Applied Mechanics and Materials Vols. 766-767

Abstract: The high crystalline fiber Kevlar 149 has a major industrial application and it is extensively used in aerospace industries due to its significant properties of ultra-high modulus, high strength, low density, high flame resistance. Kevlar 149 has an advantage over K 49, since it absorbs less moisture and has high compression strength ^[3]. In order to explore the vast application, this paper investigates the fracture response of the Kevlar material computationally, when they are subjected to biaxial loading in both tensile and compression. This loading is done to understand the response of the Kevlar how far they poor in compression and rich in tensile. The fiber induced with epoxy is to form as an effective reinforcement. Here the fiber taken as Kevlar 149 & K-49 and the epoxy resin. For easy understanding a sample of two flat plates is considered as a composite structure of standard size, which under goes the biaxial loading computationally using Abaqus/CAE. The pictorial data’s are taken from the post processing study and the data’s can be used to investigate the fracture mechanism of Kevlar 149 & K-49, under different types of strain loading. The output results of Kevlar 149 is compared with K-49 to analyze the behavior of fiber undergoes the biaxial loading both compressive and tensile and also the merits and effective utilization of K-149. It is suggested that this method can be applied to other type of composite materials.

Abstract: The Kevlar is an organic high crystalline fiber belonging to the aromatic polyamide family extensively used for its strength. Kevlar fiber posses high cut resistance and flame resistance, hence they have a wide range of application in ballistic and defense ^[2]. This paper investigates how K-149 behaves mechanically under sudden high velocity impact, it also shows which types of Kevlar grade hold the maximum impact stiffness capacity. In addition it also predicts the stress induced on the specimen at the time of impact. The ballistic impact object considered as 9mm standard size bullet used in short gun. The assumed velocity for these cases is 650m/s. The specimens K-149 & k-49 taken to be rectangle with the standard size 50 mm x 50 mm. The computational analysis done on Kevlar 49 & 149 and the results have been compared with the help of the pictorial representation of post processing abaqus results and the best ballistic material can be chosen. This paper also provided the recommended research data to fill the technology gap in defense material science.

Abstract: Many of the machines and systems having rotating components are designed for operation at high speeds, and hence, it is obvious that only these elements are damaged initially and becomes the root cause of a defect in any machine. Using on line, continuous monitoring techniques, any defect in a rotating part can be detected at its initial stage itself and the user could be alerted before it leads to a catastrophic failure. In this experimental work of the acoustical failure diagnosis, three domestic mixers, the first one in healthy condition, the next mixer about to fail and the last with completely damaged bush were analyzed, with a Type-1 and Delta ohm HD2010 Model sound level meter (SLM). The acoustical readings of the three mixers were measured and tabulated in decibel, using Delta Ohm Noise Studio software. Graphs were drawn for different sets of readings and by analyzing the graphs of the three mixers, the threshold value of the initiation of the defect was found to be 80 decibel, at which failure starts.

Abstract: An experiment sturdy has been carried out for jet impingement cooling on the spherically convex surface is the development of mechanism. The effect of curvature, Space between jet exit and target surface, and Reynolds number on heat transfer is investigated for around air jet on hemispherical surface. The flow at the jet exit has fully developed velocity profile. A uniform heat flux boundary is created on the heated surface. The experiments are performed for 5000<Re<25000, 2<L/d<10, and jet diameters ranging from 1.3, 2.1, 3.4, 4.0 and 5.2 cm. In the mean time effect of curvature on local heat transfer is negligible at the wall jet region corresponding to r/d>0.5. From the experimental results the variation of the D/d ratio with local Nusselt number (Nu_st) for various Reynolds numbers and various L/d ratios are plotted. The results show that Nu_st increase with increase in curvature and the effect of the curvature will high at high Reynolds number. i.e. Nu_st at Re=25000 is 25% higher than at Re= 5000 This may be attributed to an increase in curvature increases acceleration, & size of three dimensional counter rotating vortices at stagnation point and the increment of Reynolds number increases the jet momentum, and also enhances the vortices creation. Nu_st is peaking in the L/d ratio of 6 because of high turbulence intensity as this distance.

Abstract: The present work has carried out to enhance the engine performance with use of supercharger and exhaust gas recirculation (EGR). Experiments were conducted on a single cylinder DI diesel engine. Effects of EGR and supercharger on combustion and emissions of a diesel engine were investigated. Tests were performed on diesel engine under different load conditions. Results show that cooled EGR is an effective to reduce NO_X, because it lowers the flame temperature and oxygen concentration in the combustion chamber. Increase the inlet mass flow rate of air with aid of supercharger increases the NO_X formation and reduces the CO emission considerably. Increase of inlet air temperature with use of EGR has contrary effects on combustion and emission. Diesel engine with EGR at constant pressure is a way to drastically reduce the NO_X. Meanwhile increase in CO and hydrocarbon emissions.

Abstract: CED paint plant capacity is less than assembly production, three assembly line producing 610 wheels per hour maximum. Whereas CED paint plant capacity is just 528 wheels per hour so its leads to productivity loss and dispatch failures, on time delivery failures to customers (OEM).CED paint plant bottleneck is occurred due to existing JIG design So we should Redesigned Existing MS jig. There are two types of components i)Car wheel Jig (LP-Low pressure) ii)Tractor wheels Jig .Tractor wheel line producing 32 nos per hour that we can load 100%,CED capacity and jig pattern matches with assembly output.

Abstract: The aim of the paper is to reduce the Scrap in Transfer Pump Tightening Assembly in Common rail Pump. Low Torque rejection phenomenon was considered as it was of more rejection in past 6 months and it was having average per month scrap cost to be excessive. The objective of the work was to reduce the scrap quantity of TPC Tightening Assembly phenomenon from 3% of total scrap quantity of CR – Pump assembly to an accepted level. Due to this more rejection quantity, Loss of production and quality, High scrap cost and utilization of more man power were noticed in CR-Pump Assembly. To solve these problems seven problem Solving tools were attempted. To reduce the scrap cost and increase productivity and quality were targets with good usage of man power.

Abstract: The entropy generation of any thermodynamic system provides a useful measure of extent of irreversibility. The irreversibility causes the loss of useful work (exergy) in the system and it has to be minimized. Thermal radiation, coming from the sun is rich in exergy. Entropy generation is one of the parameter that quantifies the loss of exergy. It is a unique parameter to measure the strength of irreversibility of thermodynamic process. The criterion for the optimal thermodynamic operation of a collector is used in terms of Entropy Generation Number (N_s) and Mass Flow Number (M). In this paper, the performance of a 10 W_p photovoltaic thermal (PVT) system is analyzed. The range of mass flow rates to be used for testing is obtained by entropy minimization method. The maximum electrical, thermal and exergy efficiency of 10.9, 23.5, 14.8 % is obtained at the mass flow rate of 0.008 kg/s.

Abstract: Machining the mica insulation in commutator to provide under cut in the surface of contact with the carbon brush is a vital process related to the life of the product. Complete removal of mica in the contact surface is essential and this requires complex sensing and positioning of the thin mica layer during machining. This study revealed improving the sensing and positioning technologies is not adequate and evolved a robust product-process design to overcome the real root cause of variations in the manufacturing process. Combined use of orthogonal array, Shainin technique, physical-mechanism analysis, relations-diagram and evaporating-cloud method complemented the problem solving approach in gaining knowledge and evolving robustness.

Abstract: Lean manufacturing was initially introduced successfully in Japan to enhance the production standard of cars in Toyota Company. These lean principles were initially known as Toyota Production system (TPS)^[2]. Lean seeks to eliminate all forms of waste in the manufacturing process—including waste in the maintenance operation ^[1]. This present study about lean principles if could be introduced in maintenance of aircraft the standard of maintenance process could be significantly improved. Hence study of experimental research was carried out on pre-matured failure of lifed hydraulic components of ten aircrafts. The failure rate of each component was studied in-depth to adopt remedial measures for improving its life and in turn to reduce the period of “Aircraft on Grounds”. Aircraft on ground mean unserviceable aircraft will be on ground and not suitable for flying. In addition, a deep study was made on each component to fix a Time Between Overhaul (TBO) by analyzing the failure trend of each component to determine a common and effective TBO for enhancing the serviceability rate of aircrafts. It also prevents sudden failure of components thus improving the serviceability status. In order to enhance the standard of serviceability a “Root Cause Analysis” was carried out on those defective components to suggest remedial measures to those maintenance personnel to modify the maintenance process and reduce the TBO for effective reduction in time of occurrence of the defects. These suggestive measures were implemented by the users of the ten aircrafts on trial basis. Occurrence of such defects was minimized showing significant improvement in the subsequent maintenance of aircrafts. Further, the remedial measures have a great impact on the development of a high degree of aircraft maintenance. The final results of this research study are prepared and suggested measures are forwarded for implementation to manufactures, overhaul agency and operators.