Reinforced Plastic Composites Research Articles

Analytical model for revealing tool wear law during edge trimming of Carbon Fiber Reinforced Plastics composites

Analytical model for revealing tool wear law during edge trimming of Carbon Fiber Reinforced Plastics composites

Towards understanding the material removal mechanism on the effect of ultrasonic vibration and anisotropy for unidirectional CFRP by scratching

Rotary Ultrasonic Machining (RUM) is a well-known non-traditional machining method for hole-making and surface grinding of Carbon Fiber Reinforced Plastics (CFRP). However, the complicated material removal behavior of CFRP is difficult to understand due to its heterogeneity and anisotropy resulting from components and the nature of laminated structures. In this concern, we conducted ultrasonic vibration-assisted scratching (UVAS) to understand the material removal mechanisms with the effect of ultrasonic vibration and fiber anisotropy. Based on scratching morphology, the removal behavior of unidirectional CFRP (UD-CFRP) varied in different scratching directions. Meanwhile, the addition of ultrasonic vibration could suppress machining damage generated by the scratching process. The motion trajectory analysis and experimental results show that the ultrasonic vibration-assisted scratching load is smaller under the same machining parameters. Discussions on the material removal mechanism of UD-CFRP during the effect of ultrasonic vibration and fiber anisotropy were also provided. This research will contribute towards an in-depth understanding of the material removal mechanism for fiber reinforced plastics composites in RUM, which will be useful in optimizing the application of ultrasonic vibration assisted processes for advanced composites machining.

Influences of Main Machining Process Parameters and Tool Wear on The Machining Damage Generated During Edge Milling CFRP Composites

Machining Carbon Fibre Reinforced Plastics (CFRPs) composites are typically accompanied by the appearance of machining damage which strongly impacts the structural integrity of composite parts during their service lives. Studying the correlation between machining damage and its affected factors has still been an open issue. Hence, it is necessary to do more research. This study focuses on investigating the influences of main process parameters and tool wear phenomenon in terms of machining length on the machining quality which was characterized by the surface roughness criterion, the ten-point max, Rz. A full factorial design of experiments was conducted including three levels of feed speed and two degrees of spindle speed. The results revealed that machining damage was mainly influenced by process parameters at a small machining distance, whereas at a longer machining distance, tool wear had a dominant effect on the machining quality than machining parameters. These findings could provide guidelines for selecting suitable machining parameters to enhance the machining quality of CFRP.

An anti-wear tool structure with integrated-micro hybrid cutting edges for milling of carbon fiber–reinforced plastics composites

An anti-wear tool structure with integrated-micro hybrid cutting edges for milling of carbon fiber–reinforced plastics composites

Study on Equal Interval Sampling Method Promoting Efficiency of Post-Processing Algorithms for Infrared Thermography Inspecting Carbon-Fiber Reinforced Plastics Composites

Study on Equal Interval Sampling Method Promoting Efficiency of Post-Processing Algorithms for Infrared Thermography Inspecting Carbon-Fiber Reinforced Plastics Composites

Assessment of tensile behaviour of plain weave fabric CFRP composites using acoustic emission technique and deep learning

The applications of Carbon Fibre Reinforced Plastic (CFRP) composites in aerospace applications have increased exponentially in the last decade. CFRP composites are now replacing conventional materials used in high temperature applications. Different types and strategies of reinforcements are used in these composites to improve their applicability to high temperature applications. One of the reinforcement strategies that has been used frequently in the recent years is the plain weave fabric configuration of reinforcing fibres in polymer matrix. A comprehensive damage assessment is essential to evaluate the characteristics of these composites at elevated temperatures. The Acoustic Emission (AE) signals generated during the damage evolution stages are used for studying the damage evolution stages when the plain weave fabric composites are tested at temperatures close to their glass transition state. A new information-theoretic parameter, Lempel-Ziv (LZ) complexity and the deep learning neural network is used for understanding the damage evolution stages. Furthermore, the neural network is used for validating the utilization of LZ complexity as a potential AE parameter for damage classification applications. The results are promising with the damage classification strategy using LZ complexity exhibits an accuracy of 85.1% which is validated through the neural network.

Exploring the Elastic Properties of Woven Fabric Composites: A Machine Learning Approach for Improved Analysis and Design

Woven fabric reinforced plastic composites are highly favoured in the aerospace and automotive industries for their exceptional impact resistance and ease of manufacture. To design and analyse these structures, it is crucial to determine their elastic properties of woven fabric composites, which can be estimated through analytical, numerical, or experimental means. In this study, we propose a novel approach that combines machine learning techniques with finite-element methods based multi-scaling analysis methodology to predict the elastic behaviour of woven composites. The method leverages datasets generated from finite element methods based numerical simulations and literature to train and validate models, providing a cost-effective and computationally efficient alternative to conventional homogenization-based finite element method. The approach offers a promising solution to accurately predicting the elastic behaviour of woven fabric composites.

A Neural Network Framework for Validating Information-Theoretics Parameters in the Applications of Acoustic Emission Technique for Mechanical Characterization of Materials.

A multiparameter approach is preferred while utilizing Acoustic Emission (AE) technique for mechanical characterization of composite materials. It is essential to utilize a statistical parameter, which is independent of the sensor characteristics, for this purpose. Thus, a new information-theoretics parameter, Lempel-Ziv (LZ) complexity, is used in this research work for mechanical characterization of Carbon Fibre Reinforced Plastic (CFRP) composites. CFRP specimens in plain weave fabric configurations were tested and the acoustic activity during the loading was recorded. The AE signals were classified based on their peak amplitudes, counts, and LZ complexity indices using k-means++ data clustering algorithm. The clustered data were compared with the mechanical results of the tensile tests on CFRP specimens. The results show that the clustered data are capable of identifying critical regions of failure. The LZ complexity indices of the AE signal can be used as an AE descriptor for mechanical characterization. This is validated by studying the clustered signals in their time-frequency domain using wavelet transform. Finally, a neural network framework based on SqueezeNet was trained using the wavelet scalograms for a quantitative validation of the data clustering approach proposed in this research work. The results show that the proposed method functions at an efficiency of more than 85% for three out of four clustered data. This validates the application of LZ complexity as an AE descriptor for AE signal data analysis.

Environmental affected mechanical performance of additively manufactured carbon fiber–reinforced plastic composites

Due to their attractive strength-to-weight ratios, stiffness-to-weight ratios, thermal expansion, corrosion resistance, and vibration resistance properties, carbon fiber reinforced plastic (CFRP) composites have been widely used in applications ranging from aerospace to sporting goods. Considering some of the advantages of additive manufacturing (AM) over traditional subtractive methods, AM is being used to fabricate CFRP composites. For the fabrication method, several investigations have been conducted on materials and processing effects on the mechanical performance of the composites. However, no studies have investigated the effects of environmental conditions on mechanical performance. This study reports the environmental (temperature and relative humidity) affected mechanical performance of AM fabricated CFRP composites exposed to three different environmental conditions: warm–wet, warm–dry, and cold–dry, compared to samples tested immediately after fabrication under normal ambient conditions. The result was that the warm temperatures have insignificant effects on the mechanical performance of the composites, while near-zero degree cold temperatures have significant effects after the 96 h and 250 h short-term exposure periods. The result also showed the temperature to have more significant effects on mechanical properties than relative humidity. Under the warm conditions, the dry humidity resulted in a slight increase in material mechanical properties over the nominal ambient condition, while the wet humidity showed an insignificant reduction in material mechanical properties.

Lamb wave-based damage detection of composite structures using deep convolutional neural network and continuous wavelet transform

Carbon fiber reinforced plastics composites have been widely used in aerospace, automotive and other fields for its superior performance. To avoid possible risks, Lamb waves-based structural heath monitoring techniques have been applied to detect the internal damage of these composites. However, due to their intrinsic high degree of anisotropy which makes the failure mode complicated under fatigue loads, an accurate and timely method for damage detection of these composites is still challenging to realize. This paper proposes a novel method for detecting the internal delamination of the carbon fiber reinforced plastics by combining deep convolutional neural network and continuous wavelet transform. This data-driven method can effectively leverage the large amount of data without relying on complex feature extraction. After converting the time series signal into a two-dimensional time–frequency image by the continuous wavelet transform technique, the convolutional neural network model is applied to classify the images. Based on the prediction results of different paths by the model, a damage localization method is also proposed for ply delamination. An experimental study is implemented to verify the effectiveness of this method. The result shows this method is a useful technique for precise diagnosis and positioning of delamination damage in the composite structures.

Ultrasonic machining of carbon fiber–reinforced plastic composites: a review

Carbon fiber–reinforced plastic (CFRP) composites are extensively being applied in manufacturing sectors because of their extraordinary characteristics. However, CFRP composites often require some extra machining processes to improve the dimensional accuracy and component integrity of CFRP composites in manufacturing industries. The ultrasonic machining (USM) process progressively has been examined due to its greater ability in machining difficult to cut, brittle, and hard materials such as CFRP composites and due to its relatively low machining cost. Furthermore, USM shows to be a promising process with better surface quality, lower cutting force, less or no fiber fracture, laminate delamination, and lower tool wear rate. Recently, USM has been extensively investigated by many researchers for the machining of CFRP composites. This paper explores the literature and presents a comprehensive review of the advances in USM of CFRP composites by classifying the studies reported in two perspectives. First, the review summarizes most of the reported studies starting from 2011 to 2020 based on the applied USM process, equipment/system/platform used to carry out experiments, considered process parameters and output variables, and challenges investigated or gap filled. Then, the reported studies are summarized considering the type of USM process variant, CFRP composite, adopted process parameters on machining characteristics, and their respective results and conclusions. The aim is to present the current research status in USM of CFRP composites and thus provide guidance and foundation for future research.

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.

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.

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.

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.

Three-point bending analysis with cohesive surface interaction for improved delamination prediction and application of carbon fibre reinforced plastics composites

Carbon fibre reinforced plastics laminates were loaded through to fracture in a three-point bending configuration, to gain understanding of the cohesive interaction between plies and validate mechanical properties and predictive capability of the FE model. The effect of mesh refinement, scaling techniques, failure models and cohesive surfaces were investigated. Fibre orientations investigated were parallel, 45° and perpendicular to the loading. Experimental results showed a larger radius punch promoted failure on the intended bottom side, tensile stresses region, allowing for the Aramis strain camera to record the failure. When the fibre orientation was perpendicular to the punch load, all failure models show similar rate of force increment with respect to displacement. No difference in failure prediction is observed for the different 0° models, except for a 4.18% under prediction by LaRC02 compared to the experiment. With fibre orientations at 45° and 90°, the Maximum Strain and LaRCO2 failure models were more suitable in terms of accuracy and convergence. Incorporating cohesive surfaces between instances improve nonlinearity prediction of 45° and 90° layups. Small span-to-thickness ratio analysis predicts interlaminar shear failure, delamination, versus large span-to-thickness ratio determine normal stresses to dominate failure in laminate. The model was setup in multi-fibre orientation and cross-ply layups for extended application and was shown to successfully predict material response described in literature.

Creep/recovery and stress-relaxation tests applied in a standardized carbon fiber/epoxy composite: Design of experiment approach

Carbon fiber–reinforced plastic is a trend in the composite field since it has outstanding mechanical properties, which can be applied in several areas. For this work, carbon fiber–reinforced plastic composite using epoxy as matrix was molded by vacuum-assisted resin transfer molding to measure the individual influence of temperature and strain/stress on initial strain, permanent deformation, and modulus decay behavior of carbon fiber–reinforced plastic quantitatively. To achieve this purpose, void content, creep/recovery, and stress-relaxation properties were statistically evaluated by design of experiment approach–Taguchi method and analysis of variance. Results showed that both permanent deformation and modulus decay had influence on temperature and design of experiment confirmed that temperature is the main contributor to each response, considering all three viscoelastic regions (glassy, glass transition, and rubbery) and stress/strain.

Effect of foaming processes on the reduction of warpage in glass fiber reinforced plastic composites

In the injection molding process, dimensional stability of the product is an important factor. Because reinforced plastic composites show shrinkage and warpage that are different from non-reinforced plastics, it is necessary to compensate for these differences. In this study, two foaming methods, microcellular foaming injection molding and chemical foaming injection molding, were applied to achieve dimensional stability in the molding process of glass fiber reinforced plastic (GFRP) composites. Both microcellular foaming and chemical foaming showed a warpage reduction effect. Therefore, if a selective foaming process is applied to achieve weight reduction and necessary material properties, microcellular foaming and chemical foaming can be used to achieve dimensional stability in reinforced plastic composite materials.

Rotary ultrasonic machining of carbon fiber–reinforced plastic composites: effects of ultrasonic frequency

Rotary ultrasonic machining (RUM) is effective and efficient in cutting carbon fiber–reinforced plastic (CFRP) composites. With ultrasonic vibration assistance, both machining efficiency and machining effectiveness can be improved. Ultrasonic vibration has two major variables (including ultrasonic amplitude and ultrasonic frequency), which play important roles in RUM processes. Other intermediate variables, such as ultrasonic power and indentation depth, are directly related to these two variables. Effects of ultrasonic vibration amplitude have been extensively investigated in RUM hole making and surface machining processes. However, the effects of ultrasonic frequency in RUM have not been reported. The effects of ultrasonic frequency under different combinations of tool rotation speed, feed rate, and depth of cut on output variables, including cutting forces, surface roughness, and machined surface characteristics, are investigated, for the first time, in this study. The critical frequency is analyzed for the RUM process. Three different levels of ultrasonic frequencies are generated and applied to the RUM process. The kinematic motions of abrasive grains in RUM with different frequencies are analyzed and discussed. The results show that RUM with higher frequency of ultrasonic vibration is a more effective machining process, leading to cutting force reduction and the machined surface quality improvement.

Effect of hygrothermal aging on the interlaminar shear strength of a carbon fibre composite

Carbon Fibre Reinforced Plastic (CFRP) composites are used many applications in aerospace structures due to their high specific strength and stiffness. Composite aircraft structures are usually exposed to a range of environmental conditions such as hygrothermal, UV radiation, chemical environments, biological condition etc., in their service life and may degrade. Moisture absorption at different hygrothermal conditions and its effects on properties of CFRP composites is a useful parameter to designers and application engineers. In this study, UD carbon fiber/epoxy composite laminates were fabricated (HexPly® M21E/34%/UD/194/IMA) from prepreg using standard autoclave process. Inter Laminar Shear Strength (ILSS) test specimens were cut and prepared from theses laminates. Hot-wet specimens were aged at two different conditions; 75 0C/ 85% RH, 55 0C/ 100% RH until attaining moisture absorption saturation. Three-point bend tests were conducted as per ASTM test standard specifications using a 25 KN servo-hydraulic test machine to determine ILSS properties for aged and unaged material. Respective hot-wet conditions were maintained even during the mechanical tests. Tests results show that moisture absorption rate increases gradually and attains saturation at about 1 wt. % under both conditions. Inter laminar shear strength reduced significantly by about 33% due to presence of moisture. Microscopic observation of failed samples also investigated to study the fracture behavior and reported in this paper.