Kishore Debnath

Drilling Characteristics of Sisal Fiber-Reinforced Epoxy and Polypropylene Composites

Natural fiber composites have attracted global attention due to their lightweight, low-carbon footprint characteristics as well as good mechanical properties. Due to these distinct advantages, the application spectrum of these composites has grown at an unprecedented rate. These composites are used for making a wide variety of sophisticated engineering products; therefore, certain degree of machining operations is necessary for assembly purposes. Drilling is an indispensable machining operation that is frequently performed for making of holes to facilitate assembly of several components into an intricate part. In the present research endeavor, the drilling behavior of unidirectional sisal-epoxy and sisal-polypropylene composite laminates has been experimentally investigated. Chip formation characteristics in the context of both thermoset and thermoplastic natural fiber composite laminates have been discussed. Further, the analysis of drilling force signals has been reported and the mapping of drilling forces has been proposed. Influence of drill geometry, feed, and spindle speed on drilling forces and a comparative analysis of damage characteristics of drilled hole have also been reported. From the current research work, it has been established that the tooling requirement for drilling of composite laminates under investigation is substantially different.

Rotary mode ultrasonic drilling of glass fiber-reinforced epoxy laminates

The use of polymer–matrix composites in structural applications necessitates certain degree of machining operations to meet the final product integrity. Drilling is an essential machining operation being used in composite industries for making of holes for bolted joints. The conventional drilling, which is frequently used for making holes in polymer–matrix composite parts, is not convenient anymore because of plethora of challenges encountered. The major drawback is the drilling-induced damage, which mainly occurs due to the direct interaction between the tool and composite laminate. Therefore, there exists a research opportunity to develop cost-effective high-quality machining methods for composite laminates. In the present research endeavor, rotary-mode ultrasonic drilling process has been conceptualized and developed for the drilling of fiber-reinforced polymer composites. The influence of various process parameters including power rating, slurry concentration, and abrasive size on material-removal rate, tool wear rate, and average surface roughness (Ra) has been experimentally investigated. It has been observed that the entry and exit delamination is prevented, and hole circumferential edge quality is improved when holes are produced through rotary-mode ultrasonic drilling as compared to the conventional drilling. It has also been found that with substantial modification in the conventional ultrasonic drilling process, the drilling performance in terms of material-removal rate of glass-epoxy laminates can be significantly improved. The major contribution of the present research endeavor is the development of a novel method of making clean-cut damage-free holes in fiber-reinforced composite laminates.

Hole making in natural fiber-reinforced polylactic acid laminates: An experimental investigation

Natural fiber-reinforced composite materials are finding wide acceptability in various engineering applications. A substantial increase in the volume of production of these composites necessitates high-quality cost-effective manufacturing. Drilling of holes is an important machining operation required to ascertain the assembly operations of intricate composite products. In the present experimental investigation, natural fiber (sisal and Grewia optiva fiber)-reinforced polylactic acid-based green composite laminates were developed using hot compression through film stacking method. The drilling behavior of green composite laminates was evaluated in terms of drilling forces (thrust force and torque) and drilling-induced damage. The cutting speed, feed rate, and the drill geometry were taken as the input process parameters. It was concluded that all the three input process parameters affect the drilling behavior of green composite laminates. The drill geometry was established as an important input parameter that affects the drilling forces and subsequently the drilling-induced damage.

Drilling of metal matrix composites: Experimental and finite element analysis

Drilling is an indispensable machining operation, which is mostly performed for making holes in an intricate composite part. In this research investigation, a finite element model has been developed to simulate the drilling behavior of Al1100/10% SiC metal matrix composite using finite element platform (ABAQUS/Explicit). The effect of cutting speed and feed rate on thrust force has also been experimentally evaluated. It was found that the magnitude of thrust force obtained from the proposed finite element model is in close agreement with the experimental values. It was also established that the proposed finite element model is quite efficient to predict the thrust force signals generated during drilling of metal matrix composites.

A novel intelligent software-based approach to predict forces and delamination during drilling of fiber-reinforced plastics

Drilling of fiber-reinforced plastics (FRPs) results in drilling-induced damage which leads to reduced part life and extensive part rejection. Thus far, there exists no standard handbook or knowledge-based tool that can predict drilling-induced forces and damage. Therefore, the present research initiative is an attempt to develop a software tool based on artificial intelligence which can predict drilling-induced thrust force, torque and delamination factor during drilling of FRPs. The developed intelligent software has a friendly graphic user interface (GUI). The user just interacts through the GUI and fills the input choices, and upon execution, the software predicts the drilling forces and delamination factor. In order to generate the database for the software, drilling experiments have been performed in two different types of composite materials with four different types of drill point geometries of two distinct diameters. The drilling of composite laminate has been conducted at three different levels of spindle speed and feed rate. The software results are based on three different artificial intelligence techniques namely artificial neural network (ANN), fuzzy logic (FL) and adaptive neuro-fuzzy inference system (ANFIS). The values of thrust force, torque and delamination factor for given inputs predicted by the developed tool are in close agreement with the experimental values.

Effect of Natural Fillers on Wear Behavior of Glass-Fiber-Reinforced Epoxy Composites

Fiber-reinforced plastics have entered into the engineering marketplace few decades ago owing to their excellent mechanical properties and cost-effective high-quality manufacturing. The use of polymer matrix composites for the production of mechanical components such as gears, brakes, cams, bearings and bushes has grown tremendously in the recent years. Therefore, from the theoretical and practical engineering point of view, the study of the wear behavior of polymer matrix composites becomes highly decisive. The present experimental work endeavors at the wear behavior of glass-fiber-reinforced epoxy composites filled with three different natural fillers, such as, rice husk, wheat husk and coconut coir under various sliding conditions. The wear performance analysis of the composites was carried out on pin-on-disk wear test machine under ambient conditions (27 °C and 60 % humidity). The weight loss was measured by applying normal loads of 10, 20 and 30 N under varying sliding speeds of 1, 2 and 3 m/s. The tests were conducted for a constant sliding distance of 1,000 m. The specific wear rate for glass-fiber-reinforced epoxy laminates under dry sliding condition was of the order of 10−8 mm3/N mm. Further, the morphology of the worn surfaces was examined by using scanning electron microscope (SEM) to analyze the wear mechanism of the developed composites.