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Investigation of cut quality in fiber laser cutting of CFRP
摘要： Fiber laser cutting of CFRP sheets was investigated using a 2 kW multi-mode fiber laser, focusing on how the cut quality factors, such as kerf width, kerf depth, matrix evaporation width, matrix recession width, kerf taper angle, matrix damage zone, and cut surface morphology, change as laser power, laser scanning speed, and the number of laser passes are varied. By designing a systematic experiment on a large process window, several important parameters for kerf width, kerf depth, matrix evaporation width, and matrix recession width were identified, and using them, it was verified that the beam scanning speed is a dominant factor for minimizing thermal damages. Also, circular rings were observed in each carbon fiber at the cut surfaces, and it looked as if they were generated when each fiber was thermally fused in the radial direction. A larger number of laser passes was found to contribute to a smooth surface morphology, because of the formation of highly-fused surfaces, which prevents fiber delamination and pull-outs. Optimum process conditions were also identified by comparing various cut quality factors.
关键词： Fiber laser cutting,Optimal process conditions,Cut quality factors,Thermal damage,Carbon fiber reinforced plastic (CFRP)
更新于2025-11-28 14:24:20
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Parametric study of laser cutting of carbon fibre reinforced polymer (CFRP) and the effect of fibre orientation on cutting quality
摘要： Laser cutting of CFRP was performed using 2 kW fibre laser. A detailed analysis of the effect of various laser processing parameters on the cutting of CFRP was carried out. The present work considers mainly laser power (W), scan speed (mm/min), gas pressure (bar) and duty cycle (%) as the process parameters with average kerf width and heat affected zone (HAZ) as the output parameters. Cutting of the fibres at 90o with respect to fibre orientation was performed. The SEM and EDS analysis were also performed to understand the cut quality, matrix melting, fibre pullout and vaporisation phenomena of the matrix in the heat affected zone (HAZ). Laser cutting of CFRP with a minimum kerf width of around 184 μm was observed for 800 W, 600 mm/min, 3 bar and 25% duty cycle while HAZ in this parameter was around 1561 μm. Kerf width and HAZ directly increase with an increase in laser power, gas pressure and duty cycle, but they reduce with increase in scan speed. SEM images confirm that the CFRP cutting process generates relatively burr-free fibre edges. Matrix recession and delamination (fibre pullout) were identified as the major quality defects occurring in the laser cutting process of CFRP.
关键词： fibre delamination,matrix melting,heat affected zone,laser cutting,fibre consolidation,kerf width,CFRP
更新于2025-11-28 14:24:20
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Influence of the Ply Angle Deviation on the Out-of-Plane Deformation of the Composite Space Mirror
摘要： In order to discuss the influence of the ply angle deviation, six symmetric quasi-isotropic layup sequences imposed the fixed or random angle deviation were studied based on the numerical analysis, such as Monte Carlo stochastic finite element method and statistic analysis. The out-of-plane deformation was observed in spite of the symmetric quasi-isotropic sequences subjected to a temperature change due to the ply angle deviation in the space mirror. The surface peak-to-valley (PV), which is one kind of out-of-plane deformation, is proportional to the magnitude of the fixed angle deviation, and the mean of PVs is also proportional to the standard deviation of the random angle deviation. The out-of-plane deformation resulting from two-ply angle deviation indirectly satisfies the parallelogram law, and if each ply angle deviation is random independently, the probability density of that satisfies the Rayleigh distribution. In this paper, it is found that the most effective method to improve the surface accuracy of the space mirror is decreasing the standard deviation of the angle deviation, next to decreasing ply thickness and optimizing layup sequence, which is useful for application in the space mirror.
关键词： Rayleigh distribution,MCSFEM,Out-of-plane deformation,Mirror,CFRP
更新于2025-09-23 15:23:52
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Surface Pretreatment of Fiber-Reinforced Plastics via VUV Radiation
摘要： Fiber-reinforced plastics (FRP) are of great importance for the transport sector, the aerospace industry, for wind power plants, in the building sector and in the field of sports and leisure applications. Optimization of the adhesive bonding process for FRP structures, especially the surface preparation prior to bonding, will be of a central importance in forthcoming expansion of FRP use. In this connection the key problem depends on the FRP polymer matrix. In the case of duroplastic matrix the main problem is the presence of release agent on the surface of joining components. For the thermoplastic matrix such as polypropylene (PP), the main problems are the low surface energy and the inertness of its surface. Conventional pretreatment methods, such as manual grinding, shall be replaced by energetic radiation technics like VUV lamps (vacuum ultraviolet spectral range: 100 – 200 nm). This approach is a non-contact method, characterized by high treatment homogeneity and material-saving properties, combined with no further fibers to be released. The surface of the thermoplastics is activated by the incorporation of oxygen, release agent contamination on the thermoset is cleaned or modified [1 - 8]. The results of the VUV surface activation of PP and CFRP with regard to the incorporation of functional groups, increase of surface energy, matrix degradation and the adhesion increase of adhesive bonds are presented. In addition, studies on the release agent coating and the release agent modification by VUV radiation are presented. The work is completed by considerations concerning possibilities to accelerate the process (in particular, wavelength dependence, influence of an inert gas or the moisture content). Finally, an evaluation of the VUV pretreatment is carried out on the basis of two specific applications.
关键词： VUV,irradiation,excimer,release agent,surface pretreatment,CFRP,FRP,GRP
更新于2025-09-23 15:22:29
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Using differential spread laser infrared thermography to detect delamination and impact damage in CFRP
摘要： In this paper, the feasibility of differential spread laser infrared thermography (DSLIT) to detect delamination and impact damage in carbon fiber reinforced polymer (CFRP) is investigated. The proposed method can significantly eliminate the influence of the uneven laser energy distribution and improve the detectability of laser infrared thermography. First, numerical simulation is carried out following the procedure of DSLIT to verify the feasibility of this method. Secondly, through experiments on the detection of defects both in practical aviation CFRP and common CFRP, the feasibility of DSLIT is confirmed. For the common CFRP, this technique has excellent performance: a defect at a depth of 2.5 mm was detected successfully, with the width-to-depth ratio reaches to 2.4. Comparatively speaking, the defect detection results for the aviation CFRP are not as good as those for the common CFRP. However, defects at a depth of 1.125 mm were detected, with the width-to-depth ratio reaching 2.67. In addition, defects caused by a low-velocity impact in practical aviation CFRP were successfully detected. Finally, the thermal data were processed by image processing methods such as sequence differential preprocessing (SDP), phase analysis (PA) and principal component analysis (PCA) to enhance the defect imaging results.
关键词： Laser infrared thermography,Delamination,Impact damage,Differential processing,Aviation CFRP
更新于2025-09-23 15:21:01
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The Inspection of CFRP Laminate with Subsurface Defects by Laser Arrays Scanning Thermography (LAsST)
摘要： Laser array scanning thermography (LAsST) was used to detect the subsurface defects of carbon fiber reinforced composite (CFRP). A series of bottom flat hole (BFHs) of CFRP were prepared for LAsST. Truncation pseudo-static matrix reconstruction (TC-PSMR) method was used to reconstruct the thermal response signal. Fast Fourier transform (FFT), principal component analysis (PCA) and partial least squares regression (PLSR) were used to process the thermal response signals, forming FFT image, PCA image, and PLSR image. The signal noise ratios (SNRs) of defects is calculated, and it is used to evaluate the defect detection ability of different post-processing algorithms. The experimental results show that the image based on FFT phase has a higher signal-to-noise ratio with PLSR image, and the FFT amplitude image and PLSR image can accurately represent the defect size.
关键词： FFT,Laser arrays scan thermography,Partial least squares regression,CFRP
更新于2025-09-23 15:19:57
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Investigation of hole quality in drilled Ti/CFRP/Ti laminates using CO2 laser
摘要： The machinability of titanium (Ti) and carbon fiber reinforced plastic (CFRP) (Ti/CFRP/Ti) laminates using CO2 laser is presented in this work. The effect of line energy and laser frequency on output responses such as heat affected zone (HAZ), taper angle (TA), metal composite interface (MCI) damage, surface roughness, dross height, and circularity were investigated. Line energy - the most influential parameter - demonstrated a threshold behavior; no drilling was observed below a certain line energy. Scanning acoustic microscopy (SAM), scanning electron microscopy (SEM), micro-computed tomography (μ-CT), and other imaging techniques were used to establish a correlation between laser parameters and CO2 laser machined damage in Ti/CFRP/Ti laminates. The results show that using a higher frequency and lower line energy can significantly improve the hole quality. However, dross free holes with minimum taper can be obtained using higher line energy.
关键词： Surface roughness,Circularity,Micro-hardness,CO2 laser,Dross height,HAZ,Drilling,Ti/CFRP/Ti,MCI damage factor,TA
更新于2025-09-23 15:19:57
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Low power direct laser-assisted machining of carbon fibre-reinforced polymer
摘要： The direct laser-assisted machining (DLAM) technique is introduced to improve the CFRP machining process. The DLAM technique applies focused laser at the tool edge through a sapphire tool. A fibre laser with 4.3 W power was used to have the desired temperature, estimated from the finite element model. Experimental orthogonal cutting tests were performed to compare the DLAM technique to the conventional dry cutting of the woven CFRP. We have observed reduced cutting forces in both in-plane and side cutting orientations. Observations with 3D surface profilometer also showed a decrease in defects and improved surface roughness when DLAM was applied.
关键词： CFRP machining,thermo-mechanical properties,Laser assisted machining
更新于2025-09-19 17:13:59
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Development of Smart Structure for Satellite Using Optical Fiber Sensors
摘要： 本開発では，はじめに，宇宙熱環境における太陽電池パネルの熱構造設計を地上試験で検証するため，光ファイバセンサを活用した健全性評価手法を開発した．本手法により，低温環境でのサブストレートのディンプル変形に起因するパネル内部の損傷発生を光ファイバセンサで検知できることを示した．次に，その開発技術を応用し，センサの着脱工程を削減して試験工期を短縮するため，光ファイバセンサ一体型衛星構造「スマート熱構造」の開発に取り組んだ．光ファイバ温度センサを開発し，数十点規模の温度センサとひずみセンサを備えた実験モデルを試作し，その製造性を確認した．また，その実験モデルを用いて，熱真空試験や四点曲げ試験を実施し，従来センサとほぼ同等の精度にて温度やひずみが計測できることを示した．さらに，スマート熱構造に搭載した電子機器内の部品にも温度センサを取り付けて動作試験を行い，従来では取得できなかった狭小部の温度も計測した．これらの結果から，スマート熱構造が実現可能であることを示した．
关键词： CFRP,Strain,Temperature,Multi-point measurement,Smart structure,Satellite,Optical fiber sensor,Damage detection
更新于2025-09-16 10:30:52
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The Effect of Fiber Laser Machining Parameters on Thermal-Affected Zone of Carbon Fiber Reinforced Plastic
摘要： This study describes the effects of machining parameters on the thermal-affected zone (heat-affected zone; HAZ) of carbon fiber reinforced plastic using fiber laser. The HAZ described in this study was defined as the area where only resin was removed. In three experiments, the HAZ area and the removal shape of carbon fiber were investigated. The study revealed that pulsed laser reduces the HAZ more than continuous-wave laser does, but it causes the swelling of the carbon fiber tip. Furthermore, the HAZ decreased as the scan speed increased, even if the number of scans was increased. In addition, it was found that nitrogen could restrain the HAZ and the swelling of carbon fiber.
关键词： HAZ,fiber laser,machining of CFRP
更新于2025-09-16 10:30:52