) of hybrid unidirectional (UD)/woven carbon-fibre reinforced composite laminates.
Abstract: The evaluation of Compression-After-Impact (CAI) strength is of great significance in the design of composite aerostructures. This paper presents a model for the numerical simulation of Compression-After-Impact (CAI) of hybrid unidirectional (UD)/woven carbon-fibre reinforced composite laminates. This three-dimensional damage model is based on Continuum Damage Mechanics (CDM) and Linear Elastic Fracture Mechanics (LEFM), implemented as a user defined material subroutine (VUMAT) in Abaqus/Explicit. This model, which accounts for interlaminar and intralaminar damage, and load reversal, incorporates a non-linear shear profile to account for matrix plasticity. Two different composite laminate lay-ups with varying extent of initial impact damage were tested to validate the computational model and enable a quantitative study of the influence of using woven plies on the surfaces of a laminate. Woven surface plies are often used in composite aerostructures to mitigate damage during drilling and constrain the extent of damage during low velocity impact. Good correlation was obtained between physical testing and simulation results, which establishes the capability of this damage model in predicting the structural response of composite laminates. The fully validated model was used to compare the CAI strength of an equivalent UD-only carbon-fibre reinforced composite laminate. The results showed that the hybrid unidirectional (UD)/woven laminate had a marginally higher strength (+3.3%) than the equivalent unidirectional (UD)-only laminate.
82 citations
TL;DR: In this article, the influence of laminate thickness, ply-stacking sequence and scaling technique on the impact damage tolerance of CFRP laminates is investigated by means of compression after impact (CAI) tests.
80 citations
TL;DR: In this article, eight different formulations of thin-ply composites ranging from low modulus to high modulus carbon fibres are evaluated to understand the effects of the fibre and matrix constituents on the onset of damage and strength in unnotched tensile (UNT) tests of quasi isotropic laminates for ply thicknesses between 300 and 30 microns.
80 citations
TL;DR: In this article, the tensile, flexural, and dynamic properties of natural and hybrid thermoset composite laminates made from flax/glass and jute/glass fibres are investigated.
Abstract: This paper investigates tensile, flexural, and dynamic mechanical properties of natural and hybrid thermoset composite laminates made from flax/glass and jute/glass fibres. Hybrid laminates with va...
77 citations
TL;DR: In this paper, the effect of gaps and overlaps, so-called defects, has been investigated experimentally and tensile and compressive testing was carried out on specimens with a quasi-isotropic, symmetric layup into which artificial defects in various defined formations were introduced.
TL;DR: In this article, the authors developed high strength natural fiber based composite plates for the possible application in shear strengthening of reinforced concrete structure, which could be the alternative for reinforcement concrete structure.
TL;DR: In this article, a carbon nanotube (CNT) composite film was synthesized by a simple spray and vacuum-striping method, which demonstrated high electrical conductivity up to 20,000 S/m and excellent EMI shielding effectiveness.
TL;DR: Comparisons of guided wave simulations for CFRP composites implemented using four different simulation codes: the commercial finite element modeling (FEM) packages ABAQUS, ANSYS, and COMSOL, and a custom code executing the Elastodynamic Finite Integration Technique (EFIT).
TL;DR: In this article, the authors investigated the low-velocity impact behavior of carbon fiber composites with novel liquid Methylmethacrylate (MMA) thermoplastic matrix, Elium®.
TL;DR: In this article, a video-extensometer and an infrared thermal camera were employed respectively to measure the evolution of strain and the self-generated temperature during the fatigue experiments, and the progression of damage at different locations and the fracture surfaces were also studied.
TL;DR: In this paper, the first experimental realization of aligned carbon nanotube interlaminar reinforcement of thin-ply unidirectional prepreg-based carbon fiber laminates, in a hierarchical architecture termed "nanostitching", was reported.
TL;DR: In this paper, the mechanical properties of hybrid natural Jute/Kenaf fiber composite laminates have been investigated using a hand lay-up technique to identify the tensile, flexural, and impact test for jute/kenaf hybrid Laminates.
Abstract: Natural fiber composite laminates are nowadays used in structural application such as aerospace, automobile and in sports goods because of their high strength to weight ratio and renewability. Hence the study of mechanical behaviors of natural fiber composites is very important in using these composite laminates for such specific applications. This project aims at identifying the mechanical properties of hybrid natural Jute/Kenaf fiber. The major drawbacks in natural fiber are its Resin incompatibility. Surface treatment of fiber is made to improve the interfacial bonding between the fiber and resin and to reduce the moisture absorption. Laminates are fabricated using Hand lay-up technique. Mechanical properties such as tensile, flexural, and Impact test for jute/kenaf hybrid laminates were obtained. Specimen preparation and Mechanical property testing were carried out as per ASTM standards. Micro structures of the different layer of hybrid specimens are scanned by the Scanning Electron Microscope.
TL;DR: In this article, a two-component commercial epoxy resin was modified with a commercial nitrile liquid rubber modified DGEBA epoxy prepolymer that, prior the cure, has been mechanically dispersed at two concentration levels (20%w/w and 30% w/w).
Abstract: To improve the impact behaviour of composite laminates and to reduce the problem of the complex damages after dynamic loads, a two-component commercial epoxy resin was modified with a commercial nitrile liquid rubber modified DGEBA epoxy prepolymer that, prior the cure, has been mechanically dispersed at two concentration levels (20%w/w; 30%w/w). Experimental characterization of both neat and modified resins was performed to investigate the effect of the rubber addition on the resin properties, i.e. glass transition temperature, modulus and dynamic mechanical characteristics. Further, the rubber domain distribution in the epoxy resin was analyzed by scanning electron microscopy (SEM). The hybrid rubber modified resins did not show high viscosity allowing to manufacture E-glass fiber reinforced composites by vacuum infusion process. The laminates were characterized by tensile mechanical tests that evidenced an overall enhancement of maximum stress and deformation for the hybrid composites. In particular, results demonstrated an improvement of 10% for the shear failure stress and of 110% for the shear failure strain. Further, impact tests were carried out at penetration, to evaluate the improvement of the impact resistance over the conventional epoxy resin system, and at increasing energy levels, 5 J, 10 J and 20 J, to investigate the damage start and propagation. A higher indentation has been observed for the modified composite samples related with a lower delamination extension.
TL;DR: In this article, the effect of adding multi-walled carbon nanotubes (MWCNTs) on high-velocity impact behavior of fiber metal laminates (FMLs) was investigated.
TL;DR: In this article, a constitutive model was developed for FRP composite to simulate the elastic-damage to failure behaviors, and the results of the model predicted similar bending stiffness and damage zones, while single-layer model overestimated the composite damage behavior.
TL;DR: In this article, the hybridization effects of hydrazine reduced graphene oxide (rGO) on the inter-laminar shear strength (ILSS), impact strength, and in-plane fracture toughness of symmetric type carbon fiber/epoxy composite laminates were investigated.
Abstract: In this work, the hybridization effects of hydrazine reduced graphene oxide (rGO) on the inter-laminar shear strength (ILSS), impact strength, and in-plane fracture toughness of symmetric type carbon fiber/epoxy composite (CF/epoxy) laminates were investigated. The composite laminates were fabricated through the vacuum-assisted resin transfer molding (VARTM) process. At 0.2 wt% of rGO loading, the CF/epoxy composites showed the best load carrying capacity among the developed laminates. ILSS, impact strength, and critical stress intensity factor (KIC) were enhanced by ∼ (84, 100, and 33) %, respectively, in the case of rGO (0.2 wt%) filled CF/epoxy composite specimens, as compared to CF/epoxy composite. The consumed fracture energy of rGO (0.2 wt%)/CF/epoxy increased, as compared to the rGO (0.4 wt%)/CF/epoxy composite. The fracture surfaces obtained from field emission scanning electron microscopy of the developed composites showed compatible dispersion of rGO in the epoxy matrix, and branched fracture of the specimens. This study suggests that the rGO nanofiller might be used as a matrix modifier to resist matrix fracture, as well as fiber fracture.
TL;DR: In this article, a new anisotropic ductile fracture model based on linear transformation of stresses is proposed to account for the out-of-plane fracture strength for AHSS sheets.
TL;DR: In this paper, the authors investigated the effect of the loading rate on the Mode I interlaminar fracture toughness of unidirectional carbon/epoxy laminates using the virtual crack closure technique (VCCT).
TL;DR: In this paper, a finite element modeling strategy is presented for simulating low-velocity impact and compression after impact tests on composite laminates using Abaqus/Explicit software.
TL;DR: In this paper, the damage tolerance of cross-ply glass/epoxy composite laminates is analyzed for low-velocity impact and residual compressive strength measurements are performed.
TL;DR: In this paper, the effect of Z-pinning on the impact resistance of composite laminates with different multi-directional layups was investigated and it was found that even though Z-pins are not capable of delaying the onset of delamination, they significantly reduce delamination size for high-energy impacts.
Abstract: The paper presents the results of an experimental investigation into the effect of Z-pinning on the impact resistance of composite laminates with different multi-directional layups. Unpinned and pinned [02/902]s, [02/±45]s and [0/±45/90]s carbon/epoxy samples were subjected to low-velocity impacts resulting in damage severities ranging from barely visible damage to full laminate penetration. The responses to impact of the laminates were characterized in terms of damage evolution, load-carrying capacity, and resistance to perforation and penetration. It was found that even though Z-pins are not capable of delaying the onset of delamination, they significantly reduce delamination size for high-energy impacts. Z-pinning improves the resistance to perforation and penetration of [02/902]s, laminates, while it does not significantly affect that of [02/±45]s and [0/±45/90]s samples. The dependence of the efficacy of Z–pins on the laminate layup is attributed to the different distribution of the delaminations through the thickness of the investigated laminates.
TL;DR: In this article, a finite element model is developed based on different failure criteria of composites, such as maximum stain, maximum stress and Tsai-Hill failure criteria, which can render a clear idea about the locational sensitivity of the loading positions in a two dimensional space.
TL;DR: In this article, experiments were conducted to analyze the thrust force, delamination factor and residual flexural strength in the drilling of woven E-glass fiber-epoxy composites reinforced with functionalized multi-walled carbon nanotubes.