“…Drilling‐induced delamination refers to the interlaminar debonding occurring inside the adjacent layers of a composite as a result of bending stresses between the drill bit and the material contact point, which is firmly associated with the magnitudes of drilling thrust forces while drilling. [ 34 ] To quantify accurately the severity of the drilling‐induced delamination after machining the two types of thermoplastic composites, the newly‐developed three‐dimensional delamination factor ( F v ) was used to assess the machinability of the carbon/PI and carbon/PEEK composites. Figure 8 presents the variations of the delamination factor with respect to the cutting speed and the feed rate.…”
Section: Resultsmentioning
confidence: 99%
“…In drilling fibrous composites, thrust force signifies the machining load applied to the shear plane and it is the key cause of drilling-induced delamination which will reduce the fatigue strength of the composite materials. [33,34] Additionally, the thrust force is a fundamental indicator to assess the machinability and the power consumption during the composites machining. Since higher thrust forces often initiate higher levels of delamination damage of composites, the thrust force should be reduced as far as possible.…”
Polyimide (PI) and polyetheretherketone (PEEK) are superior high‐performance thermoplastics being extensively used in the fields of fiber‐reinforced polymer composites. However, there is very limited literature addressing the machining behavior of the PI and PEEK composites. The present paper aims to conduct a comparative study into the machining characteristics of these two representative high‐performance thermoplastic matrix composites under varying cutting conditions. Machinability aspects of the carbon/PI and carbon/PEEK thermoplastic composites were evaluated in terms of drilling forces, machining temperatures, delamination damage, surface morphologies, hole dimensional accuracy and tool wear. The results indicate that the carbon/PEEK composites generally show a much poorer machinability than the carbon/PI composites in terms of higher drilling forces, higher cutting temperatures, larger delamination extents and excessive tool wear. Since the carbon/PEEK composites exhibit certain ductility leading to the continuous chip formation, the cut hole surface morphologies and dimensional accuracy are much better than those gained in the carbon/PI composites. Both the cutting speed and the feed rate affect significantly the drilling forces and the resulting delamination damage. The fundamental wear mechanisms of drilling carbon/PI composites are abrasion wear in the form of edge rounding and slight chip adhesion, while for the carbon/PEEK composites, they are abrasion, serious chip adhesion because of the high drilling temperatures promoted at the drill‐work interface and catastrophic failures of coating peeling and edge fracture.
“…Drilling‐induced delamination refers to the interlaminar debonding occurring inside the adjacent layers of a composite as a result of bending stresses between the drill bit and the material contact point, which is firmly associated with the magnitudes of drilling thrust forces while drilling. [ 34 ] To quantify accurately the severity of the drilling‐induced delamination after machining the two types of thermoplastic composites, the newly‐developed three‐dimensional delamination factor ( F v ) was used to assess the machinability of the carbon/PI and carbon/PEEK composites. Figure 8 presents the variations of the delamination factor with respect to the cutting speed and the feed rate.…”
Section: Resultsmentioning
confidence: 99%
“…In drilling fibrous composites, thrust force signifies the machining load applied to the shear plane and it is the key cause of drilling-induced delamination which will reduce the fatigue strength of the composite materials. [33,34] Additionally, the thrust force is a fundamental indicator to assess the machinability and the power consumption during the composites machining. Since higher thrust forces often initiate higher levels of delamination damage of composites, the thrust force should be reduced as far as possible.…”
Polyimide (PI) and polyetheretherketone (PEEK) are superior high‐performance thermoplastics being extensively used in the fields of fiber‐reinforced polymer composites. However, there is very limited literature addressing the machining behavior of the PI and PEEK composites. The present paper aims to conduct a comparative study into the machining characteristics of these two representative high‐performance thermoplastic matrix composites under varying cutting conditions. Machinability aspects of the carbon/PI and carbon/PEEK thermoplastic composites were evaluated in terms of drilling forces, machining temperatures, delamination damage, surface morphologies, hole dimensional accuracy and tool wear. The results indicate that the carbon/PEEK composites generally show a much poorer machinability than the carbon/PI composites in terms of higher drilling forces, higher cutting temperatures, larger delamination extents and excessive tool wear. Since the carbon/PEEK composites exhibit certain ductility leading to the continuous chip formation, the cut hole surface morphologies and dimensional accuracy are much better than those gained in the carbon/PI composites. Both the cutting speed and the feed rate affect significantly the drilling forces and the resulting delamination damage. The fundamental wear mechanisms of drilling carbon/PI composites are abrasion wear in the form of edge rounding and slight chip adhesion, while for the carbon/PEEK composites, they are abrasion, serious chip adhesion because of the high drilling temperatures promoted at the drill‐work interface and catastrophic failures of coating peeling and edge fracture.
“…that thrust force and torque change depending on the fiber direction during drilling of this composite. 27 Test directions according to lamination and a schematic illustration of the composite material are given in Figure 1 Figure 1. Test directions of the samples according to lamination and a schematic illustration of the composite material.. Some other mechanical properties can be seen in Table 1…”
Section: Methodsmentioning
confidence: 99%
“…26 It is also reported by Erturk et al that thrust force and torque change depending on the fiber direction during drilling of this composite. 27 Test directions according to lamination and a schematic illustration of the composite material are given in Figure 1. Some other mechanical properties can be seen in Table 1.…”
This study aims to systematically investigate the abrasive wear performance of composite material with multi-layer polyester fiber interweaving and PTFE particle reinforced polyester matrix under dry friction conditions. Abrasive wear performance experimentally investigated by applying the block on ring test method depending on the direction of fiber weaving. The test material exposed to pure water, mineral oil, HNO3, and NH3 for 1, 2, 3, 4 weeks. The sliding distances and test durations were determined to be 2.26, 4.52, 6.78 and 9.04 km, 1, 2, 3 and 4 hours respectively. The best wear resistance was obtained in the perpendicular direction to the fiber reinforcement. While HNO3 and NH3 environments significantly decrease the wear resistance, oil and pure water environments increase the wear resistance by lubricant effect.
“…However, due to the low machinability of the CFRP materials caused by the abrasive character of the fiber reinforcement, the workpiece is susceptible to experience drilling induced damage, delamination being the prevalent damage [ 15 , 16 , 17 ]. The life in service of the component can be affected by this problem [ 18 , 19 , 20 , 21 ] and is still a challenge for the aerospace industry to reduce the induced damage during machining [ 14 , 22 , 23 ].…”
In this study, the open-hole quasi-static tensile and fatigue loading behavior of a multidirectional CFRP thick laminate, representative of laminates used in the aerospace industry, is studied. Non-destructive techniques such as infrared thermographic (IRT) and digital image correlation (DIC) are used to analyze the behavior of this material. We aim at characterizing the influence of the manufacturing defects and the stress concentrator through the temperature variation and strain distribution during fatigue and quasi-static tests. On the one hand, the fatigue specimens were tested in two main perpendicular directions of the laminate. The results revealed that manufacturing defects such as fiber waviness can have a major impact than open-hole stress concentrator on raising the material temperature and causing fracture. In addition, the number of plies with fibers oriented in the load direction can drastically reduce the temperature increment in the laminate. On the other hand, the quasi-static tensile tests showed that the strain distribution around the hole is able to predict the crack initiation and progression in the external plies. Finally, the experimental quasi-static tests were numerically simulated using the finite element method showing good agreement between the numerical and experimental results.
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