scholarly journals Determining stresses in the metallic structure of an overhead crane when using running wheels of the new design

2021 ◽  
Vol 1 (7 (109)) ◽  
pp. 22-31
Author(s):  
Nataliia Fidrovska ◽  
Evgen Slepuzhnikov ◽  
Ivan Varchenko ◽  
Serhii Harbuz ◽  
Serhii Shevchenko ◽  
...  
Keyword(s):  
Bridge Circuit ◽  
Original Position ◽  
Overhead Crane ◽  
Metallic Structure ◽  
Far Right ◽  
Elastic Rubber ◽  
Running Wheels ◽  
Oscillation Damping ◽  
Deformation Diagrams ◽  
Period Of Oscillation

This paper proposes a method to experimentally study the stressed state of the metallic structure of an overhead crane when using running wheels of different designs. The study employed a functioning electric, supporting, double-girder overhead crane with a capacity of 5 tons and a run of 22.5 m. Strain gauges assembled in a semi-bridge circuit and connected to the analog-digital converter Zetlab210 (Russia) were used to determine the girder deformations at the time of hoisting and moving cargoes of different masses. The cargo was lifted and displaced under the same conditions, on the regular wheels of a cargo trolley and the wheels with an elastic rubber insert. The girder deformation diagrams were constructed. The subsequent recalculation produced the stressed state's dependences at each point of cargo movement when using both regular wheels and the wheels with an elastic rubber insert. Also established were the dependences and the duration of oscillations that occur over the cycle of cargo lifting and moving. The experimental study cycle included cargo lifting in the far-left position by a trolley, moving the cargo to the far-right position, and returning the trolley with the cargo to its original position. It should be noted that the application of a new, modernized design of the running wheels of a cargo trolley with an elastic rubber insert effectively dampen the oscillations in the metallic structure of the crane. The experimental study's results helped establish an 18 % reduction in stresses in the girder of the overhead crane, as well as a decrease in peak vibrations, by 20 seconds, at the same cycles of cargo hoisting and moving. In addition, using wheels with an elastic rubber insert reduces the period of oscillation damping at the end of the cycle of cargo movement, by at least 30 %.

scholarly journals On Deformability of Crane Metallic Structures

2018 ◽  
Vol 251 ◽  
pp. 03035 ◽  
Author(s):  
Anatoly Vershinsky ◽  
Aleksandr Shubin ◽  
Aleksander Masyagin
Keyword(s):  
Life Cycle ◽  
Specific Interaction ◽  
Experimental Studies ◽  
Overhead Crane ◽  
Metallic Structure ◽  
Metallic Structures ◽  
Beam Elements ◽  
Residual Welding ◽  
Dimensional Parameters

Problems of metallic crane structure deformability are considered. This paper contains results of experimental studies on deformability of overhead crane beam elements. These studies take into account the specific interaction between stresses arising from the product’s exposure to loads at various stages of its life cycle, from manufacturing to operation, and residual welding stresses. Recommendations are provided to help stabilize the dimensional parameters of a crane metallic structure.

scholarly journals EXPERIMENTALSTUDY OF DYNAMIC EFFORTS DURING THE OPERATION OF THE MECHANISM OF MOVEMENT OF THE CARGO TROLLEYOF AN OVERHEAD CRANE

2021 ◽  
pp. 60-69
Author(s):  
Nataliia Fidrovska ◽  
Evgen Slepuzhnikov ◽  
Roman Ponomarenko ◽  
Dmytro Kozodoi
Keyword(s):  
Friction Pair ◽  
Evaluation Criteria ◽  
Rolling Friction ◽  
Technical Condition ◽  
Overhead Crane ◽  
Rail Track ◽  
Stage Of Development ◽  
Rolling Surface ◽  
Running Wheels ◽  
Shock Pulses

The article deals with the determination of the dynamic loads arising in the running wheels of a conventional (standard) and modernized design during the movement of the cargo carriage of an overhead crane. The redesigned wheel has an insert made from 7-7130 rubber compound. Also, a method for diagnosing running wheels of conventional and modernized design was determined. The ZETLAB program was chosen as a program for signal registration and analysis. This program allows not only displaying the signal in real time with the possibility of scaling, but also allows you to digitize the signal with the possibility of further processing the results in various standards. Finding out the occurrence of a defect in wheels and rails is mainly carried out by two methods, when shock pulses appear and according to an increased background of vibration. In practice, there is a process of "dry" rolling friction, and this means that the method of shock pulses for diagnosing the condition of wheels and a rail track can be used only in some cases in the form of extreme wear of the friction pairs of a wheel and a rail. That is, the method of spectral analysis of fluctuations in the power of random vibration can be successfully applied to diagnose the state of the rail track and crane wheel.  The diagnostic method based on the overall vibration level allows for an overall assessment of the technical condition. Such diagnostics makes it possible to identify defects only at the very last stage of development, when they lead or have already led to partial destruction of the rolling surface of the wheel and the surface of the rail, that is, to an increase in the overall level of vibration. The performance evaluation criteria are fully focused on the corresponding standard vibration levels for the investigated friction pair. A friction pair is considered to be defective, the vibration of which exceeds the general standard. When determining an increased overall level of vibration, maintenance personnel must make a decision to replace parts or a unit to prolong its operation. The results obtained indicate the advisability of using the wheels of the modernized design on the cargo carriage of an overhead crane.

Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating

1990 ◽  
Vol 48 (1) ◽  
pp. 198-199
Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu
Keyword(s):  
Electron Beam ◽  
Tungsten Wire ◽  
Local Heating ◽  
Electron Gun ◽  
Original Position ◽  
Beam Power ◽  
Radius Of Curvature ◽  
High Brightness ◽  
Beam Focusing ◽  
Time Operation

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

Das Ende der Postdemokratie, den Pessimismus überwinden.

2017 ◽  
Vol 47 (188) ◽  
pp. 487-494
Author(s):  
Daniel Mullis
Keyword(s):  
Political Thought ◽  
Social Dynamics ◽  
Social Conditions ◽  
The Other ◽  
Economic Decline ◽  
Far Right ◽  
Windows Of Opportunity ◽  
Political Events ◽  
Political Struggles ◽  
The One

In recent years, political and social conditions have changed dramatically. Many analyses help to capture these dynamics. However, they produce political pessimism: on the one hand there is the image of regression and on the other, a direct link is made between socio-economic decline and the rise of the far-right. To counter these aspects, this article argues that current political events are to be understood less as ‘regression’ but rather as a moment of movement and the return of deep political struggles. Referring to Jacques Ranciere’s political thought, the current conditions can be captured as the ‘end of post-democracy’. This approach changes the perspective on current social dynamics in a productive way. It allows for an emphasis on movement and the recognition of the windows of opportunity for emancipatory struggles.

Almanya’da aşırı sağ hareketler ve medyanın suçlu göçmen söyleminin resmi belgeler ışığında incelenmesi

2017 ◽  
Vol 4 (2) ◽  
pp. 201-226
Author(s):  
Soner Tauscher
Keyword(s):  
Agenda Setting ◽  
Asylum Seekers ◽  
German Society ◽  
Political Agenda ◽  
Substantial Part ◽  
Media Discourse ◽  
Open Door ◽  
The European Union ◽  
Open Door Policy ◽  
Far Right

Avrupa ülkelerinin alışık olduğu düzenli işçi göçü ve kontrollü sığınmacı alımı Suriye iç savaşının üst düzeye ulaştığı 2013/2014 yılından itibaren önemli bir değişim göstermektedir. Avrupa Birliği, kuruluşundan bu yana en yoğun mülteci göçüyle karşılaşmaktadır. Yaşanan bu kontrolsüz ve zorunlu göçe Avrupa toplumları ve devletleri hazırlıksız yakalanmıştır. Mülteci krizini ekonomik olarak fırsata çevirmek isteyen Almanya ise göçmenler için 2015 yazından itibaren açık kapı politikası uygulamaya başlamıştır. Ancak uygulanan açık kapı politikası Alman toplumunun azımsanmayacak bir kesiminde mültecilere ve Müslümanlara yönelik ağır ve şiddetli bir karşı kampanya ortaya çıkardı. Mülteciler ve Müslümanlar aşırı sağ toplumsal hareketlerin gösterilerinde “tecavüzcü”, “işgalci”, “kriminal dolandırıcılar” vb. sıfatlar ile birlikte anılmakta, medya da bu söylemlerin taşıyıcılığını yaparak kamusallaşmasını sağlamaktadır. Böylece aşırı sağı desteklemeyen, apolitik, ya da sığınmacılara karşı hoşgörülü davranan toplum kesimlerinde kamuoyu oluşturularak sığınmacı ve göçmenlere karşı olumsuz algı gündemde tutulmakta, politik olanın merkezine yerleştirilmektedir. Bu çalışmada öncelikle göçmenlere karşı aşırı sağ toplumsal hareketlerin oluşturduğu olumsuz söylemin McCombs ve Shaw’un Gündem Belirleme Kuramı (Agenda Setting Function) bağlamında medya tarafından siyasetin merkezine nasıl oturtulduğu tartışılacaktır. Ayrıca gündemde tutulan mültecilere yönelik olumsuz söylemin gerçeği yansıtıp yansıtmadığı, göçmenlerin ve sığınmacıların biyolojik Almanlardan daha çok suça meyilli olup olmadığı oluşturulan soyut söylemlerden ziyade Almanya İçişleri Bakanlığı’nın yıllık olarak yayınladığı Emniyet Suç İstatistikleri temel alınarak incelenecektir.ABSTRACT IN ENGLISHFar right movements in Germany and evaluation of media discourse of criminal immigrant in the light of official documentsFlows of regular worker migration and regular asylum seekers, of whom European countries are familiar, have significantly changed since 2013/2014 when the civil war of Syria reached its peak. The European Union face probably the most intensive refugee migration since its establishment. European societies and states have not been prepared for this uncontrolled and compulsory immigration. Germany seem to want to turn the refugee crisis into an economic opportunity as evident in their open door policy since the summer of 2015. However, implementation of open-door policy has led a substantial part of German society to a strong campaign against the refugees and Muslims. Refugees and Muslims are referred to as “rapists”, “invaders”, “criminal fraudsters”, and so on in demonstrations of far right movements and media has helped disseminating these discourses. Hence, this manipulated and hateful discourse tries to gain support from the segment of society wh normally does not support far right and often apolitical, or tolerant towards asylum seekers. In this study, the ways in which the negative discourse of far right social movements against immigrants is brought to the centre of the political agenda by media is analysed using the agenda setting framework by McCombs and Shaw. Then, the claims that immigrants are involved in crime, or they are prone to be criminals are analysed and contrasted with the data obtained from the annual Crime and Safety Reports of the German Ministry of the Interior.

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Sign in / Sign up

Export Citation Format

Share Document