Fiber Composite Layers Research Articles

Experimental and numerical investigation on shear behavior of concrete beams reinforced with CFRP grid shear reinforcements

This research investigated the shear behavior of concrete beams reinforced with Carbon Fiber Reinforced Polymer (CFRP) bars and grids as longitudinal reinforcements and stirrups, in experiment and finite element (FE) methods. Five concrete beams were tested under a monotonical load and experienced shear failure as expected. The test variables including stirrup ratio and grid dimension were considered to investigate the interaction between grid and concrete, and the influence between the horizontal and vertical fibers of the grid. It found that reducing the grid dimension with the constant stirrup ratio could effectively improve the stress distribution of the grid and the shear capacity of the beam. The grid dimension greatly determined the shear capacity of specimens when the stirrup ratio changed in a small range. The horizontal fibers of the grid had anchoring effects on the vertical fibers and directly carried the tensile stress from concrete at the top and bottom of the beam. In FE analysis, the fiber composite layer was adopted to simulate the CFRP grid. The load-midspan deflection of specimens and strain development of the grid in the FE model showed good agreement with the tests. In parameter analysis, the grid configuration with the horizontal fiber arranged in the middle or upper part of the section was recommended.

Design and material optimization of carbon fiber composite winding reinforcement layer for vehicle Type-IV hydrogen storage vessels

Due to the safety, reliability, and high hydrogen storage density of vehicle Type-IV composite overwrapped pressure vessels (COPVs), the Type-IV COPVs are currently the preferred choice for vehicle hydrogen storage vessels. The reinforcement layer bears 80 % to 90 % of the internal pressure load, and it accounts for a significant proportion of the total cost and weight of Type-IV COPVs. Thus, the reinforcement layer is the key problem in the design and optimization of the vehicle Type-IV COPVs. Firstly, this paper proposed a design method for vehicle Type-IV COPVs considering the strength and stiffness of reinforcement layer, and created the hydrogen storage vessel scheme. Then, the stress and strain of vehicle Type-IV COPVs under working and blasting internal pressure were analyzed by finite element simulation. Finally, the genetic algorithm was used to find the best carbon fiber for vehicle Type-IV COPVs. The results show that the scheme designed by the method in this paper can meet the requirements of vehicle use; The carbon fiber modulus most suitable for car hydrogen storage bottle winding is 288.8 GPa, and the weight of the reinforcement layer is reduced by 32 % compared to the T700S carbon fiber composite wound vessel.

An active-passive integrated actuator based on macro fiber composite for on-orbit micro-vibration isolation

Micro-vibration suppression is crucial for satellites to ensure high imaging performance of optical loads. Herein, an active-passive integrated actuator based on macro fiber composite for micro-vibration isolation is proposed and investigated. Integrated passive and active vibration suppression is achieved by arraying a composite laminated beam consisting of the stiffness layer, damping layer and macro fiber composite layer. A dominant-frequency-correction hysteresis modeling strategy is devised to describe the asymmetric and rate-dependent voltage-force hysteresis of the proposed actuator. By treating the correction as a disturbance, the voltage-force hysteresis is compensated in combination with an extended state observer. In order to achieve resonance suppression, a full-estimation-feedback controller featuring merely displacement response feedback is developed exploiting the estimation of the extended state observer as feedback. Simulation results verify that the full-estimation-feedback controller is capable of suppressing the resonance peak with weak adverse effects on the transmissibility in the isolation band. Finally, experiments are performed to identify the voltage-force hysteresis model and evaluate the vibration isolation performance. Periodic and sweep excitation test results demonstrate that in passive mode, the actuator has a small resonance frequency of 2.3 Hz and a wide isolation band starting from 3.5 Hz. With the full-estimation-feedback controller, the resonance peak is effectively suppressed using a single signal feedback, while maintaining excellent vibration attenuation within the isolation band. The proposed actuator provides a paradigm for the design of active-passive integration vibration isolators for broadband micro-vibration suppression, which holds significant promise in enhancing the effectiveness of current observation missions.

Preparation of ablation-resistant ethylene propylene trioxide/polyimide staple fiber composite insulation layer by solution wet mixing process

This research developed a solution wet mixing process for creating Ethylene propylene diene monomer/polyimide staple fiber composites (EPDM/PISF), overcoming the uneven fiber distribution seen in traditional dry mixing techniques. By uniformly dispersing PISF within the EPDM matrix, the wet mixing process improves the composite's performance. This is evidenced by an 18.08 % reduction in ΔG′, a 14.29 % lower linear ablation rate (0.042 mm/s), enhanced thermal stability, a higher charring rate, and a denser carbonized layer. Optimal overall performance was achieved using a PISF content of 10phr in the wet mixing process. This advancement significantly enhances the ablation resistance of EPDM/PIS, making them a promising choice for high-performance and durable insulation in solid rocket motors.

Open loop flutter control of optimally oriented smart variable stiffness plates under hygrothermal environment

The present study investigates the impact of hygrothermal effects on the free vibration and flutter characteristics of a smart variable stiffness composite laminate (VSCL). This research seeks to underscore the inherent advantages of VSCLs in contrast to conventional straight fibre constant stiffness composite laminates (CSCLs). Utilizing curvilinear fibres, VSCLs offer a heightened level of customization, culminating in notably enhanced structural performance. The Genetic Algorithm is employed to obtain optimal fibre paths for the variable stiffness laminates. Introducing an active fibre composite layer as an actuator atop the optimally oriented VSCL laminate enhances its capabilities. A parametric inquiry into the influence of hygrothermal loading on the smart structure's free vibration and flutter traits is undertaken. While hygrothermal loading imparts vulnerability to the laminate, the introduction of voltage to the active fibre composite layer counteracts this weakening effect, effectively augmenting stiffness and concurrently enhancing the flutter parameters (velocity, frequency) intrinsic to the plate structure.

A Thermal Insulation and UV-Resistant System based on Aerogel for Settlements on the Moon and Mars

Abstract: This paper presents a novel design for a habitable outpost on both the Moon and Mars that leverages the exceptional properties of aerogel - a material composed of 99% air, offering outstanding thermal insulation and UV protection. The outpost is engineered to withstand extreme temperature variations on Mars (-153°C to 20°C) and the Moon (-173°C to 127°C) using a single material. Protection against harmful UV rays is crucial for sustaining human life as prolonged exposure can lead to DNA damage and cancer. To safeguard the aerogel layer from meteoroids, Martian soil is utilized on Mars, and lunar soil on the Moon. The interior features a fiber composite layer, supported by a mechanical structure made from Martian concrete (ice, calcium oxide, and Martian aggregate) or lunar concrete (ice, calcium oxide, and lunar aggregate). The composite can be assembled on Earth with an inflatable system or sent to Mars in multiple missions for on-site assembly. Light transmission with radiation resistance is achieved using translucent silica aerogel filters for glass windows. The paper also includes heat transfer calculations between the internal and external environments of the habitat, as well as strength assessments of the habitat, taking into account the insulation and UV resistance provided by the protective soil layer.

Determination of the ballistic performance ramie-fiber-reinforced epoxy composite-sic ceramic in multilayered armor system

Multilayered Armor System (MAS) is being extensively studied around the world for its ability to retain ceramic fragmentation after a collision occurs. MAS consist of a ceramic layer placed at the front and supported by a composite layer of ramie-fiber-reinforced epoxy resin. Present study utilizes natural fibers of 50 % ramie fibers with epoxy resin as the matrix and Silicon Carbide (SiC) ceramic as the front panel. The ballistic testing in this study used 7.62×51 mm NATO Ball projectile with a firing distance of 15 m from the bullet panel. The velocity of projectile was detected using LIGHT SCREEN B471 type. The aim of the study is to conclude the optimal thickness of ramie fiber-epoxy and SiC ceramics MAS structure based on experiments which can withstand 7.62 NATO ball bullet penetration. To achieve this aim, the following objectives are accomplished: study the effect of SiC ceramic addition to ramie composite on BFS and study the effect of SiC ceramic addition to ramie composite on failure mode. Results show that the addition of the number of layers of SiC increases resistance of ballistic MAS marked by a decrease in the value of BFS clay. The 5SiC+10R is the optimal thickness in resisting the penetration of 7.62×51 mm bullets with 12 mm BFS clay. Failure phenomena found in this study were projectile fragments, matrix cracks, radial cracks, impact points, and ceramic fragments. Matrix crack formation appears on 5SiC+10R with mini deformation in rear side. Phenomenon of ceramic fragmentation in the shot causes the MAS structure to be damaged, so that the ramie fiber composite layer will face the bullet directly if it is subjected to a second shot. Ultra High Hardness Armor (UHHA) as first layer on the MAS structure is an attractive option for further research.

Identifying Void and Crack Defects in Type III Hydrogen Storage Vessels Based on Microwave Inspection

Microwave technique has become a promising candidate for non-destructive testing. In this study, microwave-based method was used to inspect type III hydrogen storage vessels and to identify void and crack defects in the carbon fiber composite wound layer. Using a vector network analyzer, the reflection coefficient S11 of type III hydrogen storage vessel samples with no defects and with a void or a crack defect in the composite wound layer was measured. The defect-containing vessels had S11 values significantly different from those of vessels without defects, based on which the defects can be detected. Moreover, identification of the two defects can be achieved by comparing the values of S11, as the void results in more microwave reflection than the crack. During the inspection, only when the horn antenna is against the defect does the S11 show great changes, indicating the detection sensitivity of the method. This work provides new insights into inspection of defects in the of carbon fiber composite wound layer of type III hydrogen storage vessels.

Detection of Void and Crack Defects in Type IV Hydrogen Storage Vessels by Microwave Technique

Non-destructive testing based on microwave technique has been developing rapidly. In the present study, microwave-based method was used to detect void and crack defects in the carbon fiber composite wound layer of type IV hydrogen storage vessels. Taking advantage of a vector network analyzer, the reflection coefficient S11 of type IV hydrogen storage vessel samples without defects and with a void or a crack defect in the composite wound layer was measured. The defect-containing vessels exhibited S11 values much different from those of vessels without defects, according to which the defects can be detected. Additionally, identification of the two defects can be realized by analyzing the S11 values, as the void gives rise to more reflection of microwave than the crack. During the inspection, only when the horn antenna is against the defect does the S11 show significant changes, suggesting the detection sensitivity of the method. This study lays a solid foundation for the development of microwave inspection of defects in the composite wound layer of type IV hydrogen storage vessels.

Numerical Analysis of Mechanical Behaviors of Composite Tensile Armored Flexible Risers in Deep-Sea Oil and Gas

As oil and natural gas production continue to go deeper into the ocean, the flexible riser, as a connection to the surface of the marine oil and gas channel, will confront greater problems in its practical application. Composite materials are being considered to replace steel in the unbonded flexible pipe in order to successfully meet the lightweight and high-strength criteria of ultra-deep-water oil and gas production. The carbon-fiber-reinforced material substitutes the steel of the tensile armor layer with a greater strength-to-weight ratio. However, its performance in deep-water environments is less researched. To investigate the mechanical response of a carbon fiber composite flexible riser in the deep sea, this study establishes the ABAQUS quasi-static analysis model to predict the performance of the pipe. Considering the special constitutive relations of composite materials, the tensile stiffness of steel pipe and carbon fiber-reinforced composite flexible pipe are predicted. The results show that the replacement of steel strips with carbon fiber can provide 85.06% tensile stiffness while reducing the weight by 77.7%. Moreover, carbon-fiber-reinforced strips have a lower radial modulus, which may not be sufficient to cause buckling under axial compression, so the instability of the carbon fiber composite armor layer under axial compression is further studied in this paper; furthermore, the characteristics of axial stiffness are analyzed, and the effects of the friction coefficient and hydrostatic pressure are discussed.

Numerical and Experimental Investigation of Flexural Properties and Damage Behavior of CFRTP/Al Laminates with Different Stacking Sequence

Fiber Metal Laminates (FMLs) are hybrid materials that combine metal components with fiber-reinforced composites. The properties and failure modes of CArbon fiber Reinforced composites/Aluminum Laminates (CARALLs) composed of T700/PA6 unidirectional prepreg and 6061 aluminum alloy were studied using experimental and numerical simulation analysis. Through three-point bending experiments, the bending behavior of CARALLs with different composite/metal layer methods was examined. It was found that FMLs in the 2/1 patch form (one layer of aluminum and two layers of T700/PA6 unidirectional prepreg) show the highest bending modulus and strength compared with other stacking sequences. With the metal volume fraction increased, the bending properties of CARALLs decreased, suggesting the important role of the carbon fiber composite layer in the load-bearing capacity. Lastly, the Linde and Hashin failure criteria were employed to analyze the bending behavior and damage mechanism of CARALLs with different stacking sequences. The simulation results were in good agreement with the experimental results, which provides more insight into the prediction of the bending behavior of CARALLs hybrids.

Experimental Analysis of Hysteresis in the Motion of a Two-Input Piezoelectric Bimorph Actuator

This article presents a comparison of hysteresis courses in the motion of a two-input actuator (bimorph) and hysteresis in the motion of a single-input actuator (unimorph). The comparison was based on the results of laboratory and numerical experiments, the subject of which was an actuator built of three layers: a carrier layer from a glass-reinforced epoxy laminate and two piezoelectric layers from Macro Fiber Composite. The layers were glued together, and electrodes in the Macro Fiber Composite layers were connected to a system that included an analogue/digital board and a voltage amplifier. The main purpose of this research was to compare the characteristic points of the hysteresis curves of the displacement of the bimorph actuator with the characteristic points of the hysteresis curves of the unimorph actuator. Based on the research results, it was noticed that, in the bimorph, the maximum hysteresis and mean hysteresis values increase faster than the maximum displacement of a beam tip. However, values of characteristic input voltages for hysteresis loops—voltage corresponding to a maximum displacement of the actuator beam tip and voltage corresponding to maximum hysteresis—are almost the same for the bimorph and unimorph. From a practical point of view, it was noticed that the unimorph is a better choice compared to the bimorph in applications in which high changes in frequencies of input voltages appear.

Strain rate effect analysis of hybrid composites under the high-velocity impact

In this paper, the damage behavior of fiber metal laminate (FML) is studied under high-velocity impact (HVI) at different strain rates (1 s−1, 100 s−1, and 1000 s−1) for flat, hemisphere, and sharp nosed projectiles. A finite element model has been used to examine the damage modes and failure processes of carbon fiber reinforced aluminium laminates (CRALLs) under HVI. This study is based on continuum damage mechanics. The damage criteria for aluminium (Al) and carbon fiber composite layers are identified by Johnson-Cook (J-C) and Hashin damage models, respectively. To analyse the inter-laminar de-lamination caused by the HVI, a cohesive surface regulated by bi-linear traction-separation is applied. The CRALL ballistic limit is analysed for different projectiles, which strike at initial velocity ranges from 60 m/s to 150 m/s to the CRALL. The obtained numerical results are in good agreement with the literature experimental results, which indicates the model is permissible for further analysis. The obtained results show that if strain rate varies from 1 s−1 to 1000 s−1 then CRALL ballistic limit velocity increases for all projectiles. The CRALL ballistic limit is the highest for flat nosed projectiles, followed by hemisphere and sharp nosed projectiles.

Mine safety and risk prediction mechanism through nanocomposite and heuristic optimization algorithm

Worker's safety and water quality maintenance are the two predominant process that is followed inside the Mines. Many models had been proposed in the past to enhance the whole process but they failed to do so due to the practical limitations in the deployment in terms of cost. Though technology had improved much, human intervention is still unavoidable in mines. Considering the practical issues, in this article, a novel methodology using the Internet of Things (IoT) is proposed. This study is mainly focused on the change in the geometry/structure of the coal mining field due to pressure and water contamination that occurs in the region during coal extraction. Several sensors are adopted to measure the water quality and computational technique is used to analyze roof pressure variation in the coalfield. The roof pressure experienced by the nascent structure is compared with a structure that is roof bonded with a glass fiber composite layer. The significance of nanofiber technology is analyzed and reported. To ensure water quality, Harmonic Water Optimization (HWO) Algorithm is developed, here 10 different water flow areas are chosen and their corresponding data is gathered using IoT sensors. Harmony Management Preprocessing (HMP) Algorithm is developed to preprocess the redundant and ambiguous data. Heuristic Fusion Clustering (HFC)algorithm is developed for the data fusion, which can cluster and improve the data quality. The analysis of the proposed work reveals that it would greatly improve the sustainable development of mining safety and water quality which is the most vital factor.

A parametric study on the behavior of FMLs based on UHMWPE composite under high velocity impact loading

Numerical parametric study is performed to investigate ballistic impact performance of a novel fiber metal laminate (FML) based on ultra-high molecular weight polyethylene (UHMWPE) fiber composite and aluminum 2024-T3 layers. A finite element modeling is developed and validated with experimental tests. A user-defined material subroutine based on continuum damage mechanics is used to define damage constitutive model of UHMWPE composite. High velocity impact simulations shows similar modes of failure to that observed in experiments. The effect of various parameters such as metal thickness, composite core thickness, metal volume fraction (MVF), and lay-up sequence on ballistic limit velocity, absorbed energy and specific perforation energy (SPE) of samples has been investigated. The results show that increasing the number of composite layers increases the SPE while increasing the thickness of metal layers decreases the SPE. Although, as the core thickness increases, the growth of SPE decreases. Changes in the lay-up sequence do not have much effect on ballistic velocity and absorbed energy. Whereas, the MVF is an important parameter in the high velocity impact performance of the PERALL specimens. In addition, with equal MVF, stacking sequence change has no significant effect on the ballistic limit velocity. Finally, a simple linear equation is suggested to describe the relationship between MVF and specific perforation energy.

Experimental and numerical characterization of flexural properties and failure behavior of CFRP/Al laminates

Fiber metal laminates (FMLs) are the assembly of composite materials and metallic sheets in an alternating arrangement. In this paper, mechanical performance and failure mechanisms of Carbon fiber-reinforced epoxy/Aluminum Laminates (CARALL) under three-point bending were investigated via experimental and numerical methods. A series of three-point bending tests are conducted to study the bending behavior of different CARALLs under fiber reinforced plastic composite/metal alternative stacking sequence. Results indicates that a comparatively high stiffness (109.70 GPa) and strength (1673 MPa) of 3/2 (3 aluminum sheets and 2 carbon fiber/epoxy laminates) FMLs are achieved in comparison to other stacking sequence of FMLs. With the increase of metal volume fraction, the bending properties are weakened, suggesting the carbon fiber composite layers play important roles in load bearing. Furthermore, bending properties and damage behavior of two fiber orientations (unidirectional and cross-ply) in 3/2-FMLs are investigated by Linde failure criterion, which is in agreement with the experimental load–deflection curves and microstructural analysis.

Channel deformation of bilayer material using tool rollers: part II-effect of layer thickness on springback

ABSTRACT In this second part of the two-part paper, the layer thickness in the top-layer aluminium alloy and bottom-layer aluminium alloy samples were changed to see the effect if layer thickness has any influence on the deformation and springback behaviour. Four thickness were considered 0.2, 0.4, 0.6, and 0.8 mm for aluminium layer either as a top layer or the bottom layer. To match the bilayer thickness of 1 mm, the remaining thickness was given to the carbon fibre composite layer. Again the 10-process variation were simulated for each layer thickness of aluminium material and results were presented. As found in the first part of the paper the fixed roller and no roller process provides the highest springback in all considered cases. Three distinct regions in the springback profiles were observed with the top-layer or the bottom-layer aluminium material. If the aluminium material layer is towards the punch side and punch rollers are fixed and if the aluminium alloy material is towards the die side and die rollers are fixed the springback profiles are in between the highest and lowest springback cases. It was also noted that the springback increases with increase in the aluminium layer thickness.

Simulation and burst validation of 70 MPa type IV hydrogen storage vessel with dome reinforcement

The dome reinforcement (DR) technology was studied to reduce the amount of carbon fiber of the type IV hydrogen storage vessel in this paper. Firstly, the influence of the angle and thickness of the dome reinforcement part on the stress distribution of the dome section is studied by finite element analysis. Secondly, the weight reduction of carbon fiber composite layer is studied based on the dome reinforcement model. The strain-based Hashin progressive damage model is used to predict the burst pressure and burst mode with user-defined material subroutine (UMAT) of ABAQUS. Finally, the dome reinforcement technology is further verified in comparison with non-dome reinforcement by burst tests. The results show that the progressive damage model can effectively represent matrix cracking and fiber fracture, and the predicted burst pressure and mode is consistent with the test results. The fiber stress near the equator of the dome section affects the burst mode, and the smaller the angle of dome reinforcement parts, the better the reinforcing effect, and the dome reinforcement technology can help to improve the fiber damage state at the dome, transfer the maximum stress to the cylinder section of the vessel, and ensure the burst mode to be a safe mode. Also, it can help to reduce the consumption of carbon fiber by up to 5.5% in composite material.

Evaluation of strength variation of domes and cylinders with different winding angle of type III high pressure storage vessel

Type III vessels are used to store gases at high pressure and, for efficient use, should be as light as possible without compromising stability. However, since the fiber composite layer has a directional property, it causes different properties depending on the order of lamination and the direction of the layer, and it is necessary to evaluate various and complex variables because both the low and high lamination angles are used in the manufacturing process. Therefore, this study evaluated the composite material layer of type III high pressure storage vessels in a single layer pattern and a composite pattern, and evaluated the effects of the inherent characteristics of each angle and the increase or decrease in the stacking angle on the strength performance of the storage vessel. As a result of analysis, it was confirmed that the change of angle not only affects the strength performance, but also affects the location of storage vessel such as domes and cylinders. In addition, in the most optimized pattern, the stress of 79 MPa in the fiber direction and 20.35 MPa in the fiber orthogonal direction could be reduced.

Superharmonic vibrations of sandwich beams with fibre composite core layer based on the multiple scale method

This paper deals with the secondary vibration problem in the superharmonic case near the harmonic excitation of 1/3w1, arising from the vibration nonlinearity that characterizes the slender and less damping laminated beam with composite material core. For this aim the multiple scale method in conjunction with the higher order zigzag theories are used to obtain the resonance responses. In the present work the nonlinear forced vibration problem of sandwich beams under harmonic excitation is solved by the multiples scales method, based by the introduction of an artificial parameter with higher order expansions, to control the nonlinear analytical solutions. The application of this method demonstrates the sensitivity of the sandwich beams with viscoelastic composite layer to the secondary superharmonic vibrations. Following, parametric study is conducted to demonstrate the vulnerability of the laminated structures to the superharmonic vibrations and to reduce as far as possible the amplitude vibrations achieved by more appropriated structural design. The results reveal the effect of the slenderness of the sandwich beams on the hardening changes. In the other hand the results demonstrate the importance of fibre orientation angle to reduce as far as possible the amplitude responses of the sandwich structures in superharmonic vibration case.