Vol 8, No 1 (2022)
- Year: 2022
- Articles: 5
- URL: https://dynvibro.ru/dynvibro/issue/view/553
Full Issue
Articles
AN INFLUENCE OF ROLLER STRENGTHENING ON MULTCYCLIC FATIGUE OF SPECIMENS WITH CUTS OF VARIOUS DEPTH AND A PRESSURIZED HUB
Abstract
The influence of roller strengthening on a residual stresses distribution and multicyclic fatigue of solid cylindrical specimens of 50 mm diameter made of steel 20 with cuts of various depths and a pressurized hub has been examined. As a result, an endurance limit of roller strengthened specimens diminishes. In order to preserve the effect of hardening with a cut’s depth increase, it’s necessary to increase the thickness of a layer with compressive residual stresses. Surface hardening influence on an endurance limit of specimens has been estimated by two criteria: axial residual stresses on a concentrator’s surface and average integral residual stresses, calculated through the dangerous section’s surface layer thickness that equal a critical depth of a non-propagating fatigue crack. It’s been stated that it’s more reasonable to use the average integral residual stresses criterion for an evaluation of roller strengthening influence on an endurance limit of specimens with cuts of various depth and a pressurized hub.
6-11
SQUEEZE FILM DAMPER DYNAMIC STIFFNESS ANALYSIS, TAKING INTO ACCOUNT THE END GAP
Abstract
One of the most common ways to reduce vibration in engines is the use of damping devices in the rotor supports. Damping devices may affect both the amplitude of the oscillations and the critical frequencies. The most commonly used damping devices are the squeeze film dampers (SFD), which can show dynamic stiffness that is proportional to frequency of oscillations and that is depends on the relative amplitude of oscillations. The stiffness of the damper is highly influenced by the end gap, which is also often seen as a non-contact radial clearance seal. In this work, a method is proposed that will take into account the effect of end gaps on the dynamic stiffness of a SFD. As a result of the calculations, it was found that the size of the end slots significantly affects the dynamic stiffness of a short SFD, and in some work modes it can exceed the stiffness of supports and bearings.
12-17
DEVELOPMENT OF A TEST RIG FOR STUDYING THE HYDRODYNAMIC NOISE LEVEL OF THROTTLE PLATES. CALCULATION OF THE CAVITATION-FREE TEST MODE FOR THE THROTTLE PLATE
Abstract
The article presents the development of a test rig for studying the hydrodynamic noise level of throttle plates. The assembled test rig is being investigated for the presence of its self-generated noise. According to the results of the research, measures were taken to reduce self-generated noise of the test rig. To exclude the occurrence of cavitation processes during the experiments, a calculation was carried out to determine the test conditions for the study of throttle plates.
18-24
LARGE SIZED PRODUCT SHELLS DISPLACEMENT MEASUREMENT UNDER STATIC LOADING USING LASER TRACKERS
Abstract
In the aerospace industry the accuracy of product geometry and the aerodynamic contour provided traditionally, by the mould loft template method. The assembly accuracy control is carried out using optical measuring instruments, such as a level and a theodolit in combination with leveling rulers came to the aircraft industry from geodesy. Measurements are carried out according to reference points pre-embedded in the product at the design stage.
The introduction of modern high precision coordinate measuring machines (CMM) into the production cycle is promising and actively developing direction to improve the quality of manufactured aircraft. To control the geometry of parts and assemblies, stationary portal-type CMMs and mobile CMMs of the "hand" type replace traditional rod tools and templates, and in the assembly and control operations of the product, traditional optical devices are replaced by a laser tracker.
The aim of this paper is the use of laser trackers for non-contact real-time large-sized product shell displacement measurement under static loading, which makes it possible to reduce the complexity and duration of tests, and ensure high measurement accuracy.
25-32
GTE GEAR TOOTH WEAR DIAGNOSIS BASED ON VIBRATION NOISE
Abstract
This paper shows that vibration-based tooth wear diagnostics through the intensity of the n-dimensional vector proved to be ineffective for planetary gearboxes of gas turbine engines as it is characterized by low intensity of multiple tooth harmonics. It was found that the intensity of the process dispersion around the third and the sixth tooth harmonic - as wear develops - could serve as a diagnostic indicator of this particular defect.
33-37