Carbon Fiber Reinforced Plastic Tubes Research Articles

A novel systematic approach for robust numerical simulation of carbon fiber-reinforced plastic circular tubes: Utilizing machine-learning techniques for calibration and validation

Developing a reliable and robust finite element model of a carbon fiber-reinforced plastic (CFRP) composite structure is investigated by using the LS-DYNA solver and Python. This study tries to provide a systematic numerical approach to cover the principal impediment to adaptation of composite energy absorbers, that is the lack of a reliable predictive method. The proposed procedure aims to further the understanding of advanced composite structures’ behavior during the crash phenomenon by developing an accurate finite element model. To do so, the mechanical properties of the material were extracted from American Society for Testing and Materials (ASTM) standard test methods, followed by experimental investigation of circular CFRP tubes undergoing quasi-static loading. A numerical simulation framework was then utilized to scrutinize the effectiveness of simulation parameters on the crushing mechanism. Finally, a systematic approach based on machine learning techniques was performed to adjust non-physical modeling parameters for further calibration and validation. In this regard, a versatile Python code was developed to automate pre-processing, processing, and post-processing steps. The code also provides a groundwork to perform machine learning techniques. Interestingly, the numerical and experimental results were highly correlated with a correlation coefficient of almost 90%. Additionally, several non-physical numerical parameters were found to be inactive, while some else were identified as effective parameters, and their corresponding effectiveness was quantitatively extracted and discussed for the first time in the literature.

Numerical crashworthiness analysis of 2014 Aluminium-Silicon Carbide Particle (SiCp) foam filled Carbon Fiber-Reinforced Plastic (CFRP) tube under impact loading

Aluminium foam and Carbon Fiber Reinforced Plastic (CFRP) are widely used composite materials in automobile industries due to the benefits of lightweight and energy absorption capacity. Therefore, in this study, the numerical crashworthiness analysis of 2014 Aluminium-SiCp (2014AA-SiCp) foam filled in CFRP tube has been performed under impact loading. Quasi-static compression tests have been conducted on 2014AA-SiCp foam to extract the mechanical parameters required for numerical simulations. To understand the crushing behavior under the axial impact loading, 2014AA-SiCp foam-filled CFRP tube has been numerically modelled using ABAQUS® software. The parametric study was carried out to explore the effects of filler material, foam densities, and impact velocities on crushing behavior. It was found that load increases with the rise in foam density and impact velocity. Moreover, the deformation increases with the increase in impact velocity. Results showed that the load carrying capacity of foam filled CFRP tubes was significantly improved compared to that of empty CFRP tubes. The foam filled CFRP specimens exhibited peak load of 122 kN and an energy absorption capacity of 3012 J, showcasing an approximate improvement of 43% and 11% respectively, over the values obtained for empty CFRP tubes.

Failure modes and energy absorption mechanism of CFRP thin-walled square tubes filled with gradient foam aluminum under axial compression

Carbon Fiber Reinforced Plastic (CFRP) thin-walled square tube filled with gradient foam aluminum represents a novel component known for its exceptional energy absorption capabilities. This paper investigates the failure modes and energy absorption mechanisms of CFRP thin-walled square tubes filled with gradient foam aluminum using a combination of numerical simulations and quasi-static axial compression tests. The influences of some factors, including lay-up angles, lay-up sequences, and lay-up thicknesses have been analyzed. Additionally, the impact of the gradient foam aluminum filler on the crashworthiness characteristics has been scrutinized. The results reveal that the samples with lay-up angles below 45° showed a failure mode characterized by layer bundle buckling during axial compression. Conversely, the samples with lay-up angles exceeding 45° exhibited lateral shear failure during axial compression, with the latter demonstrating notably higher energy absorption efficiency. Increasing the proportion of circumferential angle and setting the circumferential angle on both the inner and outer sides of the axial lay-up, the energy-absorption capacity of the filled CFRP tubes under axial compression can be improved. This study demonstrates the potential of CFRP tubes filled with gradient foam aluminum to be used as energy absorbers.

Mechanical and microstructural characterization of aluminium micro-pins realized by cold metal transfer

The European collaborative research project ADALFIC (Advanced Aluminium Fittings in CFRP tubes) focuses on the design, analysis, manufacturing and testing of ultra-lightweight carbon fiber reinforced plastic (CFRP) tubes with integrated aluminium end fittings. Reliable joining technologies for combining aluminium and CFRP are of great interest since the combination of superior mechanical properties and low density offer a wide range of applications. One such approach is the use of form locking micro-pins on the surface of the metallic part enabling the joint between metal and CFRP by mechanical interlocking. In this work Fronius’ Cold-Metal-Transfer (CMT) Print welding technology was used to generate very small, minimum-mass, spike-head pins, which are optimized for form-locked joints between aluminium and CFRP components. The aluminium pins are characterized on a macroscopic and microscopic level using light optical microscopy and hardness testing. To evaluate the behavior of the pins under mode II load conditions a new shear testing method for pins was developed and implemented. With this test equipment the maximum shear force and ultimate shear strength of individual pins were measured at different temperatures and heat treatment conditions. The failure modes and fracture surfaces were analyzed via scanning electron microscopy. The results demonstrate that the novel spike-head CMT aluminium pins can withstand considerable shear forces, especially in the peak aged condition. This makes them a viable, flexible and lightweight option for form-locked aluminium-CFRP joints.

Lateral crashworthiness performance of CFRP/aluminum circular tubes with mesoscopic hybrid design

Thin-walled fiber-reinforced plastic (FRP)/metal hybrid tubes exhibit superior crashworthy performance, which have shown promising prospect as collision-proof components to withstand lateral collisions. In the present work, novel hybrid tubes with alternated stacked FRP and aluminum layers hybridized at the mesoscopic scale were proposed. The lateral crashworthiness characteristics of carbon-fiber-reinforced plastic (CFRP)/aluminum hybrid circular tubes were investigated based on analytical, experimental and numerical method. To explore the effects of material composition on deformation patterns and energy absorption efficiencies, quasi-static lateral compressive tests were carried out and the results were compared. Under lateral compression, the CFRP/Al hybrid tubes were crushed progressively and stably. Large amounts of energy were absorbed through the progressive failure of the fiber and plastic bending of aluminum layers. Compared to pristine CFRP counterparts, the specific energy absorption (SEA) and crushing force efficiency (CFE) of CFRP/Al hybrid tubes increased by 45.58% and 73.68%, respectively. The peak crushing force (PCF) of CFRP/Al tubes was reduced by more than half when compared to pure CFRP tubes. Compared to experimental results, the numerical models predicted the crushing behavior and crashworthy performance with high accuracy. Additionally, an analytical model of CFRP/Al tubes was established to predict the energy absorption characteristics and the predict outcomes agreed well with the experimental results. The FRP/Al mesoscopic hybrid structures exhibited superior deformation stability and satisfactory energy absorption performance under lateral loading, overcoming the limitations of lightweight FRP materials for lateral collision protection. In sum, these findings look promising for lightweight anti-collision structural design.

An Experimental Comprehensive Analysis of Drilling Carbon Fiber Reinforced Plastic Tubes and Comparison With Carbon Fiber Reinforced Plastic Plate

Today, carbon fiber reinforced plastic (CFRP) composites, which are the main areas of use such as aerospace and automotive, can be produced by different methods. Especially in the production of tubular composites, filament winding and roll wrapping methods are used generally, while vacuum-assisted resin transfer molding method or vacuum bagging method comes to the fore in the production of composite plates. These materials produced by different methods may exhibit different behavior in terms of machinability. In this study, the drilling machinability characteristics of CFRP tubes produced by filament winding and roll wrapping methods were investigated and compared with the CFRP plate produced with vacuum bagging and the results were presented comparatively. Experimental results showed that the composite plate generates more force and damage when drilled compared to the tubes, so its machinability is more difficult. Higher thrust force and damage occur in filament wound tube compared to roll wrapped tube. In addition, although the thrust force does not increase with the use of support in composite tubes, a significant improvement in drilling-induced delamination damage behavior is obtained. Compared to the tubes, a better borehole surface quality is obtained in the plate, while more dust chip formation is observed.

Experimental and Numerical Studies on Fatigue Characteristics of CFRP Shaft Tube

Carbon Fiber Reinforced Plastic (CFRP) shaft tube structure is widely applied in different fields, including aerospace, automotive, and wind power. Since CFRP shaft tube is often subjected to bending fatigue loads, it is of great significance to research its bending fatigue characteristics. Because of its unique advantages, such as a smaller size, lighter weight, and the outstanding ability to form a sensor network, the Fiber Bragg Grating (FBG) sensor is very applicable for health monitoring research of composite material structures. Taking the CFRP shaft tube under bending load as the research object, based on the theory of composite material mechanics and applying the research idea of combining simulation analysis and experiment, the fatigue life, residual stiffness, and fatigue damage evolution of CFRP tubes under three-point bending fatigue loading were studied. Moreover, the fatigue characteristics of CFRP tubes under different fatigue loading were analyzed. At the same time, the ultrasonic phased array was used to obtain the fatigue damage evolution rule by scanning and analyzing the damage to the CFRP shaft tube after different fatigue loading times. Through the application of the FBG sensors, the whole process of fatigue evolution of the CFRP shaft tube was fully monitored.

Effect of thermal and hydrothermal aging on the crashworthiness of carbon fiber reinforced plastic composite tubes

Thin-walled structures constructed of fiber reinforced composites are increasingly being employed in engineering practice. However, there is limited investigation into their residual properties after high temperature and hygrothermal aging. The aim of this experimental investigation is to study how moisture absorption and high temperatures affect the mechanical characteristics of fiber reinforced plastic (FRP) composite tubes. A set of accelerated thermal and hygrothermal aging experiments are designed to imitate the service conditions of carbon fiber reinforced plastic (CFRP) structure in harsh environment. Based on the glass transition temperature obtained by dynamic mechanical analysis (DMA), the specimens are divided into two groups for various temperatures (25°C, 70°C, 100°C, 160°C) and hydrothermal aging (25°C, 70°C). The specimens of hydrothermal aging group are immersed for about 700 h to monitor the water absorption of the specimens in hygrothermal environments with different aging time. Aged composite tubes subjected to quasi-static axial compression are tested to identify compressive strength, failure modes and structural degradation process. The scanning electron microscope (SEM) is used to explore the microscopic failure mechanism of CFRP tubes. As temperature and moisture absorption rate increase, the crashworthiness characteristics decrease drastically; and the failure modes differ substantially with three different failure types identified. The crashworthiness of CFRP has a nonlinear relationship with temperature, but it is related to the glass transition temperature of the matrix. Furthermore, moisture absorption can be divided into two stages and temperature affects the moisture absorption of CFRP. Microscopically, the morphology and bonding conditions between fiber and resin is found to change significantly on the microscale as a result of various temperatures and hydrothermal aging.

Quasi-static and low-velocity axial crushing of polyurethane foam-filled aluminium/CFRP composite tubes: An experimental study

Composite structures combine the advantages of multiple materials, which can improve the structural crashworthiness performance. This paper aims to combine the high strength of carbon fibre-reinforced plastic (CFRP), the excellent ductility of aluminium alloy (Al), and the good compressibility of polyurethane (PU) foam. Quasi-static compression and low-velocity impact tests were conducted on thin-walled tubes made of single materials and composite sandwich structures made of multi-materials, namely Al-PU-Al, Al-PU-CFRP, CFRP-PU-Al, and CFRP-PU-CFRP. The structural failure modes and crashworthiness indicators were analysed and compared under different loadings. The results showed that the CFRP thin-walled tube exhibited a progressive damage and failure mode, and the resultant force changed smoothly. The CFRP tube possessed a larger mean crushing force and specific energy absorption than the corresponding aluminium tube. Composite structures exhibited more stable deformation mode and higher energy absorption, compared with the sum of linear superposition (SLS) of individual components, due to the interaction effects among components. Among the designed four combinations, CFRP-PU-CFRP exhibited an ideal energy absorption under both quasi-static and dynamic impact, while CFRP-PU-Al produced the second highest specific energy absorption (SEA), with an increment of 42.0% compared with Al-PU-Al. With full consideration of crashworthiness performance and economic cost, CFRP-PU-Al can be recommended as an impact energy absorber for vehicles due to its lower economic cost than CFRP-PU-CFRP.

Structural design of multimaterial columns accounting for multiple loads

Compressive tests are performed on hollow carbon-fibre-reinforced-plastic (CFRP)/aluminium columns (H-C), foam-filled CFRP/aluminium columns (HF-C), and the corresponding net components. The energy absorption of the H-C column is lower than the total energy absorption of the net components under loading angles of 0° and 10°. The energy absorption of the HF-C column decreases under a 0° loading angle but increases under a 10° loading angle compared with the sum of the net components. Numerical models for the net components and the multimaterial hybrid columns are developed in LS-DYNA. Simulations indicate that the energy absorption reductions of external CFRP tubes primarily decrease energy absorption of hybrid columns, whereas energy absorption improvements in internal aluminium tubes primarily increase the energy absorption of hybrid columns, and that foam fillings can significantly improve crushing behaviours of aluminium tubes. Furthermore, parametric studies indicate that the energy absorption of hybrid columns can be increased by increasing the CFRP thickness and foam density. Finally, a discrete procedure is conducted to optimise the crashworthiness of hybrid columns with structural mass and crushing force constraints under multiple loads. Results indicate that compared with the baseline design, the energy absorption is improved by 7%, whereas the cost is reduced by 1.8%.

Parametric study on the crushing performance of a polyurethane foam-filled CFRP/Al composite sandwich structure

Composite structures have drawn growing attention for their outstanding characteristics benefiting from the combination of multi materials. This paper aims to investigate the crushing performance of a hybrid system involving an outer thin-walled tube made of carbon fibre-reinforced plastic (CFRP), a medial polyurethane (PU) foam and an inner thin-walled tube made of aluminium alloy (Al). The elastoplastic model of Al, the continuous damage model of CFRP and the compressible foam model of PU were established with assistance of universal material tests. The finite element model of the composite structure, namely CFRP-PU-Al, was validated by the experimental study. Based upon the reliable numerical modelling, the parametric study was carried out for exploring the effects of the wall thickness, diameter and ply orientation of the outer CFRP tube, namely CFRP-O, on the crushing behaviours of the composite structure. It was found that increasing the diameter or wall thickness of CFRP-O was helpful to increase the mean crushing force and energy absorption of CFRP-PU-Al, however, the overall specific energy absorption of the composite sandwich structure was limited by the characteristics of constitutive materials. Compared with the diameter, the wall thickness had a higher impact on the energy absorption characteristics, and increasing the diameter may decrease the specific energy absorption due to the increase of the overall structural mass. In terms of the ply orientation, the composite structure with stacking sequence of [0°/45°]3 possessed higher mean crushing force and energy absorption than the structure with stacking sequence of [0°/90°]3 under axial compression in this study.

Energy Absorption Characteristics of a CFRP-Al Hybrid Thin-Walled Circular Tube under Axial Crushing

Thin-walled tubes have gained wide applications in aerospace, automobile and other engineering fields due to their excellent energy absorption and lightweight properties. In this study, a novel method of entropy-weighted TOPSIS was adopted to study the energy absorption characteristics of a thin-walled circular tube under axial crushing. Three types of thin-walled circular tubes, namely, aluminum (Al) tubes, carbon-fiber-reinforced plastics (CFRP) tubes and CFRP-Al hybrid thin-walled tubes, were fabricated. Quasi-static axial crushing tests were then carried out for these specimens, and their failure modes and energy absorption performance were analyzed. The CFRP material parameters were obtained through tensile, compression and in-plane shear tests of CFRP laminates. The finite element models for the quasi-static axial crushing of these three types of circular tubes were established. The accuracy of the finite element models was verified by comparing the simulation results with the test results. On this basis, the effects of the geometric dimension and ply parameters of a CFRP-Al hybrid thin-walled circular tube on the axial crushing energy absorption characteristics were studied based on an orthogonal design and entropy-weighted TOPSIS method. The results showed that Al tube thickness, CFRP ply thickness and orientation have great effect on the energy absorption performance of a CFRP-Al hybrid thin-walled circular tube, whereas the tube diameter and length have little effect. The energy absorption capability of a CFRP-Al hybrid tube can be improved by increasing the thickness of the Al tube and the CFRP tube as well as the number of ±45° plies.

Mass prediction models for air cargo challenge aircraft

AbstractDesign/Build/Fly competitions are attracting increased interest in the training of aerospace engineers at academic level worldwide. These competitions entail fundamental activities in aircraft design, optimization and manufacturing which foster student knowledge not possible in classical academic activities. Over the years, the competitiveness of these contests has increased due to the ever-increasing performance that the aircraft exhibit in the flight event. Mass prediction models, specific for competitions such as Air Cargo Challenge (ACC), are presented in this paper. These models are divided into two development methods: statistical and structure-based equations.The statistical mass models are developed based on data collected from past ACC editions where model accuracy is mainly dependent on the amount of data available. Three models are derived, one containing all available aircraft and two more obtained by dividing the aircraft into balsa- or composite-dominated structures.Using the structure-based equations method, where the amount of material required to withstand the stresses that the airplane is subjected to is determined, a model is developed for each one of the three considered wing structural concepts, namely two-cell Carbon-Fibre-Reinforced Plastic (CFRP), CFRP D-box and CFRP tube spar. The tail boom component equation is created independently, while the remaining components masses are determined from coefficients based on geometric characteristics and the computed wing or total masses. The average error associated with these models is inferior to 2% for the total mass.The results obtained from the application to the considered study cases are also presented, and the validity, accuracy, and application in terms of the design phase for each method are discussed.

Low-velocity impact performance of composite-aluminum tubes prepared by mesoscopic hybridization

Novel circular hybrid structures with overlapped carbon-fiber-reinforced plastic (CFRP), glass-fiber-reinforced plastic (GFRP) and/or aluminum layers were fabricated. Such structures were hybridized at the mesoscopic scale, generating multiple CFRP-GFRP or composite-aluminum interfaces. Also, aluminum foam was utilized as inner filler to further enhance the energy absorption of the thin-walled structures. The interactive effects on crashworthiness among different materials were explored by axial drop-weight impact testing. The experimental results showed a progressive failure process of all CFRP/GFRP and composite/aluminum hybrid tubes. The mean crushing force (MCF) of empty CFRP/GFRP hybrid structures were significantly improved by more than 20% when compared to pristine CFRP tube. On the other hand, the composite/aluminum hybrid design effectively reduced the peak crushing force (PCF) and improved the crushing force efficiency (CFE). However, the specific energy absorption (SEA) was decreased by about 10% owing to the moderate strength-to-weight ratio of inserted aluminum sheet. Compared to empty tubes, the filling of aluminum foam significantly enhanced MCF by more than 10%, while declining SEA due to the low weight efficiency of aluminum foam. In sum, the proposed hybrid design maximized some aspects of crashworthy performance at a low cost, thereby promising for the future design of practical light-weight energy absorbers.

A NOVEL DESIGN CONCEPT FOR A THERMALLY STABLE LINEAR SCALE USING TWO DIFFERENT MATERIALS

Linear scale has significant impacts on the machine tool accuracy, since the positioning of the linear axes are controlled by its measurement. This paper presents a novel concept of linear scale design which can provide high thermal stability with low cost. This concept applies two different materials: a steel linear scale attached mechanically on a carbon fiber reinforced plastic (CFRP) tube. Attaching this two materials, the thermal behavior of the steel scale can be mechanically compensated by the CFRP tube when the temperature changes. The potential of the design concept is analyzed based on the experiment results.

A comparative study on energy absorption of flat sides and corner elements in CFRP square tube under axial compression

The cross-sectional configuration is one of the factors influencing the energy absorption performance of composite tubes under axial compression. Flat sides and corners are basic elements for the configuration. However, their contributions to the energy absorption have not been systematically compared. This paper presents a “press and cut” approach which allows to investigate the energy absorption of flat side and corner elements in a condition closely resembling axial crushing of a tube. Using this method, the crushing responses and energy absorption behaviors of flat side and corner elements in carbon fiber reinforced plastics (CFRP) square tube under axial quasi-static compression were investigated experimentally. The results showed that the corner elements had higher specific energy absorption (SEA) values than the flat side elements. The higher SEA value is attributed to the additional axial tearing fracture of the fronds developed at the corner and the suppression to delamination by the hoop tension force in the round corner. A modified analytical model based on Hussein’s analytical model was established to predict the mean crushing force of the flat side and corner elements. Finally, axial crushing experiments were performed for CFRP tubes with a cross section consisting 12 corners. The 12-corner tubes exhibited an about 18% higher SEA value than the square tubes while maintaining a similar peak force.

A high-precision apparatus for dimensional characterization of highly stable materials in space applications

We present an apparatus for high-accuracy and high-resolution absolute measurement of the linear coefficient of thermal expansion (CTE). Based on a displacement measuring interferometer (DMI) system, dimensional changes of a tubular shaped specimen under controlled thermal conditions can be characterized. Our measurement apparatus was located in a vacuum where the test specimen could be controlled in a temperature range from 20 to 40 °C. We measured the CTE of a quartz tube by using the DMI system with a temperature variation close to 4 °C. The test result was (3.888 ± 0.1292) × 10−7/°C with 99% confidence probability. The measured value of 3.89 × 10−7/°C of the specimen taken from the above-mentioned quartz tube (DIL402 Expedis, NETZSCH) was within the confidence interval, which indicates that our apparatus not only has excellent repeatability but also has the correct absolute CTE value. The measurement uncertainty reached the 1.3 × 10−8/°C level. Finally, a CTE test of carbon-fiber reinforced plastic (CFRP) tubes was conducted. The test result was (1.218 ± 0.0822) × 10−7/°C with 99% confidence probability. The results show that we can manufacture CFRP tubes with a CTE of 0.12 × 10−6/°C, which could be used for aeronautical and space structures.

Energy Absorption in Carbon Fiber Composites with Holes under Quasi-Static Loading

Composite tubular structures have shown promise as energy absorbers in the automobile industry. This paper investigates the energy absorption characteristics of carbon fiber reinforced plastic (CFRP) tubes with pre-existing holes. Holes may represent an extreme case of impact damage that perforates the tube, e.g., stones from road surface impacting the tubes. Tubes with holes represent more conservative performance characteristics, since impact damage of the same size will have residual material, which may carry some load. Tubes with holes can provide the lower limit of CFRP tube performance under axial crushing relative to impact damaged tubes with perforation diameter close to the hole diameter. In this study, tubes with lay-up of [05/902/04] with one and two holes in defined locations and different diameters are experimentally studied under quasi-static loading. It was found that specific energy absorption (SEA) reduces by 50% with one or two holes of 15 mm size, 100 mm from top of the tube. The SEA reduction is about 60% lower than the regular tube when the diameter of the hole is 20 mm located at 100 mm from top. The most severe reduction occurs if the location of single or double holes are 75 mm from the top. In this case, a SEA reduction of 75% can be expected. Results indicate that holes can significantly alter the energy absorption capability of the tubes. It is also clear that in axial crushing of composite tubes, the location of the hole (100 to 75 mm) appears to create more pronounced effect than the size of the hole itself (15 vs. 20 mm) for the cases investigated. The failure modes for tubes with holes seem to preserve similar damage modes with delamination, frond creation, and brittle fracture, which is typically observed in regular composite tubes under axial crushing load. This is due to primarily front end crushing, which dominates the failure modes, while hole induced damage occurs later.

Crashworthiness of circular fiber reinforced plastic tubes filled with composite skeletons/aluminum foam under drop-weight impact loading

Carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP) have shown great promise in the design of light-weight thin-walled energy absorbers. Herein, circular CFRP/GFRP hybrid tubes and tubes, reinforced with internal composite skeletons (XS and OS), were fabricated to further enhance the energy absorption capacities. The crashworthiness and failure pattern of reinforced structures were compared with the hollow and aluminum foam-filled composite tubes. Moreover, low-velocity drop-weight impact tests were carried out to investigate the effect of hybridization design and filler types on the energy dissipation mechanism under axial compression. The experimental results revealed that the hollow composite tubes collapsed in progressive and the impact energy was absorbed by the generation of cracks, fiber fracture and friction. Also, the GFRP tubes exhibited better crashworthiness than CFRP tubes under low velocity impact, which was different from the quasi-static compression conditions. In contrast to hollow counterparts, the mean crushing force (MCF) of foam-filled tubes was improved by approximately 40%, whereas the specific energy absorption (SEA) was reduced by 30% due to the low weight efficiency of the aluminum foam. The filling of XS-skeleton divided the tube into four cells and improved the MCF by more than 10%. However, it reduced the SEA by around 8% due to unstable and inefficient deformation of XS-skeleton during crushing. By contrast, the OS-skeleton divided the hollow tube into more cells and collapsed progressively, resulting in superior energy absorption characteristics. Herein, the OS-filled GFRP tube was found to be the most crashworthy structure that improved the crushing force efficiency (CFE) and SEA by 50% and 7%, respectively.

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.