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

Abstract: After hundreds years damage, the disease of stone structure member is very severity, and so structure reinforcement has great significance. In this paper, the bending capacity of stone member reinforced with CFRP is studied through the test combined with the protective project of Huangsong Stele. The tests totally have six stone beams to study the mechanics performance and damage model of original and reinforced stone beam. The bending capacity theory of reinforced beam is discussed. The study results revealed that the bending performance of stone beam reinforced with CFRP can ameliorate greatly, and the destroy model change from brittle failure of normal section to ductile failure of oblique section, and the bend-resisting capacity of stone beam reinforced with CFRP can be enhanced greatly. But the enhanced range isnt direct proportion with the dosage of CFRP. The calculate formula of bending capacity got from theory deduce joint the test result, so it can be used to guide the design of fact project. So, the reinforcement of stone bending beam with CFRP have well effect.

Abstract: The purpose of this paper is to focus on studying its flexural behavior after different damages prestressed concrete hollow slab is strengthened with CFRP.By the experimental method, twelve residential prestressed concrete hollow slabs are tested under concentrated force at the two points of the symmetrical load in order to analyze both flexural behavior and effects factored by different bonding modes.The conclusion can be drawn that the flexural behavior of prestressed concrete hollow slabs strengthened with CFRP is well-tried.It provides design suggestions and reference for prestressed concrete hollow slabs strengthened with CFRP, and also provides an experimental basis for the repairing and reinforcing practical engineering application in Wenchuan disaster area.

Abstract: The steel reinforced concrete column is one of the important members for structures, it is essential to study the high temperature performance of concrete column. The numerical simulation research is done using finite element software ANSYS. Under the high temperature, the analysis of the compressive bearing capacity and flexural capacity of the concrete columns strengthened by CFRP is done, and the compressive bearing capacities of different cross-section concrete columns strengthened with CFRP are tested.

Abstract: The sensitivity of the electromechanical impedance to structural damage under varying temperature is investigated in this paper. An approach based on maximizing cross-correlation coefficients is used to compensate temperature effects. The experiments are carried out on an air plane conform carbon fiber reinforced plastic (CFRP) panel (500mm x 500mm x 5mm) instrumented with 26 piezoelectric transducers of two different sizes. In a first step, the panel is stepwise subjected to temperatures between-50 °C and 100 °C. The influence of varying temperatures on the measured impedances and the capability of the temperature compensation approach are analyzed. Next, the sensitivity to a 200 J impact damage is analyzed and it is set in relation to the influence of a temperature change. It becomes apparent the impact of the transducer size and location on the quality of the damage detection. The results further indicate a significant influence of temperature on the measured spectra. However, applying the temperature compensation algorithm can reduce the temperature effect at the same time increasing the transducer sensitivity within its measuring area. The paper concludes with a discussion about the trade-off between the sensing area, where damage should be detected, and the temperature range, in which damage within this area can reliably be detected.

Abstract: This paper deals with effects of damage on Carbon FRP (CFRP) elements subjected both to defects and micro-cracking due to static tensile loading through an investigation of CFRP elements under natural vibration tests. The correlation between the response and frequency decrease due to damage for cross section reduction of CFRP cantilever beam elements has been analysed. Successively, the response of CFRP subjected to different values of tensile force has been investigated; experimental frequency values are compared with theoretical values and discussed.

Abstract: The investigation was focused on Carbon Fibre Reinforced Polymers (CFRP). In the first part of research the aim was the characterization of CFRP surfaces. These surfaces were influenced by release agent, hydraulic fluid, moisture and overheating. In the second part of research adhesive bond quality was investigated. Three different cases of possible weak bonds were focused on. Weak bond caused by release agent contamination, moisture contamination and poor curing of adhesive. The characterization was conducted using laser vibrometry used as NDT tools. An active element in the form of piezoelectric transducer was used to excite the samples made out of CFRP material. Laser vibroemter was used to register the surface response. Combining the piezoelectric excitation with laser sensing a tool was obtained to measure precisely the propagating elastic waves. The excited waves were measured in defined points by the vibrometer obtaining the wavefield. In order to characterize the surface and bonding quality an indicator was proposed based on propagating wave parameters. The guided elastic wave velocity depends material properties (Young modulus, density, Poisson ratio) and thickness of the sample. It was assumed that comparison of the velocities can provide an information about the bond condition. All the investigated scenarios showed deviation from the reference case.

Abstract: Analysis of the cutting force and specific cutting pressure play vital roles in machining of the composite materials. The present experimental work describes the modeling of machining parameters using one of the soft computing techniques i.e. fuzzy logic for machining force and specific cutting pressure. The basic idea is to machine the carbon fiber reinforced plastic (CFRP) composite materials and measuring the cutting forces and then determining the machining force and specific cutting pressure. 27 experiments based on Taguchis L₂₇ orthogonal array were carried out involving three machining parameters, namely, cutting speed, feed and depth of cut, each defined at three levels. Subsequently the prediction models were developed using three different fuzzy logic membership functions, namely, triangular, trapezoidal and bell shape. It is found that the predicted values of proposed responses such as machining force and specific cutting pressure are very close to the experimental values within the chosen ranges of the process parameters. The statistical analysis using ANOVA on machining parameters are also presented and discussed. The machined surface analyzed through SEM images revealed the damages encountered during turning process.

Abstract: In this chapter the influence of tool geometry and cutting conditions on cutting forces, surface defects and the percetage of dust generated durring trimming and reaching the pulmonary alveoli is investigated. The surface defects were analysed using a scanning electron microscope and diferent surface roughness measurement devices. It was observed that these leters were highly depend on the cutting condition and the tool geometry, and more important that the effect of cutting parameters can be completely diferent from a tool to an other or even when considering different ranges of cutting parameters (standard cutting speed and high cutting speed). The compressive strenght after machining is also investigated. It is observed that whatever tool geometry, cutting conditions, surface roughnesses (defects) are, the response still the same for all the composite samples except for those machined at cutting temperatures higher than the glass fiber transition.

Abstract: For the pressure vessels made of high-strength Carbon Fiber Reinforced Plastics (CFRP) and Aluminum liner, the strength is provided by the CFRP, but the liner leak is always the bottleneck of the vessels’ safety. The carrying capacity and anti-fatigue ability of CFRP pressure vessels is largely depend on the elastic deformation range. In this research the principle of autofrettage is analyzed, the mechanical character of a certain 2 liters pressure vessel is analyzed using finite element software ANSYS, and the optimal autofrettage pressure is calculated by optimization method. The results showed that the stresses of the liner under working pressure were decreasing while applying the autofrettage pressure. The liner would gain the best plastic level under the appropriate autofrettage pressure.

Abstract: The effect of surface ply on the quality of the hole produced when drilling multi-directional carbon fiber reinforced plastic (CFRP) composite laminates was investigated. A series of drilling experiments are performed using a carbide drill tool on two multi-directional CFRP composite laminates. The two composite laminates have similar stacking sequence except the surface plies, namely woven fabric and fiberglass scrim. The thrust force and torque was collected during the drilling process. The quality of the drilled hole was examined through surface roughness measurement, fiber pull out, and delamination. Thrust force was found to be higher for the composite laminate with woven fabric surface plies. The exit delamination factor measured from the holes with woven fabric surface plies found to be lower than the holes with fiberglass scrim surface plies.