Application Of Carbon Fiber Reinforced Plastics Research Articles

Multiscale uncertainty propagation analysis and reliability optimization of the CFRP crossbeam of the twist beam axle

Carbon fiber reinforced plastics (CFRP) have the advantages of being light weight and having high strength, which means that they can be used to effectively realize the lightweight design of automobile components. In this paper, the original steel crossbeam of the twist beam rear axle of a passenger car is replaced by CFRP, and then the cross-section improvement design is implemented. The ply stacking sequence of the CFRP crossbeam is also optimized to enhance its structural performance. Considering the multiscale characteristics of CFRP, a multiscale analysis model of the CFRP crossbeam is established, and the effects of microscopic, mesoscopic and macroscopic structures and material parameters on the stiffness, maximum stress and vibration characteristics of the CFRP crossbeam are discussed. The multiscale propagation law of the random-interval mixed uncertain parameters of the CFRP crossbeam is studied by using the multiscale model. On this basis, the reliability optimization design model of CFRP crossbeam considering multiscale uncertainty is established, and the multiscale reliability optimization method of the CFRP crossbeam of twist beam axle based on approximate models, Monte Carlo simulation (MCS) and intelligent optimization algorithms is studied. The optimization method of the combination of the ply stacking sequence optimization and the multiscale reliability optimization of the CFRP structure is proposed, the mass is reduced by 46.96% while ensuring reliability, and other structural performances are improved. Meanwhile, a theoretical research basis and technical support for the design and development of CFRP suspension components are provided, and the application of CFRP in the automobile field is promoted.

Effect of marine environment on the mechanical properties degradation and long-term creep failure of CFRP

The carbon fiber reinforced plastics (CFRP) has broad application prospect in the marine field, but its significate long-term performance and failure mechanism are still unclear. In this paper, the mechanical property degradation and creep failure mechanism of CFRP in marine environment were investigated by the molecular dynamics (MD) method. Based on the CFRP molecular model established in dry, pure water and salt immersion environment, the effect of service conditions on it in marine environment was explored. The results show that the marine environment can lead to a significant decrease in the mechanical properties of CFRP only in the vertical fiber direction, and the degradation extent increases with the increase of temperature. The effects of pure water immersion and salt immersion environment on its mechanical properties are basically the same. High stress level, hygrothermal environment and high temperature salt immersion environment will accelerate the creep failure of CFRP. Later, the creep failure mechanism of CFRP is analyzed from microstructure and microscopic energy. Microstructure analysis shows that water molecules could accelerate the movement of epoxy fragments and lead to CFRP failure. Microscopic energy analysis shows that the conversion process of strain energy and the decline of interface performance are the important reasons for creep failure. The finds of this paper introduce a new method to study the long-term performance of CFRP and can provide reference for the engineering application of CFRP in marine environment.

Preparation and Mechanical Properties Analysis of Aviation Mechanical Carbon Fiber Reinforced Plastics

The study aims to explore the preparation of aviation mechanical carbon fiber reinforced plastics (CFRP) and the properties of CFRP composites. Taking the aero box body as an example, the mechanical properties of CFRP are studied. The preparation of CFRP is analyzed by searching the data. CFRP plates are explored according to the stress analysis of composite materials. The finite element analysis software ANSYS Workbench and UG software are adopted to build the 3D model of the aero box body. After adding materials in ANSYS Workbench and simplifying the UG model, the finite element analysis of the model is carried out by computer. The 3D model of the aero box is constructed, the finite element analysis of the aero box is carried out, and the mechanical properties of CFRP are explored. In this study, the possibility of the practical application of CFRP in the aviation box body lightweight is clarified, which gives a direction for the subsequent actual molding and guides the application of CFRP in aviation field.

Research of Detecting Methods of Welding Cracks in CFRP-Steel Structures Based on Eddy Current Pulsed Thermography

CFRP (Carbon Fiber Reinforced Plastics) reinforcement has a significant effect and advantages of steel structure, has extensive application prospects in the field of engineering structure. However, both of the detection methods and effects evaluation are still in blank, which has restricted the application of CFRP reinforcing steel structures. This paper is based on Eddy Current Pulsed Thermography (ECPT) and focused on the detection of fatigue damage in steel structure strengthened with CFRP sheet. The main research following several parts: first, the mechanism of eddy current thermal excitation on multilayer anisotropic medium was analyzed. Second, the direction and length of steel crack can be found out in any streel crack image. Finally, the feasibility of numerical models and recognition algorithm are verified through experiments. The paper provided an effective method in damaged structures strengthened with CFRP based on ECPT, as well as establishing the theory and technique for developing ECPT instruments for CFRP sheet-strengthened steel structures.

Application of carbon fiber-reinforced plastics in the manufacture of toroidal pressure vessels

This paper provides a comparative analysis of two design variants of two types of pressure vessels, metal and hybrid, the latter of which consists of metal and carbon fiber-reinforced plastics. The experimental results show that there is a reserve of strength that allows reducing the weight of the metal toroidal pressure vessel by thinning its metal wall and auxiliary winding with carbon-fiber prepreg. As compared with the allmetal tank, the savings in weight was 45% under the same operating characteristics. A pressure vessel design and its basic properties are provided.

極低温熱サイクル疲労を受ける平織炭素繊維布強化複合材料へのフィラー充填が窒素ガスのリーク防止に及ぼす影響

Carbon fiber reinforced plastics (CFRP) are widely used as structural components and are regarded as the major candidates for reducing the structural weight. Especially, application of CFRP to the cryogenic liquid fuel tanks is one of the most yearnings for achieving the drastic weight reduction. To apply CFRP for the fuel tank instead of the aluminium alloy, behaviors of CFRP such as fuel leakage or gas permeation under the cryogenic temperature should be cleared. The purpose of this study is to improve the nitrogen gas permeation properties of Plain-Woven CFRP. To improve the permeation properties of CFRP (V-CFRP), the nanoclay filler, which is montmorillonite is compounded (M-CFRP). The leakage pathway of nitrogen gas through the laminates is also revealed in order to identify the major factor of leakage. The leak rate of CFRP after cryothermal fatigue tests was increased as cyclic number increases. This is because that the interfacial debonding and micro cracks were initiated in CFRP due to cryothermal cycling. The increase of leak rate due to crack initiation was significantly higher than that due to the nitrogen diffusion through the matrix. The micro crack density and crack length of M-CFRP were improved compared to V-CFRP. This is because that the fracture toughness of epoxy resin improved by filling the montmorillonite. Therefore, the leak rate of M-CFRP was decreased, and the permeation properties can be improved by filling montmorillonite. The velocity of diffusion of M-CFRP until reaching steady leakage was lower than that of V-CFRP. It should be said that the montmorillonite, which is the inorganic material plays the role of the obstacle for nitrogen molecule.

Machining of carbon fiber reinforced plastics: Influence of tool geometry and fiber orientation on the machining forces

Tools optimized for machining carbon fiber reinforced plastics (CFRP) belong to the key enablers for the application of CFRP in many areas such as aerospace or automobile industry. Conventional tool designs do not consider the differing machining behavior of CFRP compared to metals. This leads to short tool lifetime and limited workpiece quality. The presented study introduces fundamental tool-geometry analyses based on orthogonal cutting of unidirectional CFRP-material. Within an extensive experiment series process-forces (i), abrasive tool-wear (ii), workpiece damages (iii) and delamination (iv) are evaluated depending on different tool geometries and fiber-orientations. In conclusion, workpiece damages and tool lifetime can be linked to tool characteristics.

Experimental Study on Impact Damage in CFRPs

With the weight-reduction requirement for transportation tools, more and more carbon fiber reinforced plastics (CFRPs) will be applied. It is known that the plastics will have a brittle fracture under impact loads, and therefore, their resistance capability on impact damage is a crucial factor which restricts the application of CFRPs. The present paper studies the impact damage and residual stiffness of the CFRPs through experiments. The identical specimens were impacted repeatedly by pendulum with a specified constant energy, and then, their residual bending stiffness and strength were measured by three-point-bending tests. Finally, the relationship between the residual stiffness and impact numbers were established. The results will be used in damage-based stiffness predition for CFRPs material and structures.