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Design of Dry Friction Damper to Reduce Vibration Impacts to Circuit Cards at Critical Frequencies

Kovtun Igor, Goroshko Andrii, Petrashchuk Svitlana

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

78--87

EN

The paper is focused on providing strength and stiffness for circuit cards exposed to vibration at critical frequencies. Since the dry friction damping is more effective than viscous damping and in case when application of viscous dampers is restricted by electronic package design the dry friction damper is proposed to be embedded to design of enclosure case in order to reduce oscillation amplitudes of circuit cards at critical frequencies. Dry friction damper produces dissipative forces – non-elastic resistance forces due to friction in kinematic pairs undergoing oscillations. The mathematical model has been developed for estimation of maximal dynamic stress and deflection in critical cross-section of circuit card with embedded dry friction damper at critical frequencies. Developed mathematical model specifies minimal limit value for stiffness of dry friction damper, which is used in engineering calculations to determine its geometric parameters. Design of dry friction damper is introduced by semi-elliptical beam with rectangular profile. The effectiveness of dry friction damper to reduce dynamic stress and deflection in circuit cards has been analytically proved and experimentally testified.

2

Analytical approach for vehicle body structures behaviour under crash at aspects of overloading and crumple zone length

Kurpisz Dariusz, Obst Maciej, Szymczak Tadeusz, Wilde Radosław

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 1

68--75

EN

Road safety problem is still topical, especially since the number of vehicles and the volume of traffic are increasing. It is possible to increase the safety of road users through systemic changes in many areas related to transport. The deformation of the vehicle body during an accident has an impact on the loads acting on the passengers. Vehicle body deformation depends on complex parameters, and knowledge of these parameters is essential for designing crumple zones and the accident reconstruction process. Knowledge of the mechanical parameters of the vehicle structure during deformation is also a reference to passenger injury indicators assessment. This paper reports results from the analytical approach for determining the protection level of personal vehicles. The proposed conception is based on the results from the static stiffness characteristic of the Ford Taurus, which gives the possibility of phenomenological and simple body crumple analytical description at a speed equal to 10 km/h, 40 km/h, 56 km/h and 60 km/h, which is an original part of the work. The approach enables us to describe the vehicle crash by focusing on variations of deformation in time, stiffness, vehicle collision time (duration), deceleration and dynamic crash force. Basing on the body stiffness data of the personal vehicle, the length of the deformation zone in the front of the car and the maximum values of force at the crash for a speed of 60 km/h are presented. Results obtained by the authors show that is possible to estimate the overloading level during the crash time of a vehicle based on the stiffness characteristic of the car body. The proposed methodology can be developed and the advantage of the presented procedure is an uncomplicated useful tool for solving complex problems of a vehicle crash.

3

Modeling and Exploitation Load Tests of the Suspended Route Slings Caused by Passage of the Locomotive at Various Speed along Mining Excavation

Drozd Kazimierz, Nieoczym Aleksander

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 1

266--281

EN

Despite the fact that suspended monorails have been used in the mining industry for over 50 years it is necessary to continue research on the possibilities of increasing the unit mass of the transported load or the speed of people transport. The first step is to establish the exact dynamic load of suspended route’ elements and compare this value with easy to calculation static load. The objective of the research was to determine the influence of speed and direction of travel on maximum load force applied to the sling of the route in mining excavation. The research results indicated that the speed of 2 ms−1 does not significantly influence the load on the sling. Theoretical hypothesis, stating that the estimation of the force value in the sling ought to be performed using projecting on a surface perpendicular to the route was confirmed. It was also proven that in order to characterize the geometry of the sling as well as a precise analysis of its load it is necessary to employ the length and the angle of the chain in relation to the above mentioned surface. Upon employing statistical analysis of the test results, the maximum dynamic effect of the locomotive passing was determined to be 20.1 ± 2.5% of the value of the calculated static load for all slings, projected onto a plane perpendicular to the route. For a single sling, mounted on a test route section inclined at an angle of about 10°, the increase in force due to the passage of the locomotive was up to 21.0% of the static load for this sling.

4

Mathematical Modeling of Stress in Circuit Cards Represented by Mechanical Oscillatory Systems

Kovtun Igor, Goroshko Andrii, Petrashchuk Svitlana

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 1

303--315

EN

The represented paper is aimed at stress calculation in circuit cards with their representation as a type of mechanical oscillatory systems in purpose of their strength assessment especially in resonance conditions. Three types of oscillatory systems are researched: single-mass; multiple mass and oscillatory system with uniformly distributed mass. In all types the cylindrical bending of circuit cards is considered to be a set of beam-strips with rectangular cross-sections so their stress calculation is performed by conventional methods applied in strength of materials and civil engineering. Mathematical model has been developed for maximal dynamic stress and deflection estimation in circuit card assemblies represented by unique oscillatory system as prismatic beam set on two oscillating supports under inertial resonance excitation generated by constant dynamic force. Comparative analysis of mathematical modeling, MatLab simulation and experimental determination of maximal dynamic stress and deflection accomplished for three types of oscillatory systems verified proximity of obtained results. Single-mass oscillatory system is proposed as equivalent to multiple mass or uniformly distributed oscillatory systems on condition of their equal mass, geometric, elastic and dissipation characteristics in resonance frequency correspondent to the main mode of oscillation, so mathematical model designed for single-mass oscillatory system is recommended for strength and stiffness assessment in engineering calculations where possible difference in determination of stress in equivalent systems can used as safety factor.

5

Operation-Oriented Studies on Wear Properties of Surface-Hardened Alloy Cast Steels Used in Mining in the Conditions of the Combined Action of Dynamic Forces and an Abrasive Material

Wieczorek A. N.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2381--2389

EN

This paper presents the results of wear tests of shot-peened and not shot-peened cast steels used in the mining machinery industry, in particular in the construction of chain drums for armoured face conveyors. Wear tests were carried out in the conditions corresponding to the real operating conditions of armoured face conveyors during drifting work in rocks such as sandstone. The operating factors subjected to the analyses included the presence of quartz abrasive and the impact of external dynamic forces. On the basis of the wear tests as well as the microhardness and microstructure examinations performed, it has been found that the action of an additional dynamic force has a synergistic impact on the process of abrasive wear in loose quartz abrasive. It has been further found that the value of abrasive wear of chain wheels operated in the conditions of a combined action of abrasive and a dynamic force depends on whether the area of mating of wheels with the chain was shot-peened or not before the wear tests – an increase in the abrasive wear was observed for the wheels made of cast steel subjected to shot peening in the area of mating with the chain. Lower resistance to abrasive wear of the cast steels subjected to shot peening before the wear tests could result from the formation of cracks in the surface layer caused by the action of shot.

6

Dynamics of electromechanical drive of suspended timbertransporting rope system

Dzyuba L., Baryliak V.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2016

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nr 19(3)

245--256

EN

Dynamic loads of drive of suspended timbertransporting rope system with an electric motor are investigated. Developed a dynamic model of the electromechanical drive considering the changing of the electric motor’s moment during start-up and the resistance force moment. The changing of the resistance force moment is expressed through the changes in tension force of the pull-bearing rope systems in various manufacturing operations. In determining the moment of inertia of the drive drum is accounted multi-winding of rope. Research on dynamic load of system elements are made with the taking into account the influence of torsional stiffness of system parts and lifting capacity of the suspended timbertransporting rope system.

7

Dynamic characteristics measurements of a force transducer against small and short-duration impact forces

Djamal M., Watanabe K., Irisa K., Prayogi I. A., Takita A., Yamaguchi T., Fujii Y.

Metrology and Measurement Systems

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2014

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Vol. 21, nr 1

59--66

EN

A method for evaluating the dynamic characteristics of force transducers against small and short-duration impact forces is developed. In this method, a small mass collides with a force transducer and the impact force is measured with high accuracy as the inertial force of the mass. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. Small and short-duration impact forces with a maximum impact force of approximately 5 N and minimum half-value width of approximately 1 ms are applied to a force transducer and the impulse responses are evaluated.

8

Ocena dokładności wyznaczania obciążenia zespołu stropnica - osłona odzawałowa sekcji obudowy zmechanizowanej na podstawie wyników pomiarów dołowych

Markowicz J., Ober G., Szweda S.

Zeszyty Naukowe. Górnictwo / Politechnika Śląska

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2004

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z. 260

439-449

PL

Praca dotyczy metody wyznaczania oddziaływania górotworu na sekcję obudowy zmechanizowanej na podstawie pomiaru sił wewnętrznych w sekcji. Oddziaływanie górotworu zamodelowano w postaci skrętnika przyłożonego do zespołu stropnica - osłona odzawałowa. Rozpatrzono wpływ dokładności pomiaru sił wewnętrznych w sekcji na parametry oddziaływania górotworu. Stwierdzono, że przedstawiona metoda badań umożliwia wystarczającą dokładność wyznaczenia wybranych parametrów oddziaływania górotworu na zespół stropnica - osłona odzawałowa.

EN

The paper deals with a method for determining of the action of rock mass on a powered roof support unit, which is based on measurements of internal forces occurring in a support unit. The action of rock mass has been modeled in a form of a wrench applied to the assembly: canopy - gob shield. The effect of measuring accuracy of internal forces occurring in a support unit on parameters of the rock mass action was subject of investigation. It has been found that the presented method provides the sufficient accuracy of determining of the selected parameters of the rock mass action on the assembly: canopy- gob shield.

9

Modelowanie dynamicznego oddziaływania górotworu na sekcję obudowy zmechanizowanej z wykorzystaniem zasady kinetostatyki

Jaszczuk M., Markowicz J., Pawlikowski A.

Zeszyty Naukowe. Górnictwo / Politechnika Śląska

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2004

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z. 260

403-412

PL

W pracy przedstawiono uproszczoną metodę wyznaczania przebiegu czasowego obciążenia dynamicznego sekcji obudowy zmechanizowanej z wykorzystaniem zasady kinetostatyki. Analizę przeprowadzono dla płaskiego modelu sekcji obudowy zmechanizowanej przy założeniu idealnej sztywności elementów sekcji. Dla przyjętych przebiegów czasowych wybranych sił wewnętrznych w sekcji i związanej z nimi zmiany długości stojaków i podpory stropnicy, występujących w trakcie obciążenia dynamicznego, wyznaczano składowe wektora obciążenia działającego na zespół stropnica-osłona.

EN

A simplified method for determining of time related course of the dynamic load of a powered roof support unit, when employing principles of the dynamic force analysis, bas been presented in the paper. The analysis was carried out for a planar model of a powered roof support unit on the assumption that the rigidity of elements of the support unit is ideal. Components of a vector of the load acting on the assembly: canopy - shield were determined for the assumed time - related courses of the selected internal forces occurring in a support unit and for the associated changes in the length of legs and of the canopy capsule taking place during action of the dynamic load.