Temat: compression - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Compressive behaviour of wheat from confined uniaxial compression tests
Autorzy:: Zeng, C.
Wang, Y.
Tematy:: wheat
compression test
elastic moduli
compression
index; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Agrofizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2082573.pdf Link otwiera się w nowym oknie
Opis:: The present paper focuses on the compression characteristics of granular wheat stored in silos. The confined uniaxial compression tests of wheat were performed to investigate the compression behaviour of granular wheat. The effects of different loading paths and different maximum loading levels on the compression index and elastic moduli were analysed. The compression curves for each specimen were obtained from the test results. It was observed that nearly 80% of the total deformation occurred in the virgin loading stage. The compression index and elastic moduli were determined, which indicates that both the parameter compression index and elastic moduli correlate with the loading path.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Numerical approach in recognition of selected features of rock structure from hybrid hydrocarbon reservoir samples based on microtomography
Autorzy:: Kaczmarek, Ł. D.
Zhao, Y.
Konietzky, H.
Wejrzanowski, T.
Maksimczuk, M.
Tematy:: compression test
flow paths
porosity
sandstone; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/178817.pdf Link otwiera się w nowym oknie
Opis:: The study employs numerical calculations in the characterization of reservoir sandstone samples based on high-resolution X-ray computed microtomography. The major goals were to determine porosity through pore size distribution, permeability characterization through pressure field, and structure impact on rock strength by simulation of a uniaxial compression test. Two Miocene samples were taken from well S-3, located in the eastern part of the Carpathian Foredeep. Due to the relation between sample size and image resolution, two X-ray irradiation series with two different sample sizes were performed. In the first approach, the voxel side was 27 µm and in the second it was up to 2 µm. Two samples from different depths have been studied here. Sample 1 has petrophysical features of conventional reservoir deposits, in contrast to sample 2. The approximate grain size of sample 1 is in the range 0.1–1.0 mm, whereas for sample 2 it is 0.01–0.1 mm with clear sedimentation lamination and heterogenic structure. The porosity, as determined by µCT, of sample 1 is twice (10.3%) that of sample 2 (5.3%). The equivalent diameter of a majority of pores is less than 0.027 mm and their pore size distribution is unimodal right-hand asymmetrical in the case of both samples. In relations to numerical permeability tests, the flow paths are in the few privileged directions where the pressure is uniformly decreasing. Nevertheless, there are visible connections in sample 1, as is confirmed by the homogenous distribution of particles in the pore space of the sample and demonstrated in the particle flow simulations. The estimated permeability of the first sample is approximately four times higher than that of the second one. The uniaxial compression test demonstrated the huge impact of even minimal heterogeneity of samples in terms of micropores: 4–5 times loss of strength compared to the undisturbed sample. The procedure presented shows the promising combination of microstructural analysis and numerical simulations. More specific calculations of lab tests with analysis of variable boundary conditions should be performed in the future.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Wstępne badania degradacji mechanicznej materiałów wkładek absorbujących energię uderzenia wykorzystywanych w hełmach strażackich
Preliminary Studies of Mechanical Degradation of Materials Used for Inserts Absorbing Impact Energy in Firefighters’ Helmets
Autorzy:: Pieniak, D.
Walczak, A.
Tematy:: hełm strażacki
próba ściskania
firefighter’s helmet
compression test; Pokaż więcej
Wydawca:: Szkoła Główna Służby Pożarniczej
Powiązania:: https://bibliotekanauki.pl/articles/136745.pdf Link otwiera się w nowym oknie
Opis:: Do podstawowych funkcji hełmu strażackiego należy przechwycenie energii obciążenia zewnętrznego i jej rozproszenie w sposób bezpieczny dla strażaka ratownika. Wkładka absorpcyjna to drugi element, po skorupie, absorbujący energię uderzenia. Wykonana jest zwykle ze sztywnych materiałów porowatych, np. pianki poliuretanowej lub styropianowej. Wkładka często oddzielona jest od głowy wyłącznie cienką siatką, przez co podczas cyklicznego wkładania hełmu na głowę, w wyniku kontaktu, powstają cykliczne obciążenia eksploatacyjne. Ponadto w trakcie działań ratowniczo -gaśniczych, często dochodzi do niskoenergetycznych uderzeń hełmem, np. w przeszkodę w zadymionym pomieszczeniu. Cykliczne naprężenia ściskające, powstające w materiale wkładki, mogą powodować lokalne zmiany w strukturze materiału, np. lokalne zagęszczenie pianki w wyniku deformacji. W wyniku deformacji może zmienić się zdolność materiału wkładki do przenoszenia obciążeń krytycznych. W odniesieniu do materiału absorbera stawiane jest wymaganie, aby naprężenie przy uderzeniu nie przekraczało wartości granicznej, przy jednoczesnym uzyskaniu jak największej wartości pochłoniętej energii (jak największego pola pod wykresem naprężenie – odkształcenie). W obecnie wytwarzanych hełmach właściwość ta może być odmienna od charakteryzującej struktury hełmów użytkowanych przez kilka lat. Degradacja mechaniczna struktury materiału wkładki amortyzującej może prowadzić do pogorszenia właściwości absorpcyjnych. Dotychczas prowadzi się niewiele badań w tym kierunku. Jednakże jest to istotny problem, choćby z tego powodu, że uszkodzenia wkładki amortyzującej są trudne do wykrycia i zazwyczaj nie są podstawą do wycofania hełmu z eksploatacji.
A basic function of firefighter’s helmet is to absorb the energy of external load and disperse it in a safe manner for a firefighter. The absorptive insert is a second component after helmet’s shell absorbing impact energy. It is usually made of a rigid porous material such as for example polyurethane or polystyrene foam. The insert is often separated from the firefighter’s head only with a thin mesh, thus due to a repeated insertion of the helmet, the cyclic operational loads occur. Additionally, during the rescue and firefighting operations, the low energy impacts with helmet occurs e.g. hitting an obstacle in a smoky room. The cyclic compressive stresses taking place in the insert material can cause local changes in the material structure e.g. local foam compaction due to deformation. As a result of the deformation, an ability of the insert material to transfer critical loads can be changed. With regards to the absorber’s material, it is required that tension on impact does not exceed critical value reaching at the same time the highest value of absorbed energy (the largest area under stress – strain graph). In nowadays produced helmets this property can differ from the structure of the older helmets in use. Mechanical degradation of insert material structure can lead to the deterioration of absorptive properties. So far, there are not many studies concerning that problem. However, it is a crucial problem even if by the reason of the fact that the damages of the insert are difficult to detect and usually are not the basis for the withdrawal of the helmets from the operational use.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Identification of Yield Point of Polymer-Based Composite Material in the Conditions of Increased Temperatures
Autorzy:: Arustamian, A.
Sołek, K.
Kalisz, D.
Tematy:: mechanical properties
yield point
compression test
composite material; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/351130.pdf Link otwiera się w nowym oknie
Opis:: Theoretical and practical research on the influence of temperature on mechanical characteristics of the composite material MM “Steel 1018” has been conducted. Both laboratory equipment used to measure of mechanical properties, the technique of material preparation and the experimental procedure were described. The analysis of the the obtained results revealed that with temperature increase the material yield point goes down.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures
Autorzy:: Lee, J.-H.
Kim, D.-O.
Lee, K.
Tematy:: alloys
rolling
strain rate
compression test
HSLA steel; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/351774.pdf Link otwiera się w nowym oknie
Opis:: The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s^-1 and 1.0 s^-1. A long plateau region appeared for the 0.002 s^-1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s^-1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n), strength constant (K), and activation energy (Q), obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z) – 716.6) · ε^{(−0.00955ln(Z) + 0.4930)} for the 1.0 s^-1 strain rate and σ = (19.9ln (Z) – 592.3) · ε^{(−0.00212ln(Z) + 0.1540)} for the 0.002 s^-1 strain rate.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: High Temperature Random Stack Creep Property of Ni-Cr-Al based Powder Porous Metal Manufactured with Powder Sintering Process
Autorzy:: Kang, Tae-Hoon
Kim, Kyu-Sik
Park, Man-Ho
Lee, Kee-Ahn
Tematy:: powder porous metal
high-temperature
compression test
creep property; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/353154.pdf Link otwiera się w nowym oknie
Opis:: Recently, attempts have been made to use porous metal as catalysts in a reactor for the hydrogen manufacturing process using steam methane reforming (SMR). This study manufactured Ni-Cr-Al based powder porous metal, stacked cubic form porous blocks, and investigated high temperature random stack creep property. To establish an environment similar to the actual situation, a random stack jig with a 1-inch diameter and height of 75 mm was used. The porous metal used for this study had an average pore size of ~1161 μm by rolling direction. The relative density of the powder porous metal was measured as 6.72%. A compression test performed at 1073K identified that the powder porous metal had high temperature (800°C) compressive strength of 0.76 MPa. A 800°C random stack creep test at 0.38 MPa measured a steady-state creep rate of 8.58×10^-10 s^-1, confirming outstanding high temperature creep properties. Compared to a single cubic powder porous metal with an identical stress ratio, this is a 1,000-times lower (better) steady-state creep rate. Based on the findings above, the reason of difference in creep properties between a single creep test and random stack creep test was discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Bending and Compression Properties of ABS and PET Structural Materials Printed Using FDM Technology
Autorzy:: Szczepanik, S.
Bednarczyk, P.
Tematy:: 3D printing
PET
ABS
three-points bending
compression test; Pokaż więcej
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:: https://bibliotekanauki.pl/articles/106917.pdf Link otwiera się w nowym oknie
Opis:: The bend and compression mechanical properties of 3D-printed polyethylene terephthalate (PET) and acrylonitrile butadiene styrene (ABS) rectangular and cylindrical specimens (fully-dense and with circular, hexagonal, and rectangular perforations) are presented. In three-point bending, fully-dense PET flexural strength was 69 MPa, yield stress was 48.9 MPa, and yield stress from compression was 31.4 MPa. For ABS, these values were 59, 41.7, and 51.2 MPa, respectively – not significantly different from those of polymers manufactured by common techniques. Whereas perforation reduced density, the strength values were significantly lower, decreased for the circular perforation to a value of 20% strength for the fully-dense specimen. Specific strengths dropped quite significantly for the specimens tested in bending, whereas they did not differ significantly when tested by compression.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Wpływ obciążenia na przebieg odkształcenia warzyw o kształcie kulistym
The impact of load on deformation progress for ball-shaped vegetables
Autorzy:: Bohdziewicz, J.
Czachor, G.
Tematy:: warzywo
właściwości fizyczne
test ściskania
vegetable
physical properties
compression test; Pokaż więcej
Wydawca:: Polskie Towarzystwo Inżynierii Rolniczej
Powiązania:: https://bibliotekanauki.pl/articles/288620.pdf Link otwiera się w nowym oknie
Opis:: Przedstawiono wyniki pomiaru cech fizycznych wybranych warzyw o kształcie zbliżonym do kulistego. Przeprowadzono selekcję wagową, następnie realizowano test ściskania dla 10 egzemplarzy z każdej grupy warzyw. Na podstawie analizy zależności siła - przemieszczenie określono wartość dopuszczalnej siły Fdop oraz względnego przemieszczenia jako reakcji na zadane obciążenie. Stwierdzono zróżnicowanie wykluczające stosowanie uniwersalnych rozwiązań w konstrukcji maszyn lub linii technologicznych.
The work presents measurement results for physical features of selected ball-shaped vegetables. Weight selection was carried out first, followed by a compression test for 10 pieces from each group of vegetables. Analysis of force-displacement relation showed the value of acceptable force Fdop and relative displacement as a reaction to preset load. The researchers observed diversification precluding the use of universal solutions for the construction of machines or processing lines.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Numerical and experimental study of the mechanical response of aluminum foams under compressive loading using CT data
Autorzy:: Mohammadi Nasrabadi, A. A.
Hedayati, R.
Sadighi, M.
Tematy:: metal foam
image processing
compression test
finite element method
CT scan; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/281633.pdf Link otwiera się w nowym oknie
Opis:: Metal foams are relatively novel materials that due to excellent mechanical, thermal, and insulation properties have found wide usage in different engineering applications such as energy absorbers, bone substitute implants, sandwich structure cores, etc. In common numerical studies, the mechanical properties of foams are usually introduced to FE models by considering homogenized uniform properties in different parts of a foamy structure. However, in highly irregular foams, due to complex micro-geometry, considering a uniform mechanical property for all portions of the foam leads to inaccurate results. Modeling the micro-architecture of foams enables better following of the mechanisms acting in micro-scale which would lead to more accurate numerical predictions. In this study, static mechanical behavior of several closed-cell foam samples has been simulated and validated against experimental results. The samples were first imaged using a multi-slice CT-Scan device. Subsequently, experimental compression tests were carried out on the samples using a uniaxial compression testing machine. The CT data were then used for creating micro-scale 3D models of the samples. According to the darkness or brightness of the CT images, different densities were assigned to different parts of the micro-scale FE models of the foam samples. Depending on density of the material at a point, the elastic modulus was considered for it. Three different formulas were considered in different simulations for relating the local elastic modulus of the foam material to density of the foam material at that point. ANSYS implicit solver was used for the simulations. Finally, the results of the FE models based on the three formulas were compared to each other and to the experimental results to show the best formula for modeling the closed-cell foams.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Grain refinement, microhardness distribution, strain hardening behaviour and mechanical proprieties of RD-ECAPed AA 1050
Autorzy:: Halimi, A.
Hemmouche, L.
Chettah, I. E.
Louchene, Z. A.
Tematy:: aluminium alloys
Rotary Die Equal Channel Angular Pressing
microstructure
longitudinal microhardness
compression test; Pokaż więcej
Wydawca:: Instytut Podstawowych Problemów Techniki PAN
Powiązania:: https://bibliotekanauki.pl/articles/38697115.pdf Link otwiera się w nowym oknie
Opis:: This study aims to investigate the evolution of mechanical and microstructural characteristics of the 1050 aluminium alloy processed by Rotary Die Equal Channel Angular Pressing (RD-ECAP). The RD-ECAPed specimens were analysed after each pass using optical microscopy, quasi-static compression test and microhardness measurements. The results revealed a reduction in grain size from 29 _m before the RD-ECAP process to a minimum value of 2 _m at the second pass, corresponding to the maximum value of compressive yield strength, reaching 184MPa. Furthermore, there was an increase in hardness from 30 Hv to 63 Hv with a homogeneous distribution along the longitudinal surface, especially in the initial four RD-ECAP passes. Additionally, the appearance of a 45_ shear plane was observed at the last fifth pass, coinciding with the region of maximum microhardness.
Dostawca treści:: Biblioteka Nauki

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