Distribution of Static Deformations along the Friction Lining of the Brake Mechanism in the Cars of GAZelle Series

The study of the shoe lining in the drum brake mechanism is of paramount importance to evaluate its wear regularity. Thereto, the computational scheme of the drum brake-shoe mechanism has been designed, the calculation formulae of tangential and radial components of the external points displacement in the lining have been analyzed, by means of which their numerical values have been determined, the diagram of the radial displacements has been designed and compared with descriptors of the wear change along the friction lining, according to which they alter with similar regularities.

Longitudinal vibrations of a cylindrical shell filled with a viscous compressible liquid

This article investigates the longitudinal vibrations of a semi-infinite circular cylindrical elastic shell filled with a viscous compressible fluid. It is believed that the vibrations are excited by a suddenly switched on longitudinal displacement at the end. To solve the problem, the refined equations of longitudinal vibrations of a circular cylindrical elastic shell interacting with an internal viscous compressible fluid, previously proposed by the authors, were taken as the main resolving equations. In this case, the lateral surfaces of the shell are considered free from external loads; in addition, considering purely longitudinal vibrations, it can be assumed that the radial displacements of the points of the shell are equal to zero.

MOMENTAL METHOD FOR CALCULATING FORCES IN CYLINDRICAL SHELLS OF ORBITAL FACILITIES

The article is devoted to the torque method, according to the principles of which it is possible to determine the loads arising in the thin-walled shell of the hulls of orbital vehicles from the action of the internal pressure uniformly distributed over the area, normally oriented to the middle surface of the shell. In this case, the load on the shell consists of normal forces (longitudinal and circumferential), a transverse force that causes radial displacements in the shell, and a bending moment in the longitudinal plane of the object. The specified bending moment can occur during the manifestation of inertial forces (for example, the Coriolis force) during the transition of the orbital vehicle in height from one orbit to another in vertical directions normal to the orbit (rotational movements); the same rotary movements can cause inertial forces to appear when maneuvering spacecraft and rocket units at the same height (in conventionally horizontal directions). To determine the above loads and radial displacements of the shell, a mathematical algorithm is proposed based on the principles of the moment calculation method according to the scheme of an infinitely long shell, which is typical for orbital vehicle housings.

On the question of cylindrical waves in elastic media

Рассматривается задача о распространении цилиндрической волны сжатия в упругой среде. Получены значения радиальных смещений точек среды и радиальных напряжений. Указаны асимптотические оценки полученных решений для поля смещений в среде на больших расстояниях от источников волны, а также статистическое распределение смещений среды. The problem of propagation of a cylindrical compression wave in an elastic medium is considered. The values of radial displacements of medium points and radial stresses are obtained. Asymptotic estimates of the obtained solutions for the displacement field in the medium at large distances from the wave sources are given, as well as the statistical distribution of the displacement of the medium.

Rotordynamics Experimental Validation of a Sliding-Blade Architecture for an Inside-Out Ceramic Turbine

The integration of monolithic ceramic blades into sub-megawatt microturbines is a low-cost option for increasing Turbine Inlet Temperature and efficiency. The Inside-Out Ceramic Turbine (ICT) is a promising concept for the integration of ceramic blades by loading each blades in compression using a carbon-polymer composite rim to convert the blade radial loads to tangential hoop stress. High tangential velocities lead to elevated radial displacement of the rim and, therefore, the rotor hub needs to be able to maintain the contact with the blades for a large range of radial displacements. This displacements comes with hub structural challenges and rotordynamics considerations. For these reasons, blade tip speed have been previously limited to about 360 m/s. This paper presents a hub design that allows high radial displacement using the combination of inclined blade roots, inclined hub grooves and an axial spring. The contact between the blade root and the hub is maintained through the inclined planes by the axial forces from the spring creating internal friction in the rotor that can induce sub-synchronous rotordynamics instabilities. The onset of instabilities is investigated experimentally with cold spin tests of a simplified ICT prototype. The results first show that the concept remains stable up to the maximum speed tested of 127 kRPM (tip speed of 387 m/s) if the spring is designed such that it remains in contact with the blade roots at all time. On the other hand, when reducing the preload sufficiently to test the limits of the concept, the rotor first mode became unstable at 120 kRPM resulting in failure of the prototype. These results suggest that, provided a sufficient spring preload to prevent excessive relative motion, the blades can reach the desired radial displacements, removing the main constraint on ICT tip speed.

Anchor Bolt Failures in Coke Drums

Anchor bolt failures that are commonly experienced by coke drums typically show signs of axial and/or shear overload. Temperature measurements and thermographic images have demonstrated that side-to-side temperature differences in coke drums can be more than 400 degrees Fahrenheit. In this paper, finite element models are used to examine the displacement of skirt base plates. Various combinations of circumferential thermal gradients, support deck slopes, and friction coefficients between drums and support structures are used. The study shows that observed thermal gradients can result in significant longitudinal, circumferential, and radial displacements and explains observed overload failures of anchor bolts. In addition, the study demonstrates the roles of deck slope and friction coefficient on base plate displacements.