Effect of workpiece stiffness on thrust force and delamination in drilling thin composite laminates

2015 ◽  
Vol 50 (5) ◽  
pp. 617-625 ◽  
Author(s):  
Bin Luo ◽  
Yuan Li ◽  
Kaifu Zhang ◽  
Hui Cheng ◽  
Shunuan Liu
Keyword(s):  
Composite Laminates ◽  
Thrust Force

Delamination-Free Drilling of Composite Laminates

1994 ◽  
Vol 116 (4) ◽  
pp. 475-481 ◽  
Author(s):  
S. Jain ◽  
D. C. H. Yang
Keyword(s):  
Composite Laminates ◽  
Thrust Force ◽  
Tool Geometry ◽  
Elliptical Plate ◽  
Hole Quality ◽  
Drilling Operation ◽  
Twist Drills ◽  
Drill Tool

Composite laminates in significant numbers are rendered unacceptable due to delamination that occurs during the drilling operation. Thrust generated during the drilling operation is identified as responsible for delamination. Expressions developed for critical thrusts and critical feed rates, by modeling the delamination zone as an elliptical plate in unidirectional laminates, appear to be fairly accurate. It has been demonstrated that the critical thrusts and feed rates obtained for unidirectional laminates can be conservatively used for multi-directional laminates. With regard to the tool geometry, the chisel edge width appears to be the single most important factor contributing to the thrust force and hence delamination. A diamond-impregnated tubular drill tool was designed and tested. This tool resulted in a much smaller thrust and much better hole quality as compared with the standard twist drills.

Machinability of drilling T700/LT-03A carbon fiber reinforced plastic (CFRP) composite laminates using candle stick drill and multi-facet drill

2015 ◽  
Vol 29 (10n11) ◽  
pp. 1540031 ◽  
Author(s):  
Cheng-Dong Wang ◽  
Kun-Xian Qiu ◽  
Ming Chen ◽  
Xiao-Jiang Cai
Keyword(s):  
Carbon Fiber ◽  
Feed Rate ◽  
Composite Laminates ◽  
Thrust Force ◽  
Spindle Speed ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Drilling Parameters ◽  
Cfrp Composite

Carbon Fiber Reinforced Plastic (CFRP) composite laminates are widely used in aerospace and aircraft structural components due to their superior properties. However, they are regarded as difficult-to-cut materials because of bad surface quality and low productivity. Drilling is the most common hole making process for CFRP composite laminates and drilling induced delamination damage usually occurs severely at the exit side of drilling holes, which strongly deteriorate holes quality. In this work, the candle stick drill and multi-facet drill are employed to evaluate the machinability of drilling T700/LT-03A CFRP composite laminates in terms of thrust force, delamination, holes diameter and holes surface roughness. S/N ratio is used to characterize the thrust force while an ellipse-shaped delamination model is established to quantitatively analyze the delamination. The best combination of drilling parameters are determined by full consideration of S/N ratios of thrust force and the delamination. The results indicate that candle stick drill will induce the unexpected ellipse-shaped delamination even at its best drilling parameters of spindle speed of 10,000 rpm and feed rate of 0.004 mm/tooth. However, the multi-facet drill cutting at the relative lower feed rate of 0.004 mm/tooth and lower spindle speed of 6000 rpm can effectively prevent the delamination. Comprehensively, holes quality obtained by multi-facet drill is much more superior to those obtained by candle stick drill.

Optimal control during drilling in GFRP composite laminates

2014 ◽  
Vol 10 (4) ◽  
pp. 611-630 ◽  
Author(s):  
Amrinder Pal Singh ◽  
Manu Sharma ◽  
Inderdeep Singh
Keyword(s):  
Optimal Control ◽  
State Space ◽  
Feed Rate ◽  
Composite Laminates ◽  
Transfer Functions ◽  
Thrust Force ◽  
Optimal Controller ◽  
Content Type ◽  
Force Profile ◽  
Critical Thrust Force

Purpose – Damage due to delamination is an important issue during drilling in polymer-matrix composites (PMCs). It depends on thrust force and torque which are functions of feed rate. Transfer function of thrust force with feed rate and torque with feed rate is constructed through experiments. These transfer functions are then combined in state-space to formulate a sixth-order model. Then thrust force and torque are controlled by using optimal controller. The paper aims to discuss these issues. Design/methodology/approach – A glass fiber reinforced plastic composite is drilled at constant feed rate during experimentation. The corresponding time response of thrust force and torque is recorded. Third-order transfer functions of thrust force with feed rate and torque with feed rate are identified using system identification toolbox of Matlab®. These transfer functions are then converted into sixth-order combined state-space model. Optimal controller is then designed to track given reference trajectories of thrust force/torque during drilling in composite laminate. Findings – Optimal control is used to simultaneously control thrust force as well as torque during drilling. There is a critical thrust force during drilling below which no delamination occurs. Therefore, critical thrust force profile is used as reference for delamination free drilling. Present controller precisely tracks the critical thrust force profile. Using critical thrust force as reference, high-speed drilling can be done. The controller is capable of precisely tracking arbitrary thrust force and torque profile simultaneously. Findings suggest that the control mechanism is efficient and can be effective in minimizing drilling induced damage in composite laminates. Originality/value – Simultaneous optimal control of thrust force and torque during drilling in composites is not available in literature. Feed rate corresponding to critical thrust force trajectory which can prevent delamination at fast speed also not available has been presented.

Delamination During Drilling in Composite Laminates

1990 ◽  
Vol 112 (3) ◽  
pp. 236-239 ◽  
Author(s):  
H. Ho-Cheng ◽  
C. K. H. Dharan
Keyword(s):  
Composite Laminates ◽  
Structural Integrity ◽  
Force Feedback ◽  
Thrust Force ◽  
Hybrid Composites ◽  
Assembly Tolerance ◽  
Delamination Fracture ◽  
Performance Deterioration ◽  
Long Term Performance ◽  
Term Performance

Delamination is the major concern during drilling of composite laminates. Delamination, in addition to reducing the structural integrity of the laminate, also results in poor assembly tolerance and has the potential for long-term performance deterioration. Drilling-induced delamination occurs both at the entrance and at the exit planes. This paper presents an analysis of delamination during drilling. The analysis uses a fracture mechanics approach in which the opening-mode delamination fracture toughness, a material parameter, is used with a plate model of the laminate. The analysis predicts an optimal thrust force (defined as the minimum force above which delamination is initiated) as a function of drilled hole depth. Good agreement is achieved with data obtained from drilling carbon fiber-epoxy laminates. An advantage of the model is that it can predict varying degrees of delamination for other materials, such as glass fiber-epoxy, and for hybrid composites. In addition, the optimal thrust force for no delamination can be used to control a drilling machine with thrust force feedback for maximizing productivity.

Effects of Feedrate and Chisel Edge on Delamination in Composites Drilling

1993 ◽  
Vol 115 (4) ◽  
pp. 398-405 ◽  
Author(s):  
S. Jain ◽  
D. C. H. Yang
Keyword(s):  
Composite Laminates ◽  
Thrust Force ◽  
Plate Theory ◽  
Tool Geometry ◽  
Laminated Plate ◽  
Elliptical Plate ◽  
Time Optimal ◽  
Critical Thrust Force ◽  
Clamped Edges ◽  
Central Load

Delamination accompanied with the drilling of composite laminates has been recognized as a major problem. An analytical model is established to predict critical thrust force and critical feedrate at which the delamination crack begins to propagate. For unidirectional composites, the delamination zone is modeled as an elliptical plate, with clamped edges and subjected to a central load. Based on fracture mechanics, laminated plate theory and cutting mechanics, expressions are developed for critical thrusts and critical feedrates at which delamination is initiated at different ply locations. This model has been verified by experiments. A variable feedrate strategy is formulated based on this model, which avoids delamination while drilling in a time-optimal fashion. In addition, the need to modify tool geometry to avoid delamination is highlighted. Chisel edge width has been identified as an important factor contributing to the thrust force and hence delamination.

scholarly journals Optimization for drilling process of metal-composite aeronautical structures

2021 ◽  
Vol 28 (1) ◽  
pp. 264-275
Author(s):  
Cristiano Devitte ◽  
Gabriel S. C. Souza ◽  
André J. Souza ◽  
Volnei Tita
Keyword(s):  
Feed Rate ◽  
Composite Laminates ◽  
Thrust Force ◽  
Cutting Speed ◽  
Statistical Design ◽  
Burr Formation ◽  
Drilling Process ◽  
Metal Composite ◽  
Aircraft Manufacturing ◽  
Delamination Factor

Abstract Metal-composite laminates and joints are applied in aircraft manufacturing and maintenance (repairing) using aluminum alloys (AA) and glass fiber-reinforced polymer (GFRP). In these applications, drilling has a prominent place due to its vast application in aeronautical structures’ mechanical joints. Thus, this study presents the influence of uncoated carbide drills (85C, 86C, H10N), cutting speeds (v c = 20, 40, and 60 m min−1), and feed rates (f = 0.05, 0.15, and 0.25 mm rev−1) on delamination factor, thrust force ( F t {F}_{\text{t}} ), and burr formation in dry drilling metal-composite laminates and joints (AA2024/GFRP/AA2024). Experiments were performed, analyzed, and optimized using the Box–Behnken statistical design. Microscopic digital images for delamination evaluation, piezoelectric dynamometer for thrust force acquisition, and burr analysis were considered. The major finding was that the thrust force during drilling depends significantly on the feed rate. Another significant factor was the influence of the drill type (combined or not with feed rate). In fact, it was verified that the feed rate and the drill type were the most significant parameters on the delamination factor, while the feed rate was the most relevant on thrust force. The cutting speed did not affect significantly thrust force and delamination factor at exit ( F da S ) \hspace{.25em}({F}_{{\text{da}}_{\text{S}}}) . However, the combination f × v c was significant in delamination factor at entrance   ( F da E ) \text{ }({F}_{{\text{da}}_{\text{E}}}) . Based on the optimized input parameters, they presented lower values for delamination factors ( F da E = 1.18 {F}_{{\text{da}}_{\text{E}}}=1.18 and F da S = 1.33 {F}_{{\text{da}}_{\text{S}}}=\hspace{.25em}1.33 ) and thrust force ( F t = 67.3 N {F}_{\text{t}}=67.3\hspace{.5em}\text{N} ). These values were obtained by drilling the metal-composite laminates with 85C-tool, 0.05 mm rev−1 feed rate, and 20 m min−1 cutting speed. However, the burrs at the hole output of AA2024 were considered unsatisfactory for this specific condition, which implies additional investigation.

Chisel Edge and Pilot Hole Effects in Drilling Composite Laminates

2002 ◽  
Vol 124 (2) ◽  
pp. 242-247 ◽  
Author(s):  
M. S. Won ◽  
C. K. H. Dharan
Keyword(s):  
Composite Laminates ◽  
Thrust Force ◽  
Threshold Value ◽  
Entry And Exit ◽  
Drilling Force ◽  
Pilot Hole ◽  
Reinforced Composite ◽  
Wide Range ◽  
Twist Drills ◽  
Good Agreement

Previous studies have shown the severe limitations that have to be placed on machining forces when drilling composite laminates due to their propensity for delamination. Delamination, which consists of separation between the plys in a laminate, is due to the relatively poor strength of these materials in the thickness direction. In drilling, delamination is initiated when the drilling force exceeds a threshold value, particularly at the critical entry and exit locations of the drill bit. While abrasive machining results in damage-free holes in most composites, such processes are slow and expensive when compared to drilling with conventional twist drills. Here it is shown that the chisel edge in such drills is a major contributor to the thrust force that is the primary cause of delamination when drilling composite laminates. In this study, a series of drilling experiments were conducted on carbon fiber-reinforced composite laminates to determine quantitatively the effect of the chisel edge on the thrust force. In addition, tests were conducted to determine the effect of pre-drilling the laminate with a pilot hole. The results show a large reduction in the thrust force when a pilot hole is present which, in effect, removes the chisel edge contribution. An analytical model that incorporates the presence of a pilot hole is also described. The results from the thrust force-feed relationships show good agreement with experimentally determined values for the thrust force for a wide range of feeds for drilling tests conducted on laminates with and without pilot holes.

Prediction of critical thrust force for exit-ply delamination during drilling composite laminates: thermo-mechanical analysis

2016 ◽  
Vol 18 (1/2) ◽  
pp. 77 ◽  
Author(s):  
Jamel Saoudi ◽  
Redouane Zitoune ◽  
Suhasini Gururaja ◽  
Salah Mezlini ◽  
Akshay Amaranath Hajjaji
Keyword(s):  
Composite Laminates ◽  
Thrust Force ◽  
Mechanical Analysis ◽  
Critical Thrust Force
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