scholarly journals Analysis of Changes in Parameters of Free Vibration of Single and Multi-span Girders with Semi-rigid Joints

2021 ◽  
Author(s):  
Witold Basiński
Keyword(s):  
Theoretical Analysis ◽  
Joint Stiffness ◽  
Experimental Tests ◽  
Free Vibrations ◽  
Continuous Change ◽  
Rotational Stiffness ◽  
Concentrated Mass ◽  
Corrugated Web ◽  
Different Types ◽  
Rigid Joints

This study presents the analysis carried out for changes in parameters of free vibrations of single-span corrugated web girders with a semi-rigid joint at midspan and multi-span girders with spans connected by semi-rigid joints. Based on the experimental tests and the theoretical analysis, the behavior of six simply supported girders with the semi-rigid joint at midspan was analyzed. They were straight and double-slope girders with a span of 6.02 m, made of corrugated web sections WTA 500/300x15 with different types of semi-rigid end plate joints. It was demonstrated that the variable rotational stiffness Sj of the joint affected the equivalent concentrated mass of the girder mz, the frequency of damped free vibrations α, damping ρ, and the frequency of free vibrations ω. The theoretical analysis was conducted for a change in the equivalent concentrated mass of the single-span girders fixed at both ends and of the multi-span girders. It was described how the change in the support stiffness in the single-span girders fixed at both ends and the change in joint stiffness of spans affected the equivalent concentrated mass mz as a function of non-dimensional stiffness k. The equivalent concentrated mass mz of the girder was found to affect the values of maximum vibrations in the structure. A continuous change in the rotational stiffness of joints was taken into account from the pinned to the rigid joint.

An Integral Equation Method for Free Vibration of Circular Plate with Concentrated Mass at Arbitrary Positions

2011 ◽  
Vol 255-260 ◽  
pp. 1830-1835 ◽  
Author(s):  
Gang Cheng ◽  
Quan Cheng ◽  
Wei Dong Wang
Keyword(s):  
Integral Equation ◽  
Eigenvalue Problem ◽  
Free Vibration ◽  
Green’S Function ◽  
Circular Plate ◽  
Green's Function ◽  
Integral Equation Method ◽  
Free Vibrations ◽  
Equation Method ◽  
Concentrated Mass

The paper concerns on the free vibrations of circular plate with arbitrary number of the mounted masses at arbitrary positions by using the integral equation method. A set of complete systems of orthogonal functions, which is constructed by Bessel functions of the first kind, is used to construct the Green's function of circular plates firstly. Then the eigenvalue problem of free vibration of circular plate carrying oscillators and elastic supports at arbitrary positions is transformed into the problem of integral equation by using the superposition theorem and the physical meaning of the Green’s function. And then the eigenvalue problem of integral equation is transformed into a standard eigenvalue problem of a matrix with infinite order. Numerical examples are presented.

scholarly journals Numerical Evaluation of a Light-Gas Gun Facility for Impact Test

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
C. Rahner ◽  
H. A. Al-Qureshi ◽  
D. Stainer ◽  
D. Hotza ◽  
M. C. Fredel
Keyword(s):  
High Velocity ◽  
Numerical Evaluation ◽  
Impact Test ◽  
Experimental Tests ◽  
Reservoir Pressure ◽  
One Stage ◽  
Gas Gun ◽  
Numerical Predictions ◽  
High Velocity Impacts ◽  
Different Types

Experimental tests which match the application conditions might be used to properly evaluate materials for specific applications. High velocity impacts can be simulated using light-gas gun facilities, which come in different types and complexities. In this work different setups for a one-stage light-gas gun facility have been numerically analyzed in order to evaluate their suitability for testing materials and composites used as armor protection. A maximal barrel length of 6 m and a maximal reservoir pressure of a standard industrial gas bottle (20 MPa) were chosen as limitations. The numerical predictions show that it is not possible to accelerate the projectile directly to the desired velocity with nitrogen, helium, or hydrogen as propellant gas. When using a sabot corresponding to a higher bore diameter, the necessary velocity is achievable with helium and hydrogen gases.

scholarly journals Formation of skills to create stories of different type in senior preschool children

2018 ◽  
pp. 111-119
Author(s):  
Alexander Savchin
Keyword(s):  
Preschool Children ◽  
Theoretical Analysis ◽  
School Environment ◽  
Preschool Age ◽  
Different Types ◽  
Definition Of ◽  
Main Definition

The article gives an analysis of problems of formation of skills in children of the senior preschool age to build stories of different types. On the basis of the theoretical analysis of psycho-pedagogical and special literature, based on the main definition of «building a story», a subordinate term is formulated in relation to the topic of the study: «building stories of different types» The psychological and pedagogical conditions of formation of sustainable skills of creation and expedient use of stories of different types in children of the senior preschool age are revealed and substantiated. The components, criteria, indicators and levels of formation of abilities to build a different type of narration in children of the sixth year of life are determined. The stages of formation of persistent skills for building different types of stories by senior preschoolers are singled out. The lack of effective pedagogical technologies in relation to the formation of skills in the children of the senior preschool age to build and expedient use of narration of comprehensive typing significantly reduces the effective preparation of children to school. The proposed pedagogical and motivational technology for the formation of children of the sixth year of a sustainable ability to create stories of various types provides the small person an effective communicative tool, which will definitely promote its self-realization both in school environment and in career, society, own life. The prospects for further research are outlined, such independent types of stories are presented as a story - an instruction and a story - a presentation.

scholarly journals FEM Study of a Steel Corrugated Web Plate Girder Subjected to Fire

2021 ◽  
Vol 26 (2) ◽  
pp. 201-218
Author(s):  
D. Sokołowski ◽  
M. Kamiński
Keyword(s):  
High Strength Steel ◽  
Constitutive Relations ◽  
High Strength ◽  
Experimental Tests ◽  
Physical Parameters ◽  
Bottom Flange ◽  
Gas Temperature ◽  
Temperature Dependent ◽  
Corrugated Web ◽  
Plate Girder

Abstract The main aim of this work is a computational nonlinear analysis of a high strength steel corrugated-web plate girder with a very detailed and realistic mesh including vertical ribs, all the fillet welds and supporting areas. The analysis is carried out to verify mechanical structural response under transient fire temperature conditions accounting for an efficiency and accuracy of three various transient coupled thermo-elastic models. All the resulting stress distributions, deformation modes and their time variations, critical loads and eigenfrequencies as well as failure times are compared in all these models. Nonlinearities include material, geometrical and contact phenomena up to the temperature fluctuations together with temperature-dependent constitutive relations for high strength steel. They result partially from steady state and transient experimental tests or from the additional designing rules included in Eurocodes. A fire scenario includes an application of the normative fire gas temperature curve on the bottom flange of the entire girder for a period of 180 minutes. It is computed using sequentially coupled thermo-elastic Finite Element Method analyses. These account for heat conductivity, radiation and convection. The FEM model consists of a combination of 3D hexahedral and tetrahedral solid finite elements and uses temperature-dependent material and physical parameters, whose values are taken after the experiments presented in Eurocodes. Numerical results presented here demonstrate a fundamental role of the lower flange in carrying fire loads according to this scenario and show a contribution of the ribs and of the welds to the strength of the entire structure.

scholarly journals THE ROLE OF THE RELATIONSHIP WITH THE MOTHER IN CHILDHOOD IN FORMING A WOMAN'S ATTITUDE TOWARDS HER OWN MOTHERHOOD

2020 ◽  
Vol 11 (87) ◽  
Author(s):  
Tatiana Sidorenko ◽  
◽  
Natalia Grisenko ◽  
Keyword(s):  
Theoretical Analysis ◽  
Adult Age ◽  
Personal Attitude ◽  
Psychological Science ◽  
Factors Influencing ◽  
Different Types ◽  
Main Factors ◽  
Psychological Features ◽  
The Relationship

The article is devoted to the study of such an important psychological phenomenon as an attitude of women to their own motherhood. It is summarizes the study of the problem of motherhood in psychological science in general. The article analyzes the problem of the influence of the relationship with the mother in childhood on the formation of a woman's attitude to her own motherhood in adult age. It is illuminates views of foreign and national researchers on the study of this phenomenon, as well as the essence of different areas of research on this phenomenon. Based on the theoretical analysis of the literature on this topic, the concept of "motherhood", its content and psychological essence is studied. Cultural-historical, biological, physiological and psychological aspects to the study of motherhood are singled out. The main content of scientific views on the formation of the phenomenon of motherhood is generalized. The main factors influencing the development of a woman's maternal sphere and the formation of the attitude to one's own motherhood are analyzed and considered. The content of such basic concepts as "mother's image" and "maternal relations" is revealed. The psychological features of the formation of an adequate image of the mother in the theoretical analysis of the ontogenesis of the maternal sphere are analyzed. The article also reveals the dynamics of motherhood in ontogenesis. The types of maternal relations and their role in the life of a mature woman are determined, as well as the influence of these relations on the formation of a woman's attitude to her own motherhood. The influence of different types of relationships between women and their own mothers on the level of formation of their attitude to personal motherhood has been empirically studied. Two groups of women were studied, one group had a positive relationship with their own mother, and the other had a negative one. In the course of the research the differences between different types of maternal relations and the level of formation of a woman's personal attitude to motherhood are singled out.

scholarly journals Experimental tests of the impact of selected parameters on the indentation rolling resistances

2018 ◽  
Vol 29 ◽  
pp. 00002 ◽  
Author(s):  
Dariusz Woźniak ◽  
Lech Gładysiewicz ◽  
Martyna Konieczna
Keyword(s):  
Main Part ◽  
Rolling Resistance ◽  
Experimental Tests ◽  
Conveyor Belt ◽  
Significant Component ◽  
Different Types ◽  
Indentation Rolling Resistance ◽  
Belt Conveyors ◽  
The Impact

Belt conveyors are main part of transporting systems in mines and in many other branches of industry. During conveyor belt works different types of resistances are generated. Indentation rolling resistance is the most significant component of the resistances from the perspective of energy losses and it cause the biggest costs as well. According to latest state of analyses and measurements it is well known that theoretical rolling resistance were underestimated in comparison with the measured in-situ one. In this paper new method for determination indentation rolling resistance is presented. The authors compared theoretically and experimentally established damping factors. The relation between these two values enabled to obtain more precise equation for damping function. This function is one of the most important component in calculation of the rolling resistance. In new theoretical model value of rolling resistance is nearly twice higher than this used so far.

Free Vibrations of Constrained Beams

1952 ◽  
Vol 19 (4) ◽  
pp. 471-477
Author(s):  
Winston F. Z. Lee ◽  
Edward Saibel
Keyword(s):  
Natural Frequencies ◽  
Degree Of Approximation ◽  
Free Vibrations ◽  
Frequency Equation ◽  
Continuous Beam ◽  
Concentrated Mass ◽  
Simple Manner ◽  
Natural Modes ◽  
Modes Of Vibration ◽  
Rigid Supports

Abstract A general expression is developed from which the frequency equation for the vibration of a constrained beam with any combination of intermediate elastic or rigid supports, concentrated masses, and sprung masses can be found readily. The method also is extended to the case where the constraint is a continuous elastic foundation or uniformly distributed load of any length. This method requires only the knowledge of the natural frequencies and natural modes of the beam supported at the ends in the same manner as the constrained beam but not subjected to any of the constraints between the ends. The frequency equation is obtained easily and can be solved to any desired degree of approximation for any number of modes of vibration in a quick and simple manner. Numerical examples are given for a beam with one concentrated mass, for a beam with one sprung mass, and a continuous beam with one sprung mass.

Design and Underwater Tests of Subsea Walking Hexapod MAK-1

2016 ◽  
Author(s):  
Vadim V. Chernyshev ◽  
Vladimir V. Arykantsev ◽  
Andrey E. Gavrilov ◽  
Yaroslav V. Kalinin ◽  
Nikolay G. Sharonov
Keyword(s):  
Movement Control ◽  
Experimental Tests ◽  
Energy Usage ◽  
Walking Machine ◽  
Walking Machines ◽  
Sea Bottom ◽  
Different Types ◽  
Robotic Devices ◽  
And Control ◽  
System Power

An important role among machines for sea bottom exploration is assigned to the autonomous ground devices. Some rescue tasks also require subsea robotic devices. The main purpose of the work is to investigate and improve adaptive characteristics, traction properties and control methods of cyclic walking movers in underwater conditions. Traction properties of walking machines, which moves at sea bottom was analyzed. Some experience of development and experimental tests of the walking robot “Vosminog”, designed for work at weak and waterlogged grounds. Dynamic model of a walking machine has been shown. Studied an opportunity to increase adaptive characteristics and shape passableness of walking machines. Also design and results of underwater tests of subsea walking unit MAK-1 are discussed. During tests the performance of a walking unit has been checked and the influence of design features of a walking mover on its traction characteristics and ground passability has been investigated. Some details about control system, power system and energy usage, vertical motions and accelerations for different types of walking and conditions of movement has been given. Also, certain attention was given to testing of methods of standalone movement control of subsea unit in conditions of incomplete and ambiguous vision of current situation. Tests have shown that walking movers in subsea conditions can provide higher traction properties, in comparison with wheeled and tracked ones. The unit can be used for exploration of seabed resources and for rescue tasks.

Mathematical Modeling of Abrasive Waterjet Turning of Ductile Materials

2010 ◽  
Author(s):  
Iman Zohourkari ◽  
Mehdi Zohoor
Keyword(s):  
Abrasive Particle ◽  
Experimental Tests ◽  
Traverse Speed ◽  
Impact Angle ◽  
Abrasive Waterjet ◽  
Continuous Change ◽  
Turning Process ◽  
Ductile Materials ◽  
Proposed Model ◽  
Cylindrical Workpiece

In this paper, an erosion-based model for abrasive waterjet (AWJ) turning process is presented. In the AWJ turning process a particular volume of material is removed by impacting of abrasive particles to the surface of the rotating cylindrical workpiece. This volume is estimated according to the modified Hashish erosion model; thus radius reduction at each revolution is calculated. The distinctively proposed model considers the continuous change in local impact angle due to change in workpiece diameter, axial traverse speed of the jet, the abrasive particle roundness and density. The accuracy of the proposed model is approved by experimental tests under various traverse speeds. The final diameters estimated by the new model are in good accordance with the experiments.

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