Analytical research of steel rope dynamic properties

Transverse and rotational vibrations of steel rope are important issues in various technical installations. Dynamic properties of rope fragment are also useful as diagnostic parameters for broken wire detection within steel rope. This paper is intended to research the steel rope dynamic properties using lumped mass model. Theoretical detection of desired natural frequencies and corresponding forms of axially tensed rope fragment is useful for the proposed method implementation. The proposed theoretical model is verified with results of experimental research of steel rope. The proposed model is focused on transversal and rotational rope vibration analysis; there is an aim to obtain rotational vibration shape of rope from excitation in transversal direction to rope axis. Obtained theoretically calculated amplitude-frequency characteristics are compared with experimentally measured and good coincidence noticed. Finally, conclusions are drawn on the performed rope modelling results

Analytical research of steel rope dynamic properties

Transverse and rotational vibrations of steel rope are important issues in various technical installations. Dynamic properties of rope fragment are also useful as diagnostic parameters for broken wire detection within steel rope. This paper is intended to research the steel rope dynamic properties using lumped mass model. Theoretical detection of desired natural frequencies and corresponding forms of axially tensed rope fragment is useful for the proposed method implementation. The proposed theoretical model is verified with results of experimental research of steel rope. The proposed model is focused on transversal and rotational rope vibration analysis; there is an aim to obtain rotational vibration shape of rope from excitation in transversal direction to rope axis. Obtained theoretically calculated amplitude-frequency characteristics are compared with experimentally measured and good coincidence noticed. Finally, conclusions are drawn on the performed rope modelling results

Dependency of bearing noise properties on surfaces lubrication

This paper presents the investigation on bearing noise and vibration characteristics, when they are made from different material and lubricated with different materials. Experimentals research was performed on special workbenches, where ceramic and steel ball bearings were tested with equal loads and rotational speed. Parameters of their vibrations and acoustic noise were measured and dependencies of noise or vibration frequency lubricating material were found. There was found the decrease of resulting frequencies when thick oil was used. Hypothesis of tribological nature of the effect was raised and verified. Decrease of resulting frequencies in vibration spectrum of about 2 kHz when thicker lubricant was used proves initial prescriptions. Noise of ceramic bearing without lubrication and with similar surface parameters and testing conditions is generated in higher frequencies and high noise intensities are observed up to 20 kHz

Skeletal muscle adaptation of speed and the power–speed exercise

Topicality of the study –– the study has practical significance, since the examination of the skeletal muscle of young footballers, adaptive changes can be successfully plan for their training process, to select the optimum loads for running and jumping results in a profit. Hypothesis –– the young soccer players speed training used more physical workloads trigger off adaptive changes in skeletal muscle than the power–speed of force loads. Results and conclusions: 1. Top adaptive changes in speed physical property observed among young soccer players (12-13 and 15-16 years) in speed and jump tests (P <0.05). In later ages the results get more stable. Sprinters performance in all age groups and changes in tests improved gradually (P <0.05). 2. Increased adaptive changes in youth soccer players for speed and jumping through the physical characteristics of the speed physical exercise (P <0.05). By force–speed physical loads occurring muscle damage and caused the speed and jumping parameters and decrease during the study, and observed improvement of the results after the rest

Research of broken wire on the rope surface using dynamic method / Lyno išoriniame sluoksnyje nutrūkusių vielų tyrimas, taikant dinaminį metodą

This paper is intended to reveal possibilities to research of brokenwire on the wire ropes using dynamic properties of tensedwire rope and research properties of broken wire in piece ofwire rope when it is affixed on the wire rope in special testrig. During experimental test wire rope and broken wire on thetensed wire rope dynamic properties was estimated dependingon excitation frequency, also including affixed weight on thetensed wire rope dynamic properties. Finally, results are givenand conclusions are made. Santrauka Straipsnis skirtas mokslinių tyrimų galimybėms atskleisti. Naudojant dinamines savybes, bandyta aptikti nutrūkusias vielas ant įtempto plieninio lyno ir ant plieninio lyno gabaliuko rasti nutrūkusią vielą, kai šis lyno gabaliukas mechaniškai tvirtinamas ant plieninio lyno specialiame bandymų stende. Eksperimentinių tyrimų metų buvo išmatuotos plieninio lyno ir ant įtempto plieninio lyno nutrūkusios vielos dinaminės savybės priklausomai nuo lyno žadinimo dažnio, taip pat įvertinant įtempto plieninio lyno dinamines savybes, pritvirtinus ant jo papildomą svorį. Pateikiami tyrimų rezultatai ir išvados. Reikšminiai žodžiai: plieninis lynas, defektai, diagnostika, poslinkio amplitudė

Analysis of a flat-plate solar collector

The paper deals with a flat plate solar collector. The experiment was conducted using the finite element method and described the theoretical effectiveness of the flat solar collector as well as the factors that produce the major loss of heat. Investigation has concentrated on several different transparent surfaces used for determining the efficiency of the collector: 5 mm thick transparent glass and 5 mm thick transparent glass coated with a film of 120 μm. Article in Lithuanian. Plokščiojo saulės kolektoriaus tyrimas Santrauka.&nbsp;Darbe tirtas plokščiasis saulės kolektorius. Baigtinių elementų metodu nustatytas teorinis saulės kolektoriaus efektyvumas ir didžiausius šilumos nuostolius lemiantys veiksniai. Atliktas eksperimentas, kurio metu ištirtas kolektoriaus efektyvumas naudojant skirtingas skaidrias dangas: 5&nbsp;mm skaidrų stiklą ir 5&nbsp;mm skaidrų stiklą su 120&nbsp;μm storio papildoma plėvele. Raktiniai žodžiai: saulės kolektorius, šiluma, baigtiniai elementai, eksperimentiniai tyrimai

Experimental research of steel rope integrity problem

This paper is dedicated to treatment of a problem of a steel rope diagnostics. Research was carried out in order to reveal possibilities of diagnostics of steel rope integrity by virtue of dynamical properties of tensed steel rope in a special test rig, which was designed and fabricated for this particular research work. Excitation of the considered system was accomplished by means of a special shaker, which was connected to the rope body. Vibration measurements were performed with respect to the test rig frame for the whole rope to detect the broken wire. During experimental research the efforts were made to excite the broken wire of the rope through the whole rope. Another series of experiments were conducted in order to determine the dynamic response of the wire to forced vibration of the rope with the constant amplitude of rope vibrations. In addition, attempts were made to define the influence of rope tension onto resonant frequency of the broken wire. Results of research are presented as spectrums of forced vibrations in a frequency range of interest. Major experimental findings are summarized by the conclusions

Analysis of a mechanical structure of a microscope sensor of atomic force / Atominių jėgų mikroskopo jutiklio mechaninės struktūros analizė

Atomic Force Microscopy (AFM) is a method that allows obtaining an image of the surface of the sample in high resolution. This article investigates the problems associated with modeling a mechanical structure of a microscope sensor of atomic force.The paper refers to the previous scientists’ works and describes most frequently used methods of modeling, basic equations and a variety of factors that have an influence on the dynamics of the system. Also, the obtained results of earlier works are discussed. Santrauka Atominės jėgos mikroskopija (AJM) – metodas, leidžiantis gauti ypač didelės skiriamosios gebos tiriamojo bandinio paviršiaus vaizdą. Straipsnyje nagrinėjamos problemos, susijusios su atominių jėgų mikroskopo jutiklio mechaninės struktūros modeliavimu. Remiantis mokslininkų atliktais darbais aprašomi dažniausiai taikomi modeliavimo metodai, pateikiamos pagrindinės lygtys, nagrinėjama įvairių veiksnių įtaka sistemos dinaminėms charakteristikoms, aptariami atliktų tyrimų rezultatai. Reikšminiai žodžiai: atominių jėgų mikroskopija; modeliavimas; sistemos dinaminės charakteristikos

Tribological Properties of Biodiesel Fuel and Its Mixtures with Diesel Fuel

Implementation of biodiesel fuel in bus fleet or other responsible transport requires research of biodiesel properties, influencing lifetime of machines and performance quality. One of important side of fuel properties is tribological properties of fuels and mixtures of them with diesel fuel. Due to different origin and chemical structure, real fuel can contain non-stable states of liquid with undesired behavior in real fuel system. Such situation can cause undesired wearing of sliding surfaces in case of low lubricating film, seizing of jets in case of undesired sticking to metal and create big general resistance of fuel system. Aim of the paper is to reveal results and noticed properties of such mixtures using HVAC test and create some points in stable mixture behavior. Paper includes description of experiment, experiment equipment, methodology of experiment. Further results and graphs of most remarkable tests are presented and conclusions are made

Theoretical research of magnetorheological shock absorber damping force

In the article an overview of magnetorheological shock absorbertypes is presented, theoretical calculations of heat dispersion,magnetic field strength produced by shock absorber as well asmaximum power of electromagnet are provided. The article alsoprovides device damping force in line with a change of devicetemperature. In the end of the research the results of experimentare presented in the graph format as well as the conclusions. Article in Lithuanian. Magnetoreologinį skystį naudojančio slopintuvo slopinimo jėgos teoriniai tyrimai Santrauka.&nbsp;Apžvelgti magnetoreologinį skystį (MR) naudojančių slopintuvų tipai, atlikti slopintuvo išskiriamos šilumos, sukuriamo magnetinio lauko skaičiavimai, nustatyta didžiausia leistinoji elektromagneto galia, apskaičiuota įrenginio sukuriama pasipriešinimo jėga, įvertinant įrenginio veikimo metu išskiriamos šilumos temperatūrą. Darbe pateikti tyrimo metu gautų rezultatų grafikai ir išvados. Reikšminiai žodžiai: teoriniai tyrimai, slopintuvai, magnetoreologinis skystis