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To control the noise pollution through sound absorption, the development of natural fiber-reinforced hybrid composites (NFRHCs) using waste tea leaf fibers (WTLFs) and pineapple leaf fibers as reinforcing materials with epoxy matrix will act as an initial step to address this issue. Also, a minimal additional reinforcement of glass fibers was added for achieving mechanical strength too. The fabricated samples underwent a sound absorption test for assessing their capability of absorbing unwanted noise. With the help of sound absorption coefficient (SAC) curves acquired from the impedance tube method, the effects of the weight fraction and mass densities of WTLF and the thicknesses of the fabricated composites on their sound absorption ability were investigated. From the investigation, it was found that the noise reduction coefficient of the developed NFRHCs was more than 0.7 at a broad frequency spectrum. The fractal dimensions were estimated using the MATLAB program by utilizing the box-counting dimension method to correlate the effects of porosity percentage with weight fractions and mass densities of WTLF and the thicknesses of the fabricated NFRHCs. Following that, a quantitative relationship between the fractal dimension and SACs of the developed NFRHCs was derived to offer a theoretical concept for the future design of similar sound-absorbing materials.

In this paper, an attempt was made to study the ballistic resistance of Friction Stir Welded (FSW) AZ31B magnesium alloy. The base metal AZ31B plates were sliced to required size and FSW was carried out using a non-consumable taper pin tool made up of HCHCr steel. Samples were taken out from the FSW plates to study the microstructure and microhardness. The FSW AZ31B contain refined grains and tiny Mg17Al12 precipitates which were formed because of severe plastic deformation during FSW. The FSW AZ31B targets also showed ∼7.47% increase in microhardness compared to BM target. Further, ballistic test was conducted by impacting Ø7.62 × 39 mm hard steel core projectiles at an initial velocity of 420 m/s. AA6062 material of 25 mm was used as backing plate to measure the Depth of Penetration (DOP) of the projectile. The failure mechanism and the ballistic resistance of BM and FSW AZ31B samples were studied and compared. Finally, post ballistic analysis was made to study the failure modes of the target at microscopic level. Through various experimental results, it was identified that the increase in ballistic resistance of FSW AZ31B target was mainly due to two reasons; the refinement of grain size and small strengthening precipitates.

The effect of shot peening on mechanical properties and ballistic resistance of plates from magnesium alloy AZ31B 25 × 300 × 300 mm in size to the piercing action of a projectile (diameter 7.62 mm, velocity 690 m/sec) is studied. The yield strength, the ultimate strength, the elongation, the impact toughness and the microhardness of the alloy are determined prior to and after shot peening with glass beads. The surface of the internal channel of penetration of the projectile is investigated by scanning electron microscopy. The shot peening is shown to have a positive effect on the ballistic resistance of targets from alloy AZ31B.

Tool & Die is one of the important department in the manufacturing industries that takes care of proper designing and fabrication of tools and dies required for the production. In this sector, tool steels are used as the primary source of materials. These tool steels belongs to the family of carbon and alloy steels. Mostly used alloying elements are chromium, tungsten, molybdenum and vanadium and are heat-treated. The objective of the work involves machinability study of AISI H11 chromium hot-worked steel extensively used for tool & die making. It deals with the analysis of machining parameters and its influences on the responses considered. Here the controlling parameters considered are cutting speed (Cs), feed rate (Fr) and depth of cut (Dc) and responses as surface roughness (Ra) and material removal rate (Mrr). Each controlling parameters are assigned with 3 levels and experimental runs were executed as per taguchi robust design. To determine multi-objective optimal solution, grey relational analysis (GRA) is employed. GRA is used as it provides a feasible platform for converting a multi-objective function into single-objective function. The experimental runs were performed as per L27 orthogonal array sequence in CNC end-milling. The responses recorded are then analyzed using analysis of variance (ANOVA) and optimal solutions are validated through confirmatory runs. The entire machinability study of AISI H11 is performed in two conditions involving rough machining and finish machining. This has been addressed based on the machining scenario followed in industries taking up job orders. The confirmatory results for rough machining recorded was found to be 0.7871 microns against predicted value of 0.7654 microns resulting with a deviation error of 2.88%. Similarly, for finish machining, confirmatory runs recorded 0.8579 microns against predicted value of 0.8357 microns resulting with a deviation error of 2.66%. The deviation level indicated above between predicted and observed values are minimum, which shows the reliability of the optimal solutions arrived in.

Aluminum alloy finds its applications in various sectors of engineering. This paper discusses the investigation of mechanical characteristics of butt weld joints of aluminum alloy AA6063 along with AA5083. An experiment was conducted for different tool rotational speeds of 600 rpm, 800 rpm and 1000 rpm. Specifications of friction stir welding machine were 4 kN axial load and welding speed of 40 mm/min. Friction stir welded (FSW) joints of higher tensile strength, lower flexural strength and lower impact strength with maximum hardness, for the work piece fabricated at 1000 rpm using a high speed steel tool with a cylindrical profile was observed. Better understanding of the effect of tool rotational speed and mechanical properties was illustrated through the experimental result.

To determine the engine performance and emission parameters of diesel engine using diesel and bio diesel blends with nano additives. Blends of biodiesel of different proportions are prepared to which the zirconium oxide and titanium oxide nano additives are added. Here Wheat Germ Oil is taken as base oil with both the nano additives. The nano additives which are used here are of 30-50 nm and are added to biodiesel in different proportions. The following properties like density, viscosity, flash point, fire point, calorific value, pour and cloud point are been taken for this investigation. The experiments were conducted on a single cylinder direct injection (4) stroke diesel engine. The fuel is used in diesel engine the performance is noted along with the emission characteristics. The experiments have been conducted for Carbon Monoxide(CO), Hydro Carbons (HC), Carbon Dioxide (CO2), Oxygen (O2), NO, Specific Fuel Consumption (SFC), Brake Thermal Efficiency (BTE). The variations are seen in above characteristics. All these are compared with Pure Diesel.

Polymer Matrix Composites (PMCs) are the promising materials for numerous engineering applications. In this paper, the static mechanical properties of both Glass Fibre (PMC) and Glass-Jute Fibre (HPMC) reinforced composites were studied and compared experimentally. The hand lay technique was adopted to fabricate the composites. The static mechanical properties namely hardness, yield strength, Ultimate tensile strength, flexural strength and impact were obtained as per ASTM standards. Quantitative comparison of these properties between PMC and HPMC reveals improvement of flexural strength in HPMC.

The shock/blast waves generated due to explosions cause wide spread damage to the objects in its path. Different techniques have been used to attenuate shock wave over pressure, to reduce the catastrophic effects. Perforated plates can be used effectively to attenuate the shock wave pressure. In this paper shock wave interaction with perforated plates is simulated using COMSOL multiphysics software. The pressure drop varied from 43.75% to 26% for porosity varying from 10% to 40.

Vehicle suspension plays a vital role in maintaining the center of gravity to achieve perfect balancing of the vehicle to provide the comfortable ride. While designing the suspension system of automobile, vibration is the main aspect to be considered. This paper aims to analyze the automobile front and rear suspension for a four wheeler using analytical and numerical approach. Existing details of the suspension is collected using the concept of reverse engineering. Natural and forced frequency of the front and rear suspension system is calculated theoretically based on the collected data's. The natural frequency and forced frequency is numerically computed for front and rear suspension. The amplitude of vibration is reduced by replacing the spring material and its forced frequency is reduced by 1.18 % and 1.56 % for front and rear suspension system respectively. This result reveals that low carbon steel has ability to reduce the forcing frequency and can produce comfort ride.