Vol 5, No 1 (2019): 18.02.2019
- Year: 2019
- Published: 18.02.2019
- Articles: 5
- URL: https://dynvibro.ru/dynvibro/issue/view/358
-
Description:
опубликован 18.02.2019 г.
Full Issue
Articles
Some aspects of the squeeze film damper with elastic rings parametric modeling under the fluid-structural coupling conditions
Abstract
The operation of the squeeze film damper (SFD) is highly depend on the lubricant layer behavior as well as on the stiffness of its elements. The interesting part is the mutual influence of the elastic part and an incompressible fluid squeezing around the ring during the operation of the SFD occurring due to the precession in the rotor. The article describes the approach to the modeling to the fluid-structural interaction simulation of the SFD as a system of similar section.
6-13
The influence of initial radial deformations on the residual stresses distribution in the hardened layer
Abstract
The study of the initial radial deformations influence on the residual strained state components distribution through the hardened layer thickness under various types of surface hardening has been conducted. Chemical thermal machining (CTM) and shot blasting (SB) have been examined on the example of smooth solid steel cylindrical specimens with diameters D=10 mm and D=25 mm under a linear distribution of initial deformations through the hardened layer thickness (the maximum value is on the surface and zero on the maximum depth of hardening). The calculation has been conducted with use of the program complex PATRAN/NASTRAN. The solution has been carried out in axial symmetric positing by thermo elasticity method. On study results it’s been stated that the radial stresses through the hardened layer thickness under CTM and SB are positive. Incidentally the radial component of initial deformations under chemical thermal machining and shot blasting doesn’t exercise essential influence on the radial and axial residual stresses distribution through the hardened layer thickness. Hence the initial radial deformations haven’t much significance at the evaluation of the residual strained stress state influence on the hardened parts endurance limit increment calculated by the average integral residual stresses criterion.
14-21
To the question of the design of direct-flow gas pressure regulator direct actions
Abstract
In this paper, issues that need to be considered when designing direct-flow gas pressure regulators of direct action are addressed. A constructive scheme of a piston type gas pressure regulator is presented. Experimental studies of gas pressure regulators of standard sizes DN50 and DN80 at the facility of the existing gas pipeline were conducted, and adjustment of regulators was carried out at the pneumatic stand of the university. The influence of friction forces on the quasi-harmonic low-frequency self-oscillations of the control system is shown. This phenomenon is due to the nature of friction when using rubber and fluoroplastic sealing rings in the moving elements of the regulator and the presence (or absence) of a film of lubricant. This is directly related to transients, stability conditions in transients during regulation due to changes in gas flow.
22-29
Evaluation of the dynamic load of valve elements for determining the optimal parameters of the unit
Abstract
The article proposes a generalized mathematical model of the valve, based on the representation of its structural diagram in the form of interconnected viscoelastic elements. According to the proposed method, a pneumatic valve with a seal on the basis of polycarbonate PK-M-3 was calculated. Values of speed of movement of the plate of the valve, at which collisions of elements of the valve seal occur, accompanied by vibration of the whole body, are determined. The analysis showed that the proposed mathematical model with sufficient accuracy simulates the dynamic processes when the pneumatic valve is triggered. The developed mathematical model makes it possible to justify the implementation of accelerated life tests for the failure of valve seals.
30-38
Dynamic characteristics identification and nonlinear regulator synthesis of a small gas turbine engine based on neural networks
Abstract
Latterly, neural networks have been used to simulate gas turbine engine dynamics and regulator synthesis. However, little attention has been paid to structure rationalizing of the neural network for identification problems. In addition, neural networks are often used for control issues. Usually these problems are tuning PID regulator coefficients or control in the certain modes. Therefore, it is important to study of the neural network structure dependence on the simulated engine parameter and the neurocontroller synthesis to control the engine in all modes. The neural network architecture was studied for rotor frequency parameter based on the engine tests. In the result neurocontroller was synthesed based on the JetCat P-60 SE engine model taking into account the limitations of the engine fuel consumption. The results allow us to reduce the total time to model engine and synthesys nonlinear controller.
39-45