Critical thrust force at propagation of delamination zone due to drilling of FRP/metallic strips

2005 ◽  
Vol 69 (2) ◽  
pp. 137-141 ◽  
Author(s):  
Geun Woo Kim ◽  
Kang Yong Lee
Keyword(s):  
Thrust Force ◽  
Critical Thrust Force

Critical thrust force and critical feed rate in drilling flax fibre composites: A comparative study of various thrust force models

2019 ◽  
Vol 165 ◽  
pp. 222-232 ◽  
Author(s):  
Aiman Akmal Abdul Nasir ◽  
Azwan Iskandar Azmi ◽  
Tan Chye Lih ◽  
Mohd Shukry Abdul Majid
Keyword(s):  
Comparative Study ◽  
Feed Rate ◽  
Thrust Force ◽  
Flax Fibre ◽  
Fibre Composites ◽  
Critical Thrust Force

Effect of Peripheral Drilling Moment on Critical Thrust Force Using Twist Drill in Drilling Composite Materials

2011 ◽  
Vol 66-68 ◽  
pp. 528-533
Author(s):  
Chung Chen Tsao
Keyword(s):  
Composite Materials ◽  
Thrust Force ◽  
Construction Materials ◽  
Cutting Speed ◽  
Practical Experience ◽  
Twist Drill ◽  
Linear Elastic ◽  
Superior Mechanical Properties ◽  
Elastic Fracture ◽  
Critical Thrust Force

Composites have become valuable construction materials in the aerospace, defense, automobile, and civil industries due to their superior mechanical properties. However, there are significant differences between the machining of metals and alloys and that of composites, because composites are anisotropic and inhomogeneous. Drilling with a conventional twist drill is characterized by a relatively large thrust force due to a negative rake and negligibly small cutting speed at the chisel edge. Such a large thrust force causes defects and damages the composites, leading to poor hole quality, and reduced in-service life under fatigue loads. Although significant efforts have been made to realize the thrust force of twist drill, there are few papers reporting the effect of peripheral drilling moment (torque) on delamination in drilling composite materials. In this paper, an attempt is made to develop the critical thrust of the twist drill with peripheral drilling moment using linear elastic fracture mechanics (LEFM) and energy conservation. The theoretical results agree well with the practical experience in industries.

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.

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.

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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