Effect of Pin Geometry and Orientation on Friction and Wear Behavior of Nickel-Coated EN8 Steel Pin and Al6061 Alloy Disc Pair

Most mechanical systems (in particular, gear transmission system) undergo relative motion which results in increased friction phenomenon (friction coefficient, stresses, and wear rate) and thereby results in loss of efficiency. Mechanical parts undergo relative motion in different geometry configurations and orientations that induce a different state of stress as a result of friction. Till date, attempts are being made to minimize the friction with full sphere pin geometry configuration. The present work focused to reduce the frictional and wear rate, and experiments are conducted with tribo-pairs. i.e., nickel-coated pin surface slide against Al6061 alloy disc. The friction studies are carried out at different loads and geometries of pin surfaces (sphere and hemisphere configured at different orientations such as full sphere and hemisphere configured at 0°, 45°, and 90°) to induce different stress states with reference to sliding directions. Change in the geometry of EN8 pin material and their orientation with reference to sliding direction resulted in a different state of stress. The resulting stress levels were examined under the scanning electron microscope, which revealed the mechanisms of adhesion, abrasion, and extrusion. At a lower magnitude of orientation and load, the extent of asperity breaking lessens and material removal from pin surface decreases. Abrasion wear mechanism was observed corresponding to full sphere configuration on Al 6061 disc, whereas adhesive wear mechanisms are seen with hemisphere pins. The amount of aluminum transfer on pin surface with a hemisphere pin is comparatively more than that of full sphere configuration. At a lower magnitude of state of stress, the mechanism of sliding was dominated by the adhesion effect. At a higher level of state of stress, the mechanism of sliding was dominated by abrasion and extrusion.

THE INTRAPLATE VOLCANO-TECTONIC ACTIVITY IN NORTH-EASTERN AND SOUTH SECTORS OF THE PACIFIC LITHOSPHERIC PLATES WITH THE CONNECTION OF THE CHANGE OF ITS RELATIVE MOTION

The analysis of altimetric data in combination with bathymetry and gravimetry materials in the north-eastern and southern sectors of the Pacific Ocean, as well as detailed data on the underwater relief, the structure of the sedimentary cover, the composition and absolute age of basalts obtained within the area of domestic geological exploration for ferromanganese nodules (the Clarion-Clipperton zone) is carried out. Structural trends formed by local cone-shaped local structures of presumably volcanic nature, grouped along transform faults belonging to various stages of the kinematics of the Pacific Plate, have been traced in the structure of the oceanic lithosphere at various scale levels. The first trend corresponds to the extension of the fault system corresponding to the spreading system on the crest of the East Pacific rise before the restructuring of its planned geometry in the Paleocene-Eocene, the second coincides with their extension after the change in the relative movement of the Pacific Plate. The trends are characterized by planned disagreement, and an increase in the number of seamounts is observed in the areas of their intersection. Within the area of detailed studies, obvious signs of volcanic-tectonic activity were revealed: high dissection of the underwater relief, hills of different heights with steep slopes, whose volcanic nature is confirmed by differentiated basalts raised from their slopes, the absolute age of which indicates the multistage outpourings that occurred in an intraplate environment. The angular velocity of rotation of the spreading axis and the linear velocity of its advance with changes in the kinematics of the Pacific plate are estimated and possible reasons for changes in its relative motion are considered. An improved scheme of adaptation of the spreading zone to a change in the direction of relative plate movement is proposed, acc0ording to which an essential factor of intraplate volcanic-tectonic activity is the relaxation of stresses in the plate caused by external influence on it.

Design and fabrication of wheel removing machine

The proposed system's basic premise is to reduce personnel during nut fitting and removing wheels from autos. The motor is at the heart of the project and its implementation. Motor, Nut fitting arrangement (multi nut remover), and spur gear arrangement are the components employed here for the efficient operation of separate blocks. The model's main goal is to remove all of a wheel's nuts at once, rather than one by one. The model's premise is to use a spur gear to transfer relative motion to other gears. The primary spur gear is connected to the motor shaft in the model, which rotates due to the motor. The primary gear is the driver, while the secondary gears are the driven. The major gear is located in the model's center. The secondary gears and the primary gear are in sync. To ensure precise meshing and tool spacing, the secondary gears are set at predetermined distances. The drive axle is equipped with primary gear. The cover has several auxiliary axles that extend through it. Each secondary axle has a first end that is positioned inside the housing and a second end that extends outwardly from the cover. One of the first ends is attached to each of several secondary gears. Each of the secondary gears is in contact with the primary gear. One of the secondary axles is connected to each of the couplers. The project and implementation must provide the motor with both positive and negative potential. If we press the corresponding switch for forwarding rotation, the nut will be fixed; if we press the corresponding switch for reverse rotation, the polarity will be reversed, and the nut will be removed. The motor can be controlled according to the needs of the operator. To tighten or remove the nut, the operator should lift the model and place it in the proper location.

NUMERICAL MODELLING AND ASSESSMENT OF THE UGEN FLOATING WAVE ENERGY CONVERTER

The paper presents a linear hydrodynamic model for the UGEN wave energy converter, an analysis of the dynamics of the system and the predicted ability to extract energy from the waves. The UGEN (floating device with a U tank for GENeration of electricity from waves) consists of an asymmetric floater with a large internal U tank filled with water, where the energy is extracted from the relative motion between the water inside the tank and the rolling of the floater. The floater rolling mode of motion is the main stimulator of the motion of the water in the tank, however the sway and heave motions are also coupled therefore the system has motion.

DETERMINATION OF WAVE SLAMMING LOADS ON HIGH-SPEED CATAMARANS BY HYDROELASTIC SEGMENTED MODEL EXPERIMENTS

A 2.5m hydroelastic segmented catamaran model has been developed based on the 112m INCAT wave-piercer catamaran to simulate the vibration response during the measurement of dynamic slam loads in head seas. Towing tank tests were performed in regular seas to measure the dynamic slam loads acting on the centre bow and vertical bending moments acting in the demihulls of the catamaran model as a function of wave frequency and wave height to establish the operational loads acting on the full-scale 112m INCAT catamaran vessel. Peak slam forces measured on the bow of the model are found to approach the weight of the model, this being similar to the findings of full-scale vessel trials. A review of the motions of the hydroelastic segmented catamaran model found that the heave and pitch motions give a good indication of slamming severity in terms of the dimensionless heave and pitch accelerations. The dynamic wave slam forces are closely related to the relative motion between the bow and the incident wave profile.

TRANSIENT ANALYSIS OF HYDRODYNAMIC INTERACTION EFFECTS ON AN AUTONOMOUS UNDERWATER VEHICLE IN PROXIMITY OF A MOVING SUBMARINE

When an Autonomous Underwater Vehicle (AUV) is operating close to a moving submarine, the hydrodynamic interaction between the two vehicles can prevent the AUV from maintaining its desired trajectory. This can lead to mission failure and, in extreme cases, collision with the submarine. This paper outlines the transient interaction influence on the hydrodynamic coefficients of an AUV operating in close proximity and in relative motion to a larger moving submarine. The effects of relative motion on the interaction behaviour were investigated via two manoeuvres, i.e. the AUV overtaking and being overtaken by the submarine at different relative forward velocities and lateral distances. The results presented are from a series of Computational Fluid Dynamics (CFD) simulations on axisymmetric AUV and submarine hull forms, with validation of the CFD model carried out through scaled captive model experiments. The results showed that an AUV becomes less susceptible to the interaction influence when overtaking at speeds higher than the submarine. The implications of the interaction influence on the AUV’s ability to safely manoeuvre around the submarine are also discussed.