scholarly journals INFLUENCE OF A SYNCHRONIZED HUMAN DYNAMIC LOAD ON VIBRATIONS OF MACHINE STRUCTURES

2021 ◽  
pp. 1-9
Author(s):  
Goran Nikola Radoicic ◽  
Miomir Jovanovic
Keyword(s):  
Experimental Testing ◽  
Dynamic Loads ◽  
Variable Load ◽  
Bridge Crane ◽  
Support Structure ◽  
Dynamic Coefficients ◽  
Rhythmic Behavior ◽  
Test Platform ◽  
Human Crowd ◽  
Main Girder

This paper contributes to the research of rhythmic behavior of a group of people, which, more or less synchronized, moves or jumps on a thin and elastic plate, thus performing a dynamically variable load. The analysis of the rhythmic behaviour of the crowd carried out on the basis of the experimental testing on the special steel test platform. The experiment consisted of sixteen measurements of live force and acceleration of the test platform. The dynamic loads caused by the mass of the human crowd and individuals had different intensities. The measurements of acceleration of the carrying platform were performed in order to estimate how the live human force influences on vibrations of machine structures. This research allows us to gain a picture of how serious the threats are from some human actions on the support structure of machines that are handled when performing works in industry, construction or mining. On the basis of these experiments, the mathematical models of the equivalent excitation forces were developed. The measured accelerations of the test platform tread surface and calculated dynamic coefficients of human force indicate that similar actions can seriously endanger balance of the support structure of some machine, and even, for example, can cause the main girder of the bridge crane to fall out. This and similar experiments allow us to formulate appropriate models of excitation loads by human force, which can then be used in simulation analyses in order to develop future systems of electronic protection of machines structures from adverse events.

Fatigue Research on Welding Joint of the Main Girder in Bridge Crane

2013 ◽  
Vol 711 ◽  
pp. 323-326
Author(s):  
Nan Liu ◽  
Dong Xiang ◽  
Peng Mou ◽  
Ying Ren ◽  
Ning Xie
Keyword(s):  
Fatigue Life ◽  
Welding Process ◽  
Scientific Basis ◽  
Main Beam ◽  
Bridge Crane ◽  
Mechanical Products ◽  
Weld Fatigue ◽  
Model Set ◽  
Set Up ◽  
Main Girder

Fatigue problems about large sized structure components ,such as bridge crane girder , has always been the bottleneck of mechanical products lightweight, reliability, security. In order to study fatigue problem about crane girder in the actual conditions, the dangerous spot of the girder is identified by using the finite element method to analyze structural stress. By simplified model , set up to reflect the main beam welding details of the characteristics of the small size of the process welding fatigue specimen model, and carried out a series of fatigue life test. Specimen fatigue test results quantitative descript the actual fatigue life of the bridge crane girder welded structures. By data fitting, the S-N curve equation of the bridge crane girder include the specific materials, the stress ratio, the welding process and special structure is obtained. It provides a scientific basis and practical methods to solve weld fatigue life design and the remaining life prediction about the crane girder.

Effect of Welding Procedure on Main Girder Fatigue Property

2014 ◽  
Vol 496-500 ◽  
pp. 666-672
Author(s):  
Gang Shen ◽  
Dong Xiang ◽  
Nan Liu ◽  
Peng Mou ◽  
Yong Yang ◽  
...  
Keyword(s):  
Fatigue Failure ◽  
Manufacturing Industry ◽  
Fatigue Property ◽  
Vertical Force ◽  
Bridge Crane ◽  
Fatigue Reliability ◽  
Welding Joint ◽  
Welding Procedure ◽  
Main Girder ◽  
Crack Position

Hoisting machinery is an important part of the equipment manufacturing industry, and the general bridge crane is the most widely used hoisting machinery. The main girder of bridge crane is the main load-bearing structure. Further, fatigue failure of main girder usually occurs not on the material itself but in the welding joint. The article has carried out three groups of experiments, which are experiment on fatigue property under vertical force, experiment on fatigue property under the comprehensive function of vertical force and horizontal force and experiment on failure mode of main girder under the prefabricated crack, to further discuss the effect of welding procedure on main girder fatigue property. Finally the following three conclusions are obtained. Firstly, the crack occurs closely to the middle position of welding place of the lower board and the main web, with the trend of scaling up along the main web perpendicular to the welding place. Secondly, the crack occurs on the main web close to the upper board, with the two-way expansion trend. Thirdly, fatigue failure cracks do not occur in the welding joint except the prefabricated crack position close to the square steel rail after the cyclic loading of two million times on main girder, which indicates that the uniformity of welding quality has an importance influence on the fatigue reliability of the whole main girder.

Optimization of the box section of the main girder of the bridge crane with the rail placed above the web plate

2012 ◽  
Vol 47 (2) ◽  
pp. 273-288 ◽  
Author(s):  
Mile M. Savković ◽  
Milomir M. Gašić ◽  
Dobrivoje M. Ćatić ◽  
Ružica R. Nikolić ◽  
Goran V. Pavlović
Keyword(s):  
Bridge Crane ◽  
Box Section ◽  
Main Girder ◽  
The Web

Experimental Testing of Retaining Walls of Precast Elements

2015 ◽  
Vol 725-726 ◽  
pp. 168-175
Author(s):  
Zoran Bonić ◽  
Nebojša Davidović ◽  
Verka Prolović ◽  
Nikola Romić ◽  
Nikolay Vatin
Keyword(s):  
Experimental Testing ◽  
Retaining Walls ◽  
Dynamic Loads ◽  
Future Research ◽  
Mechanically Stabilized Earth ◽  
Static Loads ◽  
Retaining Structures ◽  
Mechanically Stabilized ◽  
Precast Elements ◽  
Construction Practice

In contemporary construction practice is increasingly being applied flexible retaining structures of mechanically stabilized earth, gabions and precast elements. Although widely used only recently, their benefits are proven and widely accepted. The first part of the paper provides an overview of the possible ways of using of precast elements in the construction of retaining walls. The second part gives a detailed overview of the experimental testing of stability of retaining walls of prefabricated betonblok elements. The effect of static loads on the wall was examined in the first, and the effect of the dynamic loads in the second experiment. The results are analyzed and recommendations for future research are given.

Structural Optimization Research on Girder of 200t Bridge Crane Based on ANSYS

2012 ◽  
Vol 430-432 ◽  
pp. 1708-1711
Author(s):  
Zhao Yang Ning
Keyword(s):  
Structural Optimization ◽  
Economic Benefit ◽  
Element Model ◽  
Optimization Method ◽  
Operating Conditions ◽  
Bridge Crane ◽  
First Order ◽  
Initial Sequence ◽  
Main Girder ◽  
The Finite Element Model

According to the practical production of 200t bridge crane, the structure and operating conditions of the main girder were studied and the optimal mathematical model was established. Through determining the objective function and boundary constraint conditions, the finite element model was established based on ANSYS and the analysis results were obtained. Using the first order optimization method to optimize the calculating results and comparing with the initial sequence, it shows that the total volume of girder is decreased by about 19.4%. The structural optimization of the main girder gets a preferable economic benefit and provides a foundation for designing the bridge crane girder.

scholarly journals A HUMAN CROWD EFFECT MODELLED BY THE DISCRETE-TIME FOURIER SERIES

2018 ◽  
pp. 139
Author(s):  
Miomir Jovanović ◽  
Goran Radoičić
Keyword(s):  
Discrete Time ◽  
Experimental Testing ◽  
Fem Analysis ◽  
Experimental Tests ◽  
Human Power ◽  
Equipment Safety ◽  
Crowd Effect ◽  
Transport Machine ◽  
Human Crowd ◽  
The Mathematical Model

Accidental actions caused by vibrations of supporting structures in mechanical systems represent the dynamic tasks of specific scientific and professional research in the field of human and equipment safety. This paper determines the mathematical model of physical excitation force created by   human power, based on the discrete-time Fourier transformation. For experimental verification of the model, we made a special platform for measuring bouncing force of people who create natural impulse oscillation. The paper shows the results of individual and group experimental testing of living force as the cause of accidents and dangerous effects on the structure. In the end, the excitation of the human operation of a malicious nature (heavy transport machine – crane) has been used to show the application of Fourier model to simulate one incident. For this purpose, the transient FEM analysis and the eigenvalues predetermined modal analysis are used. The paper is illustrated with photographs of experimental tests of dangerous human impulse in several working machines (objects).

Modal Analysis of Crane Girder Based on ANSYS Workbench

2014 ◽  
Vol 951 ◽  
pp. 58-61
Author(s):  
Ran Peng ◽  
Xiao Yu Qin
Keyword(s):  
Finite Element ◽  
Optimal Design ◽  
Modal Analysis ◽  
Theoretical Basis ◽  
Natural Frequencies ◽  
Frequency Region ◽  
Dynamics Analysis ◽  
Bridge Crane ◽  
Main Girder ◽  
Ansys Workbench

Finite element modal analysis of main girder of bridge crane is conducted, the natural frequencies and the vibration-made vectors of the first 6 orders are obtained, and the vibration hazardous areas are found. It provides a theoretical basis for optimal design and dynamics analysis for girder. The natural frequency and mode shape animation of the modal analysis can be used as the optimal design reference of the girder. Rational optimization of girder is able to avoid the resonance frequency region, which will help to improve the reliability and life-span of the girder.

Modeling and Machine Learning Aided Analysis of a Claw-Less Magnetically Coupled Ball-Drive Design

2018 ◽  
Author(s):  
Biruk A. Gebre ◽  
Kishore Pochiraju
Keyword(s):  
Machine Learning ◽  
Design Space ◽  
Learning Algorithm ◽  
Experimental Testing ◽  
Magnetic Coupling ◽  
Principal Component ◽  
Critical Parameters ◽  
Support Vector ◽  
Support Structure ◽  
Coupling Force

Ball-driven mobility platforms have shown that spherical wheels can enable substantial freedom of mobility for ground vehicles. Accurate and robust actuation of spherical wheels for high acceleration maneuvers and graded terrains can, however, be challenging. In this paper, a novel design for a magnetically coupled ball drive is presented. The proposed design utilizes an internal support structure and magnetic coupling to eliminate the need for an external claw-like support structure. A model of the proposed design is developed and used to evaluate the slip/no-slip operational window. Due to the high-dimensional nature of the model, the design space is sampled using randomly generated design instances and the data is used to train a support vector classification machine. Principal component analysis and feature importance detection are used to identify critical parameters that control the slip behavior and the feasible (no-slip) design space. The classification shows an increase in the feasible design space with the addition of, and increase in, the magnetic coupling force. Based on the results of the machine learning algorithm, FEA design tools and experimental testing are used to design a spherical magnetic coupler array configuration that can realize the desired magnetic coupling force for the ball drive.

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