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ThesisItem Open Access Impact of surfactant modified ferrite nanoparticles on mechanical and thermal characteristics of epoxy(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Singh, Ashtosh Kumar; Saxena, RakeshPresent investigation deals with development of surfactant modified ferrite nanoparticles (FNs) to achieve the epoxy ferrite composites (EFCs) bearing enhanced dispersion and compatibility of filler with epoxy matrix. This has afforded a series of EFCs with improved tensile, bending, compressive and impact strength. EFCs has shown improved hardness with characteristic reduction in their wear loss. However, a marginal increase in thermal stability of EFCs has been observed. Formation of surface modified FNs (SFNs) and their compatibility with epoxy matrix was clearly revealed through Fourier transformed infra- red spectra. Diversified microscopic methods in combination with X-ray diffraction spectra, magnetometry and DC conductivity experiments reveals enhanced dispersion of SFNs into EFCs. The overall experimental outcome reveals that SFNs (2 phr) imparts improved dispersion, compatibility with epoxy matrix that leads to the formation of EFCs with improved mechanical properties and controlled wear loss. Study further reveals that, EFCs developed through SFNs were of improved durability over those derived from FNs under identical filler loadings. Study finally disclose the importance of surfactants as modifiers for magnetically active fillers such as ferrites and their similar analogues making them suitable for development of high performance polymer nanocomposites suitable for the appliances useful for transportation, stealth and energy management, and biomedical applications.ThesisItem Open Access Effect of stress ratio on fatigue crack growth behaviour of friction stir welding between AA6061 and AA7075 alloys(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Kandwal, Abhishek; Gope, P.C.In the present work, fatigue crack growth in friction stir welded dissimilar AA6061 and AA7075 is performed under different stress ratio and maximum load condition. Crack is a damage that often occurs in members of structures and may cause sudden serious failure of the structures. In a structure generally weld is the weakest section and therefore more prone to failure due to crack propagation. Therefore the study of mechanism of crack growth and its parameters is of paramount importance. The effects of presence of crack on fracture parameters like crack opening stress (Sop) and stress intensity factor (K) of specimen has been the subject of various investigations. However, the parametric studies like effect of stress ratio and amplitude; on the fracture parameters of specimen for friction stir welded joints has gaps in the literature and therefore needs further investigation. Aluminium alloys AA6061 and AA7075 have been chosen for the present study as they are both used in conjunction in many areas of engineering such as marine and aircraft structures. The crack growth rate data for the weld shows that with the increase in stress ratio, fatigue life of the joint decreases. The fatigue life obtained for constant maximum load and varying stress ratio condition shows that the highest Fatigue life is obtained for stress ratio R= -0.5 (48200 cycles) and lowest for R=0.8 (22200 cycles). The curve obtained using Newman equations is closer to plain strain condition. For the constant stress ratio and varying maximum load, it was observed that the fatigue life of joint decreases with the increase in applied maximum load (Pmax) with the highest fatigue life observed for Pmax=4kN (28908 cycles) and lowest for Pmax=6kN (21635 cycles).ThesisItem Open Access Effects of randomly oriented secondary cracks on the fracture parameters in a rectangular plate under static loading(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Ansari, Gulfam Akhtar; Bisht, NeerajIn the present work, a numerical study using finite element is performed to investigate the effects of randomly oriented secondary cracks on the fracture parameters in a rectangular plate under static loading. Crack is damage that often occurs in members of structures and may cause the sudden serious failure of the structures. The effects of the presence of crack on fracture parameters like stress intensity factor and T-stress of specimen has been the subject of various investigations. However, the parametric studies like the effect of crack offset distance, crack size, orientation and number of crack present on the fracture parameters of the specimen are scarce in the literature. The finite element software ANSYS is used to simulate the fracture parameters. Numbers of studies were conducted to study the accuracy of ANSYS and the meshing parameters on which the accuracy depends. Two types of crack geometries were considered viz. parallel cracks and inclined cracks with different crack ratios. Also, the effect of several secondary cracks was studied. The presence of secondary cracks induced a shielding effect on the primary crack. The presence of secondary crack results in the development of mode II SIF. The mode mixing, however, was minimal and the mode II SIF was insignificant compared to mode I SIF. It is observed that when the cracks are closer to each other the shielding effect is high and as the cracks move away the shielding effect decreases. With the increase in inclination angle intensification effect is decreases. The shielding was also higher for a greater number of neighbouring cracks. Higher length of secondary cracks also increased the shielding effect. A correlation between SIF and T stress was also developed and it was seen that they are highly correlated. T stress can also be an important alternative fracture parameter to study crack interaction problems. Statistical analysis was performed to study the impact of various parameters in comparison to each other for all the geometries it was seen that the crack offset distance has a major influence on SIF compared to the crack ratios. Also, inclined cracks were seen to have a profound impact on SIF compared to parallel cracks. Multi-site damage is a common occurrence in aircraft and nuclear industries and the results of the study can contribute to accessing the structural integrity of the structure and estimate the in-service life of the component.ThesisItem Open Access Investigation of thermal characteristic behavior of rotating packed bed using air-water system(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-10) Saurabh; Murthy, D.S.The investigation of thermal characteristic behavior of rotating packed bed has been conducted in a three-tire approach. Initial testing for the feasibility of thermal responses in the device upon varying the mass flow rate and inlet temperature respectively gave the way for next level of investigation. Here in, the fluid’s mass flow rate ratio, fluid’s inlet temperature ratio, packing rotation and porosity were identified as input/ independent parameters; whereas, pressure drop across the packing, water temperature drop, and heat transfer rate are scheduled as the response variables. The computational fluid dynamics approach has been opted for the entire purpose as it proves beneficial in providing data pertaining to intricate locations that would otherwise have not been possible using conventional methods alone. The implementation of central composite rotatable design scheme has been made in order to obtain corresponding range of data for the analysis of independent parameters.Statistical interpretation of the data for significance of effects caused by the independent variables on to the thermal response variables has been discussed. The use of response surface methodology to discern the thermal behavior of rotating packed bed using surface contours has also been attempted. The vivid discussion of main effects and interaction effects plot is elaborately presented. The use of rotating packed bed secures an overall increment of 157% in the value of heat transfer coefficient for approximately the same temperature drop (~8 K) along with the volumetric reduction in packing/ fills, as high as upto 96.5%.These results justify not only the thermal process intensification in rotating packed bed, but also render sufficient encouragement for futuristic use of this device in the domain of heat transfer applications.ThesisItem Open Access Effect of artificially included defect on mechanical and fracture properties of Al 7075-T651 MIG welded butt joint(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Joshi, Shomesh; Gope, P.C.Aluminium 7075-T651 is one of the widely used materials for various applications in industry, aerospace, utensils, etc. In the present investigation, fatigue crack growth on CT specimenand tensile experiments are performed on MIG welded butt joint of aluminium 7075-T651 with artificially included defect of carbon nanoparticles with Pmax= 5 kN, Pmin= 0.5 kN, frequency of 6 Hz and R=.1 under constant amplitude loading and under universal testing machine of 25 kN. The experimental data obtained has been used to plot a-N, da/dN vs. K curve, stress-strain curve and Paris crack growth constants. The fatigue life is found to be 25500,22400,29500 and 27800 cycles respectively for MIG welded CT specimen with single V-notch without defect, single V-notch with defect, double Vnotch without defect and double V-notch with defect respectively for across weld region. But for the along the weld region for the same conditions mentioned above the life came out are 27300, 23500, 31200, 26900, respectively. Also, the ultimate strength is found to be 244.70, 208.31, 274.6, 259.8 MPa for the single V-notch without defect, single V-notch with defect, double V-notch without defect and double V-notch with defect respectively for along weld region. Moreover, for the across the weld region for the same conditions mentioned above, the ultimate strength comes out to be 211.18, 200.12, 242.02, 234.56 MPa, respectively. The values of material constants C and m are calculated through single Paris Curve fit. Mathematical modelling is also done for the above study to find out the trend of the fracture properties and the ultimate strength with respect to the percentage of the defected area in the weld.ThesisItem Open Access Simulation of vapor compression-absorption refrigeration system(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Chauhan, Ritik; Pratihar, A.K.The compression-absorption refrigeration systems has been considered to be the possible replacement of the vapor compression and vapor absorption refrigeration system due to their useful features like better capacity control and its operation at low-pressure levels in the system due to the use of mixtures and higher coefficient of performance compared to vapor compression system. In the present work, thermodynamic analysis of compression-absorption system has been carried out for milk chilling application at 4 ℃. In order to study the performance of system computer simulation of actual system has also been carried out where effect of some important parameters on the coefficient of performance of the system has been studied using Warner’s method. In the simulation of absorber and desorber fourth order Runge-Kutta method has been used. A COP of 4.435 has been obtained at a compression ratio of 4.0, desorber temperature of 8°C, an absorber pressure of 20 bar, maximum concentration of 0.8. It is observed that the exergetic efficiency increases with the decrease in desorber temperature and exergetic efficiency decreases if the value of compression ratio increases. Simulation has been performed for three different lengths of absorber and desorber, 5.0 m, 7.0 m and 10.0 m and three different relative area of solution heat exchangers area, 10%, 20% and 30%. The effect of the mass flow rate of the weak solution, length of absorber and desorber and relative area of solution heat exchanger on the COP, cooling capacity and absorber heat load has been studied. The results show that the COP of the system can be increased by maintaining a low mass flow rate of the weak solution, large relative area of solution heat exchanger and a large absorber and desorber length. From simulation it is found that COP of the system attains a maximum value at a given mass flow rate of weak solution. By increasing the length of absorber and desorber from 5 m to 10 m, the COP of the system increases from 2.96 to 3.25 i.e. an increase of 9% is attained.ThesisItem Open Access Performance comparison of solar cooker using different phase change materials during off sunshine hours(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Abhishek Kumar; Bhandari, Susheel SinghThe continuous increase in the level of greenhouse gas emissions and the increase in fuel prices are the main driving forces behind efforts to more effectively utilize various sources of renewable energy. In many parts of the world, direct solar radiation is considered to be one of the most prospective sources of energy. Energy requirement for cooking accounts for 36% of total primary energy consumption in India. Hence, there is a critical need for the development of alternative, appropriate, affordable mode of cooking for use in developing countries. However, the large scale utilization of this form of energy is possible only if the effective technology for its storage can be developed with acceptable capital and running costs. Solar cooker is the best way to utilize solar energy. In the present work thermal performance of a box type solar cooker has been evaluated according to the bureau of Indian standard (BIS). The BIS suggested two test for evaluation of thermal performance. The first test is stagnation test for evaluation of first figure of merit F1.The second test is full load test for the determination of second figure of merit F2. The first figure of merit is obtained by conducting the stagnation temperature test without load for empty box type solar cooker. The first figure of merit is the ratio of optical efficiency to heat loss factor. The second figure of merit is obtained by sensibly heating a known amount of water and it is a measure of heat exchange efficiency factor of a box type solar cooker. The variation in second figure of merit is also studied by increasing load and number of pots. It is found from experimental study that second figure of merit increases with load and number of pots. The value of figure of merit imply that the cookers are identical and satisfy BIS standard. The performance comparison of solar cooker using different phase change materials during off sunshine hours is main emphasis of the present experimental study. Cookers are also studied using modified finned cooking vessel. Three different phase change materials paraffin wax, stearic acid, lauric acid are selected. It is found from experimental studies that finned cooking vessel increases efficiency and reduces the cooking time. Paraffin wax is best phase change material to store latent thermal energy during sunshine hours and to retrieve back its conserve energy to thermic fluid water during off sunshine hours.ThesisItem Open Access Experimental studies on a double slope single basin solar still using sensible heat storage materials(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Negi, Pankaj; Varshney, LokeshMany countries are facing a shortage of potable water, as the population is increasing rapidly. Most of the water present on earth’s surface is in oceans and lakes which is either saline or brackish water. This water can solve water-related issues by converting it into potable water through desalination process. Many people are suffering from water-borne diseases by consuming contaminated water, therefore there is an essential requirement of potable water production technology for its distillation. Solar energy is cheap and easily available and can be utilized for converting saline water into potable water. Solar still is a device which uses solar energy to convert saline water into distilled. Productivity of conventional solar still is found to be low. Attempts have been made by researchers to improve the productivity of solar still. Present work is an attempt to increase the productivity of double slope single basin solar still by utilizing sand bed as sensible heat storage material beneath the basin of solar still. Experiments have been conducted for sand bed of thickness 0.5 and 1.0 cm and furthermore for mixing engine oil (SAE 20W40) with the sand bed of thickness 0.5 cm up to saturation limit for filling voids and minimizing contact resistance for heat transfer between basin and storage bed. Intermittent glass cover cooling has also been done for reducing the temperature of the glass cover and increasing the amount of condensate. Results of experiments revealed that daily productivity of solar still is increased by utilizing sand bed beneath the basin of solar still. Daily productivity of still increased by 10.72% and 3.16 % by utilizing 0.5 and 1.0 cm thick sand bed respectively for basin water depth 0.6 cm. There is an increment of 11.16 % in daily productivity of modified still with a 0.5 cm thick sand bed by intermittent glass cover cooling. Daily productivity of solar still modified with 0.5 cm thick sand bed increases by 6.16 % by mixing engine oil in the sand bed.ThesisItem Open Access Dynamic analysis of honeycomb sandwich laminated composite plate(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Adlakha, Prash; Mishra, AnadiA structural sandwich is a peculiar form of a laminated composite comprising of a combination of distinct materials which are bonded together to use effectively the properties of each separate component to the structural advantage of the whole assembly. Two thin, rigid and quite strong faces in the framework are partitioned by a thick, light and weaker core. The faces are attached adhesively to the core to ensure effective load transfer between the components. Owing to the core structure, such composites are differentiated by their stiffness. Despite the thickness of the core, sandwich composites are characterized by their light structure and a good flexural strength. These composites possess unique structure, which provides it a good thermal insulator property. Sandwich composites finds a wide range of application in aeronautics, transportation such as road vehicles, ships, winds, marine and civil engineering. The Laminated sandwiched composite pate is preferred over simple laminated composite plate due to their great ability to essentially decrease weight while maintaining optimum mechanical performance. This weight reduction provides a large number of benefits which includes higher payloads, increased range and comparatively less fuel consumption. The Present study is done to study and investigate the Sandwich composite Panel which is formed by laminating composite sheets with Aluminium Honeycomb core and Dynamic Analysis is done to study its behaviour by computing natural frequency and corresponding deflection. Triangular, Square and Hexagonal cell for the honeycomb will be used to find the best shape under dynamic loading. Further, the effect of hexagonal cell parameter will be studied in order to find optimum parameters in ANSYS 18.1 Software.
