COMPUTATIONAL AND EXPERIMENTAL STUDY OF THE FALLING LOAD TEST OF HIGH-STRENGTH PIPE STEEL X100 (K80)

The behavior of samples of the promising pipe steel X100 under dynamic three-point bending is studied. This steel is compared with steel X80 currently used in the gas transmission pipeline engineering. Experimental and calculated mechanical characteristics were obtained for pipe steel X100 produced by JSC “VMZ” using data of the standard tests for laboratory samples and drop-weight tests (DWT). Steel X100 demonstrates higher strength indexes in comparison with steel X80, however, it has lower indexes of plasticity and ductile fracture resistance. High-speed video-recording of the crack propagation in a sample of steel X100 was performed in the drop-weight test. In combination with the sample resistance force dependence on the drop-weight movement distance, such testing provided much more information for studying the metal resistance to ductile fracture and allowed revealing the crack propagation law, estimating the specific dissipation energy during the crack propagation, and verifying the computational model used in DWT. Parameters of the X100 steel strain and fracture model were calibrated. The numerical simulation of the behavior of the X100 steel samples in tests at room temperature was performed. Simulation results satisfactorily agree with data of the tests with regard to such parameters as: the sample resistance force dependence as a function of the drop-weight movement distance; the striker work; strained foils, and macrogeometry of fractures in the tested sample. This results may be used for the development of requirements and conditions of using equipped DWT, as well as for the numerical simulation of full-scale tests of pipes made of steel X100 to predict the pipeline resistance to a propagating ductile crack.

Efek Magnetoimpedansi pada variasi Ketebalan lapisan Cu sampel Multilapisan [Ni80Fe20(800nm)/Cu (x)nm ]4 Substrat Cu-PCB (Printed Circuit Board)

<p class="AbstractEnglish"><strong>Abstract:</strong> Magnetoimpedance (MI) effect was observed on multilayer samples [Ni80Fe20_(800)nm)/Cu_{(<strong>x</strong>)nm}]₄Cu-Printed Circuit Board substrates. The multilayer system was grown through an electrodeposition process by modifying thickness of the Cu layer. The MI effect was analyzed by means of an impedance test under an external magnetic field at low frequency 100 kHz. The results found that MI ratio increased ± 1.02 fold with the reduction Cu layer (800 nm until 0 nm) from 2.39% to 3.44%. This condition is believed by differences resistance of magnetic layer to conductive layer in the multilayers system. The measured sample resistance value is inversely proportional to the function of “x” as the thickness of the conductive layer. This means that the reduction conductive layer can be improve magnetic properties for a multilayer [Nife/Cu]_N system. The analysis calculation of the sensitivity value also shows the potential increase sample sensitivity to 0.9746% / mT.</p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> <em>Magnetoimpedansi (MI) telah diamati untuk sampel multilapisan [Ni80Fe20_(800)nm)/Cu_{(<strong>x</strong>)nm}]₄substrat Cu-Printed Circuit Board. Sistem multilapisan ditumbuhkan melalui proses elektrodeposisi dengan memodifikasi ketebalan lapisan Cu. Efek MI dianalisis melalui pengujian impedansi dibawah medan magnet luar pada frekuensi 100 kHz. Hasil uji ditemukan rasio MI meningkat ±1.02 kali lipat dengan berkurangnya lapisan Cu (800 nm sampai 0 nm) dari 2,39 % menjadi 3,44 %. Kondisi ini diyakini oleh adanya perbedaan resistensi lapisan magnetik dengan lapisan konduktif pada sistem multilapisan. Nilai resistensi sampel yang terukur berbanding terbalik terhadap fungsi <strong>x</strong> sebagai ketebalan lapisan konduktif. Artinya berkurangnya lapisan konduktif dapat meningkatkan sifat magnetik sampel untuk sistem multilapisan [Nife/Cu]_N. Analisa perhitungan nilai sensitifitas juga menunjukan potensi kenaikan sensitifitas sampel tertinggi sampai 0,9746 %/mT. </em></p>

Study on the use of Aerogel on the Surface of Basalt Fabric

The layer of aerogel was applied to the surface of basalt fabric due to the possibility of improving a fabric protecting against the influence of hot environmental factors. The analysis of aerogel surface roughness and thickness of the obtained sample, resistance to contact heat for the contact temperature between 100°C and 250°C, and tests of resistance to the penetration of thermal radiation were carried out. In addition, thermal conductivity, thermal resistance, thermal diffusion, thermal absorption, and surface roughness were determined. The obtained results indicate the unevenness of aerogel application on the surface of basalt fabric. For this reason, work should be carried out on an appropriate technology that will allow them to be applied evenly on the surface of the fabric. The parameters tested and the results obtained are promising in terms of the possibility of using the fabric obtained in protective gloves.

The Electric and Dielectric Properties of SrF2:Tb3+ Nanocrystals Revealed by AC Impedance Spectroscopy

The electric and dielectric properties of SrF2:Tb3+ nanocrystals were studied by AC impedance spectroscopy. The grain and grain boundary resistances and the complex permittivity with different Tb-doped concentrations were obtained. As the Tb-doping concentration increases, the grain and grain boundary resistances decrease until 6% and then increase. The Tb doping leads to the increase of interstitial F− quantity and the decrease of the activation enthalpy, and finally causes the decreases of grain and grain boundary resistances. When the Tb-doping is larger than 6%, the effect of the deformation potential scattering is dominant, which leads to the increases of grain and grain boundary resistances. The strong dispersion of the permittivity at the low frequencies indicates the carrier was hopping in the transport process. The ε′ and ε″ values at the low frequencies decrease as the sample resistance increases.

Гетероструктура BaTiO-=SUB=-3-=/SUB=-/LaSrMnO-=SUB=-3-=/SUB=- на сапфире для сегнетоэлектрических туннельных переходов

BaTiO_3/LaSrMnO_3 (BTO/LSMO) structures with a ferroelectric layer thickness of 10 nm have been formed on r -cut sapphire substrate by means of high-frequency magnetron sputtering. Investigations of the sample structure showed the presence of a crystalline phase, while measurements of electrical properties revealed piezoelectric response of the BTO films. The study of local current–voltage characteristics showed dependence of the sample resistance on the prehistory of voltage application as determined by ferroelectric hysteresis of the BTO layer.

Dynamic Viscosity and Activation Energy of Wort During Fermentation and Storing

This paper presents the results of wort dynamic viscosity and activation energy during fermentation. The effect of temperature and storing time on both parameters was investigated. Measurements were performed on two wort samples. The first sample was taken at the beginning of fermentation, and the second sample after three hours of fermentation. Both samples were also measured after three weeks of storing. Dynamic viscosity measurements were performed with a digital rotational viscometer Anton Paar DV-3P, the principle of which is based on the dependency of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of both analysed parameters on temperature. The temperature dependence of dynamic viscosity can be characterised by a decreasing exponential function, while in case of activation energy linear increasing characters were obtained. Longer fermentation and storing period caused a decrease in both analysed parameters, due to the structural changes in wort samples during fermentation and storing.

Temperature Relations of Selected Engine Oils Dynamic Viscosity

This article focuses on temperature relations of dynamic viscosity for selected engine oils. The effect of temperature on new and used oil dynamic viscosity was investigated. Measurements were performed on three different motor oil samples. All the three motor oil samples were synthetic. The first oil sample was new, the second sample was used for 15,000 km, and the third sample was used for 30,000 km. There were made two measurements of samples in one week. Dynamic viscosity was measured using a digital rotational viscometer Anton Paar DV-3P. The principle of measurement is based on the dependence of sample resistance to probe rotation. The results of measurements are shown as graphical relationships between dynamic viscosity and temperature. Decreasing exponential functions in temperature relationships were used for all the samples. The highest difference between the first and second measurement was observed in the new oil, and very small differences were found in other oils. Due to different types of oils and different stage of usage, the results could not be compared.

Comparison of thermal and rheologic properties of Slovak mixed flower honey and forest honey

The article deals with the comparison of thermal and rheologic properties of two types of honey &ndash; mixed flower honey and forest honey made in Slovak Republic. All honey parameters were measured during temperature manipulation in the temperature interval from 5 to 45&deg;C. Two series of thermal and rheologic parameters measurements were done. Firstly samples of both types of fresh honey were measured at the beginning of storage and then the same samples of honey were measured again after one week of storage. The measuring of thermal parameters i.e. thermal conductivity, thermal diffusivity and specific heat was performed by the instrument Isomet 2104, which uses Hot Wire method, and the principle of measuring being based on the analysis of time-temperature relation. The measurements of dynamic viscosity were done by the viscometer Anton Paar (DV-3P), the principle of measuring being based on the dependence of the sample resistance on the probe rotation. Other rheologic parameters as kinematic viscosity and fluidity, were also determined. For the rheologic parameters measurements exponential relations are typical while for the thermal parameters linear relations were obtained.