Delamination In Carbon Fiber Reinforced Plastic Research Articles

Effects of Graphene Oxide Nanoparticles on Delamination in CFRP and Optimization Using Response Surface Modeling

AbstractCarbon fiber composites recently have captured the attention of many for their wide array of properties surpassing those of traditional metals. Carbon fiber‐reinforced plastic (CFRP) has several excellent properties like a high strength‐to‐weight ratio, better chemical resistance, and other strength characteristics. But one problem affecting the use of CFRP is its delamination. This occurs during drilling holes for various operations. It is a known fact that the aircraft industry is one such industry very much dependent on such drilling operations. Failures such as fiber rupture, surface irregularities, micro‐crack formation, and deformations around drilling regions are commonly encountered during the machining of CFRP composite. This research has studied the effects of graphene oxide nanoparticles on delamination in the drilling of CFRP composite. Carbon fiber is manufactured using a vacuum bag process. The optimum conditions for the drilling process are found by using response surface modeling (RSM) which leads to minimum delamination in CFRP fabricated.

Ultrahigh Resolution Pulsed Laser-Induced Photoacoustic Detection of Multi-Scale Damage in CFRP Composites

This paper presents a photoacoustic non-destructive evaluation (pNDE) system with an ultrahigh resolution for the detection of multi-scale damage in carbon fiber-reinforced plastic (CFRP) composites. The pNDE system consists of three main components: a picosecond pulsed laser-based ultrasonic actuator, an ultrasound receiver, and a data acquisition/computing subsystem. During the operation, high-frequency ultrasound is generated by pulsed laser and recorded by an ultrasound receiver. By implementing a two-dimensional back projection algorithm, pNDE images can be reconstructed from the recorded ultrasound signals to represent the embedded damage. Both potential macroscopic and microscopic damages, such as surface notches and delamination in CFRP, can be identified by examining the reconstructed pNDE images. Three ultrasonic presentation modes including A-scan, B-scan, and C-scan are employed to analyze the recorded signals for the representation of the detected micro-scale damage in two-dimensional and three-dimensional images with a high spatial resolution of up to 60 µm. Macro-scale delamination and transverse ply cracks are clearly visualized, identifying the edges of the damaged area. The results of the study demonstrate that the developed pNDE system provides a non-destructive and robust approach for multi-scale damage detection in composite materials.

Effects of machining conditions on the hole wall delamination in both conventional and ultrasonic-assisted CFRP drilling

The need of carbon fiber–reinforced plastics (CFRP) has been driven by the increasingly wide applications in many industrials including sports, transportation, and energy. However, until now, the poor machinability of CFRP can be still considered the key problem and the most urgent machining-induced issue can be the delamination damage in the drilling process. Although many efforts have been paid to investigate this topic, most of them investigated the delamination at either the hole entrance and the exit. Very few of these studies focused on the internal delamination defects on the hole wall, although these internal defects can be as important as the entrance and exit defects. To fill this gap, this paper investigated the condition effects (feed rate, spindle speed, ultrasonic vibration of drills, and the workpiece support strategy) on the delamination in CFRP drilling, with the special focus on the internal delamination damage on the inside hole walls. Based on both the experimental and theoretical analysis, the effectiveness of the back supports and the variable feed rates was investigated as well. Considering few published studies reported the delamination on the hole wall, the key findings in this paper are expected to be meaningful to deepen the understanding of CFRP drilling and helpful to provide some industrial guidance.

Eddy Current Volume Heating Thermography and Phase Analysis for Imaging Characterization of Interface Delamination in CFRP

Imaging inspection is highly demanded in the optimization of industry processes. Optical imaging inspection is not applicable for inside defects, while infrared (IR) imaging inspection can provide information about internal structure of objects. Eddy current thermography is an emerging IR imaging inspection technique for conductive materials or objects. This paper presents eddy current volume heating thermography (ECVHT) and phase analysis for delamination inspection in carbon fiber reinforced plastics (CFRPs) based on the previously proposed eddy current pulsed phase thermography (ECPPT). The proposed method has been verified through experimental studies under both transmission and reflection modes. After discrete Fourier transform (DFT) of temperature responses, the phasegram and phase spectra can be used to image and characterize interface delamination in CFRP due to elimination of nonuniform heating effect and carbon fiber structures. With the whole temperature response processed by DFT, carbon fiber structures and delamination can be differentiated due to periodic oscillation of phase spectra. With temperature response in cooling phase processed by DFT, some characteristic features can be extracted to construct the new phase images according to the shape of phase spectra. In all, using ECVHT and phase analysis, imaging characterization for delamination can get much better performance than conventional visible optical inspection system and eddy current pulsed thermography.

Mid IR pulsed light source for laser ultrasonic testing of carbon-fiber-reinforced plastic

A quasi-phase-matched (QPM) optical parametric oscillator (OPO) was developed using a periodically poled Mg-doped stoichiometric LiTaO3 crystal to generate mid-IR light for excitation of laser ultrasound in carbon fiber reinforced plastic (CFRP). The ultrasound generation efficiency was measured at the three different wavelengths that emanate from the OPO: 1.064 μm, 1.59/1.57 μm, and 3.23/3.30 μm. The measurements indicate that mid-IR 3.2–3.3 μm light generates the most efficient ultrasonic waves in CFRP with the least laser damage. We used mid-IR light in conjunction with a laser interferometer to demonstrate the detection of flaws/defects in CFRP such as the existence of air gaps that mimic delamination and voids in CFRP, and the inhomogeneous adhesion of CFRP material to a metal plate was also clearly detected.

Detection of Delamination in GFRP and CFRP by Microwaves with Focusing Mirror Sensor

A technique to detect delamination in composite materials by noncontact, rapid and high sensitive microwave reflectometry with a focusing mirror sensor was proposed. The focusing mirror sensor, which has high sensitivity and resolution, is expected to detect delamination sensitively. In this paper, the ability of microwave inspection to detect delamination in glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) was verified. As the results, the existences of 100 μm thick delamination in 3 mm thick GFRP laminate and 2 mm thick CFRP laminate were detected.