Fiber Reinforced Polymer Composite Materials Research Articles

A finite crack growth energy release rate for interlaminar fracture analysis of composite material at different temperatures

The interlaminar fracture toughness of unidirectional fiber reinforced polymer composite material is temperature and crack growth history dependence. The non-constant interlaminar fracture toughness challenges the wide application of the linear elastic fracture mechanics-based approach for analyzing the interlaminar crack growth in composite material and structures. In addition, a quantitative relationship between the ductility of the matrix and interlaminar fracture toughness of the fiber reinforced composite is still highly desirable. In this paper, both pure resin and composite double cantilever beam (DCB) are tested at different temperatures. A finite crack growth energy release rate is used to analyze the interlaminar crack growth behavior of composite material at different temperatures. The plasticity of the composite DCB is modeled by Hill’s anisotropic plasticity, with the properties determined from multiscale analyses. It is found that a single constant finite growth energy release rate can well predict the interlaminar mode I crack growth of composite material at different temperatures. The roles of the ductility of matrix, thickness of the DCB, and crack growth history on the interlaminar mode I fracture toughness of composite material are quantitatively determined by using the present method.

An interlaminar fatigue damage model based on property degradation of carbon fiber-reinforced polymer composites

Interface delamination is a significant damage mechanism in fiber-reinforced polymer (FRP) laminated composites caused by interlaminar normal and shear stresses. This is due to the low interlaminar properties including interface stiffness and strength that continuously degrade to cause fatigue crack nucleation and growth. In this respect, an interlaminar fatigue damage model is proposed to accurately address the reliability aspect of the FRP composite materials and structures. The model considers a damage process that consists of two stages: (1) fatigue damage evolution due to interlaminar properties degradation to the onset of crack nucleation. A cyclic cohesive zone model with a bilinear softening behavior is introduced along with the fatigue life model to capture the mean stress effect of the interface. This is followed by (2) the crack nucleation process leading to the physical separation/debonding of the interface material point, as governed by the cycle-dependent fracture energy dissipation. The mechanical prediction of the interlaminar fatigue damage process is illustrated through finite element simulation of a mixed-mode flexural test of a carbon fiber-reinforced polymer (CFRP) composite beam subjected to fatigue loading. The results indicate that the interlaminar normal and shear crack opening displacement increases exponentially with the larger number of load cycles. In addition, the high-stress gradient is limited to the interface crack front zone with the normal and shear stress peaks at 69.2 and 16.5 % of the respective interlaminar strength. Moreover, controlled interlaminar crack growth is initially foreseen at 7.0 × 10-6 mm/cycle, followed by an abrupt crack “jump” at 287,000 load cycles.

Fractographic analysis of fiber‐reinforced polymer laminate composites for marine applications: A comprehensive review

AbstractIn the past decade, polymer‐based glass fiber‐reinforced laminate composites have gained significant popularity in various mass transit applications, including marine, aircraft, and automotive industries. However, it is crucial to consider the degradation and potential failure of these materials, especially in mass transit networks. To address this concern, fractographic analysis has emerged as a valuable approach for investigating fracture surfaces, extracting vital information, and facilitating the development of new materials. Furthermore, it sheds light on the underlying physical mechanisms that contribute to composite failure. This paper primarily focuses on examining flaws, failure modes, and performing fractography analysis on fiber‐reinforced polymer (FRP) laminate composites subjected to various loading conditions such as tension, compression, flexure, impact, shear, and fracture. Fractography, as an indispensable method, plays a pivotal role in the comprehensive development of composite structures and has become a reliable tool for composite engineers. The outcomes of this study are expected to serve as a foundation for identifying areas that require further investigation in terms of fracture analysis and failure modes specific to FRP composite materials, particularly those used in marine applications.Highlights Introduction to FRP laminate composites in marine structures. Concise analysis of failure modes in FRP laminate composites. SEM fractography review of FRP laminate composites under varied loading conditions. Comprehensive study on tensile, flexural, impact, compression, shear, and fracture toughness failure modes. Summarization of identified defects in FRP composites.

Strengthening of slender webs of steel plate girders using FRP composites

Web buckling of steel plate girders creates an undesirable failure mode as it can limit the ultimate load capacity of plate girders. This paper presents details of an experimental investigation aimed at strengthening slender end panels of steel plate girders using three different types of fibre-reinforced polymer (FRP) composite materials (glass-fibre-reinforced polymer (GFRP) pultruded section stiffeners and woven carbon-fibre-reinforced polymer (CFRP) and GFRP fabrics). The plate girders were fabricated using non-rigid end posts and were tested in three-point bending. The test results showed an increase of up to 54% in the ultimate strength of the FRP-strengthened end panels compared with the non-strengthened control panel, which was the result of increased out-of-plane stiffness of the web. A breakdown of the bond between the steel and the FRP fabric occurred in the end panels strengthened with CFRP and GFRP fabrics, while no bond breakdown of the pultruded sections was observed at the ultimate load. Analytical methods proposed by some of the design codes underestimated the critical buckling load and overestimated the ultimate load of the non-strengthened end panel.

Exceptional mechanical performance by spatial printing with continuous fiber: Curved slicing, toolpath generation and physical verification

This work explores a spatial printing method to fabricate continuous fiber-reinforced thermoplastic composites (CFRTPCs), which can achieve exceptional mechanical performance. For models giving complex 3D stress distribution under loads, typical planar-layer based fiber placement usually fails to provide sufficient reinforcement due to their orientations being constrained to planes. The effectiveness of fiber reinforcement could be maximized by using multi-axis additive manufacturing (MAAM) to better control the orientation of continuous fibers in 3D-printed composites. Here, we propose a computational approach to generate 3D toolpaths that satisfy two major reinforcement objectives: (1) following the maximal stress directions in critical regions and (2) connecting multiple load-bearing regions by continuous fibers. Principal stress lines are first extracted in an input solid model to identify critical regions. Curved layers aligned with maximal stresses in these critical regions are generated by computing an optimized scalar field and extracting its iso-surfaces. Then, topological analysis and operations are applied to each curved layer to generate a computational domain that preserves fiber continuity between load-bearing regions. Lastly, continuous fiber toolpaths aligned with maximal stresses are generated on each surface layer by computing an optimized scalar field and extracting its iso-curves. A hardware system with dual robotic arms is employed to conduct the physical MAAM tasks depositing polymer or fiber reinforced polymer composite materials by applying a force normal to the extrusion plane to aid consolidation. When comparing to planar-layer based printing results in tension, up to 644% failure load and 240% stiffness are observed on shapes fabricated by our spatial printing method. We demonstrate the versatility of our approach through various complex load cases which demonstrate their successful implementation of continuous fiber printing in 3D.

Thermal and Morphological Assessment of the Penta-Layered, Hybrid U-Polyester Composite Reinforced with Glass Fibers and Polypropylene

The interaction between the fibers and matrix in a fiber-reinforced polymer composite material is important in figuring out its properties. The incorporation of fibers with polymers can result in composites with enhanced strength and stiffness. This study aims to investigate the thermal and morphological characteristics of hybrid u-polyester composites reinforced with glass fibers and polypropylene. The fabrication of composite specimens was conducted through a straightforward cold press method. The compositions of the composites were held constant, except for the orientation of the glass fibers and polypropylene. In this study, the TG/DTG technique was used to analyze the thermal characteristics of the composites. In addition, transverse thermal conductivity was measured using the ASTM E1530 method. The test results showed that the composite reinforced with glass fibers exhibited the lowest weight loss and minimal thermal conductivity among all the samples, followed by the hybrid composite. Based on the TGA curves of the samples, the matrix experienced a weight loss of 9.7% at a temperature of 300°C, which reduced to 2.6% and 2.1% for hybrid composites and glass fiber-reinforced composites, respectively. DTG curves for composites demonstrate that the hybrid and fiber-reinforced composites degraded at rates of 0.64 mg/min and 0.36 mg/min, respectively, at 392.3°C and 395.7°C. Moreover, transverse thermal conductivity of the composite which consists of five-glass-fibered layers shows a minimal thermal conductivity of 0.05 W/m·K. The morphological properties were also investigated using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The findings from SEM and FTIR showed that a higher proportion of glass fibers led to a more oriented composite structure, demonstrating enhanced crosslinking between fibers and polyester. Therefore, the insights of this study can be used to improve the performance of glass fibers and polypropylene hybrid-laminated composites intended for high-temperature applications.

Non-contact heating methods of carbon fiber thermoplastic composites based on Joule thermal properties: Optimization and validation

Carbon fiber matrix composites have garnered significant attention due to their exceptional properties, finding wide-ranging applications in industries such as aerospace, transportation, and military. In this study, a novel approach involving the addition of nickel was explored to fabricate carbon fiber-reinforced thermoplastic polymer composites and composite materials filled with nylon 12, utilizing nickel foam as matrix. Subsequently, electromagnetic-thermal multiphysics coupling models were established to analyze the induction heating process. The study investigated the effects of nickel content, spatial location of the main heat source, coil current, and coil frequency on the temperature rise and heat generation. Additionally, a linear fit was applied to determine the material surface temperature and related factors during induction heating. Furthermore, a theoretical formula was derived for induction heating under ideal conditions, elucidating the heat transfer mechanism and the influence of various factors on heat generation. The findings of this research serve as a reference for optimizing the utilization of Joule heat in composites, thereby expanding the application of carbon fiber-reinforced polymer composites in temperature regulation and operational control.

An Experimental and Comparative Analysis of Glass Fibre Reinforced with Mobile Phone Display (Powder) with Epoxy Resin

The impact of the widespread use of electronic products in the information technology era is known as e-waste. Electronic waste increased as a result of the rising use of electronic products. These wastes polluting the environment leads to degradation of soil and water. By converting electronic waste into useful materials will reduce the electronics wastes. In this research work the composite materials were prepared with the mobile phone display powder mixed with 5% and 10 % to the epoxy resin act as matrix material glass fibers as reinforcement. The mechanical properties of the composites were tested, the tensile strength has been improved more than 10% and compressive strength has been improved more than 35%. Regarding the application of powdered particles to enhance the resistance to delamination initiation and propagation of fiber-reinforced polymer composite materials.

An enhanced constitutive model to predict plastic deformation and multiple failure mechanisms in fibre-reinforced polymer composite materials

Spurious damage modes in continuum damage mechanics models for fiber-reinforced polymer composite materials based on the effective stress tensor can be generated when large strains occur. A methodology to prevent this spurious phenomenon is developed in the present work. The longitudinal damage activation functions are based on the effective stress tensor, however, nominal stresses are used on the transverse damage activation functions. The proposed method can be straightforwardly implemented on previously-developed constitutive models which use the effective stress tensor, an explicit implementation of the proposed constitutive model is presented. The enhancement of the predicted failure mechanisms obtained from the present constitutive model, with respect to the models which use the effective stress tensor, is demonstrated. The proposed constitutive model presents a good agreement of the predicted failure pattern obtained from open-hole compressive experimental tests, as well as on the predicted failure strength.

Flexible photonics in carbon and glass fiber reinforced polymers for new multifunctionality: Exploring the advances, challenges, and opportunities

Flexible photonics, characterized by their planar design and integrated features, have surfaced as a promising technology to unlock new possibilities for multifunctionality within fiber reinforced polymer composite materials. A comprehensive review of current progress, challenges, and opportunities associated with flexible photonic integration into carbon and glass fiber reinforced polymers is provided. A systematic examination of the literature has revealed several flexible photonic technologies that have demonstrated potential for integration in composite components to monitor performance in manufacture, service, and reuse. The review highlights the advantages and limitations of the current state-of-the-art in flexible integrated photonics for making assessments of compatibility with carbon and glass fiber reinforced polymer structures. By examining proof-of-concept demonstrations, the improved performance and novel functionalities that can be achieved for industrial applications are identified. The challenges associated with the integration process, such as durability and scalability are discussed in the context of the manufacturing processes required to create composite components. The concept of integrating flexible photonics in composite structures is relatively new, hence the paper closes by highlighting opportunities for further research and development in this field.

Cognizant Fiber-Reinforced Polymer Composites Incorporating Seamlessly Integrated Sensing and Computing Circuitry.

Structural fiber-reinforced polymer (FRP) composite materials consisting of a polymer matrix reinforced with layers of high-strength fibers are used in numerous applications, including but not limited to spacecraft, vehicles, buildings, and bridges. Researchers in the past few decades have suggested the necessary integration of sensors (e.g., fiber optic sensors) in polymer composites to enable health monitoring of composites' performance over their service lives. This work introduces an innovative cognizant composite that can self-sense, compute, and implement decisions based on sensed values. It is a critical step towards smart, resilient infrastructure. We describe a method to fabricate textile sensors with flexible circuitry and a microcontroller within the polymer composite, enabling computational operations to take place in the composite without impacting its integrity. A microstructural investigation of the sensors showed that the amount of oxidative agent and soaking time of the fabric play a major role in the adsorption of polypyrrole (PPy) on fiberglass (FG). XPS results showed that the 10 g ferric chloride solution with 6 h of soaking time had the highest degree of protonation (28%) and, therefore, higher adsorption of PPy on FG. A strain range of 30% was achieved by examining different circuitry and sensor designs for their resistance and strain resolution under mechanical loading. A microcontroller was added to the circuit and then embedded within a composite material. This composite system was tested under flexural loading to demonstrate its self-sensing, computing, and actuation capabilities. The resulting cognizant composite demonstrated the ability to read resistance values and measure strain using the embedded microcontroller and autonomously actuate an LED light when the strain exceeds a predefined limit of 2000 µε. The application of the proposed FRP system would provide in situ monitoring of structural composite components with autonomous response capabilities, as well as reduce manufacturing, production, and maintenance costs.

Study on the Manufacturing of Composite Materials Made from Glass Fiber Reinforced Polymer (GFRP) in Indonesia for Use as Lining in Open Channels

This study explained the potential use of glass fiber-reinforced polymer (GFRP) composite materials as an alternative lined material for irrigation channels in Indonesia. Currently, only four recommended materials are used as lining in irrigation channels in Indonesia, i.e., stone masonry, concrete, soil-cement, and ferrocement. Almost all lined material's main constituents are sourced from nature/environment. The exploitation of these mined materials will impact environmental destruction. This study focused on the manufacturing process of GFRP material, GFRP surface roughness testing, and the water flow characteristics in the hydraulic model experimental testing. The manufacturing process of GFRP material used polyester resin as the polymer matrix, E-glass type with a combination of woven roving mat covered by non-woven standard mat as the glass fiber reinforcement, and manufacturing process with a combination of hand lay-up and spray-up techniques. The GFRP material product has an average surface roughness coefficient value of Ra around 5.19 to 5.97 μm. The GFRP manufacturing has a good uniform product, as the average surface roughness coefficients of GFRP material have relatively the same values. It is shown that a factory in Indonesia has sufficient capacity to manufacture GFRP material for lining in open channels. The water flow characteristics in the flume were turbulent during testing in the hydraulic laboratory. The experimental study concluded that the GFRP composite materials could be implemented as preliminary references for alternative lined material in irrigation channels in Indonesia.

Segmentation of structural defects in polymer composite computed tomography images with deep learning models

We investigate appliance of different deep learning models to the problem of semantic segmentation of structural defects in computed tomography images of fiber-reinforced polymer composite material. Specifically, we try to segment porosities and delaminations in a specimen using U-Net and DeepLabv3 neural networks. We find out that complex models struggle to generalize solutions on small data samples that are generally available to individual research teams, whereas smaller models are the right choice for approaching defect segmentation in CT images. Our experiments are based on our own laboratory data, collected with X-ray microtomography and labeled manually for the semantic segmentation task.

Novel Sustainable Composites Incorporating a Biobased Thermoplastic Matrix and Recycled Aerospace Prepreg Waste: Development and Characterization.

Carbon fiber-reinforced polymer (CFRP) composite materials are widely used in engineering applications, but their production generates a significant amount of waste. This paper aims to explore the potential of incorporating mechanically recycled aerospace prepreg waste in thermoplastic composite materials to reduce the environmental impact of composite material production and promote the use of recycled materials. The composite material developed in this study incorporates a bio-based thermoplastic polymer, polyamide 11 (PA11), as the matrix material and recycled aerospace prepreg waste quasi-one-dimensionally arranged as reinforcement. Mechanical, thermal, and thermomechanical characterizations were performed through tensile, flexural, and impact tests, as well as differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Compared to previous studies that used a different recycled CFRP in the shape of rods, the results show that the recycled prepregs are a suitable reinforcement, enhancing the reinforcement-matrix adhesion and leading to higher mechanical properties. The tensile results were evaluated by SEM, and the impact tests were evaluated by CT scans. The results demonstrate the potential of incorporating recycled aerospace prepreg waste in thermoplastic composite materials to produce high-performance and sustainable components in the aerospace and automotive industries.

Comparison in the transient regime of four lock-in thermography algorithms by means of synthetic and experimental data on CFRP

Lock-in thermography is considered a well-established technique for investigating fiber-reinforced polymer composite (FRP) materials. These materials are characterized by a low thermal diffusivity and for this motivation, lock-in tests on composite materials generally are time consuming and then, for some applications, not suitable for industrial in-situ inspections. A way for reducing the testing time is to carry out the lock-in tests in the transient regime, although the most well-known lock-in algorithms were originally developed for the post-processing analysis in the steady-state regime. In this regard, the aim of this paper is to present a comprehensive comparison, in the transient regime, of four well-known lock-in thermography algorithms: the Signal Reconstruction (SR), Fast Fourier Transform (FFT), Dual Integration (DI), and Four Points method (4PM). In particular, to evaluate and compare how the transient regime can affect the accuracy and precision of the algorithms in determining the phase contrast of defects, several experimental tests were carried out on a carbon fibre-reinforced polymer (CFRP) test piece having different artificial defects by modulating the sine excitation periods by means of halogen lamps. Furthermore, synthetic data were used for simulating and investigating the four lock-in algorithms in a steady-state regime, as well. In addition, in order to evaluate the robustness of each algorithm, some offline processing analyses were carried out on the experimental data to evaluate the performance of each algorithm as a function of two user-controllable parameters, the number of frames and the number of cycles, and one not directly controlled by the operators, the dropped frame. For each analysis, qualitative and quantitative results in terms of phase and normalized phase contrast are presented and discussed.

Engineering software development for strengthening concrete structures using fiber-reinforced polymers

In this study, engineering software for the calculations of the strengthening applications of reinforced concrete (RC) load-bearing elements with Fiber Reinforced Polymer (FRP) composite materials is developed. This software is developed to increase the axial compression strength and ductility capacity of columns and improve the shear capacity of beams using FRP material according to provisions of the Turkısh Building Earthquake Code 2018 (TBEC-2018). In addition, this software offers designers the opportunity to perform calculations to increase the bending moment capacity of beams using FRP composite material, according to the American Concrete Institute 440-2R.17 (ACI 440-2R.17). Algorithms to be used to increase the capacities of RC load-bearing elements with FRP composite materials are formed according to the provisions of the mentioned codes. Then, computer and web-based engineering software with different coding languages are developed depending on these algorithms.

Effect of hybridization on natural fiber reinforced polymer composite materials – A review

AbstractThis review explores the hybridization effect of natural fiber‐reinforced composites (NFRCs) to reduce energy consumption and environmental pollution. Although natural fibers offer several advantages over synthetic fibers, such as biodegradability, lightweight, and low cost, their application in NFRCs is challenging due to inherent issues such as variable fiber quality, constrained mechanical properties, water absorption, and poor thermal stability. However, recent research has made significant progress in addressing these issues, resulting in better NFRCs. This article surveys the latest developments in plant‐based NFRCs, focusing on methods and innovations to enhance their performance through fiber modification, hybridization, incorporation of lignocellulosic fillers, and fabrication techniques for mechanical, sound absorption, and wear performance. It also discusses the expanding uses of NFRCs in various industrial sectors and the sustainability of plant‐based NFRCs using life‐cycle assessment.

Development of an AI system for characterization of fiber-reinforced polymer composite materials

Development of an AI system for characterization of fiber-reinforced polymer composite materials

Exploration And Research on The Durability of FRP Composite Materials

Concrete cracking caused by steel corrosion is the main form of concrete structure deterioration at present. In order to solve the problem of steel corrosion, people begin to seek to replace steel with corrosion-resistant materials. Fiber reinforced polymer (FRP) has the advantages of high strength to mass ratio, good fatigue resistance, simple construction, corrosion resistance, etc., and has been widely used in engineering in recent years. In this paper, it analyzes the research status of FRP composites and introduces the properties of different kinds of FRP composites in detail. Then, by comparing with ordinary steel bar, the advantages of steel bar containing FRP material are highlighted. Subsequently, the durability of FRP composite materials in corrosion environment is studied. Finally, this paper introduces the practical application of FRP composites in engineering. The results are helpful to popularize the application of FRP composites in practical engineering.

On axial crushing behavior of double hat-shaped CFRP and GFRP structures

This study aimed to investigate the energy-absorbing mechanisms of composite structures subjected to quasi-static and dynamic axial crushing loads. Double hat-shaped composite tubes were prepared using carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) composite materials. The results indicated that these composite tubes exhibited a progressive end-crushing mode and had a comparable load-carrying capacity at a crushing velocity of 2 mm/min. When the loading rate was increased to 6.1 m/s, a 23.3% reduction in the energy absorption of the CFRP structures was observed; whereas the energy absorption of the GFRP structures remained relatively constant. A stacked-shell finite element model, which considered the effects of strain rate on intra-layer and inter-layer properties, was developed to simulate the axial crushing behavior of the CFRP and GFRP tubes. The predictions made by the finite element model were found to correlate well with the tested crushing process, force–displacement curves, and final failure mode. The mechanical properties of the composite materials were also observed to play a critical role in the energy-absorbing mechanisms, contributing to the distinct crushing responses of the CFRP and GFRP structures. The results of this study are expected to help clarify the differences in the energy-absorbing mechanisms between CFRP and GFRP tubes, thereby contributing to the crashworthiness design of composite energy-absorbing structures.