Papers by Keyword: Carbon Fiber Reinforced Polymer/Plastic (CFRP)

Abstract: Carbon fiber reinforced plastics (CFRP) has increasing applications in aerospace and other fields, due to low density, high strength, high stiffness, great resistance to corrosion, etc. Although, delamination damages in drilling holes for assembly influence the final characteristics of CFRP components. This paper presents an experimental investigation to analyze delamination damage, in which acoustic emission and thrust force are monitored during drilling CFRP laminates to clarify the relationship between AE signals and delamination damages. The results show that delamination damage has close correlation with thrust force and acoustic emission energy. AE root mean square (rms) is recommended to be selected as AE signal parameter. Abrupt peak feature of AE rms can be used as a dependable trigger for delamination monitoring. The number of abrupt pulses of AE rms can be counted online to predict the degree of delamination damages, based on which delaminations can be monitored and controlled online.

Abstract: Based on the tested data, the ANSYS finite element analysis software was adopted to establish the finite element model for the concrete beam nonlinear analysis.The finite element models were developed using 3-D solid element for concrete and shell element for the Carbon Fiber Reinforced Ploymer (CFRP) sheet. The results obtained from the ANSYS were compared with the experimental data for two strengthened beams with different thickness CFRP sheet. The comparisons were made for the curves of load-midspan deflection, yielding load and ultimate load. Models were calculated at the same condition as the experimental beams. Two reinforced beams strengthened with CFRP sheet were calculated in four-point bending. The load-deflection curves from the finite element analysis agree well with the experimental results. The average difference in ultimate load for two cases is 5.5%.

Abstract: There are lots of defects in the drilling process of CFRP, such as splitting, etc, which may affect the assembly quality of the composite materials. Through the analysis of the drilling mechanism of CFRP, and with the help of the correlation experiments of drilling tools, the effects of machining parameters and machining tools on hole quality are studied, the optimal selection method of the drilling tools for CFRP and the selection principle of technical parameters under different machining conditions are also discussed. And the tools geometry affects the hole-machining quality of CFRP materials directly, which should be chosen in accordance with the hole-machining method.

Abstract: In machining to CFRP material has many important problems, about necessary of high-precision machining, improvement of tool life and dispose of cutting chips etc. Especially in case of twist drill almost cant collect under 0.5 μm cutting chip, the fine-cutting chips diffuse into the sliding table and spindle head with the machine. Moreover, the fine-cutting chip is mixed and diffuse into the atmosphere. The possibility to remarkable decline of working efficiency so the dust-collection provision technology is wished. It is important also from the viewpoint of keep safety of a worker and work environment preservation because the CFRP utilizes in market for industrial structure materials, is increasing. As one method of solving this problem which aspirates and ejects cutting chip from a penetration hole through outside in the central part of the drill shank the new tool and cyclone type dust-collection system were developed. These technologies were used for perforate of CFRP material, and investigated about the cutting characteristic of the hollow type drill, and the effect of work environment improvement to dust-collection performance of cutting chips. As the result, our development machine tool and cutting tool can collect approximate 99.5% cutting chip.

Abstract: In drilling deep holes with small-diameter tools in particular, chip shape is a major problem along with tool rigidity. In this study, we developed a spindle machine that has regularly repeating acceleration and deceleration regions in each drill rotation (called modulated rotation) as a new drilling spidle machine that can improve chip discharge ability. For an analysis of the cutting mechanism based on the basic principles of this device and its drilling characteristics, holes were drilled in CFRP, and Ti alloy (Ti-6A1-4V) materials using a straight shank drill. The relationship between the torque and thrust of cutting resistance force was obtained to show the relationship between cutting chips shape and cutting force. The characteristics of drilling with the developed spindle device were evaluated in comparison with regular drilling methods. It was found that the torque with this device was reduced by about 10% compared with general drilling. Outstanding chip breakup was seen with Titanium alloys in particular, as a result of which chip discharge could be improved.

Abstract: This paper discusses the research conducted on prepreg composites interfaces engineered with, either carbon nanotubes (CNTs), or core shell micro-particles (CSMs). The emphasis is given on the fractography details that highlight various mechanisms involved in strengthening the ply-to-ply surface contacts due to the addition of these nanoand micro-particles.

Abstract: In this study, effect of Carbon Milled Fiber (CMF) addition on interlaminar fracture toughness of carbon fiber reinforced plastics (CFRP) was investigated. Plain woven carbon fiber was used as reinforcement. Epoxy resin was used as matrix. The addition amounts of CMF are 0.5wt%, 0.8wt%, 1.0wt% and 1.2wt% for the epoxy resin. Mode I and mode II interlaminar fracture toughness tests were conducted based on JIS K 7086. As a result, mode I and mode II interlaminar fracture toughness increased with an increase of addictive amount of CMF. But excess addition was not effective. Pull out of CMF in matrix was found after mode I and mode II interlaminar fracture toughness tests. The mode I and mode II interlaminar fracture toughness of CMF added CFRP can be improved by fiber bridging of CMF.

Abstract: A research study was undertaken to investigate the mechanical performance of glulam beams reinforced by CFRP or bamboo. Local reinforcement is proposed in order to improve the flexural strength of glulam beams. The glulam beam is strengthened in tension and along its sides with the carbon fiber-reinforced polymer CFRP or bamboo. A series of CFRP reinforced glulam beams and bamboo reinforced glulam beams were tested to determine their load-deformation characteristics. Experimental work for evaluating the reinforcing technique is reported here. According to experiment results, the CFRP and bamboo reinforcements led to a higher glulam beam performance. The results show a considerably improved stiffness of the reinforced over the non-reinforced specimens. By using CFRP and bamboo reinforcements several improvements in strength may be obtained.

Abstract: Carbon fiber reinforced plastics (CFRP) were prepared by manual molding technology and the effect of loading speed on the piezoresistive property of CFPR was discussed. The piezoresistive sensitivity of CFRP with the different content of carbon fibers was contrasted and the interface morphology of CFRP was observed by SEM. The results show that CFRP has the obvious piezoresistive property and it can provide early warning as a kind of strain sensor. The piezoresistive sensitivity of CFRP decreases as the increasing of the content of carbon fibers in CFRP. Moreover the piezoresistive sensitivity of CFRP reduced as the increasing of loading speed. The SEM showed that the interface was good between carbon fibers and epoxy resin.

Abstract: Water absorption behavior and mechanical properties variation of the carbon fiber reinforced epoxy matrix composites (CFRP) immersed into artificial seawater were investigated by experiments. The rate of water absorption of the composite specimens is gradually reducing as the duality of immersion increasing. Due to the reversible and irreversible changes in the resin matrix and the failure of the fiber/matrix interface, the tensile strength, the flexural strength, and the ILSS of the composite specimens after 70 days immersion decreased 9.3%, 13%, and 17% respectively. And the tensile modulus and the flexural modulus the specimens after desorption were 83% and 70% of the original state, respectively