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1

Experimental and numerical determination of the longitudinal modulus of elasticity in wooden structures

Hasanagić Redžo, Kapić Zinaid, Crnkić Aladin, Hrnjica Bahrudin, Fathi Leila, Bahmani Mohsen, Humar Miha

Drewno : prace naukowe, doniesienia, komunikaty

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2022

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Vol. 65, nr 210

art. no. 1644-3985.421.10

EN

This paper aims to experimentally and numerically determine the longitudinal modulus of elasticity by the four-point bending method. Samples of wooden beams over which the experimental research was performed were made of silver fir (Abies alba) as prescribed by standard EN 408. The experimental part includes determining bending strength and deformation forces. Experimentally determined bending strength and deflection forces were the input data for evaluating the modulus of elasticity of wooden beams. A numerical analysis of the bending strength by the finite element method was carried out using the ANSYS software package. The numerical model agreed well with the experiments in terms of bending. A numerical model can predict the bending of beams of different sizes. Results showed that the experimental and numerical values are close and usable for further exploitation. Comparison between the experimental and computational force versus the displacement response showed a very good correlation in the results for the fir wood specimens under four-point bending tests.

2

Design of modernization of control valves for the counter-bending forces regulation in finishing mill

Evin E., Tkáčová J., Lengyel Z., Vidašič A.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 80, nr 2

56--64

EN

Purpose: The aim of this paper is design of modernization of control valves of finishing mill to control the counter-bending forces on the last stands by replacement of proportional valves with regulating ones. Design/methodology/approach: New board (construction, location and arrangement of valves) was designed, model of which was constructed by SolidWorks software. Findings: The solution was oriented to optimization by replacement of proportional valves for regulating ones to control the counter-bending forces on the rolling mills. The selected types of proportional and regulating valves were compared. The main advantage of the application of regulating valves is integrated electronics with position controller for pilot valve control and position feedback disposal. Based on the parameters of the regulating valve the new respite and relief valves were designed. Research limitations/implications: Design of substitution of upper and lower blocks of control valves and modelling the motherboards using SolidWorks software was conditional by dimensions of currently used hydraulic components and dimensions of the proposed valves. Designed blocks ensure the functioning of the control system of counter bending of working rolls. In the future the perspective to control the counterbending forces can be carried out by innovation of the rolling mill by pump control using asynchronous converters and/or by changing the structure of the arrangement of rolling mill and by design of CVC control of the rolling mill. Practical implications: New board (construction, location and arrangement of valves) was designed, model of which was constructed by SolidWorks software. Designed board ensures the functioning of the control system for counter-bending of working rolls. Originality/value: The result of the proposed solutions is increasing the quality of the hot rolled strip i.e. reduction of the strip waviness and keeping the cross section of the strip.

3

Effect of shunting zone plastic strains on bend force during the butt welding of rings

Moltasov A. V., Tkacz P. N., Motrunicz S. I.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2016

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Vol. 60, No. 6

48--54

PL

Artykuł dotyczy opracowania metody analitycznej obliczania siły stosowanej do zginania wyrobu w kształcie pierścienia podczas zgrzewania doczołowego z uwzględnieniem obecności odkształceń plastycznych w strefie bocznikowania. Zbadano reguły odkształcania sprężysto-plastycznego prętów krzywoliniowych w wyniku zginania oraz opracowano podstawy teoretyczne określania przemieszczeń w tych prętach. Uzyskano równania analityczne, który łączą wielkość siły zginania z przemieszczeniami ruchomych szczęk mocujących zgrzewarki, parametrami geometrycznymi i własnościami fizyko-mechanicznymi materiału zgrzewanego wyrobu pierścieniowego. Na przykładzie szeregu wręgów wykazano, że uwzględnienie odkształceń plastycznych posiada istotny wpływ na wielkość siły zginania. Wyniki obliczeń wielkości siły zginającej z zastosowaniem opracowanej metody analitycznej są zbieżne z wynikami obliczeń numerycznych. Za pomocą odpowiednich wzorów opisano granice obszarów sprężystych i plastycznych strefy bocznikowania przy jej zginaniu podczas zgrzewania doczołowego. Określono wielkość krytyczną siły zginającej, przy osiągnięciu której wymagany kształt geometryczny zgrzewanego wyrobu pierścieniowego zostaje zniekształcony.

EN

The article is concerned with the development of an analytical method enabling the calculation of force used for the bending of a ring-shaped product during the butt welding allowing for the presence of plastic strains in the shunting zone. The research involved the investigation of principles governing the plastic-elastic strain of curvilinear bars subjected to bending and the development of theoretical foundations enabling the identification of displacements in such bars. The research-related investigation led to the obtainment of analytical equations combining bend force with movements of welding machine fixing clamps, geometrical parameters and physico-mechanical properties of a ring-shaped product material subjected to welding. Using a number of frames as an example, it was demonstrated that plastic strains significantly affected the value of bend force. The calculation results concerning the volume of bend force obtained using the above named analytical method converged with the results obtained using numerical calculations. Appropriate formulas were used to describe the boundaries of elastic and plastic areas of the shunting zone subjected to bending during butt welding. The research resulted in the determination of the critical value of bend force, the exceeding of which led to the deformation of the required geometrical shape of a ring-shaped product subjected to welding.

4

Bending force and springback characteristics of the tailor-welded 18G2A-E355 steel strips

Froń P., Strachowicz F.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2012

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z. 84[284], nr 4

5--13

EN

In many studies a wide range of information about the bendability, failure patterns and the springback of homogeneous as well as tailor-welded sheet metal parts are presented. However, accurate prediction of the springback remains elusive, especially in the case of thick sheet metal. The purpose of this study was experimental determination of the bending force and springback coefficient of the tailor-welded 18G2A-E355 steel strips. Especially, it was focused on comparing the differences in the mechanical properties and bending characteristics between the tailor-welded strips and non-welded ones under the same experimental conditions. The set-up mounted on the testing machine, instrumentation and process control system allows the rig to operate in displacement as well as load control. The MAG method with the Argon + CO2 atmosphere was used for strips welding.

PL

W wielu opracowaniach można znaleźć znaczną liczbę informacji dotyczących możliwości gięcia, rodzaju uszkodzeń oraz sprężynowania w procesie gięcia blach jednorodnych oraz łączonych przez spawanie. Jednakże dokładne określenie wielkości powrotnych odkształceń sprężystych nadal wymaga dalszych badań, szczególnie w przypadku gięcia blach grubych. Celem prezentowanych badań eksperymentalnych było określenie siły oraz współczynnika sprężynowania podczas gięcia spawanych pasm ze stali 18G2A-E355. W szczególności skoncentrowano się na porównaniu różnic właściwości mechanicznych oraz charakterystyk gięcia blach jednorodnych oraz spawanych uzyskanych w takich samych warunkach testów. Przyrząd do gięcia zamontowany na maszynie wytrzymałościowej, czujniki oraz system pomiarowy umożliwiały rejestrację przemieszczenia oraz siły gięcia. Spawanie pasm blach przeprowadzono metodą MAG w atmosferze CO2.

5

Flexibility and trackability of laser cut coronary stent systems

Szabadíts P., Puskás Z., Dobránszky J.

Acta of Bioengineering and Biomechanics

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2009

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Vol. 11, nr 3

11-18

EN

Coronary stents are the most important supports in present day cardiology. Flexibility and trackability are two basic features of stents. In this paper, four different balloon-expandable coronary stent systems were investigated mechanically in order to compare their suitability. The coronary stent systems were assessed by measurements of stent flexibility as well as by comparison of forces during simulated stenting in a self-investigated coronary vessel model. The stents were cut by laser from a single tube of 316L stainless steel or L-605 (CoCr) cobalt chromium alloy. The one- and four-point bending tests were carried out to evaluate the stent flexibility EźI (Nmm2), under displacement control in crimped and expanded configurations. The flexibility of stents would be rather dependent on the design than on raw material. In general a more flexible stent needs lower tracking force during the implantation. The L-605 raw material stents need lower track force to pass through in the vessel model than the 316L raw material stents. The sort and long stents passed through the curved vessel model in different ways. The long stents nestled to the vessel wall at the outer arc and bent, while the short stents did not bend in the curve, only the delivery systems bent.