scholarly journals Features of calculation of steel structures of bridge cranes at variable loads

2019 ◽  
Vol 298 ◽  
pp. 00032
Author(s):  
A. L. Akhtulov ◽  
O. M. Kirasirov ◽  
M. O. Kirasirov
Keyword(s):  
Dynamic Characteristics ◽  
Entire Range ◽  
Steel Structures ◽  
Point Of View ◽  
Operating Conditions ◽  
Variable Load ◽  
Linear Summation ◽  
Static And Dynamic Characteristics

The article deals with the calculation of metal bridge cranes operating under the influence of variable loads. Requirements to static and dynamic characteristics of mechanisms of load-lifting cranes are caused by specifics of work, features of a design and operating conditions of the cranes working at variable loadings. Thus, it is proposed to perform calculations of parts of crane mechanisms for endurance, operating under non-stationary variable load, based on the principle of linear summation of damage, allowing the calculation from the point of view of the load equivalent to the entire range of operating loads.

Study of the Static and Dynamic Performance of Rectangular Air Pads by Means of Lumped Parameters Models

2012 ◽  
Author(s):  
Guido Belforte ◽  
Federico Colombo ◽  
Terenziano Raparelli ◽  
Andrea Trivella ◽  
Vladimir Viktorov
Keyword(s):  
Pressure Distribution ◽  
Design Process ◽  
Dynamic Characteristics ◽  
Analytical Methods ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Positioning Systems ◽  
Static And Dynamic Characteristics ◽  
Distributed Parameters ◽  
Lumped Parameters

Externally pressurized gas bearings are widely used in linear guide-ways for measuring machines and precision positioning systems. The number and the diameter of the supply orifices and their position strongly influence the characteristic of the pad. Usually during the design process of a pad a distributed parameters model is used to simulate the pressure distribution under the pad because it doesn’t exist a general formula suitable for all possible geometries. Analytical methods can be applied for simplified geometries to calculate static and dynamic performance of pneumatic bearings. Analytical and lumped parameters models are of faster implementation with respect to distributed parameters models and are easier to implement in the design process. The present paper proposes different lumped parameters models to obtain the static and dynamic characteristics of pneumatic pads. These methods can be used in order to optimize the stiffness in correspondence of the operating conditions. Rectangular air pads of size 30×60 mm are considered. The results are compared with that obtained with a distributed parameters model to estimate the accuracy of the models.

Adiabatic Approximate Solution for Static and Dynamic Characteristics of Turbulent Partial Journal Bearings With Surface Roughness

1994 ◽  
Vol 116 (4) ◽  
pp. 672-680 ◽  
Author(s):  
H. Hashimoto ◽  
M. Mongkolwongrojn
Keyword(s):  
Surface Roughness ◽  
Approximate Solution ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Journal Bearings ◽  
Numerical Results ◽  
Operating Conditions ◽  
Finite Width ◽  
Homogeneous Surface ◽  
Static And Dynamic Characteristics

Hydrodynamic bearings are generally used for a long term, so the bearing surfaces may be roughened for many reasons such as wear, impulsive damage, foreign particles, cavitation erosion, rust, and so on. Under the turbulent operating conditions of high speed bearings, the surface roughness may result in considerable increase in both film pressure and temperature. This paper describes an adiabatic approximate solution for the static and dynamic characteristics of 180 deg partial journal bearings with homogeneous surface roughness. Applying the modified lubrication equation and energy equation, considering the combined effects of turbulence and surface roughness, to the finite width 180 deg partial journal bearings, the static and dynamic characteristics such as pressure and temperature distributions, Sommerfeld number, attitude angle, spring and damping coefficients and whirl onset velocity are obtained numerically. In the numerical analysis of the temperature distribution, adiabatic boundary conditions are assumed and then the heat transfer effect to the journal and bearing-bush surfaces is omitted. The numerical results are indicated in graphic form for various relative roughness under the mean Reynolds number of Re = 5000 and 10,000. Moreover, some numerical results of static characteristics are compared with the experimental results.

Static and dynamic characteristics and stability analysis of high-speed water-lubricated hydrodynamic journal bearings

2021 ◽  
pp. 135065012110270
Author(s):  
Bo Xu ◽  
Hun Guo ◽  
Xiaofeng Wu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Load Capacity ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Inertia Effect ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Stiffness And Damping

The purpose of this paper is to analyze the influence of turbulent, inertia, and misaligned effects on the static and dynamic characteristics and stability of high-speed water-lubricated hydrodynamic journal bearings. Based on the Navier–Stokes equation, the mixing-length theory, and the essential assumption that the velocity profile is not strongly affected by inertia force, the fluid lubrication model with turbulent, inertia, and misaligned effects is established, and then the stability analysis of bearings is carried out based on the equation of motion with four degrees of freedom. The model is solved by the finite difference method and the numerical results are compared under different operating conditions. The results show that the turbulent effect greatly increases the load capacity, power consumption, stiffness and damping coefficients, and stability of bearings, and the inertia effect significantly increases the volume flow rate of bearings, and the misaligned effect increases the load capacity, stiffness and damping coefficients, and stability of bearings. In high rotary speed and moderate eccentricity ratios, the influence of the inertia effect on the load capacity, stiffness coefficients, and stability cannot be neglected.

Invited PaperTemperature dependence of SiGe HBT static and dynamic characteristics

1998 ◽  
Vol 08 (PR3) ◽  
pp. Pr3-81-Pr3-86
Author(s):  
F. Aniel ◽  
N. Zerounian ◽  
A. Gruhle ◽  
C. Mähner ◽  
G. Vernet ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Static And Dynamic Characteristics ◽  
Sige Hbt

CAD Of Anticorrosive Protection Of Steel Structures

2019 ◽  
pp. 18-23
Keyword(s):  
Protective Coating ◽  
Computer Aided Design ◽  
Steel Structures ◽  
Cost Effective ◽  
Operating Conditions ◽  
Computational Tool ◽  
Protection Method ◽  
Cost Effective Method ◽  
The Cost ◽  
Aided Design

The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.

Tertiary Nitrification Pilot Plants on Parisian Waste Water

1990 ◽  
Vol 22 (1-2) ◽  
pp. 347-352 ◽  
Author(s):  
C. Paffoni ◽  
B. Védry ◽  
M. Gousailles
Keyword(s):  
Waste Water ◽  
Metropolitan Area ◽  
Fixed Bed ◽  
Point Of View ◽  
Operating Conditions ◽  
Research Center ◽  
Daily Output ◽  
Practical Point ◽  
Fixed Bed Reactors

The Paris Metropolitan area, which contains over eight million inhabitants, has a daily output of about 3 M cu.meters of wastewater, the purification of which is achieved by SIAAP (Paris Metropolitan Area Sewage Service) in both Achères and Valenton plants. The carbon pollution is eliminated from over 2 M cu.m/day at Achères. In order to improve the quality of output water, its tertiary nitrification in fixed-bed reactors has been contemplated. The BIOFOR (Degremont) and BIOCARBONE (OTV) processes could be tested in semi-industrial pilot reactors at the CRITER research center of SIAAP. At a reference temperature of 13°C, the removed load is approximately 0.5 kg N NH4/m3.day. From a practical point of view, it may be asserted that in such operating conditions as should be at the Achères plant, one cubic meter of filter can handle the tertiary nitification of one cubic meter of purified water per hour at an effluent temperature of 13°C.

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