Development of a dynamic model for vibration during turning operation and numerical studies

Turning operation is a very popular process in producing round parts. Vibration and chatter noise are major issues during turning operation and also for other machining processes. Some of the effects of vibration and chatter are short tool life span, tool damage, inaccurate dimension, poor surface finish and unacceptable noise. The basic dynamic model of turning operation should include a rotating work piece excited by a force that moves in the longitudinal direction. Dynamic interaction between a rotating work piece and moving cutting forces can excite vibration and chatter noise under certain conditions. This is a very complicated dynamic problem. Vibration and chatter in machining is one example of moving load problems as the cutter travels along the rotating work-piece. These moving cutting forces depend on a number of factors and regenerative chatter is the widely accepted mechanism and model of cutting forces which then introduce time delays in a dynamic model. In this investigation, the work piece is modelled as a rotating Rayleigh beam and the cutting force as a moving load with time delay based on the regenerative mechanism. The mathematical model developed considers work piece and cutting tools both as a flexible. Without doubt, this dynamic model of vibration of work piece in turning operation is more realistic than previous ones as the dynamic model has multiple-degrees-of-freedom and considers the vibration of the cutter with regenerative chatter. It is found that the cutting force model of regenerative chatter which introduces time delay in a dynamic model leads to interesting dynamic behaviour in the vibration of rotating beams and a sufficient number of modes must be included to sufficiently represent the dynamic behaviour. The effects of depth of cut, cutting speed and rotational speed on the vibration and chatter occurrence are obtained and examined. Simulated numerical examples are presented. These three different parameters are vital and definitely influence the dynamic response of deflection in the y and z directions. The depth of cut is seen to be the most influential on the magnitude of the deflection. In addition, higher cutting speed combined with high depth of cut promotes chatter and produces a beating phenomenon whereas rotational speeds have a moderate influence on the dynamic response. Furthermore, several turning experiments are conducted that demonstrate vibration and chatter in the machining operations. There is fairly good qualitative agreement between the numerical results and the experimental ones

A Numerical Study About the Flow Around Motorbike with Different Types of Fairing When Travel Through Crosswind

Riding a motorbike possess to a dangerous situation because of its stability and balance.  Crosswind has a significant impact on riding since, with a strong gust, it can easily drive the motorbike off the road or into another lane or traffic. A numerical study has been conducted to investigate the aerodynamic loads of the drag, side, and lift coefficient and to analyze the flow pattern occurs of the motorbike with different types of fairing when travel under various angle of crosswind that was set ranging 0◦, 15◦, 30◦, 60◦ to 90◦. Two models of  Yamaha YZF M1 with different types of fairing were designed using SolidWorks 2020 and then simulated using Ansys CFX with 25m/s as the velocity for main and crosswind inlet. The aerodynamic loads coefficient was calculated for each model and the streamlines flow were analyzed. The aerodynamic loads coefficient was found increases as the yaw angle increases. Half fairing model was found to have higher aerodynamic coefficient compared to fully fairing model since half fairing model was not aerodynamic shape

Investigation of curing silver conductive inks on fabrics using dlp projector and hot plate

This study is to investigate the curing of silver conductive ink tracks on fabrics using a combination of direct light projector (DLP) and hot plate since conventional curing process using laser and oven suffer from several weaknesses mainly costly process and warping defect. The fabrics used are made from nylon and polyester while silver conductive inks were used for the entire study. Samples were made by coating the fabrics with rubber dye inks using silkscreen process and conductive inks were manually laid out on top of the rubber dye according to the designated pattern. A Microsoft power point slide is used to shape the light image on top of the hot plate where the sample is located. Variation of curing time and temperature with constant curing distance were investigated. Several mechanical and electrical tests were conducted to determine the cure, hardness, adhesion and resistance level of the ink tracks. The results obtained were as expected which the longer curing time taken and a higher temperature used, a lower resistance is produced. It is proven that a combination of projector and hot plate is capable of curing the ink tracks properly, a cheap process and easy to handle

A preliminary study of turning of composite

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Printing and Curing of Conductive Ink Track on Fabric using Syringe Deposition System with DLP Projector and Hot Plate

Printing is a technique to transfer ink onto substrates to create pattern and syringe deposition system has shown some great potential in printing due to its ability to produce filamentary bead tracks which is important concerning conductivity and easily adopted on conformal surfaces which could not be realized by conventional technique. Fabrics with integrated electrical features able to create intelligent articles and may potentially open up new perspective areas of application in textile printing. However, the applicability of this technique on fabrics remains unknown which the ink used has to meet certain requirements including high electrical conductivity, resistance to oxidation, dry out without clogging, good adhesion with suitable viscosity and surface tension. Thus, there is a need to do this study which is to determine the feasibility of syringe deposition system to print a conductive ink tracks using silver epoxy-based conductive ink on fabric substrate via lycra material. This study is also aim to investigate the feasibility of using DLP projector with hot plate as another source of heat to be used in curing the ink tracks on fabric. The effect of printing and curing parameters to the characteristics and conductivity of the ink track is investigated. Several mechanical and electrical tests were also administered to determine the cure, hardness, adhesion and resistance level of the ink tracks. The results obtained were as expected which higher printing speed and lower deposition height used, a narrower and thinner ink tracks were produced. Sample with 4 mm/s of printing speed and deposition height of 1 mm resulted in dimension closer to the targeted dimension. The longer curing time and higher temperature used, a lower resistance is produced. The lowest resistance achieved is 0.9 Ω cured at 150°C for 60 minutes. The conductivity of the ink track was affected by curing process and cross-sectional area of the ink track. It is proven that a syringe deposition system is capable of printing the ink track and DLP projector with hot plate is suitable to cure the ink track properly on fabric

V sicules et v sicules polym riques Caract risations et applications

SIGLEBSE B225637Q / UCL - Université Catholique de LouvainBEBelgiu