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Polymer nanocomposite is commonly used to develop structural components of space, aircraft, biomedical, sensor, automobile, and battery sector applications. It remarkably substitutes the heavyweight metallic and nonmetallic engineering materials. The machining principles of polymer nanocomposites are intensely different and complex from traditional metals and alloys. The nonhomogeneity, abrasive, and anisotropic nature differs its machining aspect from conventional metallic materials. This investigation aims to execute the CNC drilling of modified nanocomposite using Graphene–carbon (G-C) @ epoxy matrix. The process constraints, namely, cutting speed (S), feed (F), and wt.% of graphene oxide (GO) vary up to three levels and are designed according to the response surface methodology (RSM) array. The nonlinear model is created to predict surface roughness (Ra) and delamination (Fd) on regression analysis. It has been found that the average error for Ra is 0.94% and for Fd it is 3.27%, which is acceptable in model predictions. The metaheuristics-based evolutionary Dragonfly algorithm (DA) evaluated the optimal parametric condition. The optimal setting prediction for the DA is observed as cutting speed (S)-37.68m/min, feed (F)-80mm/min, and wt.% of graphene oxide (GO)-1%. This algorithm demonstrates a higher application potential than the previous efforts in controlling Ra and Fd values. Both the drilling response values are found to be minimized when the cutting speed increases and the feed decreases. The best fitness value for the DA is 1.626 for surface roughness and 5.086 for delamination. This study agreed with the prediction model’s outcomes and the process parameters’ optimal condition. The defects generated during the sample drilling, such as fiber pull out, uncut/burr, and fiber breakage, were examined using FE-SEM analysis. The optimal findings of the DA module significantly controlled the damages during machining.

In the present study, we contrast the change of mechanical and physical properties between VaRTM (Vacuum Assisted Resin Transfer Molding) and hand lay-up process. In the results of mechanical tests, VaRTM specimen is stronger than hand lay-up specimen and hand lay-up specimen became delamination. In the results of physical tests, the resin content of VaRTM specimen is lower than hand lay-up specimen. On micrograph, the strength of specimen by VaRTM between fiber and resin is stronger than that of one by hand lay-up. And the specimen by hand lay-up contains more defects than one by VaRTM. So, VaRTM process can practically apply for automobile engine hood. This paper shows that VaRTM process is one of the most suitable processes for composite parts of automobile.

In this study, the heat-damage process of a carbon fiber reinforced plastic (CFRP) under monotonic tensile loading was characterized by acoustic emission. Additionally, epoxy specimens and prepreg specimens were used to determine the characteristics of acoustic emission (AE) signals of epoxy and fiber, respectively. The AE characteristics of CFRP showed three types of distinct frequency regions. Time-frequency analysis methods were employed for the analysis of fracture mechanisms in CFRP such as matrix cracking, debonding and fiber fracture. To evaluate the cumulative counts of AE signals, it seems that the results can be applied usefully to guarantee structural integrity and/or to the survey of destruction of the structure with heat-damage, that was made to the composite materials.

Carbon Fiber Reinforced Plastic (CFRP) composite laminates are widely used in aerospace and aircraft structural components due to their superior properties. However, they are regarded as difficult-to-cut materials because of bad surface quality and low productivity. Drilling is the most common hole making process for CFRP composite laminates and drilling induced delamination damage usually occurs severely at the exit side of drilling holes, which strongly deteriorate holes quality. In this work, the candle stick drill and multi-facet drill are employed to evaluate the machinability of drilling T700/LT-03A CFRP composite laminates in terms of thrust force, delamination, holes diameter and holes surface roughness. S/N ratio is used to characterize the thrust force while an ellipse-shaped delamination model is established to quantitatively analyze the delamination. The best combination of drilling parameters are determined by full consideration of S/N ratios of thrust force and the delamination. The results indicate that candle stick drill will induce the unexpected ellipse-shaped delamination even at its best drilling parameters of spindle speed of 10,000 rpm and feed rate of 0.004 mm/tooth. However, the multi-facet drill cutting at the relative lower feed rate of 0.004 mm/tooth and lower spindle speed of 6000 rpm can effectively prevent the delamination. Comprehensively, holes quality obtained by multi-facet drill is much more superior to those obtained by candle stick drill.

The purpose of this study is to determine the correct estimation of the concept design for high strength composites applied to the intermediate shaft of a ship. Recently, the application of composites has increased in the ship industry area for weight reduction and marine environmental protection. Carbon fiber reinforced plastic (CFRP) has characteristics of high strength, high elasticity and high corrosion resistance. Therefore, it is a suitable material for reducing the weight of the ship. So, weight reduction and high fuel efficiency can be expected. However, little research has been carried out on the technology development of a composites shaft for ships. In this study, analysis is carried out on the application of a high-strength CFRP shaft.

This study investigates an analysis of the healing behavior of carbon-based nanocomposites by using the finite element (FE) method and provides the quantitative healing values based on the efficiency with respect to the volume, C${}_h=1-$V${}_{\mathrm{\text{healed}}}$/V${}_{\mathrm{\text{nonhealed}}}$. An approximation of the geometrical relationship on the profile was considered, and the results compared with the model were used to estimate the healing efficiency based on the initial open profiles. In this model, it contains the interface elements between damaged crack faces. We adjust their sizes and stiffness of elements to compare the profiles with a geometrical equation. We propose that the results of their efficiencies can be compared with the strength of the healing elements that depend on the size of healed volume by the approximation.

This study has analyzed the welding joint of carbon fiber reinforced plastics (CFRP) and aluminum alloys. The surface of CFRP and 5083 Al alloy was modified by electroplating with nickel at first. Then the effect of electroplating parameters on coating was explored. SEM images revealed that the coating gradually became well but then began to fall off with the current density and the plating time increased. CFRP and aluminum alloys were brazed at 285${}^{\circ }$C and held for 20 s. Shear test was used to evaluate the strength of the joint and the strength was probably 7.56 MPa. SEM and EDS tests showed that there existed diffusion of the elements in the welding process and the joint reached the bonding of atomic or molecular sizes. Thus, this experiment achieved the tight brazing joining between thermoset CFRP and aluminum alloys providing the joining method of the application for CFRP.

The purpose of this study is to develop a lightweight design model for an 18ft leisure boat. The existing leisure boat is manufactured using glass fiber-reinforced plastics (GFRP) material and the hand lay-up process. Carbon fiber-reinforced plastics (CFRP) was applied to the new design to reduce the boat’s weight, while an automated tape laying machine was applied to the lightweight boat’s manufacturing process to increase boat manufacturing productivity. The newly designed CFRP model is 25% lighter than the existing GFRP model. It was confirmed that the newly designed lightweight hull has sufficient structural integrity compared to the existing hull through the structural integrity evaluation by the FEA.

Three types of CFRP/aluminum (Al) alloy riveted joints, single-rivet joint, double-rivet joint and three-rivet joint, were prepared by the riveting technique. The fatigue limit of the three-rivet joint was 27.35 MPa. The fatigue failure mechanism of the joint was that Al alloy cracks on the surface of rivet holes and propagates to fail.

In this study, diamond thin films were deposited on tungsten carbide tools using surface-wave plasma-enhanced chemical vapor deposition (SWP-CVD). To eliminate the adverse effects of cobalt on the diamond deposition process, the cobalt was removed from the surface of the tools by etching with Murakami’s reagent for various times (30, 60, and 120 min). The cutting performance of the untreated and the diamond-coated WC tools was examined by performing cutting test on carbon fiber-reinforced plastic (CFRP). The results showed that all the diamond-coated tools exhibited great improvement on the durability and wear resistance compared to the uncoated one. In addition, the diamond-coated tool lift time is found to be proportional to the etching time. An increase more than twofold has been achieved when the etch time was increased from 30 min to 120 min.

This paper presents a new design procedure for large wind turbine blades, which can be used in various case studies. The structural design of 2MW CFRP blade was performed using a verified 2MW GFRP blade model. The structural integrity assessment of the CFRP model demonstrated that the design criteria for tip deformation, buckling failure, and laminate failure in normal wind turbine operating conditions were met. The existing aero-elastic analysis code was not used to estimate the blade load, but the blade’s surface pressure was calculated using CFD. The conventional load analysis code necessitates the establishment of a turbine system and the input of structural characteristics with changes in the structural design specifications. However, when CFD was used to estimate the load, the turbine system was not required and the structure was evaluated against various design cases, making this a useful approach in preliminary design. This new structural design and evaluation procedure for wind blades can be used to review diverse design specifications in the initial design stage.

This research presents structural design and analysis results of applying a composite boom structure on a Concrete Pump Truck (CPT). Carbon Fiber Reinforced Plastic (CFRP) is used to complete the structural design of the end boom to reduce the weight of the CPT. The weight of the newly designed end boom is reduced by 32% compared to the original steel component. Structural analysis is accomplished by applying static load combinations of self-weight of the boom and the weights of the pipes, the concrete and the drain hose. The results show that the tip deflection is reduced by 30% compared to the conventional end boom. Also, equivalent stress is considerably lower than the conventional design. Composite failure evaluation of the CFRP end boom is conducted by post-processing the stress results using Puck’s failure criteria. The evaluation results show that the design criteria are met on the static load of the pump truck. Specifically, it is expected that fiber failure and inter fiber failure of the boom do not occur under loading conditions according to the design evaluation results.

The purpose of this study is to reduce the weight of elevator components in order to save energy and apply the findings to the new drive-type elevator system. Structural design has been carried out for two lightweight elevator models in which the damped aluminum laminate (DAL) and carbon fiber reinforced plastics (CFRP) are utilized for the elevator walls, respectively. The structural designs of the new elevator walls are based on the bending stiffness of the existing steel walls. The aluminum elevator model is designed to exhibit a bending stiffness similar to that of the existing steel elevator, while the CFRP model is designed to possess 20% of the existing wall bending stiffness considering that the tensile strength in the fiber direction is about nine times higher than that of the existing structural steel material. DAL and CFRP are applied to the elevator walls, respectively, and aluminum sandwich structures are applied to the ceiling and platform of two kinds of lightweight elevator models. It has been ascertained that the aluminum elevator model is about 40% lighter than the existing steel elevator, and the CFRP elevator model is about 50% lighter than the existing elevator. In order to evaluate the structural integrity of the newly designed elevator model, the criteria presented in the elevator inspection guideline are applied. The designed elevator model is confirmed to satisfy the strength and stiffness criteria presented in the elevator inspection parameter.

This research presents the structural design and mechanical performance evaluation results of a lightweight belt for high-rise elevators. Weight reduction of elevator components is indispensable in developing ultra-high-rise elevators. In this study, the structural design and performance evaluation of high-rise elevator ropes were carried out. The weight of the newly designed Carbon Fiber Reinforced Plastic (CFRP) belt was reduced by 30% compared with the original steel wire rope. The structural analysis results of the CFRP belt showed that the design criteria were met on the design load condition of the belt. Also, mechanical tests were executed to verify the mechanical characteristics of the newly developed belt, with the results showing that the belt had sufficient structural performance compared with conventional steel wire rope.

This study was conducted for the purpose of deriving the optimal process conditions for the pultrusion of carbon fiber–polyester composite materials. For this purpose, the mechanical characteristics were evaluated according to fiber content, curing time, and curing temperature. Tensile strength characteristics are improved as the fiber content, curing temperature, and curing time increased. But, in a fiber content of 70% over, it does not improve due to internal defects such as delamination and voids. The effect of curing temperature and curing time was analyzed through the fracture mode. Fracture characteristics due to un-curing were observed in tensile specimens. In addition, the curing reaction of the polyester as the heating rate was confirmed through differential scanning calorimetry. Finally, the optimal process conditions for the pultrusion of carbon fiber–polyester composite materials were derived.

In this study, we investigated the impact of adding Triphenylphosphine (TPP) at concentrations of 1wt.%, 3wt.%, and 5wt.% to an epoxy-anhydride system that displays, a degradation in mechanical properties at high temperatures. We conducted an analysis of cure behavior using differential scanning calorimetry and evaluated flexural, shear, and tensile strengths at room temperature. To assess heat resistance, CFRP specimens were exposed to 100^∘C for 1h, and tensile strengths were subsequently measured. The addition of 3wt.% TPP resulted in a 5min reduction in the time required to reach a 95% degree of cure, but it was observed that mechanical properties at room temperature were compromised. CFRP exposed to 100^∘C indicated that an increase in TPP content helped mitigate the degradation of mechanical properties.

A pulsed fiber laser was used to conduct laser cleaning experiments on the composite paint layer on the surface of carbon fiber composite materials (carbon fiber-reinforced plastic (CFRP)). The influence of laser energy density and laser travel speed on the cleaning effect was studied. The surface morphology, surface roughness and phase composition of the cleaned sample were analyzed. After bonding, tensile testing was conducted on the bonding part to verify the impact of laser cleaning on the bonding performance. The research results indicate that the cleaning effect gradually improves with the increase of laser energy density or the decrease of travel speed. In this experiment, when the laser energy density is 4.00J/cm² and the travel speed is 6.5mm/s, the phase composition of the cleaned substrate surface is only C, without TiO₂ and BaSO₄. This indicates that the paint layer has been completely removed under this process parameter. By selecting reasonable process parameters, the surface paint layer of CFRP can be effectively removed, and a good surface morphology can be obtained without damage to the carbon fiber. Meanwhile, the mechanical properties after bonding can be improved.

A reinforced concrete frame with masonry wall infill, “framed-brick work”, is a composite basic structure demonstrated to be feasible and effective on account of in-plane smooth excitations. Numerous models have been proposed for simulation of the behavior of masonry infills. The act of utilizing infill walls has been under investigation as it has both positive and negative impacts on the behavior of the structure under horizontal load. An enormous number of experimental and diagnostic examinations have been embraced in the past to research the behavior of such frames. The paper has focused on the working principles and the fundamental highlights of a recently created retrofitted masonry infill frames (RMIF) with carbon fiber–reinforced polymer (CFRP) sheets of RMIF. The presence of CFRP retrofitted in infill frames changes the behavior of the structure under substantial loads. The behavior examination, for example, deflection, ductility and tensile strength, is investigated for clay brick and fly ash bricks examples. For approval reason, this investigation utilizes feed forward back propagation neural network (FFBN) procedure. The correlation between experimental and the predicted values demonstrated that while the mechanical properties can be predicted for each specimen up partly by a portion of these models with the exact outcome achieved as a minimum error.

The usages of carbon-fiber reinforced polymer (CFRP) in aerospace, defense, and structural fields are increasing due to their excellent properties. However, the materials design, forming of material, machine tool and processing conditions are major tasks in manufacturing industries. Particularly, the micro feature making on macro-components using vertical machining center is a challenge nowadays. In this work, two different drill bits, such as high-speed steel (HSS) and solid carbide (SC) micro-drill, were used to make drilling on CFRP material. The performance of drills was evaluated by obtaining minimum delamination and stress in drilling by varying cutting velocity (CV), feed rate (FR), and air pressure (AP). Regression equations were formed according to the measured quality performance characteristics. The linear weighted method-based combined objective function algorithm and Genetic Algorithm was followed to multi-objective optimization. Besides, the most influencing factors were also identified and discussed using analysis of variance. The results explained that the SC micro-drill performance was better than HSS micro-drill. Also, the CV has the most eminent parameters followed by FR.

This article describes new control criteria and robust optimization methodology to balance drilling parameters and machining characteristics. Experimentation was performed according to response surface methodology (RSM) using a TiAlN coated SiC tool. The full drilling force signal and cutting parameters tested are categorized into five stages, indicating the drilling tool-workpiece interactions’ different statuses. Principal component analysis (PCA) assigns real response priority weight during the aggregation of conflicting characteristics. The hybrid module of combined compromise solution and PCA (CoCoSo–PCA) is used to decide the optimal parametric setting. It efficiently undertakes a trade-off between minimal thrust ($Th=30.02$N), torque ($T=0.05$Nm) surface roughness ($R_a=1.55\mu$m). A regression model between input parameters and output function was established using RSM quadratic model. The validation experiment shows significant improvement, and the proposed module can be recommended for quality-productivity characteristics control.