Accuracy and surface quality of abrasive waterjet machined CFRP composites

2020 ◽  
pp. 002199832097442
Author(s):  
HA Youssef ◽  
HA El-Hofy ◽  
AM Abdelaziz ◽  
MH El-Hofy
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
Removal Rate ◽  
Kerf Width ◽  
Fiber Reinforced Polymers ◽  
Abrasive Waterjet ◽  
Experimental Investigations ◽  
Fiber Reinforced ◽  
Cfrp Laminates ◽  
Carbon Fiber Reinforced

The use of carbon fiber-reinforced composites is increasing today since they have an excellent weight-to-mechanical properties ratio. Traditional machining of this material is difficult. Abrasive water jet machining (AWJM) is an advanced non-traditional material removal process that can machine hard-to-cut materials. The process is widely used in aerospace, marine, and automotive industries. However, it encounters several challenges when cutting carbon fiber reinforced polymers (CFRP). The present work aims to study the characteristics of AWJM of CFRP laminates. Detailed experimental investigations are conducted to explore the effect of traverse feed and standoff distance (SOD) on top kerf width, bottom kerf width, kerf angle, profile area, volumetric removal rate, and the average surface roughness, and jet deviation factor. Repeatability tests are also used to assess the kerf dimensional accuracy and surface roughness tolerance achieved by AWJM of CFRP laminates. Results showed that the surface roughness increases along with the cut thickness, especially at large traverse feed and SOD. Both the kerf taper angle and the volumetric removal rate increase with traverse feed and SOD.

High Speed Routing of Woven Carbon Fiber Reinforced Epoxy Laminates

2012 ◽  
Author(s):  
M. Meshreki ◽  
A. Sadek ◽  
M. H. Attia
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
Tool Wear ◽  
High Speed ◽  
Thermal Characteristics ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Axial Forces ◽  
Carbon Fiber Reinforced ◽  
Dimensional Errors

Little is known about the high speed routing of Carbon Fiber Reinforced Polymers (CFRP). Most of the work in the literature has focused on the drilling of CFRP. In this paper, an extensive experimental study has been conducted to better understand the dynamic, tribological, and thermal characteristics of high speed milling of CFRPs, in the range of 10,000 to 40,000 rpm (200 to 800 m/min, for 6.35 mm end-mill). The material used was a quasi-isotropic laminate comprising 35 plies of woven graphite epoxy. The tool wear was investigated on the flank and the rake faces. The machined slots were characterized in terms of straightness errors, dimensional errors, surface roughness, and delamination. The tool over-hang controls the tool dynamics, in this high speed range, and significantly affect various quality attributes of the produced holes; roughness, dimensional errors, and straightness. Similar trends were observed for the forces and the temperatures, whereby there is a given speed at which they reach a minimum and then they start to increase for higher speeds. The machining force and temperature trends with varying speeds and feeds are controlled by the chip load, the specific cutting pressures, and the effect of the frictional forces. The increased tool wear was found to directly affect the cutting forces and consequently lead to high delamination and surface roughness. The milled surface quality was mainly controlled by the feed rate. Limited surface delamination was observed due to the low axial forces associated with the routing process.

Fire Resistance of Structural Concrete Retrofitted with Carbon Fiber–Reinforced Polymer Composites

2015 ◽  
Vol 2522 (1) ◽  
pp. 151-160 ◽  
Author(s):  
D. V. Reddy ◽  
Khaled Sobhan ◽  
Jody D. Young
Keyword(s):  
Carbon Fiber ◽  
Fire Resistance ◽  
Fire Protection ◽  
Fiber Reinforced Polymers ◽  
Experimental Investigations ◽  
Small Scale ◽  
Fire Exposure ◽  
Fiber Reinforced ◽  
Rc Structures ◽  
Carbon Fiber Reinforced

This paper presents an experimental investigation for evaluating the effects of fire exposure on properties of structural elements retrofitted by carbon fiber–reinforced polymers (CFRPs). Mechanical properties of CFRP-strengthened reinforced concrete (RC) members, protected with secondary insulation, were investigated, before and after (residual) direct fire exposure. Direct fire contact resulted in a reduction in capacity of 9% to 20% for CFRP-strengthened RC beams and 15% to 34% for CFRP-strengthened RC columns. Furthermore, a similitude analysis was developed for a heat transfer relationship between full-scale and small-scale specimens, allowing a one-fourth exposure time reduction for the latter. Results from the experimental investigations demonstrated the benefits of employing secondary fire protection to CFRP-strengthened structures, despite the glass transition temperature being exceeded in the early stages of the elevated-temperature exposure. Therefore, it is suggested that fire protection is necessary for a CFRP-strengthened structure to retain integrity throughout the duration of the fire exposure and on return to ambient temperature. The conclusions of this investigation will lead to recommendations and guidelines to designers and practicing engineers for using CFRP materials in retrofitting RC structures with adequate fire resistance by contributing to the missing information for fire protection requirements not available in codes of practice.

CRYOGENIC DRILLING OF CARBON FIBER-REINFORCED COMPOSITE (CFRP)

2019 ◽  
Vol 26 (09) ◽  
pp. 1950060 ◽  
Author(s):  
UĞUR KOKLU ◽  
SEZER MORKAVUK
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
Tool Wear ◽  
Thrust Force ◽  
Fiber Reinforced Polymers ◽  
Cryogenic Machining ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Carbon Fiber Reinforced

In order to reduce the adverse effects on the environment and economy and to avoid health problems caused by the excessively used cutting lubrications, cryogenic machining is drawing more and more attention. In this work, a novel cryogenic machining approach was applied for drilling of carbon fiber-reinforced polymers (CFRPs). According to this approach, CFRP was dipped into the liquid nitrogen (LN2) and it was machined within the cryogenic coolant directly. Various machinability characteristics on thrust force, delamination damage, tool wear, surface roughness, and topography were compared with those obtained with dry condition. This experimental study revealed that the novel method of machining with cryogenic dipping significantly reduced tool wear and surface roughness but increased thrust force. Overall results showed that the cryogenic machining approach in this study improved the machinability of CFRP.

scholarly journals Ultrasonic Imaging of Thick Carbon Fiber Reinforced Polymers through Pulse-Compression-Based Phased Array

2021 ◽  
Vol 11 (4) ◽  
pp. 1508
Author(s):  
Muhammad Khalid Rizwan ◽  
Stefano Laureti ◽  
Hubert Mooshofer ◽  
Matthias Goldammer ◽  
Marco Ricci
Keyword(s):  
Carbon Fiber ◽  
Pulse Compression ◽  
Phased Array ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Ultrasonic Imaging ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Custom Made ◽  
Carbon Fiber Reinforced

The use of pulse-compression in ultrasonic non-destructive testing has assured, in various applications, a significant improvement in the signal-to-noise ratio. In this work, the technique is combined with linear phased array to improve the sensitivity and resolution in the ultrasonic imaging of highly attenuating and scattering materials. A series of tests were conducted on a 60 mm thick carbon fiber reinforced polymer benchmark sample with known defects using a custom-made pulse-compression-based phased array system. Sector scan and total focusing method images of the sample were obtained with the developed system and were compared with those reconstructed by using a commercial pulse-echo phased array system. While an almost identical sensitivity was found in the near field, the pulse-compression-based system surpassed the standard one in the far-field producing a more accurate imaging of the deepest defects and of the backwall of the sample.

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