Wyniki wyszukiwania - BazTech

1

Model-based design approach to reducing mechanical vibrations

Czop P., Wszołek G.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 60, nr 1

39--47

EN

Purpose: The paper presents a sensitivity analysis method based on a first-principle model in order to reduce mechanical vibrations of a hydraulic damper. Design/methodology/approach: The first-principle model is formulated using a system of continuous ordinary differential equations capturing usually nonlinear relations among variables of the hydraulic damper model. The model applies three categories of parameters: geometrical, physical and phenomenological. Geometrical and physical parameters are deduced from construction and operational documentation. The phenomenological parameters are the adjustable ones, which are estimated or adjusted based on their roughly known values, e.g. friction/damping coefficients. Findings: The sensitivity analysis method provides major contributors and their magnitude that cause vibrations Research limitations/implications: The method accuracy is limited by the model accuracy and inherited nonlinear effects. Practical implications: The proposed model-based sensitivity method can be used to optimize prototypes of hydraulic dampers. Originality/value: The proposed sensitivity-analysis method minimizes a risk that a hydraulic damper does not meet the customer specification.

2

A modification of the method for determination of surface fractal dimension and multifractal analysis

Kwaśny W.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 33, nr 2

115-125

EN

Purpose: In this work modification of the PCM method for determination of the surface fractal dimension is proposed. Complete reasoning, leading to correct formula for determination Ai(ä) is presented. In order to test modified method, data sets characterised by fractional fractal dimension were generated. Design/methodology/approach: Three different algorithms to receive data sets describing surfaces with fractional fractal dimension were exploited (two algorithms of midpoint displacement and Falconer algorithm). Findings: In this work detailed methodology for surface multifractal description, which may be directly applied for data obtained from the AFM microscope, was presented. Research limitations/implications: The geometrical features description of surfaces of the coatings obtained in the PVD and CVD processes. Practical implications: In presented work modified PCM method for determination of the surface fractal dimension was proposed. Performed calculations proved that new method make possible to determine this parameter more correctly. Differences are especially significant for rough surfaces, as what tested using series of data sets generated by algorithms for modelling surfaces with fractional fractal dimension. Proposed modified method for determination of the fractal dimension can be used for description of the geometrical features of coatings obtained in the PVD and CVD processes. Originality/value: Fractal and multifractal analysis gives possibility to characterise the extent of irregularities of the analysed surface in the quantitative way.

3

Wibroizolowany przejazd samochodowy

Targosz J.

Mechanics / AGH University of Science and Technology

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2005

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Vol. 24, no. 4

281-289

PL

W pracy przedstawiono problem elementów dróg torowych i samochodowych na ich skrzyżowaniach. Praca dotyczy zagadnień istotnych z punktu widzenia projektowania i budowy przejazdów na skrzyżowaniach transportu samochodowego i torowego. Transportowi towarzyszy nieodłącznie oddziaływanie dynamiczne na otoczenie. Szczególnie w czasie najazdu lub zjazdu ze skrzyżowania tych dróg, ze względu na zgromadzoną w nim wysoką energię kinetyczną (przekraczającą kilkudziesięciokrotnie energię kinetyczną w trakcie jazdy w warunkach normalnych, tzn. na drodze) dochodzi do długotrwałego przenoszenia fali drgającej poprzez grunt na obiekty inżynierskie, zaś powstające w jego wyniku silne drgania mogą doprowadzić do katastrofy lub uszkodzeń fundamentów obiektów, znajdujących się w pobliżu. Opierając się na analizie układu dyskretno-ciągłego podano nową ideę koncepcji rozwiązania wibroizolowanego przejazdu na skrzyżowaniach dróg transportu samochodowego, przedstawiono symulację dynamiki przejazdu pojazdów samochodowych oraz jej wyniki uzyskane przy wykorzystaniu pakietu systemu MSC YisualNastran4D. Przedstawiono także możliwość zastosowania tej koncepcji w konkretnych przypadkach na skrzyżowaniu dróg jezdnych. W wyniku pracy powstały dwa zgłoszenia do Urzędu Patentowego, które przedstawiono w literaturze.

EN

In the article we analyze the problem of elements of railways and car road at their crossings. The work raises issues critical from the perspective of designing and building driveways at the crossings of car and rail transport. Transport of this kind is inherently accompanied by the dynamic effect on the surroundings. Especially at the moment of entering and leaving the crossing due to the kinetic energy accumulated in it (highly exceeding the usual amount of kinetic energy accompanying the "normal" journey i.e. on the road), there is a prolonged transmission of a vibrating wave through soils onto the engineering structures. The resulting strong vibrations may lead to disaster, damage of the foundations of the buildings nearby or other constructions. On the basis of the analysis of the discrete-linear equation we presented a new concept of vibroisolated solution, a passage at the crossings of car transport roads, a simulation of the dynamics of crossing vehicles and its results on the basis of MSC VisualNostron4D System and its possible usage on given crossings. As the result of the research two applications to the Patent Office were created, which are presented in the literature.