Heat-Affected Zone and Mechanical Analysis of GFRP Composites with Different Thicknesses in Drilling Processes

Abstract

This article presents a comprehensive thermomechanical analysis and failure assessment in the drilling of glass fiber-reinforced polymer (GFRP) composites with different thicknesses using a CNC machine and cemented carbide drill with a diameter of 6 mm and point angles of ϕ = 118°. The temperature distribution through drilling was measured using two techniques. The first technique was based on contactless measurements using an IR Fluke camera. The second was based on contact measurements using two thermocouples inserted inside the drill bit. A Kistler dynamometer was used to measure the cutting forces. The delamination factors at the hole exit and hole entry were quantified by using the image processing technique. Multi-variable regression analysis and surface plots were performed to illustrate the significant coefficients and contribution of the machining variables (i.e., feed, speed, and laminate thickness) on machinability parameters (i.e., the thrust force, torque, temperatures, and delamination). It is concluded that the cutting time, as a function of machining variables, has significant control over the induced temperature and, thus, the force, torque, and delamination factor in drilling GFRP composites. The maximum temperature recorded by the IR camera is lower than that of the instrumented drill because the IR camera cannot directly measure the tool–work interaction zone during the drilling process. At the same cutting condition, it is observed that by increasing the thickness of the specimen, the temperature increased. Increasing the thickness from 2.6 to 7.7 had a significant effect on the heat distribution of the HAZ. At a smaller thickness, increasing the cutting speed from 400 to 1600 rpm decreased the maximum thrust force by 15%. The push-out delaminations of the GFRP laminate were accompanied by edge chipping, spalling, and uncut fibers, which were higher than those of the peel-up delaminations.

Experimental Study and Artificial Neural Network Simulation of Cutting Forces and Delamination Analysis in GFRP Drilling

“…Similar observations were made in [ 36 ] with respect to the drilling of unidirectional CFRP. Additionally, T. Panneerselvam [ 23 ] concluded that the parameter that has the greatest impact on delamination is the feed rate. The lowest amplitude values of the cutting-force component F z were obtained for the lowest tested feed per tooth value of 0.04 mm/tooth for all tested materials (A1 = 132 N, A2 = 154 N, B1 = 121 N, B2 = 218 N), and it can be observed that the materials produced with the use of a special pressing device are characterized by lower values of the cutting-force component F z .…”

“…A peeling force is induced through the slope of a drill flute and separates the top layers, causing peel-up delamination [ 22 ]. Push-out delamination of the bottom surface is caused by both failure mechanisms because the drilled composite is subjected to an axial force and bending [ 23 ].…”

“…U. A. Khashaba [ 23 ] in the paper analyzed the influence of machining parameters on heat zone, thrust force, torque, and delamination in drilling GFRP composite laminates. It was found that the delamination is proportionally dependent on the thrust force and inversely dependent on the temperature.…”

Evaluation of the Mechanical Properties and Drilling of Glass Bead/Fiber-Reinforced Polyamide 66 (PA66)-Based Hybrid Polymer Composites

“…Polyamide, epoxy, polyester, phenolic, and vinyl ester are used as a matrix in polymer composite materials due to their high strength, low density, excellent chemical stability, and superior corrosion strength [1,2]. However, these materials are reinforced with different types of fibers [3] such as glass, carbon, basalt, and aramid, as they show comparatively low hardness and propensity to creep at high temperatures [4,5]. Glass beads (solid glass micro-beads or glass beads) are suitable for aviation and marine applications thanks to their excellent mechanical and thermal properties [6,7].…”

Machinability analysis of delamination and thrust force in drilling of pure and added GFRP composites

“…It was found that lamination thickness made the most significant contribution and drill angle made the lowest contribution to the machinability. Khashaba et al 27 improved the investigation of GFRP composites' machinability by considering the material’s heat-affected areas. The main conclusion of this study is the dependency of delamination on the thrust force and the temperature.…”