scholarly journals OSCILLATIONS OF LAYED STRUCTURES WITH CONSOLIDATED MECHANICAL CHARACTERISTICS

2021 ◽  
pp. 1-3
Author(s):  
Сергій Трубачев ◽  
Валерій Колодежний ◽  
Владислав Петрик ◽  
Анатолій Сіренко
Keyword(s):  
Composite Materials ◽  
Dynamic Characteristics ◽  
Mechanical Characteristics ◽  
Layered Structures ◽  
Operating Conditions ◽  
Forced Oscillations ◽  
Design Parameters ◽  
The Real ◽  
Urgent Task ◽  
Vibration Loads

Modern industry requires the creation and use of materials and structures with improved performance. Such structures include layered structures made of com-posite materials. Layered systems made of high-strength composite materials with different layers have found wide application in aviation technology as elements of the bearing surfaces of aircraft, as well as in many other industries. The use of composite plates in loaded structures is one way to improve the weight characteristics of rocket and space technology. Also layered structural elements are widely used in transport engineering, used in construction practice. Multilayer systems in the conditions of bending deformation are the most rational in terms of strength and rigidity. Thus, the improvement of methods for calculating inhomogeneous layered structures is an urgent task. Along with the methods of non-destructive testing, defectoscopy of structures using hardware methods, analytical research methods remain relevant, which allow to predict the possible destruction of the structure. When designing equipment, it is necessary to take into account the real operating conditions of structures. In the process, the mechanisms work under the action of vibration loads, so determining the dynamic characteristics of structures is an urgent task. This determines the need to study the oscillating processes taking into account the real conditions of vibration load, which will determine the optimal design parameters and modes of operation of the machine with the maximum distance from critical modes that are dangerous. One of the reasons for the destruction of elements of machine-building structures is that they resonate. Therefore, the problem of forced oscillations needs to be solved. To solve this problem, it is necessary to determine the natural frequencies and their corresponding natural forms of oscillations. The paper presents a method of calculating a layered structure to determine the physical characteristics for the whole package, taking into account the physical and mechanical characteristics of each of the layers. This approach allows to determine the dynamic characteristics and stress-strain state of multilayer composite structures, using classical equations for homogeneous struc-tures. This approach greatly simplifies the equation and allows you to find a solution that can be used in the design of structures made of composite materials under vibration loads.

Effect of structural design parameters on nonlinear dynamic characteristics of the gear transmission

2021 ◽  
pp. 095440702110294
Author(s):  
Tiancheng Ouyang ◽  
Rui Yang ◽  
Yudong Shen ◽  
Jingxian Chen ◽  
Nan Chen
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Gear Tooth ◽  
Spur Gear ◽  
Operating Conditions ◽  
Design Parameters ◽  
Meshing Stiffness ◽  
Nonlinear Dynamic Characteristics ◽  
Potential Energy Method

The calculation of time-varying meshing stiffness caused by the alternate contacting of the gear tooth is an essential prerequisite to obtain real and effective nonlinear dynamic characteristics of the transmission system, so that the significance of which cannot be overemphasized. Accordingly, this work proposes an improved method to get meshing stiffness with taking fillet-foundation and gear rim deflection into consideration. Compared to the traditional potential energy method, the proposed method has more superior accuracy and performance, and its effectiveness has been further verified by the finite element analytical model. After that, an ideal eight degree of freedoms (DOFs) dynamic model of one stage mass-spring-damper involute spur gear, including lateral and torsional motions, is established to study the dynamic characteristics. Due to the complexity of the gear system operating conditions, we also investigate the influence of various parameters including hub bore radius, transmitting load, and rotation speed on dynamic features, especially in heavy-load and high-speed conditions. From the results, it can be concluded that these parameters will play a prominent role in the spur gear pair dynamic behaviors, providing a certain guidance for gear design.

On Hydraulic Brake System Using Bench Experiments for Off-Road Vehicles

2012 ◽  
Vol 588-589 ◽  
pp. 327-330
Author(s):  
Fang Zhao ◽  
Mu Yi Lin ◽  
Zhun Wang
Keyword(s):  
Dynamic Characteristics ◽  
Calculated Data ◽  
Operating Conditions ◽  
Brake System ◽  
Design Parameters ◽  
Road Vehicles ◽  
Construction Machinery ◽  
Hydraulic Brake ◽  
Full Power ◽  
Actuation Systems

The full power hydraulic brake system has several advantages over traditional brake actuation systems. These systems are capable of supplying fluid to a range of very small and large volume service brakes with actuation that is faster than air/hydraulic brake systems. Implementation of full power hydraulic brake system in off-road vehicles calls for good understanding of its dynamic characteristics. In this paper, we consider the problem of dynamic modeling of the brake system and develop a dynamic model for a hydraulic brake valve. First, the dynamic characteristics of full power hydraulic brake system are analyzed theoretically. The effects of varying design parameters (brake valve, accumulator and so on) and the different operating conditions are then analyzed. Second, we investigate the dynamic characteristics of a full power hydraulic brake system using a test bench, which is a loader brake system specifically designed for one construction Machinery Company. Finally, based on the experimental results, the mathematical models are amended and verified. The result shows that the model-calculated data agree well with tested data. The dynamic behavior of hydraulic valve can be well predicted with the model. The simplified models can be applied to the studies of full power hydraulic brake system dynamics.

Dynamic Structural Properties of Compliant Foil Thrust Bearings—Comparison Between Experimental and Theoretical Results

1994 ◽  
Vol 116 (1) ◽  
pp. 70-75 ◽  
Author(s):  
C.-P. Roger Ku
Keyword(s):  
Dynamic Characteristics ◽  
High Performance ◽  
Operating Conditions ◽  
Design Parameters ◽  
Static Loads ◽  
Thrust Bearings ◽  
Equivalent Damping ◽  
Foil Bearings ◽  
Compliant Surface ◽  
Wide Range

This paper describes an experimental investigation into the dynamic characteristics of corrugated foil (bump foil) strips used in compliant surface foil thrust bearings. This study provided the first opportunity to quantify the dynamic structural stiffness and equivalent damping coefficients of bump foil strips for a wide range of operating conditions. The experimental data were compared to results obtained by a theoretical model developed earlier. The effects of bearing design parameters, such as static loads, dynamic displacement amplitudes, bump configurations, pivot locations, surface coatings, and lubricant were also evaluated. An understanding of the dynamic characteristics of bump foil strips resulting from this work offers designers a means for enhancing the design of high-performance compliant foil bearings.

An Experimental and Theoretical Study of Dynamic Structural Stiffness in Compliant Foil Bearings

1993 ◽  
Author(s):  
C.-P. Roger Ku
Keyword(s):  
Dynamic Characteristics ◽  
High Performance ◽  
Operating Conditions ◽  
Design Parameters ◽  
Structural Stiffness ◽  
Static Loads ◽  
Foil Bearings ◽  
Compliant Surface ◽  
Wide Range ◽  
Bearing Design

Abstract This paper describes an experimental investigation into the dynamic characteristics of corrugated foil (bump foil) strips used in compliant surface foil bearings. This study provided the first opportunity to quantify the dynamic structural stiffness of bump foil strips for a wide range of operating conditions. The experimental data were compared to results obtained by a theoretical model developed earlier, and the comparisons show very good agreement. The effects of bearing design parameters, such as static loads, dynamic displacement amplitudes, bump configurations, pivot locations, surface coatings, and lubricant were also evaluated. An understanding of the dynamic characteristics of bump foil strips resulting from this work offers designers a means for enhancing the design of high-performance compliant foil bearings.

Power Test System Development and Dynamic Performance State Estimation Based on Hub Motor Vehicle

2020 ◽  
Vol 13 (2) ◽  
pp. 126-140
Author(s):  
Jing Gan ◽  
Xiaobin Fan ◽  
Zeng Song ◽  
Mingyue Zhang ◽  
Bin Zhao
Keyword(s):  
Real Time ◽  
Dynamic Performance ◽  
Test System ◽  
Operating Conditions ◽  
Motor Vehicles ◽  
Maximum Speed ◽  
Performance Parameters ◽  
Power Performance ◽  
Power Test ◽  
The Real

Background: The power performance of an electric vehicle is the basic parameter. Traditional test equipment, such as the expensive chassis dynamometer, not only increases the cost of testing but also makes it impossible to measure all the performance parameters of an electric vehicle. Objective: A set of convenient, efficient and sensitive power measurement system for electric vehicles is developed to obtain the real-time power changes of hub-motor vehicles under various operating conditions, and the dynamic performance parameters of hub-motor vehicles are obtained through the system. Methods: Firstly, a set of on-board power test system is developed by using virtual instrument (Lab- VIEW). This test system can obtain the power changes of hub-motor vehicles under various operating conditions in real-time and save data in real-time. Then, the driving resistance of hub-motor vehicles is analyzed, and the power performance of hub-motor vehicles is studied in depth. The power testing system is proposed to test the input power of both ends of the driving motor, and the chassis dynamometer is combined to test so that the output efficiency of the driving motor can be easily obtained without disassembly. Finally, this method is used to carry out the road test and obtain the vehicle dynamic performance parameters. Results: The real-time current, voltage and power, maximum power, acceleration time and maximum speed of the vehicle can be obtained accurately by using the power test system in the real road experiment. Conclusion: The maximum power required by the two motors reaches about 9KW, and it takes about 20 seconds to reach the maximum speed. The total power required to maintain the maximum speed is about 7.8kw, and the maximum speed is 62km/h. In this article, various patents have been discussed.

On corrosion properties of ceramic materials for pump friction pairs in lead – bismuth environment

2019 ◽  
pp. 116-122
Author(s):  
V. V. Stepanov ◽  
A. D. Kashtanov ◽  
S. U. Shchutsky ◽  
A. N. Agrinsky ◽  
N. I. Simonov
Keyword(s):  
Composite Materials ◽  
Heat Resistance ◽  
Experimental Research ◽  
Ceramic Materials ◽  
Operating Conditions ◽  
Metallic Materials ◽  
Corrosion Properties ◽  
Liquid Coolant ◽  
Radial Bearing ◽  
Axial Pump

We consider the results of studies on the choice of material of the lower radial bearing of the pump, designed to circulate the coolant lead – bismuth. The circulation of the liquid coolant is provided by a vertical axial pump having a “long” shaft. In this design it is necessary to provide for the lower bearing the lubrication carried out with lead – bismuth coolant. Having analyzed the operating conditions of the axial pump, we decided to carry out the lower bearing in accordance with the scheme of a hydrodynamic sliding bearing. The materials of friction pairs in such a bearing must withstand the stresses arising from the operation of the pump, as well as the aggressive conditions of the coolant. Non-metallic materials – ceramics and carbon-based composite materials – were selected basing on the study of literature data for experimental research on the corrosion and heat resistance in the lead-bismuth environment. 

Viability of turbine blade material with a long service life

2019 ◽  
pp. 28-35
Author(s):  
O. B. Berdnik ◽  
I. N. Tsareva ◽  
M. K. Chegurov
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Yield Strength ◽  
Mechanical Characteristics ◽  
Operating Time ◽  
Structural Features ◽  
Operating Conditions ◽  
Standard Methods ◽  
Experimental Values ◽  
Plasticity Coefficient

This article deals with structural features and characteristic changes that affect the mechanical characteristics after different service life in real conditions using the example of the blades of the 4th stage of turbine GTE-45-3 with an operating time of 13,000 to 100,000 hours. To study the change in the state of the material under different operating conditions, determine the degree of influence of heat treatment on the regeneration of the microstructure, and restore the mechanical characteristics of the alloy after different periods of operation, non-standard methods were used: relaxation tests on miniature samples to determine the physical yield strength and microplasticity limit and quantitative evaluation of the plasticity coefficient of the material from experimental values of hardness, which allow us to identify the changes occurring in the microvolumes of the material and predict the performance of the product as a whole.

scholarly journals Binary Amplitude Reflection Gratings for X-ray Shearing and Hartmann Wavefront Sensors

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 536
Author(s):  
Kenneth A. Goldberg ◽  
Antoine Wojdyla ◽  
Diane Bryant
Keyword(s):  
Operating Conditions ◽  
Design Parameters ◽  
Wavefront Aberration ◽  
Light Sources ◽  
Wavefront Sensors ◽  
X Ray ◽  
New Class ◽  
Coherent Wave ◽  
Reflection Gratings ◽  
Dynamic Operating

New, high-coherent-flux X-ray beamlines at synchrotron and free-electron laser light sources rely on wavefront sensors to achieve and maintain optimal alignment under dynamic operating conditions. This includes feedback to adaptive X-ray optics. We describe the design and modeling of a new class of binary-amplitude reflective gratings for shearing interferometry and Hartmann wavefront sensing. Compact arrays of deeply etched gratings illuminated at glancing incidence can withstand higher power densities than transmission membranes and can be designed to operate across a broad range of photon energies with a fixed grating-to-detector distance. Coherent wave-propagation is used to study the energy bandwidth of individual elements in an array and to set the design parameters. We observe that shearing operates well over a ±10% bandwidth, while Hartmann can be extended to ±30% or more, in our configuration. We apply this methodology to the design of a wavefront sensor for a soft X-ray beamline operating from 230 eV to 1400 eV and model shearing and Hartmann tests in the presence of varying wavefront aberration types and magnitudes.

scholarly journals DeepFogSim: A Toolbox for Execution and Performance Evaluation of the Inference Phase of Conditional Deep Neural Networks with Early Exits Atop Distributed Fog Platforms

2021 ◽  
Vol 11 (1) ◽  
pp. 377
Author(s):  
Michele Scarpiniti ◽  
Enzo Baccarelli ◽  
Alireza Momenzadeh ◽  
Sima Sarv Ahrabi
Keyword(s):  
Neural Networks ◽  
Real Time ◽  
Future Internet ◽  
Operating Conditions ◽  
Graphic User Interface ◽  
Energy Aware ◽  
Internet Applications ◽  
The Real ◽  
Delay Performance ◽  
Hard Constraints

The recent introduction of the so-called Conditional Neural Networks (CDNNs) with multiple early exits, executed atop virtualized multi-tier Fog platforms, makes feasible the real-time and energy-efficient execution of analytics required by future Internet applications. However, until now, toolkits for the evaluation of energy-vs.-delay performance of the inference phase of CDNNs executed on such platforms, have not been available. Motivated by these considerations, in this contribution, we present DeepFogSim. It is a MATLAB-supported software toolbox aiming at testing the performance of virtualized technological platforms for the real-time distributed execution of the inference phase of CDNNs with early exits under IoT realms. The main peculiar features of the proposed DeepFogSim toolbox are that: (i) it allows the joint dynamic energy-aware optimization of the Fog-hosted computing-networking resources under hard constraints on the tolerated inference delays; (ii) it allows the repeatable and customizable simulation of the resulting energy-delay performance of the overall Fog execution platform; (iii) it allows the dynamic tracking of the performed resource allocation under time-varying operating conditions and/or failure events; and (iv) it is equipped with a user-friendly Graphic User Interface (GUI) that supports a number of graphic formats for data rendering. Some numerical results give evidence for about the actual capabilities of the proposed DeepFogSim toolbox.

Development of High-Speed Response Electromagnetic Linear Actuator Using for Pneumatic Control Valve

2014 ◽  
Vol 532 ◽  
pp. 41-45 ◽  
Author(s):  
Myung Jin Chung
Keyword(s):  
Optimal Design ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Design Method ◽  
Control Valve ◽  
Design Parameters ◽  
Linear Actuator ◽  
Analytic Model ◽  
Electromagnetic Linear Actuator ◽  
Quadratic Programming Method

Analytic model of electromagnetic linear actuator in the function of electric and geometric parameters is proposed and the effects of the design parameters on the dynamic characteristics are analyzed. To improve the dynamic characteristics, optimal design is conducted by applying sequential quadratic programming method to the analytic model. This optimal design method aims to minimize the response time and maximize force efficiency. By this procedure, electromagnetic linear actuator having high-speed characteristics is developed.

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