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1
Content available remote Variable Friction Coefficient Research on the Base of Motorbike Discbrake Assembly
Obst M., Kurpisz D., Ostrowska K., Majewski K.
Machine Dynamics Research
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2017
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Vol. 41, No. 2
71--84
EN
This article presents the research of the motorcycle braking process in real road conditions. The theoretical considerations of braking mechanics, construction of braking systems and friction phenomena that take place during motorcycle braking are presented. New and original concepts of acceleration and brake fluid pressure measuring systems are also submitted. The built measuring system was installed on a motorcycle and applied to experimental studies in order to investigate the variable friction coefficient. This original measuring system allows for recording values of pressure changes in the hydraulic braking system, acceleration in three axes and the temperature of the brake disc all at the same time. The obtained data allowed the calculations of several characteristics, e. g. motorcycle speed, brake power, braking distance and variable friction coefficient. As a result of this research, a special measuring system was prepared and a series of characteristics showed an interesting reflection of complex physical phenomena which motorbikes are subjected to during braking time. Information about variable friction coefficient obtained from energy based methods can be useful in theoretical investigation of friction phenomena.
2
Content available remote Three-Wheeler Electric Energy Saving Vehicle Prototype and Experimental Energy Intensive Research
Obst M., Kozłowski W., Gajda A.
Machine Dynamics Research
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2016
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Vol. 40, No. 4
33--50
EN
The three-wheeled vehicle construction and ready prototype are described. The vehicle is equipped with two energy recovery systems: one based on lithium-ion battery and electrical engine while the other one is applied with the spring mechanisms to accumulate energy. Both systems are combined together by an energy managing system based on a microcontroller. The construction serves as a testing and developing platform for energy save and recovery systems. At the end of the paper conveyed studies involving the vehicle range and efficiency are described and discussed.
3
Content available Limit load of cold formed thin-walled nonstandard channel beams
Obst M., Rodak M., Paczos P.
Journal of Theoretical and Applied Mechanics
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2016
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Vol. 54 nr 4
1369--1377
EN
Cold-formed thin-walled beams may lose the stability in different ways. The common buckling modes which have an influence on the failure of the beam are lateral-torsional, local and distortional buckling. The strength of cold-formed members can be calculated with the Effective Width Method which is incorporated in many international and national standards. In this paper, the experimental and theoretical results calculated with the aforementioned method have been compared
4
Content available remote Energy Based Mechanical Characteristics of Polymers POM-C, PET, PA6, PVC, PVDF
Obst M., Kurpisz D., Mencel K.
Machine Dynamics Research
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2015
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Vol. 39, No. 4
93-106
EN
Classical carried out tensile tension test relating to the basic research of mechanical properties of materials doesn’t always provide comprehensive information about the realistic nature of discussed materials. To complement research of typical lead material properties characteristics, you have to consider the accurate measuring of the transverse strain of specimens which can be used as the basis to assess the dangers relating to said materials which can be defined as the partial or total loss of its mechanical properties. In engineering practices, it can be observed that there is a the lack of indications which could be useful for engineers and could help to take an accurate assessment during polymers mechanical components design. Results obtained during tensile tension test of chosen polymers will be based on strain energy related, polymer models, which accurately allow us to estimate various conditions to be compromised by plastic flow or total material destruction. Research was done for rods made of POM-C, PET, PA6, PVC, PVDF, applied as constructible materials in machines, processing, agricultural, food and the chemical industry. Investigated polymers showed interesting elastic properties, especially in the event of very flexible materials, where strain energy changes are possible to estimate.
5
Content available remote Disc Brake Assembly Test Stand Design and Preliminary Motorbike Brake Process Indicators Test
Obst M., Kurpisz D., Zalas A., Stachowski M.
Machine Dynamics Research
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2015
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Vol. 39, No. 2
15-31
EN
In the paper friction phenomena test stand concept and technical solution is presented. Authors subjected on friction phenomena, based on motorbike disc brake assembly, prepared its original concept of friction and motorbike brakes research. In the publication, a detailed description of construction and system control is contained. Designed motorbike disc brake assembly friction test stand can offer few research programs. It is also possible to introduce own research program based on a real motorbike driving in different traffic conditions. Preliminary motorbike road test results are presented. A motorbike drive possesses characteristics of acceleration, speed, brake road distance, power of acceleration and deceleration. The initial investigation described in this paper can be a good introduction for a more advanced research where variable coefficient of friction and other friction phenomena values can be estimated. On the basis of presented methods, this can also develop an investigation of energy dissipation values. Energy parts designated in brake and friction process can be applied to mathematical description of friction phenomena and mechanical material destruction.
6
Content available remote Aluminum Alloy Welded Connection Tension Test and Energy Strain Investigation
Obst M., Kroczak J., Kurpisz D.
Machine Dynamics Research
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2014
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Vol. 38, No. 3
81-86
EN
Welded connections are very popular and applicable joints methods of materials. Welding technology and methods intensely developed in recent times and now its base technology is used in different industrial branches. Pressure vessels, boilers, working machines parts, plane bodies, ship hulls and other structures are made of metal, parts connected together by welding. Many welded connections work under complex stress and strain state also thermally loaded. Engineers apply typical, formulas during the design process of welded connections, some designers attempt also to use Finite Element Method in the modelling and design process of welded connections. It’s well known, welded connections zones enclose a place where materials have different properties than properties of parent materials of connected parts. In this area can cracks initiate and propagate. This paper presents tension test results of welded parts of aluminium alloy sighed as AL 5084. Authors investigated strain energy density and volume energy density dependence in the tension test process of welded specimens. Energy as an universal measure can be applied to investigate complex strength and exploitation problems. Presented results can be used as an introduction for more complicated problems of welded connections where strain energy is a base for mechanical modelling of welded connections.
7
Content available remote Displacemet determination of a thin-walled bush loaded by force and temperature
Kroczak J., Kurpisz J., Obst M.
Journal of Mechanical and Transport Engineering
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2013
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Vol. 65, No. 4
29--37
EN
Pin joints are very popular couplings in applied mechanical engineering. A lot of constructions and mechanisms are equipped with such type of kinematic pair. Pin joints are often applied as hinge connections in many responsible assemblies such as engine parts, bridges set systems, cranes etc. These connections work in different operating conditions which play a fundamental role during the design process. The paper presents the analysis of thermo-mechanically loaded thin-walled pin joint and the analytical solution of displacement equation for a bush. The obtained solution was verified by the finite element method. The presented results and proposed solutions can be applied for more complex problems where nonlinearity of strains, heat transfer, contact dependencies and grease coating influence are considered.
PL
W artykule przedstawiono analizę cienkościennego połączenia sworzniowego obciążonego termomechanicznie oraz analityczne rozwiązanie równania przemieszczenia ścian tulei. Otrzymane rozwiązanie zweryfikowano za pomocą metody elementów skończonych. Przedstawione wyniki stanowią podstawę do analiz bardziej złożonych zagadnień, w których można uwzględnić nieliniowość odkształceń, przepływ ciepła, warunki kontaktu pomiędzy współpracującymi powierzchniami oraz wpływ smarowania na zachowanie tulei.
8
Przebieg procesu jednoosiowego rozciągania w przestrzeni głównych składowych odkształcenia
Wegner T., Obst M.
Zeszyty Naukowe Politechniki Poznańskiej. Budowa Maszyn i Zarządzanie Produkcją
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2007
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Nr 7
129-152
PL
W pracy przedstawiono wyniki badań jednoosiowego rozciągania stali konstrukcyjnej zwykłej jakości o oznaczeniu ST3s. Badania prowadzono na maszynie wytrzymałościowej ZWICK. Wyznaczono zależności między działającą siłą i odkształceniem w kierunku jej działania oraz równolegle przeprowadzono pomiary odkształceń poprzecznych badanych próbek. Informacja na temat odkształceń materiału, zarówno w kierunku wzdłużnym do przyłożonego obciążenia, jak i w kierunku poprzecznym, przy różnych wartościach obciążeń, jest niezbędna do tworzenia energetycznych modeli aproksymujących właściwości mechaniczne materiału.
EN
This paper presents the results of a single-axial tension test of low-carbon regular quality steel marked ST3s. The research was conducted on a material-testing machine ZWICK. The relationship was determined between force and the strain of its direction. Simultaneously, measurements of transverse strains were carried out for examined specimens. Information on material strains, in both axial and transverse directions and for different loads, is essential to create strain energy based models, which approximate mechanical properties of material.
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