Surface Of Fiber Reinforced Plastic Research Articles

Prediction of the Quality of Thermally Sprayed Copper Coatings on Laser-Structured CFRP Surfaces Using Hyperspectral Imaging

With the progressive replacement of metallic parts by high-performance fiber-reinforced plastic (FRP) components, typical properties of metals are required to be placed on the material’s surface. A metallic coating applied to the FRP surface by thermal spraying, for instance, can fulfill these requirements, including electrical conductivity. In this work, laser pre-treatments are utilized for increasing the bond strength of metallic coatings. However, due to the high-precision material removal using pulsed laser radiation, the production-related heterogeneous fiber distribution in FRP leads to variations in the structuring result and consequently to different qualities of the subsequent coating. In this study, hyperspectral imaging (HSI) technologies in conjunction with deep learning were applied to carbon fiber-reinforced plastics (CFRP) structured by nanosecond pulsed laser. HSI-based prediction models could be developed, which allow for reliable prediction, with an accuracy of around 80%, of which laser-treated areas will successfully be coated and which will not. By using this objective and automatic evaluation, it is possible to avoid large amounts of rejects before further processing the parts and also to optimize the adhesion of coatings. Spatially resolved data enables local reworking during the laser process, making it feasible for the manufacturing process to achieve zero waste.

Study of the decrease in print-through phenomenon on fiber-reinforced plastic material

Fiber-reinforced plastic (FRP) is a general kind of composite material used in many industries. This study examines the print-through phenomenon (PTP) via quantitative measurements on the gel-coated surface of FRP specimens. Moreover, finite element analysis is also adopted in this investigation. Based on a large number of experiments and computations, an average parameter, the arithmetic mean deviation is utilized to determine the degree of the PTP. Further, the reflections of a light image on a FRP surface were observed in photographs. Experimental results show that insulating residual stress can reduce PTP. Adding a core-mat layer to the FRP stacking scheme is a good solution for minimizing the PTP. In addition to using the core-mat materials, substitute materials used to prevent the PTP are also investigated.

Methods to Reduce the Print-through Phenomenon on the Surface of FRP

The reflected image on the surface of the fiber-reinforced plastic (FRP) often presents twists and wrinkles. This phenomenon is called print-through phenomenon (PTP) in this investigation and the lines present on the material surface are called print-through lines (PTL). Earlier studies and experimental observations indicate that PTP is related to the non-uniform inner stress in the gel coating layer of the FRP. The non-uniform inner stress is caused by the various shrinkages of the plastic matrix and fibers of the fiber layers during the laminating process. So the main idea to reduce PTP is to reduce or uniform the non-uniform inner stress in the gel coating layer of the FRP. Several methods can be used to reduce PTP and two of them are investigated in this paper. One is removing atmospheric pressure before the plastic matrix of the fiber layers hardens. The other method is inserting a core-Mat layer into the Mat layers during laminating the FRP. Removing atmospheric pressure before the plastic matrix hardens can remove the influence of atmospheric pressure on causing the inner stress of the gel coating layer. Once the inner stress of the gel coating layer is reduced, PTP on the surface of the FRP can be eased off. Inserting a core-Mat layer into the Mat layers will form a buffer zone which can uniform the inner stress in the gel coating layer of the FRP. Therefore, PTP on the surface of the FRP can be eased off. To verify the present contentions, some experiments and qualitative analysis were performed. Both experimental and analysis results show that the PTP on the surface of FRP can be reduced by the present methods.

On the parameters influencing the performance of reinforced concrete beams strengthened with FRP plates

This paper presents a summary of our investigations that were aimed to assess the influence of various physical and mechanical parameters on the performance of reinforced concrete (RC) beams strengthened with fiber reinforced plastic (FRP) plates. The work was divided into two phases. The first phase investigated the influence of FRP plate length, fiber orientation, and surface preparation on the performance of FRP-reinforced RC beams. The FRP in this phase of the work was E-glass/epoxy. The second phase of the study was designed to confirm the validity of our hypothesis, which postulated that the delamination of the FRP plate would be a function of the Poisson ratio mismatch between concrete and FRP plate. Results from the second phase also suggested that less expensive glass FRP plates could adequately replace the more expensive carbon FRP plates by offering the beam more ductility, without sacrificing its expected performance. Moreover, results from both phases showed that the lateral stiffness of the FRP plate contributed to the overall flexural stiffness of the strengthened beam.

The effect of surface roughness on the adhesion properties of ceramic / hybrid FRP adhesively bonded systems

The adhesion properties of ceramic/hybrid fiber reinforced plastic (FRP) adhesively bonded systems were investigated with variations in the FRP surface roughness. The FRP substrate was subjected to mechanical abrasion in order to produce the surface roughness. The contact angles of water, formamide, and ethylene glycol on the FRP substrate were determined, and double lap shear and flexural tests were used to measure the joint strength of the ceramic/FRP adhesively bonded systems. In addition, the fracture surface of the adhesive layer at the adhesive/FRP interface was investigated by scanning electron microscopy (SEM). The wetting property of the adhesives was dependent on the amount of aramid microfibers induced on the FRP surface. The major source of the improvement in adhesion was attributed to changes in the stress distribution between the adhesive and the FRP substrate, due to fiber bridging. The high joint strength of the ceramic/FRP bonded systems resulted from cohesive failure in the fiber bulk and the larger volume of plastic deformation in the adhesive. In the flexural test, a drop in load occurred in three regions, and as the interfacial adhesion strength at the adhesive/FRP interface increased, the extent of the second load drop decreased with increasing load.