Wyniki wyszukiwania - Biblioteka Nauki

1

Stopnie regulacyjne z wydłużonym czy zawężonym przelewem?

100%

Mokwa M. , Pietraszko K.

Gospodarka Wodna

|

2009

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tom Nr 3

116-121

PL

Artykuł przedstawia argumentację przemawiającą za stosowaniem stopni z wydłużonym przelewem jako budowli, które stwarzają korzystniejsze warunki przepływu wody i rozproszenia energii i które okazały się budowlami mniej podatnymi na uszkodzenia.

EN

The article puts forward arguments for the use of degrees with elongated overflow as constructions that create better conditions of water flow and energy diffusion and that are less prone to damages.

2

Wpływ struktury przodu nadwozia na energochłonność

100%

Romaniszyn K. M.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

|

2006

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tom Z. 84

287-292

PL

W publikacji przedstawiono porównanie energochłonności nadwozia o zmodyfikowanej konstrukcji przedniej części nadwozia w stosunku do nadwozia przed zmianami. Oceniono zarówno wartość, jak i przebieg rozpraszanej energii w przypadku uderzenia w pionową sztywną ścianę. Wykazano, że nawet niewielkie zmiany konstrukcyjne mogą istotnie wpływać na wielkość i charakter przebiegu rozprasza-nia energii.

EN

The comparison was restated in the publication dissipation bodywork about the modified design of the front part of bodywork in the relation to bodywork before changes. Both the value and course of diffused energy were evaluated in case of the bump to vertical fixed wall. They showed that even small constructional changes were able essentially to influence size and the character of course of dif-fusing of energy.

3

Effect of angle of thread inclination and equivalent radius on energy dissipation in screw joints

63%

Kaczmarek W.

Journal of Theoretical and Applied Mechanics

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2008

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tom Vol. 46 nr 2

367-381

EN

The paper presents the problem of structural friction appearing in a screw joint with frictional and elastic-frictional effects between its elements. Two mathematical models of the screw joint taking into acount Lame’s problem are analysed.

PL

W artykule przedstawiono problem tarcia konstrukcyjnego w aspekcie rozpraszania energii w połączeniu gwintowym. Rozpatrzono dwa modele matematyczne połączeń gwintowych: czysto- i sprężysto-tarciowy z uwzględnieniem twierdzenia Lame'go.

4

Zależność pomiędzy dyssypacją mechaniczną a zużyciem ściernym stopów odlewniczych

63%

Binczyk F. , Śmieszny G.

Archiwum Odlewnictwa

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2006

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tom R. 6, nr 18/2

537--544

PL

W pracy wykazano, że zużycie w wyniku tarcia pary tribologicznej jest proporcjonalne do wartości dyssypacji mechanicznej, mierzonej w początkowym okresie współpracy elementów, gdy temperatura w układzie zmienia się jeszcze w sposób liniowy. Miarą odporności systemu na zużycie jest ilość energii wymaganej do zmiany masy układu o jednostkę (J/kg). Badania przeprowadzono dla par tribologicznych ze stopów odlewniczych żelaza, aluminium i miedzi.

EN

They demonstrated at work, that abrasive using tribological system is having good proportions to value mechanical dissipation, measured up in the initial period of the cooperation of elements. The quantity of energy of mass required to the change of the system is a measure of the resistance of the system to wiping off for the individual (J/kg).

5

Experimental investigation of energy dissipation properties of fibre reinforced plastics with hybrid layups under high-velocity impact loads

63%

Romano M. , Hoinkes C. , Ehrlich I. , Höcherl J. , Gebbeken N.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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tom Vol. 64, nr 1

5--19

EN

Purpose: The present work deals with the experimental investigation concerning the energy dissipation capacity of different kinds of reinforcement fibres in monolithic and hybrid layups under high velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt. Design/methodology/approach: The test panels have been impregnated with thermoset resin. Curing was done by autoclave processing. In order to obtain comparable fibre volume contents of approx. 60 % in the different layups (monolithic and hybrid without and with separating layer), curing cycles adapted to the type of layup have been identified. The resulting fibre volume content of the test panels has been determined both by weighing and experimentally by chemical extraction and calcination. The impact load was applied by an instrumented experimental setup. Thereby both commercially available bullets and bearing balls accelerated with weighted propellant in a sabot have been used as impactors. The measured values are the velocities of the bearing balls as the impactor before and after penetration of the test panels. Findings: In both cases the results show the energy dissipation capacity of each single kind of fibre in case of the monolithic layups as well as the enhanced properties of the hybrid stacked layups without and with the separating layer as a core material. Typical failure modes on the impact surface and on the outlet areas are identified. Research limitations/implications: The influence of the respective kind of impactors, namely bullets and bearing balls, on the evaluated results is identified. Thereby the bearing balls exhibited a higher degree of reproducibility due to several reasons. Originality/value: Fibre reinforced plastics with hybrid stacking sequences can be used as load-bearing structures and at the same time as safety structures for passengers in automotive or aerospace applications. Moreover, with the hybrid stacked composites lightweight concepts can efficiently be realized regarding energy saving issues.

6

Dissipation of energy in tissues of berry fruit of selected plants species under cyclic load conditions

63%

Bohdziewicz J. , Czachor G.

Agricultural Engineering

|

2016

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tom Vol. 20, No. 4

5--14

EN

Dissipation hypothesis of energy under cyclic loads conditions was used to characterize the behavior of berry fruit. The possibility of dissipation of energy as a result of plastic deformations (Dawidenkow hypothesis) or visco-elastic deformations (Voigt hypothesis) was considered. Tests of hysteresis of whole fruit squeezed among two rigid plates for various levels of load and with various speeds of deformation of samples for two directions of load application were conducted for verification of the usefulness of both hypotheses. The strength tests were preceded by the test of hysteresis, the mass and the geometry of fruit were determined additionally as well as conventional density and moisture was counted. A mutual relation of average values of the coefficients of elasticity EC was accepted as the measure of dissipation of energy as a result of changes in the angle of inclination of the curve in the springy return phase. Voigt hypothesis was confirmed as useful within the range of small speeds of deformation and lack of usefulness of the Dawidenkow hypothesis was proved.

PL

Do scharakteryzowania behawioru owoców jagodowych wykorzystano hipotezy rozproszenia energii przy obciążeniach cyklicznych. Uwzględniono możliwość rozpraszanie energii na skutek odkształceń plastycznych (hipoteza Dawidenkowa) lub odkształceń sprężysto-lepkich (hipoteza Voigta). Do weryfikacji przydatności obu hipotez przeprowadzono testy histerezy całych owoców ściskanych pomiędzy dwiema sztywnymi płytami dla różnych poziomów obciążenia i przy różnych prędkościach odkształcenia próbek dla dwóch kierunków przyłożenia obciążenia. Test histerezy poprzedzono testami wytrzymałościowymi, dodatkowo wyznaczono masę i geometrię owoców, obliczano umowną gęstość i wilgotność. Jako miarę rozproszenia energii przyjęto wzajemną relację średnich wartości współczynników sprężystości EC jako skutek zmian kąta nachylenia krzywej w fazie sprężystego powrotu. Stwierdzono przydatność hipotezy Voigta w zakresie niewielkich prędkości odkształcenia i wykazano brak przydatności hipotezy Dawidenkowa.

7

Application of energy dissipation analysis for identification of machine component condition

63%

Sadowski A. , Żółtowski B. , Kuliś E.

Journal of Polish CIMAC

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2014

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tom Vol. 9, no 3

81--89

EN

Energy transformation in power transmission systems of machines is accompanied by occurrence of a series of processes which cause energy losses. Analysis of the phenomena occurring in the process of energy transformation and energy transmission and the methods used for determination of its dissipation paths is the major task of this study. Structural components of a three-axle vehicle with all-axle drive were used for a description and analysis of degradation mechanisms involved in energy dissipation. Practical aspects of the proposed methodology allow to define precisely the sites and the major factors affecting occurrence of losses in the power transmission systems of vehicles. Demand for methods and means enabling effective insight into the causes and effects of energy losses in machine components are issues that need to be addressed using available means and in a possibly short time.

8

Seismic behaviour of traditional half-timbered walls: cyclic tests and strengthening solutions

63%

Vasconcelos G.

Wiadomości Konserwatorskie

|

2012

|

tom Nr 32

137-142

EN

Half-timbered buildings represent an important historical heritage in many countries. They are diffused in various regions for different reasons, such as availability of materials, to lighten a structure, their low cost, the strength they offer and as a construction element able to resist seismic actions. This latter issue is the research topic analysed here, as half-timbered buildings have been specifically used in reconstruction plans as earthquake-resistant buildings in many countries, such as Portugal, Italy, and Greece. All these buildings were characterized by an internal timber skeleton constituted of vertical and horizontal elements and braced with diagonal elements (St. Andrew's crosses). This structure aimed at improving the global stability of masonry buildings, enhancing their capacity to dissipate energy during earthquakes. The aim of this paper is to study the behaviour under cyclic loading of such half-timbered walls, with typical connections, materials and geometries encountered in existing buildings. In general, half-timbered walls act as shear walls and confer to the masonry structure a better seismic resistance than that provided by a traditional masonry wall. Cyclic tests were performed on traditional walls and their behaviour was studied in terms of ultimate capacity, deformability, energy dissipation and stiffness. Subsequently, the tested walls were retrofitted with traditional techniques in order to understand the influence of the reinforcement and to estimate its effectiveness, or lack thereof.

PL

Budynki o konstrukcji szkieletowej stanowią ważny element historycznego dziedzictwa w wielu krajach. Są rozproszone w rozmaitych regionach z różnych powodów, takich jak dostępność materiałów, zmniejszenie ciężaru konstrukcji, jej wytrzymałość, niskie koszty, oraz jako element konstrukcyjny zdolny wytrzymać wstrząsy sejsmiczne. Ta ostatnia kwestia jest przedmiotem niniejszej analizy, gdyż budynki o konstrukcji szkieletowej są wykorzystywane szczególnie w projektach rekonstrukcji w krajach, takich jak Portugalia, Włochy czy Grecja, jako odporne na trzęsienia ziemi. Wszystkie te budynki charakteryzuje obecność wewnętrznego szkieletu drewnianego składającego się z pionowych i poziomych elementów, połączonych elementami ukośnymi (krzyże św. Andrzeja). Taka konstrukcja ma na celu poprawę ogólnej stabilności budynków murowanych, zwiększając ich zdolność do rozpraszania energii w wypadku trzęsienia ziemi. Celem niniejszej pracy jest przestudiowanie zachowań ścian szkieletowych wykonanych z użyciem typowych połączeń, materiałów i geometrii, spotykanych w istniejących budynkach, pod cyklicznym obciążeniem. Na ogół ściany szkieletowe odpowiadają za przenoszenie ścinanania i nadają konstrukcji murowanej lepszy opór sejsmiczny, niż ten jaki daje tradycyjna ściana murowana. Badania cykliczne zostały wykonane na tradycyjnych ścianach, a ich zachowanie przestudiowane pod kątem całkowitej nośności, odkształceń, rozproszenia energii i sztywności. Następnie testowane ściany zostały wzmocnione metodami tradycyjnymi, co miało pomóc w zrozumieniu wpływu takiego działania i ocenie jego efektywności, bądź jej braku.

9

Metoda projektowania elementów pomiarowych o charakterystyce nieliniowej

63%

Osiński J. , Zbrowski A.

Problemy Eksploatacji

|

2001

|

tom nr 3

215-225

PL

W artykule została zaprezentowana metoda projektowania elementów pomiarowych o nieliniowych własnościach materiałowych. Wybrane problemy zostały omówione na przykładzie zbudowanego w ITeE hydraulicznego przetwornika siły i samochodowej wagi przejazdowej, w której takie przetworniki zastosowano. metoda wykorzystuje możliwości stworzone przez technikę komputerową, przede wszystkim Metodę Elementów Skończonych i symulację cyfrową.

EN

The paper presents the method of designing measurement elements with non-linear material properties. It describes selected problems on the example of built in ITeE: a hydraulic force transducer and an automotive in-motion weigher, in which such transducers were used. Posibilities created by computer science, first of all Finite Elements Method and digital simulation were used in the described methods. Executed comparison of results of calculations and experimental tests proves that the weight measurement system designed with the use of this method may have better properties than carlier used solutions. The method's advantage is a considerable reduction in the number of experimental tests, which results can be predicted thanks to digital simulation and FEM calculations. The method is a flexible tool, which at the design stage enables multivariant analysis of the construction and its optimisation according to a criterion taken by the designer.

10

Shear failure and mechanical behaviors of granite with discontinuous joints under dynamic disturbance: laboratory tests and numerical simulation

63%

Gong H. , Wang G. , Luo Y. , Liu T. , Li X. , Liu X.

Archives of Civil and Mechanical Engineering

|

2023

|

tom Vol. 23, no. 3

art. no. e171, 2023

EN

To investigate the fracture mechanical behavior and failure mechanism of jointed rock mass under compression and shear load. Conventional shear tests and shear tests under normal disturbances were conducted using an electro-hydraulic servo-motor loading system. Meanwhile, the discrete-element program particle flow code was adopted to establish a numerical shear model, and to discuss the microscopic deterioration characteristics and energy dissipation mechanism during shear fracture of rocks with discontinuous joints under joint action of normal static loads and dynamic disturbance. Compared with the conventional shear tests, shear test results under normal disturbances show the following specificities in terms of their macroscopic and microscopic mechanical properties as well as energy evolution: (1) frequent dynamic disturbances accelerate the non-steady fracture process of jointed rock samples and promote occurrence of the weakening effect of shear fracture. (2) The step-like abrupt increase in micro-cracks becomes more obvious before reaching the peak shear stress. (3) The energy-storage capacity and failure resistance of the rocks are weakened. The research results are of great significance for further understanding the dynamic catastrophe effect of deep rock mass.

11

Comparative Analysis of Theoretical and Experimental Studies of Energy Dissipation for Model of a Ring Spring

51%

Skup Z.

Machine Dynamics Problems

|

2006

|

tom Vol. 30, No. 2

146-157

EN

The article presents the problem of energy dissipation in ring spring joints with structural friction taken into account. A comparative analysis was conducted to compare the theoretical results obtained by means of the digital simulation method with the results of experimental research assisted by an MTS testing machine. This paper shows an outline of theoretical considerations, the method for conducting tests as well as selected comparative results.

12

Antiplane deformation of a bimaterial containing an interfacial crack with the account of friction. [P.] 1, Single loading

51%

Sulym H. , Piskozub L. , Piskozub Y. , Pasternak I.

Acta Mechanica et Automatica

|

2015

|

tom Vol. 9, no. 2

115--121

EN

The paper presents the exact analytic solution to the antiplane problem for a non-homogeneous bimaterial medium containing closed interfacial cracks, which faces can move relatively to each other with dry friction. The medium is subjected to the action of normal and arbitrary single loading in a longitudinal direction. Based on the discontinuity function method the problem is reduced to the solution of the system of singular integral-differential equations for stress and displacement discontinuities at the possible slippage zones. Influence of loading parameters and the effects of friction on the sizes of these zones is analyzed. The stress intensity factors, stress and displacement discontinuities, energy dissipation are determined for several characteristic types of external loading.

13

Effect of strain rate on static elastic response of glass-polyester composite. Part 1, Description of test method

51%

Kozioł M.

Composites Theory and Practice

|

2023

|

tom R. 23, nr 1

22--29

EN

This paper is the first of two parts of a pioneering study to evaluate the effect of the strain rate of a GFRP laminate on the stress response. The assessment concerns the elastic range of deformation only. The publication contains the assumptions and methodological description of the conducted experiments. The non-destructive bending tests and the methodology for determining the modulus of elasticity and the energy of the load-unload cycle are presented in detail. The full set of test results is presented in the appendix. The results and conclusions are discussed in the second part of the study, which is a separate publication.