Papers by Keyword: Speed

Abstract: Microfluidics is an efficient technology for controlling fluid movement in microchannels at extremely low speeds. The main advantage lies in the significant reduction of samples and reagents, thereby reducing costs and analysis times. Three devices with retention systems are introduced that are manufactured through 3D printing (SLA) incorporating microchannels with variations in levels and dimensions. Fluid velocity is studied, considering factors such as channel width, length, rounding, height, and shape. The analysis of velocity along the channel reveals liquid retention at the devices' maximum point, ensuring more precise results in microdevices.

Abstract: The dry turning was done on 304 austenitic stainless steel using a carbide insert (Tungaloy, SNMG 12 04 04). Speed, feed, and depth of cut (DOC) were the machining parameters. The chip reduction coefficient (CRC) and elementary energy consumption were the output responses. Twenty-seven experiments were performed by following the L27 Taguchi design plan-decoupled TOPSIS method. The minimal elementary energy consumption was attained at moderate speed (44.28 m/min.), high feed (0.20 mm/rev.), and low DOC (0.66 mm). This result has been validated by the fuzzy inference system (FIS) simulation. The details of minimising elementary energy consumption have been explained by implementing Taguchi design plans, TOPSIS, chip macrographs, and FIS simulation studies. The very thin continuous chip (very low CRC) was found at optimal parameters, indicating minimal energy consumption during machining. The aim of the work is to find out the machining condition at which the elementary energy consumption during machining was minimum. The validation of the optimal solution by qualitative assessment and by the FIS simulation emphasizes the novelty of the work. The nature of the study is newer in kind with validation of results. The simulation result shows the increasing trend of closeness coefficient (CC) with increased feed at moderate speed and low depth of cut (DOC).

Abstract: The dry turning was done on the high tensile low alloy steel. The Indoloy carbide tool was used. The input parameters were speed, feed, and depth of cut (DOC, d). The chip reduction coefficient (CRC) and von Mises stress (VMS) were the output responses. Universal tensile testing was done to find out the strength coefficient (K) and strain hardening exponent (n). "K" and "n" were incorporated to obtain the von Mises stress (VMS). The experiments were performed following the L₉ array (Taguchi). The analysis of variance (ANOVA) was done for the CRC, with the lower the better condition. The ANOVA was done for VMS with the lower-better condition. The ANOVA was done by developing a MATLAB program. The feed contributed strongly to both the CRC (80.1381% contribution) and VMS (33.1490% contribution) minimizations. A Taguchi-Fuzzy inference system (FIS) simulation was done (MATLAB software) to select optimal parameters. CRC and VMS were the inputs, and MPCI (multi performance characteristic index) was the output for the simulation. The simulation was done based on the rules. The optimal parameters were found at moderate speed, high feed, and moderate DOC. Machining chips were collected for different experimental conditions. The chip form study was done. The chip surfaces were examined in the scanning electron microscope (SEM). The simulation result was validated by chip form study and SEM observation of chip.

Abstract: Metal cutting is the way of processing the workpiece with tool having sharp cutting edges of different materials generating chips of different shapes and sizes. In present era of industry 4.0, metal machining should not be unrated during processing of hard grades metals and superalloys where large amount of cutting forces are generated. Also, the measurement of cutting forces provides the basic of economical machining and hence accurate evaluation in experimental and analytical manner has great importance. The traditional models of metal cutting have disagreement with experimental results due to missing of important mechanics terms. With the development of digital technology, the errors in calculation of cutting force have also been shortened due to consideration of terms absent in conventional models. In present investigation, the cutting forces have been evaluated experimentally using dynamometer and analytically with Astakhov’s methodology during turning of EN-31 steel. The results revealed that 12.9% observations have deviation more than 20%, whereas 16.67 % has zero deviation. Further, the feed rate has more influence on cutting forces as compared to speed and nose radius. In addition, the minimum quantity lubrication (MQL) of vegetable oil has lowered the cutting forces appreciably compared to dry machining.

Abstract: In this scientific study, the problem of automation of machine-building production is justified. A 3D model of the lathe is presented and its design is improved. Standard layout schemes based on the upgraded spindle assembly have been developed, which make it possible to increase the speed of this type of machine. The results obtained make it possible to achieve the desired cutting speed, which has significantly increased by 2-2,5 times. The constructed dependence of the deviation on the roundness of samples by the finite element method allows predicting the main indicators: feed rate, spindle speed, cutting depth, static imbalance, initial and final pressure. Also, the obtained analytical results allow us to establish the main regularities of forming the accuracy of this lathe.

Abstract: The results of experimental studies of a separate contact dynamic interaction of a spherical non-deformable pellet with a plastic flat metal surface at different angles of attack (20° ≤ α ≤ 90°) at high speeds (v ≈ 100m/s) are presented. A method is described for determining the nature of the viscoelastic resistance of a surface layer attacked by a pellet during contact displacement along the normal to the surface and rigid plastic resistance during tangential displacement, which can be used to establish the processing regimes of products by a mass flow of abrasive particles, in particular, shot-blasting cleaning. The results of comparing the obtained and known theoretical data with each other and with experimental studies are presented.

Abstract: According to official statistics, road transport is one of the most dangerous and costly in terms of life and costs of hospitalization and post-accident medication. Thus, safety is a matter of great interest at national level and, perhaps internationally. Road safety on public roads in Romania is low compared to international standards. The mortality rate is more than twice the EU average. Given that road traffic and victim maintenance costs are a real economic problem, a European harmonization of the recording and assessment of events involving the bodily injuries of those involved in road events is necessary. Road events are one of the main causes of mortality in modern society. For this reason, the safety of motor vehicles has become the most important issue in their development. Road traffic injuries are a problem that can be controlled by proper attention to traffic avoidance strategies. Side impact is the second major cause of mortality and injury after frontal impact in road traffic analysis.

Abstract: The relationship of oscillations amplitude of the granular medium-elastic screw system whilst passing over resonance at different values of the bulk mass per unit length at different motion velocity has been studied. The relation of resonance oscillations of the granular medium-elastic screw system described by ratio α(t) and ν(t) has been shown. Based on these ratios, we plotted time variations of amplitude against quick passing over resonance.

Abstract: The article considers the modeling of dynamic processes in buildings and structures. A general formulation of the dynamic problem of a massive load motion on a massive structure is considered. The equation of motion is obtained in the form of a finite element method. The equations solving is performed using direct methods of integrating dynamic problems. Absolutely stable schemes of direct integration are constructed, where the system of solving equations is trivial and the matrix of the system is diagonal. Due to this, the complexity at the time step is as low as in explicit schemes. Therefore, the proposed methods can be considered as explicit absolutely stable schemes of direct integration of a dynamical problem with a variable in time mass. These recommendations are for estimating the accuracy of a numerical solution.

Abstract: A benchmark test will insure that the equipment, procedures, and uncertainty estimates are adequate. The experiments of a well-known bulk carrier bare hull shape (the model LHI-007) has been set up and conducted at towing tank Indonesian Hydrodynamic Labotatory. The aim of the present study is to contribute data of the surface ship resistance model-scale database in calm water on one hand, and on the other – reliable Experimental Fluid Dynamics (EFD) data, as part of an internal benchmark test. Conclusions are made with regard to the available data and past uses and recommendations are provided for future uses of the available data and future data procurement.