Carbon Fiber Reinforced Polymer Hybrid Research Articles

Numerical Investigation on the Structural Behavior of a Short-Span Cable-Stayed Bridge with Steel and CFRP Hybrid Cables.

In this paper, a thorough investigation is presented on the static and dynamic behaviors of a short-span cable-stayed bridge (CSB) incorporating steel and carbon fiber reinforced polymer (CFRP) hybrid cables. The study focuses on the world's largest span and China's first highway, CFRP CSB. The performance of the CSB was compared using numerical simulations under four different cable patterns: steel cables, CFRP cables, and steel, and two types of hybrid cables with different structural arrangements. The results indicate that the use of the use of CFRP cables in the long cable region in the short-span CSB project investigated in this study offers improved performance in terms of stability, seismic response, and reduced displacements. In comparison to CFRP cables, hybrid cables have demonstrated a reduction of 12% in the maximum vertical displacement of the main girder. On the other hand, the hybrid cables result in reduced maximum internal forces and longitudinal and lateral displacements of the main girders and towers compared to steel cables. The difference in the arrangement of CFRP cables in the long cable region or short cable region is not obvious under dead loads, but significant differences still exist between the CFRP cable bridges in the short cable region and the long cable region in terms of live load effects, temperature effects, and dynamic characteristics.

Improving cyclic response of heat-damaged non-ductile RC joints using CFRP hybrid systems

The behavior of non-ductile, heat-damaged reinforced concrete (RC) beam column joints was investigated in this experimental research work. A hybrid system formed of carbon fiber-reinforced polymer (CFRP) sheets and strings was used to improve the cyclic response of these non-ductile, heat-damaged joints. To evaluate the cyclic performance of these joints, twelve RC beam-column joints were cast and classified into four categories: Three joints were kept without strengthening as control specimens. Three joints were strengthened with one layer of CFRP sheets and one NSM-CFRP string in the beam and in the column; three joints were strengthened with two layers of CFRP sheets and two NSM-CFRP strings in the beam and in the column; and three joints were strengthened with three layers of CFRP sheets and three NSM-CFRP strings in the beam and in the column. In addition, the joints were tested at three different temperatures, which are: ambient, 400 °C, and 600 °C. The experimental findings show a considerable improvement in the cyclic performance of non-ductile heat-damaged RC beam-column joints strengthened with a hybrid CFRP system (greater lateral displacement, higher load capacity, higher energy dissipation, higher displacement ductility, and slower secant stiffness degradation). Furthermore, the effectiveness of CFRP composites increases as the degree of heat damage increases.

Enhancing the mechanical performance of carbon fiber reinforced polymer using carbonized coconut shell particles

Inorganic fillers have been used to improve the out-of-plane mechanical properties of carbon fiber reinforced polymer (CFRP) composite laminates for decades. Nonetheless, its associated high cost and environmental unfriendliness is a concern. Biomaterials are currently being explored as fillers in polymeric materials due to their low cost, wide availability, and biodegradability. However, the use of coconut shell based biofillers together with carbon fibers in epoxy matrix has not been investigated. This research seeks to improve the out-of-plane mechanical properties of CFRP with low fiber volume fraction using carbonized coconut shell particles (CCSP). Five hybrid epoxy biocomposites with varying concentrations of CCSP were used to impregnate four plies of woven carbon fabric, making up a fiber volume fraction of 29%. The tensile, flexural, and impact behavior of the laminated biocomposites were investigated. The mechanical properties of the biocomposite laminates were enhanced compared to a reference CFRP without CCSP. This work provides a cheaper and greener alternative to inorganic CFRP hybrid composite for potential use in automotive and aerospace industries.

Effects of different interface conditions on energy absorption characteristics of Al/carbon fiber reinforced polymer hybrid structures for multiple loading conditions

AbstractThe treatment of carbon fiber reinforced polymer (CFRP)–metal bond interface is very important for the practical application of CFRP‐reinforced metal structures in automobile, aviation, and other transportation vehicles. In this article, the effects of different interface connection conditions on the failure mode and energy absorption of hybrid tubes were studied by experimental and simulation methods. For this purpose, the two aspects metal surface treatment (sandblasting) and connection mode (socket, co‐curing, and secondary bonding) were used for adhesive joining. By observing the force–displacement curve, the energy absorption capacity of the hybrid tube under different interface connection conditions was quantified, and the performance was evaluated. The calculation results show that the interfacial connection conditions have different effects on the crashworthiness of the hybrid tube under different loading conditions. Among them, for axial crushing and transverse bending loads, the energy absorption characteristics of the hybrid tube can be effectively improved by sandblasting and cementing. Under the action of radial compression, although the roughness of the interface is increased by sandblasting, the energy absorption capacity is reduced rather than enhanced. In order to reveal the mechanism and make parameterized definitions of the interface characteristics, so as to effectively predict the finite element model is especially necessary. With the improvement of interface bond strength, its bearing limit distribution area also increases, and the corresponding deformation is also large, which eventually leads to more energy absorption under axial crushing and transverse bending loads. The increase in the interface connection strength has little effect on its crashworthiness under radial pressure.

Experimental study on high-speed saw cutting of hybrid composite stacks using nanoparticle-enhanced minimum quantity lubrication

An extensive investigation into thermal stress mitigation of high-speed machining (machining speeds exceeding 3800 rpm) of hybrid composite stacks using nanoparticle-enhanced minimum quantity lubrication (MQL) is presented and discussed. Ten different interface machining conditions are examined using five different nanoparticles, namely Al2O3, 1%SWCNT, 1%MWCNT, Ni, and Al. Interface roughness measurements are recorded, and thermal stress effects are collected via digital microscopy images. Nanoparticle-enhanced MQL (NEMQL) chemical and physical properties in the form of viscosity and heat transfer capabilities are discussed in accordance with vegetable oil–based MQL. Two different vegetable oils are utilized in a 1:1 ratio to explore viscous effects in the NEMQL suspension and their respective cooling capabilities from conventional forms of machine cooling. Furthermore, the results indicate 2.5%vol Al2O3 + MQL showed the best interface roughness improvements by over 170% from the standard control dry machining of carbon fiber–reinforced polymer (CFRP) and titanium (Ti) hybrid composite stacks. Moreover, the results indicated 1%SWCNT + MQL showed the best interface roughness improvement by over 100% for CFRP and aluminum (Al) hybrid composite stacks from the standard control: dry machining. Chemical and physical properties of the NEMQL, such as thermal conductivity, viscosity, and convective heat transfer capabilities, explain to some extent the results depending on the hybrid composite stack application. The results of this experiment provide insight that NEMQL is a promising cooling lubrication method for conventional manufacturing processes in a wide array of industrial applications. The results of this study are expected to open new possibilities for eco-friendly and cost-effective methods for a high-speed cold saw cutting in advanced engineering materials.

The Multi-objective Optimization Design Approach for Carbon Fiber Hybrid Nanocomposites Containing NanoClay and NanoZnO Particles by Using OptiComp

This paper presents the multi-objective design optimization of Carbon Fiber-Reinforced Polymer hybrid nanocomposites by OptiComp. The use of nanoparticles not only improves the interface strength but also significantly improves stress and hence the propagation of strain in composite laminates, which ultimately improves the stiffness of the composite laminate. The OptiComp is the comprehensive generic procedure for design optimization of the composites. With the utilization of OptiComp, the discrete form Variable thickness approach (VTA) used in this study can discover the minimum laminate thickness, and for maximum stiffness in one step instead of two-step method. The Max stress theory and Tsai-Wu theory as constraints for the current study in optimization are performed using a direct value coding genetic algorithm. It is found that the CFRP nanocomposites up to 2 to 3 wt% range of nanoparticles can be designed for max. stiffness and min. weight.

Influence of glass/carbon fiber stacking sequence on mechanical and three-body abrasive wear resistance of hybrid composites

Glass and carbon fiber reinforced polymer hybrid composites are the need of the hour to overcome the weakness of individual fibers. The mechanical and abrasive wear property of the hybrid composites needs to be evaluated to ascertain the feasibility in structural and tribological applications. In this article, hybrid composites of different stacking sequence such as [G3C2]S, [GCG2C]S and[G2C2G]S has been designed. The flexural strength and three body abrasive wear resistance of the hybrid composites were evaluated and compared among themselves. It is observed that the flexural strength and modulus of [GCG2C]S type hybrid composite was improved by 46.1% and 49.5% respectively as compared to plain glass fiber reinforced polymer composites. The specific wear rate was evaluated by three-body abrasive wear at different operating parameters and optimized the same through response surface methodology. Box–Behnken design of the experiment was adopted to design the experiments. The model has predicted the minimum specific wear rate for [GCG2C]S hybrid composite is18.8476 × 10–3 mm3 Nm−1 at applied load of 33.15 N and sliding distance of 1100 m. The model predicted results were compared with experimental one and found a good agreement between them. The worn surface of the composites was analyzed by scanning electron microscope to understand the wear mechanism.

Structural Performance of Super-Long-Span Cable-Stayed Bridges with Steel and CFRP Hybrid Cables

This paper presents an investigation of super-long-span cable-stayed bridges with hybrid cables, including steel and carbon fiber-reinforced polymer (CFRP) cables arranged in the short- and long-cable regions, respectively. Three 1600-m-span cable-stayed bridges with steel, CFRP and hybrid cables are first designed. Their static and dynamic structural performance was subsequently investigated by finite element analysis. Simulation results demonstrate that arranging CFRP cables in the long-cable regions can fully utilize the advantage of CFRP through examining their equivalent elastic modulus, load-carrying efficiency ratio and self-weight/stress ratio. The hybrid cable-stayed bridge exhibits the higher stiffness enhancement in comparison with the CFRP cable-stayed bridge. In comparison with the CFRP cables, the use of hybrid cables is able to increase the frequency for the first-order vertical mode, thus overcoming the weakness of the CFRP cable-stayed bridge in terms of stiffness. In addition, the natural frequencies of CFRP cables are much higher than the low-order vertical vibration frequencies of cable-stayed bridge, which is beneficial to reducing the probability of cable–deck coupling vibrations.

Optimization and Analysis of Wear Rate of CFRP-NanoZno/Nanoclay Hybrid Composites Using RSM

The aim of the current work is to do an experimental study and investigation of the sliding wear behavior of carbon fiber reinforced polymer (CFRP) hybrid nano composite with montmorillonite nanoclay and nanoZnO as fillers. The wear properties of CFRP hybrid nanocomposites were tested by using a pin-on-disc machine under various loads. Optimization of the wear rate of CFRP hybrid nanocomposites was carried out by using the central composite design method, subset of the response surface methodology. The mathematical model predicts the significance of the independent variables, i.e., wt% of nanoZnO, nanoclay, and fiber orientation angle on the wear rate of CFRP hybrid nanocomposites. The lowest value obtained for wear rate was 2.22 mg/Nm which appeared when actual values were nanoclay = 3 %wt, nanoZnO = 3 %wt, and fiber orientation = 45°, respectively. The results of optimization also showed that the wear rate at the optimum value was much improved or minimized by about 3 times than that of the controlled sample. From the SEM micrographs, surface readings also show the effective improvement in the wear resistance in CFRP with the addition of nanoparticles.

Enhanced interfacial properties of graphene oxide incorporated carbon fiber reinforced epoxy nanocomposite: a systematic thermal properties investigation

In this study influence of the graphene oxide (GO) inclusion on the thermal properties of carbon fiber reinforced polymer (CFRP) hybrid composite is reported. Different wt% content of GO used for development of epoxy matrix and CFRP hybrid composite was prepared using compression moulding process. The nanocomposites were characterized by various techniques viz. DMA, DSC, TMA, and TGA. It is observed that in GO-epoxy resin composites, storage and loss modulus reached maximum for 0.3 wt% of GO. The storage modulus of CFRP hybrid composite is achieved almost double with the addition of 0.3 wt% of GO. The glass transition temperature (Tg) calculated from DMA and TMA of GO incorporated CFRP hybrid composites demonstrated the enhancement in Tg by 4 °C and 12 °C respectively over to CFRP composites at 0.3 wt% GO. This improvement at GO loading is because of constraint effect of GO sheets on the polymer chain mobility in the composite.

Fracture analysis of a metal to CFRP hybrid with thermoplastic interlayers for interfacial stress relaxation using in situ thermography

In this work a plane hybrid-structure composed of a metal and a carbon-fiber-reinforced-polymer (CFRP) constituent is introduced. Hereby an interlayer is inserted between the metal and the CFRP constituent, pursuing the task of stress relaxation. In order to study the effect of interfacial stress relaxation several thermoplastics are investigated. In situ passive thermography is used to assess the damage during quasi-static and fatigue mechanical loading. Thus, mechanical properties are correlated with corresponding damage-quantities from non-destructive testing (ndt). These results reveal that transversal cracking and mode-I delamination are the dominant failure processes, which strongly depend on the thermoplastic material. Additional finite element analysis describes strain-energy- and stressconcentrations, which coincide with the observed damage mechanisms and the origins of fracture.

Emergency repair of severely damaged reinforced concrete column elements under axial compression: An experimental study

Reinforced concrete (RC) columns in a framed construction can be severely damaged under earthquake, blast, fatigue and other loads. It is essential to quickly restore the strength and stiffness of columns after its damage for maintaining the serviceability of the building. The objective of this study is to assess the efficiency of different strengthening techniques on emergency repair of the severely damaged RC columns under axial compression. Six short RC columns elements were cast and tested under axial compression until 20% drop in the peak strength. Thereafter, these severely damaged columns were repaired using strengthening schemes, namely (i) repairing the damaged portions using quick setting cement mortar, (ii) Near Surface Mounting (NSM) of CFRP (Carbon Fiber Reinforced Polymer) laminates and (iii) Hybrid strengthening technique. The hybrid strengthening technique uses the combination of CFRP NSM laminates as additional longitudinal reinforcement and external bonding with CFRP fabric for confinement. The hybrid strengthening scheme was found to be the most efficient in restoring the lost strength and initial stiffness when compared to the only NSM strengthening or repair with quick setting cement mortar.

Improved mechanical properties of carbon fiber/graphene oxide-epoxy hybrid composites

The mechanical properties of carbon fiber reinforced polymer composites depend upon fiber-matrix interfacial properties. In this investigation to improve the mechanical properties of polymer composites, graphene oxide was used as one of the filler for the development of carbon fiber/graphene oxide-epoxy hybrid composites. Initially, epoxy resin was modified by incorporating different weight% of graphene oxide from 0.1 to 0.6 wt%. The desired size of carbon fiber fabric was impregnated with modified epoxy resin to develop hybrid composites by compression molding technique. The graphene oxide synthesized was characterized by various techniques such as FTIR, XPS, NMR, XRD and Raman Spectroscopy. It is observed that graphene oxide synthesized possesses different type of functional groups which are responsible for making interactions with epoxy resin and Carbon fibers. The hybrid composite flexural strength increases by 66%, flexural modulus by 72%, while interlaminar shear strength (ILSS) increases by 25% at 0.3 wt% of graphene oxide included in the carbon fiber reinforced polymer hybrid composites. The enhancement in the properties of composites at the percolation threshold of graphene oxide is due to hydrogen type bonding and mechanical interlocking of graphene oxide with carbon fibers and epoxy resin. The graphene oxide utilization is one of the approaches for improving the properties of carbon fiber polymer composites.

지속하중을 받는 탄소섬유판의 장기 거동

본 연구에서는 외부프리스트레스 탄소섬유판에 의한 보강기술에서 긴장력을 포함하는 지속하중이 작용하였을 때의 장기거동을 평가하기 위한 실험연구를 수행하였다. 지속하중 도입을 위한 실험계획은 탄소섬유판에 직접 인장력을 도입하는 직접 지속하중 방식과 휨 실험체를 통한 휨 지속하중으로 구분하여 실시하였다. 직접 지속하중에 의한 실험은 탄소섬유판의 종류별로 약 700일에 걸쳐 실시하여 탄소섬유판의 장기 크리프/릴렉세이션 등의 변형을 주로 평가하였으며, 휨 지속하중 실험에서는 탄소섬유판의 정착시 정착장치에서의 슬립량을 주로 평가하기 위해 약 90일 간으로 수행되었다. 일방향 탄소섬유판에 대한 2년간의 지속하중 실험 결과에 의하면, 탄소섬유판의 크리프나 릴렉세이션과 같은 재료자체의 변형 및 정착장치에서의 슬립에 기인한 응력손실은 적은 것으로 나타났다. 그러나, 강판매입형 탄소섬유판은 강판의 항복변형률을 초과하여 도입된 긴장력으로 인하여 재료 자체의 변형에 의한 자체 응력손실이 발생되었으므로 이에 대한 보완이 필요한 것으로 판단된다. 아울러, 탄소섬유판의 정착과정에 발생되는 긴장력의 즉시 손실량은 응력도입 초기의 약 10% 정도이므로 프리스트레스의 도입시에는 이를 고려하여 긴장력을 결정할 필요성이 있을 것으로 판단된다.