ANALYSIS AND OPTIMIZATION OF FRICTION WELDING PARAMETERS FOR AA6061-AA2014 DISSIMILAR JOINTS

Friction welding is a solid state welding used owing to its properties such as low heat input, high production efficiency and environment friendliness. Materials which aredifficult towelded by fusion welding processes can be successfully done friction welding. In this work, an effort was made to predict the maximum tensile strength of friction welded AA 6061 and AA 2014 aluminium alloy dissimilar joints incorporating the process parameters such as rotational speed, friction pressure and forging pressures which have immense on the strength of joints. The friction welding process parameters were optimized to achieve maximum tensile strength of the joint. The maximum tensile strength of 210MPa  for the joints fabricated under the welding conditions ofrotational speed 1508 rpm, friction pressure of 8.16 MPa/secand forging pressure of 6.79 MPa/sec using the optimization techniques

EFFECTS OF PROCESS PARAMETERS AND OPTIMIZATION OF MECHANICAL AND METALLURGICAL BEHAVIOUR FOR DISSIMILAR MATERIAL BY ELECTRICAL RESISTANCE SPOT WELDING.

Electrical resistance Spot Welding is a pressure welding used for joining of sheet metals or wires. The welding heat is produced at the desired location by electrical resistance through the metal pieces. ERSW is highly used due to its fast rate of production, less maintenance, free from smoke etc… ERSW is experimented in dissimilar materials (Stainless steel –Mild steel) to analyze the effect of process parameters such as welding current, welding time and electrode force. The welded parts were applicable to tensile test and hardness test .Thus the influence of parameters on weld quality was categorized

Static Analysis of Rigid Airfield Pavement Using Finite Element Method Vs Closed-Form Solution

In addition to the geometry of runway design, a good runway should also meet the structural requirements. In this way, the analysis and design of pavement slabs need to be given more attention. The study looks at the static analysis of a 3D-modeled concrete slab resting on a subgrade foundation that is a homogeneous, isotropic elastic half-space model. This is done so that the effect of a change in Young's modulus can be compared to Winkler's reaction modulus. ANSYS's finite element software, which models the slab as a 3D element with 8 nodes and a solid 185-element type, is used to estimate the combined stresses caused by the weight of the plane and the temperature difference. Conventional slab analysis is done using modified Westergaard's allowable stress method and Eisenmann's method (warping stresses). This is because the two aircraft on the slab have different structural parameters, like the concrete's elasticity modulus, slab thickness, and temperature gradients. From both the outside and inside landing gear loading positions, the maximum values of bending tensile stress were found to go up a lot as the elastic modulus and compressive strength of concrete went up, but they went down at the same time as the thickness of the pavement slab went up. When both + and - temperature gradients were measured on the slab, the corner moved more than the centre. When it comes to stress, a positive curling temperature gradient is worse than a negative curling temperature gradient

Dynamic and Fatigue Life Prediction Analysis of Airfield Runway Rigid Pavement Using Finite Element Method

The significance of rigid airfield pavements is growing as airline travel becomes more sophisticated. Apart from the geometrics of runway design, an efficient runway should satisfy structural aspects. In this connection, greater emphasis should be placed on pavement slab analysis and design. The research analyzes the dynamic analysis of a 3-dimensionally formed concrete slab resting on a subgrade foundation, which is a homogeneous, isotropic elastic half-space model, in order to assess the performance of variation in Young's modulus in compared to Winkler's reaction modulus. The influence and impact of two distinct landing gear configurations, especially tridem and tandem-dual wheels of the A-380 and A-310, on varying slab structural parameters such as concrete's modulus of elasticity, slab thickness, and temperature gradients are explored. The aircraft load stresses are evaluated using the finite element programme ANSYS APDL 2021R2 version, which models the slab as a 3-D element with an 8-noded-solid 185 element type. The above-mentioned pavement models' modal and dynamic (transient) analyses were performed for different take-off speeds, and a comparison is conducted for the present standard strength and high strength concrete types. Miner's rule and the Rainflow counting technique are used to estimate the fatigue life based on the findings of the transient analysis. The fatigue life for high-strength concrete is found to be 50% more. The fatigue life is 36% higher for the A-380 load, indicating that a material's fatigue property is entirely determined by its load frequency rather than its magnitude

Study of radiative and kinetic properties of femtosecond laser ablated brass plasma by optical emission spectroscopy

Femtosecond laser induced plasma (LIP) in brass was characterized by optical emission spectroscopy (OES). The LIP spectra is dominated by emission from excited neutral species of Cu and Zn. The ionic emission lines are found to decay more rapidly compared to the atomic emission lines. Time resolved OES studies on the expanding plasma plume have provided some insight into probable excitation pathways and the temporal behavior of the excited species.Further assuming local thermodynamic equilibrium (LTE), the fs-LIP source was characterized for excitation temperature and electron number densities by using the Boltzmann plot method and the width of Stark broadened line profiles respectively. The influence of laser fluence on excitation temperature and electron density was also investigated. The emission intensities exhibit two ablation regimes corresponding to ablation dominated by optical penetration depth at low fluence and by electron thermal diffusion length at higher fluence. Comparative studies on the behavior of copper emission lines from both pure copper and brass samples suggest that femtosecond laser pulses might mitigate the matrix effect in the ablation process

The Present Status of Meat Processing and Preservation in the Pastoral Regions of Kenya

The meat value chain in pastoral regions is characterized by large post-slaughter losses due to lack of appropriate preservation technologies. Reports indicate that sun-drying, salting and deep frying have been practiced for meat preservation in the pastoral regions but there is limited empirical information on the manner and extent of practice of these methods. This study was therefore designed to collect and authenticate information on meat preservation technologies practiced in the pastoral areas. Using a structured questionnaire, key informants interviews and focused group discussions, data was collected from four pastoral counties, namely Marsabit, Turkana, Garissa and Kajiado counties, in a cross-sectional survey. Data was also collected from processors and handlers in Nairobi County to provide reference of modern handling and processing. Results revealed that different communities in the pastoral areas have adopted preservation technologies based on deep frying, salting and sun-drying while cooling and curing are practiced in the modern processing facilities in Nairobi. The main storage containers used in the pastoral districts are wooden, metallic and plastic containers. Meat handling was done by men, while by-products handling was by women, the two processes are usually separated in the production floor. Deep-frying, salting and sun-drying were predominantly done to extend the shelf life and to impart the distinct flavor of pastoral meat products. Where wooden containers were used, the containers were fumigated with smoke from burned wood (Adung). Meat quality deterioration was caused mainly by unhygienic handling practices which results to microbial contamination. Spoilage was aggravated during sun-drying which is a slow process. The study concludes that there are technologies of meat processing and preservation in the pastoral areas with the potential for upgrading in terms of process hygiene and product quality to reduce post-harvest loss and make the products competitive. Keywords: indigenous technologies, meat products, pastoral region

Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation

The glucagon-like peptide receptor (GLP-1R), which is a G-protein coupled receptor (GPCR), signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R) expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39) and JANT-4 and the orthosteric binding site mutation (V36A) in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B