Carbon Fiber Reinforced Plastic Composites Research Articles

Optimization of Cutting Tool Geometry for Milling Operation using Composite Material – A Review

Fibre reinforced composite materials having their own specific advantages are why they currently gain more and more attention. A vital procedure once preparations of materials are done is the machining process. Various secondary operations such as milling, drilling, turning and various unconventional processes are used for achieving near net shape and size of desired component. Compared to conventional materials, fibre reinforced composite materials are more practical to be use in machining process due to less amount of cutting forces are required to complete the exact shape and size of desired component. Therefore, a review on milling of fibre reinforced composite material will be helpful for numerous researchers and other manufacturing industries, which are currently working in this field. This review paper represents the classification of composite materials, Fiber Reinforced Plastic (FRP) Composites and Carbon Fibre Reinforced Plastic (CFRP) Composites. In addition, this review also defines the machinability of CFRP composites selection and tool design of end mill.

On design of carbon fiber reinforced plastic (CFRP) laminated structure with different failure criteria

This study develops a topology optimization approach for design of carbon fiber reinforced plastic (CFRP) laminated components with different failure criteria to reduce the risk of structural failure. The discrete material and thickness optimization (DMTO) method is adopted to parameterize the design variables of thickness and orientation of CFRP composites, which is driven by the Method of Moving Asymptote (MMA) algorithm. A large number of local constraints associated with the failure criteria are aggregated in terms of a p-norm function. Analytical sensitivities are derived with respect to the design variables. In this study, a battery hanging structure in electrical vehicle (EV) is exemplified; and a DMTO based design is prototyped and validated through the in-house experimental tests first. To prevent different failure modes, the Hashin, Hoffman and Tsai-Wu failure criteria are then imposed as the design constraints together with manufacturing requirements in the optimization. A comparative study is performed for the design with and without such failure criteria. The results demonstrate that the maximum failure index of the optimized structure with the Tsai-Wu failure criterion decreases the most by 40%; and follows by the Hashin and Hoffman criteria by 24% and 33%, respectively. Finally, the CFRP structure is also optimized to design a so-called double-double laminates for demonstrating the generality of the proposed method. The study is anticipated to gain in-depth understanding of how the failure criteria would affect the design of fiber reinforced composite structures to ensure structural integrity.

Numerical and experimental investigation of the delamination in drilling of the carbon fiber-reinforced plastic composite

During the drilling of the carbon fiber-reinforced plastic composite, delamination causes undesirable defects that degrade the quality of products. Thus, the backup plate has been adapted to the composite drilling to prevent delamination. In this study, we present a method to predict the delamination factor of composite laminate according to the cutting conditions as well as the backup plate condition using FE model. We analyzed the damage generated at the exit surface of the composite laminate, using cohesive zone model with user-defined material model of the Abaqus/Explicit software. Damage behavior was simply simulated and quantified to the delamination factor using the parameter criterion CSDMG. Furthermore, appropriate CSDMG variables were selected to predict the accurate delamination factors considering the backup plate condition. Based on the experiment, the delamination factor was calculated with the computed tomography images of the drilled workpiece to quantify the damage. Delamination factors of prediction results and experimental data were performed. It was observed that the maximum error was 10.1% and 19.6% with and without backup plate condition respectively.

Progressive damage characterization of biaxial carbon fiber Reinforced epoxy composites

The objective of the work was to investigate bi-axial characteristics of composite materials with cruciform geometry in both experimental and numerical techniques. The carbon reinforced fibers with epoxy composites prepared by hand lay-up technique with various stacking sequences such as 0°/90°, 45°/45°, 15°/75° and 30°/60°. The fabricated composites were machined in cruciform shape, having different notches namely circular, square and rhomboidal according to ASTM – D6856 standard by abrasive water jet machining to ensure dimensional accuracy of ± 0.1 mm. The prepared cruciform specimens were tested using a biaxial fixture developed indigenously by taking the specifications of universal testing machine. The Young’s modulus, proof stress, ultimate tensile strength and fracture toughness were evaluated for 16 specimens of different fibre orientations and notches using software. The response from the biaxial tensile test showed highest stress developing in [0°/90°] Carbon Fibre Reinforced Plastic (CFRP) composites of 61.37 MPa with highest ultimate tensile strength of 71.93 MPa experimentally. Numerical simulation with ANSYS was showing maximum stresses developing in [0°/90°] Carbon Fibre Reinforced Plastic (CFRP) composites 65.37 MPa.

Preparation and Mechanical Properties Analysis of Aviation Mechanical Carbon Fiber Reinforced Plastics

The study aims to explore the preparation of aviation mechanical carbon fiber reinforced plastics (CFRP) and the properties of CFRP composites. Taking the aero box body as an example, the mechanical properties of CFRP are studied. The preparation of CFRP is analyzed by searching the data. CFRP plates are explored according to the stress analysis of composite materials. The finite element analysis software ANSYS Workbench and UG software are adopted to build the 3D model of the aero box body. After adding materials in ANSYS Workbench and simplifying the UG model, the finite element analysis of the model is carried out by computer. The 3D model of the aero box is constructed, the finite element analysis of the aero box is carried out, and the mechanical properties of CFRP are explored. In this study, the possibility of the practical application of CFRP in the aviation box body lightweight is clarified, which gives a direction for the subsequent actual molding and guides the application of CFRP in aviation field.

Relationship Between Functionalized Multi-Walled Carbon Nanotubes and Damping Properties of Multi-Walled Carbon Nanotubes/Carbon Fiber-Reinforced Plastic Composites for Shaft.

The mechanical properties and damping behavior of carbon fiber-reinforced plastic composites with functionalized multi-walled carbon nanotubes were examined. The functionalized multi-walled carbon nanotubes were blended with epoxy resins to prepare multi-walled carbon nanotubes/carbon fiber-reinforced plastic composites. The dispersion properties of functionalized multi-walled carbon nanotubes in epoxy resins were examined using surface free energy. The mechanical properties of functionalized multi-walled carbon nanotubes/carbon fiber-reinforced plastic composites were measured by interlaminar shear strength and torsion strength. The functionalized multi-walled carbon nanotubes/carbon fiber-reinforced plastic composites had superior mechanical properties due to the increase in dispersion properties of functionalized multi-walled carbon nanotubes in epoxy resins. However, the tan delta values of damping behavior, analyzed by dynamic mechanical analysis, varied with the type of functional groups of functionalized multi-walled carbon nanotubes. The composites obtained from functionalized multi-walled carbon nanotubes obtained through spermidine amidation reaction and carbon fiber-reinforced plastic showed excellent tan delta values due to the flexible segments in side chains.

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber reinforced plastics

Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

Tensile-strength-controlling factors in unidirectional carbon fiber reinforced plastic composites

Factors governing the tensile strength of unidirectional carbon fiber reinforced plastic (CFRP) composites were experimentally investigated by focusing on the mechanical characteristics of the epoxy matrix. Correlation analysis was conducted to reveal the mechanical characteristics of the matrix that affect the surface stress concentration of an intact fiber caused by a fracture site in an adjacent fiber. The stress concentration factors (SCFs) were evaluated by implementing double-fiber fragmentation tests in conjunction with spring element model simulations. From investigating six types of epoxy materials, a reasonable correlation was observed between the matrix crack tip opening displacement (CTOD) and the SCF; the SCF increased approximately linearly with increasing CTOD. The results reported here suggest that CTOD is one of the important tensile-strength-controlling factors to consider for the development of stronger CFRP composites.

Factors influencing the tensile strength of carbon fiber reinforced plastic laminates for laser machining method and the underlined mechanisms

This paper presents an investigation into the influence of laser drilling on the tensile strength of carbon fiber reinforced plastic (CFRP) laminates of 1 and 2.5 mm thickness. The CFRP laminates were drilled using the microsecond laser, nanosecond laser, and picosecond laser, and the heat-affected zone (HAZ) was characterized and measured by optical microscopy. Through setting laser parameters, specimens with different HAZs were prepared, and then tensile strength tests were conducted. The results indicate that the tensile strength linearly depends on the width of HAZ. The tensile strengths of 1 mm specimens decrease by approximately 122 MPa/mm HAZ, and 2.5 mm specimens decrease by approximately 33.9 MPa/mm HAZ. Comparing the results of different thicknesses of CFRP, the effect of HAZ on tensile strength would be weakened with the increasing of laminate’s thickness. Actually, besides HAZ, cutting-induced geometric defects also seriously influence tensile strength, because of the stress concentration around these defects during the stretching process. Additionally, the mechanism why the HAZ influences tensile strength was revealed visually through FEM simulation: the resin matrix damage within HAZ causes the tensile loads not be transferred effectively between the fibers and then weakens the strength. It was the first time the underlined mechanism is revealed for HAZ-inducing strength reduction through FEM simulation. The laser machining method is more suitable for processing the thicker CFRP composites because the negative effect of HAZ is weakened for the thicker material.

Effects of carbide substrate properties and diamond coating morphology on drilling performance of CFRP composite

Abstract The properties of a cemented carbide tool substrate and diamond coating were studied for the precision drilling of carbon fiber-reinforced plastic (CFRP). The microstructures and mechanical properties of WC–6 wt.% Co substrates using different WC particle sizes were examined to determine correlations between the mechanical properties and the drilling performance. The results demonstrated that WC powders with an average particle size of 2.3 μm were suitable drill substrates. Coatings of either microcrystalline diamond (MCD) or gradient nanocrystalline diamond (NCD) were deposited using hot-filament chemical vapor deposition. A drilling test using T700-grade CFRP was conducted to evaluate the drilling performance, tool wear resistance, and CFRP hole quality achieved based on the diamond coating morphology. In the CFRP drilling tests, the diamond-coated drills showed superior tool lifetimes four times longer than that of the uncoated drill. The MCD-coated drill exhibited good wear resistance compared to the gradient NCD-coated drill; however, the gradient NCD-coated drill demonstrated better machining quality in terms of the delamination factor, surface roughness inside the machined hole, and accuracy of the machining dimensions. In this study, we aimed to develop the optimal tool substrate for the drilling of general-purpose CFRP and proposed directions for the development of diamond coatings to maximize drilling performance.

Effects of axial and longitudinal-torsional vibration on fiber removal in ultrasonic vibration helical milling of CFRP composites

Abstract Helical milling (HM), axial ultrasonic vibration helical milling (A-UVHM) and longitudinal and torsional ultrasonic vibration helical milling (LT-UVHM) were developed for hole-making of Carbon Fiber Reinforced Plastic (CFRP) composites. Cutting trajectory, cutting speed, acceleration and effective rake angle of peripheral edge in HM and UVHM processes were modeled. Compared with HM, axial forces with UVHM processes were reduced by 9.0 %–35.7 %. The burrs at entrance and exit with UVHM were also reduced. In A-UVHM and LT-UVHM processes, an effect of shear with variable direction which is good to fracture fibers was presented, according to the relative movement of peripheral edge and fibers. Additionally, the variations of cutting speed and acceleration in A-UVHM and LT-UVHM are also helpful to fracture fibers, due to the wide range of speed and impact effect. Smooth surface with regular fiber fracture morphology and tiny fragments was generated in UVHM due to the effect of shear along variable direction. Compared with HM, the maximum effective rake angle of peripheral edge in UVHM was increased by 112.1 %–192.6 %, which is helpful to fracture fibers by sharper cutting edge.

Internally stiffened foam-filled carbon fiber reinforced composite tubes under impact loading for energy absorption applications

Fiber reinforced plastics can absorb energy, in the unlikely event of a crash, on the other hand, foam improves the structural integrity of the device being filled with. Therefore, foam-filled carbon fiber reinforced plastic (CFRP) composites are extensively used as an energy absorber for safety enhancement. Current study aims to characterize the impact response of CFRP composite tubes filled with polyurethane foam with five different combinations. The CFRP tubes were internally stiffened with sheets, tubes and hats made of CFRP composite. In addition, the internally stiffened tubes were filled with polyurethane (PU) foam for structural integrity. Specimens were then tested under dynamic crushing using a drop weight impactor with an impact energy of 75 J. During the tests, the behaviors of specimens were recorded by high speed camera. Visual inspections and micrographs of the specimens were also investigated. The results revealed that the peak force, threshold force, and energy absorbed were increased by using the PU foam inside the CFRP composite tubes. The energy absorption did not show significant improvement by adding the internal CFRP reinforcements, whereas, the peak load improvement was considerable. The specimen filled with only PU foam yielded the best specific energy absorption among all the specimens.

The Very-High-Cycle Fatigue Properties of Carbon Fiber Composite under Three-Point Bending

This paper starts from the need for an improved testing system of carbon fiber reinforced plastic composites (CFRP) under three-point-bending to investigate its properties under very high cycle fatigue. An improved testing system for composite material under three-point-bending very-high-cycle fatigue has been thus established. It was found that there is no traditional fatigue limit of carbon fiber composite under very high cycle loading conditions, and the CFRP ultra-high-cycle fatigue specimen exhibits three failure morphology, namely matrix damage at the intersection of fiber bundles, matrix voids near parallel sections of fiber bundles, and penetration of the matrix.

A three-dimensional elastic-plastic damage model for predicting the impact behaviour of fibre-reinforced polymer-matrix composites

A three-dimensional (3-D) Finite Element Analysis (FEA) model incorporating an elastic-plastic (EP) damage model, which was implemented as a user-defined material (‘VUMAT’) sub-routine in a FEA code (‘Abaqus/Explicit’), is developed to simulate the impact response of carbon-fibre reinforced-plastic (CFRP) composites. The model predicts the load versus time and the load versus displacement responses of the composite during the impact event. Further, it predicts the extent, shape and direction of any intralaminar damage and interlaminar delaminations, i.e. interlaminar cracking, as a function of the depth through the thickness of the impacted CFRP test specimen, as well as the extent of permanent indention caused by the impactor striking the composite plate. To validate the model, experimental results are obtained from relatively low-velocity impact tests on CFRP plates employing either a matrix of a thermoplastic polymer, i.e. poly(ether-ether ketone), or a thermosetting epoxy polymer. The 3-D EP model that has been developed is shown to model successfully the experimentally-measured impact behaviour of the CFRP composites.

A study on the machinability of advanced arc PVD AlCrN-coated tungsten carbide tools in drilling of CFRP/titanium alloy stacks

This study aims to investigate the effect of an aluminum chromium nitride (AlCrN) coating on tool wear and hole quality in the conventional drilling process of carbon fiber-reinforced plastic (CFRP) composites, titanium alloy (Ti), and CFRP–Ti stack workpieces popular in the aerospace industry. The advanced arc plasma acceleration (APA) method of physical vapor deposition (PVD) was used for all AlCrN coatings. The drilling experiments were conducted with uncoated drills as well as AlCrN-coated drills. When drilling CFRP only, the AlCrN coating was removed at the drill cutting edges and the margin area, which suggests the carbon fibers abraded the coatings. When drilling Ti only, the AlCrN-coated drill mitigated the Ti adhesion formation, which resulted in less tool wear. In addition, hole quality for both CFRP and Ti was improved when the coating was used versus the uncoated tool. The machinability of CFRP–Ti stacks in the drilling process was improved by utilizing the advanced AlCrN coating on the WC tool in terms of drilling forces and hole quality parameters such as average hole size, average hole roundness, hole surface roughness, and Ti exit burr height.

Characterization of impact fatigue damage in CFRP composites using nonlinear acoustic resonance method

Accidental impacts may induce impact fatigue damage in carbon fiber reinforced plastic (CFRP) composite and the progressive fatigue damage is difficult to detect by traditional non-destructive techniques. In this work, a nonlinear acoustic resonance method was proposed for characterizing the impact fatigue damage in CFRP composites. Based on the hysteretic nonlinearity of heterogeneous materials, a fatigue model was constructed to evaluate the impact fatigue damage and predict the residual service life of the composite material. Thereafter, experiments of pendulum impact were conducted on the CFRP composites and nonlinear acoustic resonant were measured to evaluate the impact fatigue damage. Additionally, the impact fatigue damage in the CFRP composites was inspected by an infrared thermography and an optical microscopy. The results indicate that the shift of resonance frequency occurs due to the stiffness degradation and the relative frequency shift has a good linear relation with excitation voltage and strain change. In addition, the damage index rises slowly at the beginning of the impact cycle and rapidly increases when the impact fatigue life exceeds 70%. The experimental results demonstrate that characterizing the impact fatigue damage in CFRP composites using nonlinear acoustic resonance method is an effective and reliable approach.

Quantifying hole quality through geometry accuracy and surface qualities in rotary ultrasonic machining of carbon fiber–reinforced plastic composites

Rotary ultrasonic machining has been approved as an effective and efficient hole making process for carbon fiber–reinforced plastic composites. Hole quality plays an important role in assembling carbon fiber–reinforced plastic components and can be affected by the carbon fiber reinforcement structures. In this study, experiments are conducted to assess hole quality in carbon fiber–reinforced plastic composites with three carbon fiber reinforcement structures under different combinations of machining variables. Hole quality is quantified through geometrical accuracy (perpendicularity, cylindricity, and hole diameter) and surface qualities (delamination and surface roughness). Results show that the highest level of interlacement among yarn of plain woven structure induce the highest level of compression to the workpiece and the largest amount of additional material removal, leading to the largest perpendicularity and hole diameter. The worst fabric integrity of unidirectional structure generates the largest amount of non-uniform material removal on the machined surface, resulting in the largest cylindricity. It is also found that compared with woven structures, unidirectional structure is more likely to induce push-out delamination due to its smaller critical energy release rate. The lowest constancy of the fabric in twill woven structure leads to the largest surface roughness.

Numerical simulation of water jet–guided laser micromachining of CFRP

Carbon fiber-reinforced plastics (CFRP) composites are increasingly used in the aerospace and automotive industries due to their excellent properties, which require higher processing accuracy to ensure their performance. Water jet-guided laser processing technology is a modern processing method, which can effectively reduce the thermal damage caused by laser processing. In order to understand the transient thermal effect of water jet-guided laser processing on CFRP materials and its removal mechanism and the influence of the duty cycle of laser pulse on the temperature field distribution of materials, this paper is based on the “element birth and death” technique in the finite element method, the three-dimensional transient temperature field of heterogeneous fiber matrix and the subsequent material removal model are established. The results show that the CFRP composites processed by water jet-guided laser processing can obtain better processing results over traditional laser processing. Adjusting the duty cycle of laser pulses can significantly affects the shape and temperature distribution of the composites after drilling.

Selective Phenol Recovery by Catalytic Cracking of Thermal Decomposition Gas from Epoxy-Based Carbon-Fiber-Reinforced Plastic

In order to promote the recycling of carbon fiber reinforced plastic (CFRP), catalytic cracking of hazardous gases generated by thermal decomposition from epoxy-based CFRP composites was performed....

Laser ultrasonic visualization technique using a fiber-optic Bragg grating ultrasonic sensor with an improved adhesion configuration

In this research, we attempt to establish a reliable structural health monitoring technique for composite materials by combining phase-shifted fiber-optic Bragg grating sensing with the laser ultrasonic visualization technology. In the first part of this article, a novel cross-adhesion configuration is designed to resolve the directionality problem of the phase-shifted fiber-optic Bragg grating ultrasonic sensing. In the adhesion configuration, Lamb waves are guided by an orthogonally bonded optical fiber from the adhesion point to the phase-shifted fiber-optic Bragg grating sensor. The analysis of the ultrasonic measurement results reveals that the proposed adhesion method enables us to use one sensor to receive Lamb waves in all in-plane directions with similar magnitude because two wave components propagating along with the two orthogonal directions are guided to the phase-shifted fiber-optic Bragg grating sensor and exhibit a linear superposition in the sensor. This simplified configuration gives our method an advantage over the existing approaches, such as the rosette configuration in which three or more phase-shifted fiber-optic Bragg grating sensors are required to relieve the sensing directionality. The phase-shifted fiber-optic Bragg grating ultrasonic sensor with the proposed adhesion configuration is then applied to visualize the propagation of ultrasonic waves in aluminum plates and carbon fiber–reinforced plastic laminates. Those verification experiments also show us that the new adhesion configuration is effective at protecting the phase-shifted fiber-optic Bragg grating ultrasonic measurement from the sensing directionality. Meanwhile, the broad bandwidth of the phase-shifted fiber-optic Bragg grating sensor enables us to visualize the propagation behavior of various Lamb wave modes over a broad frequency range. Finally, we also validate that the ultrasonic visualization technique merged with the phase-shifted fiber-optic Bragg grating ultrasonic sensing can be used to identify the hidden damage in the carbon fiber–reinforced plastic composite.