1. Ph.D Theses
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/1/11
Browse
2 results
Search Results
Item Development of Sandwich Composites from Natural Materials for Bullet Proofing(National Institute of Technology Karnataka, Surathkal, 2019) Sangamesh; RaviShankar, K. S.; Kulakarni, S. M.Ballistic protective materials have been used in the past are replaced with synthetic polymer composites due to their strength to weight ratio. Nowadays, these synthetic materials are being replaced by natural fiber reinforced composites due to the cost and environmental issues. The present investigation relates to the development of natural sandwich/laminated composite material interlock blocks for bullet arresting. Bullet arresting capacity depends on energy absorption. The energy absorption of the material could be increased by different ways. Among which sandwich form of the composite is one of the effective ways of improving the energy absorption capability of PMCs. This study was undertaken to explore the use of natural materials such as Jute epoxy fly ash composite (JEFC), Jute-epoxy fly ash rubber (JEFRC) sandwich composite for ballistic energy absorption. Prior to FE analysis, mechanical characterization of three varieties of jute composites were carried out namely Tossa jute single woven composite (TSWC), White jute single woven composite (WSWC), White jute double woven composite (WDWC) among all Tossa jute single woven composite (TSWC) revealed better mechanical properties. Hence for further analysis, Tossa jute single woven epoxy fly ash composite nothing but Jute epoxy fly ash composite (JEFC) is only used for ballistic FE simulation and as well as for ballistic impact testing of composite plates, blocks and interlock blocks. Finite Element analysis of these plates was carried out for thicknesses (5, 10, 15 mm). JEFC plates and JEFRC sandwiches with the same thickness (15 mm) were fabricated and tested to measure residual velocity and energy absorbed. Among JEFC and JEFRC, JEFRC showed better ballistic performance hence further analysis is carried out on jute-epoxy-fly ash natural rubber sandwich block composite (JEFRC), at different thicknesses of the target plate (50, 75, 100, 150 mm) and three velocities of the projectile (150, 250, 350 m/s). Ballistic parameters were evaluated using commercial FE software. Further same thickness and same configuration sandwich blocks were produced using compression molding machine; these prepared samples were subjected to ballistic impact test by impacting the projectile. From FE analysis and ballistic test, it is confirmed that at about 75 mm thickness the sandwich blockswere capable of arresting the bullet. Further interlock sandwich blocks were produced and tested for ballistic impact, which arrested the bullet half of its thickness. Hence such sandwich interlock blocks are produced to prototype for arresting bullet up to velocity 350 m/s. Fracture behavior is analyzed using SEM.Item Study on the Material Engineering aspects of Microwave sintered Aluminum– Cenospheres Composites(2016) Ananda Kumar, M. G.; Nayak, Jagannatha; Seetharamu, S.The thesis brings out the findings from the study undertaken on development of Aluminium based Metal Matrix composite through Powder Metallurgy route. The composite has been fabricated reinforced with various volume percentages of Fly ash Cenospheres particulates ranging from 0 to 50 vol %. The densification of the composites has been achieved through a non conventional sintering route known as Microwave sintering which is different from the well known conventional processing routes. The microwave sintering process appears rapid and economical. The Aluminium composites reinforced with Cenospheres and sintering through Microwave sintered composites have been later characterized for physical properties such as Density, Porosity, Hardness and Water Absorption, Chemical characteristics and Morphology of the synthesized composites and that of the raw materials through Scanning Electron Microscopy and Energy Dispersive X-ray Fluorescence methods. The Phase Analysis of the composites has been carried through Powder route X-ray Diffraction. The composites have also been studied for Mechanical properties such as Compression Strength with Finite Element Analysis and Modulus of Rupture. The composites have been studied for Tribological properties such as Wear and Erosion Resistance, Thermal properties such as Co-efficient of Thermal Expansion, Thermal Shock Resistance and Fusion Temperatures. The above test results have been compared with the results of conventionally prepared AMCs. The study on the various properties on the PM based Aluminium Cenospheres composites sintered in Microwave at 6650C have indicated that Apparent Porosity was about 35% compared to conventionally sintered ones which was around 40.7%. The Bulk Density was seen to reduce from 2.2 to 1.75 g/cc and the BHN values were found decreasing from 46 to 24% for the Microwave sintered samples. The conventionally sintered sample showed Bulk Density reducing from of 2.1to 1.75 g/cc and BHN values were found decreasing from 46 to 24. The BHN values were better than the conventional ones by about 26 %. The CTE of the composites decreased from 25.6 to 7.4 x 10-6/0C with increase in cenospheres content from 0 to 50 vol % forx the conventionally sintered composites. For the microwave sintered composites, the CTE of the composites decreased as the cenospheres content from 25.6 to 3.6 x 10- 6/0C which is much lower than the conventionally sintered samples by 51%. The microwave sintered composites showed lesser erosion loss by about 12-15% compared to conventionally sintered samples. The slide wear data shows that conventionally sintered samples has higher slide wear losses compared to conventionally sintered ones by about 86%. The Flexural strength of the conventionally sintered composites was seen decreasing from 52 to 8.8 MPa while Flexural strength of microwave sintered composites were decreasing from 71.9 to 31.5 MPa with increase in cenospheres content from 10 to 50 vol %. MW sintered was better by about 40% in Flexural Strength compared to the conventionally sintered composites. The Compression strength of the composites containing Cenospheres from 10 vol. % to 50 vol. % was found to decrease from 140.3 to 71.7 MPa with the increase in Cenospheres content, for microwave sintered samples. For the conventionally sintered composites the strength reduced from 140.3 to 71.7 MPa. The compressive strength of microwave sintered samples was more by 17.4 % compared to the conventionally sintered samples. Aluminium metal matrix composites can be fabricated through powder metallurgy route sintered in microwave sintering which is found to be adoptive & effective rapid sintering method. It is possible to fabricate Aluminium Cenospheres ‘Syntactic Foams’ through powder metallurgy microwave sintering and the properties for the same match with those materials for applications in automotives.