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Compressive deformation characteristics of crushed sandstone based on multiple experimental factors

Sun Yanan, Zhang Peisen, Yan Wei, Yan Fenqian, Wu Junda

Archives of Mining Sciences

2020

Vol. 65, no. 1

129--146

In this study, the compressive deformation of crushed sandstone was tested using a crushed rock deformation-seepage test system, and the effects of various factors, including crushed rock grade, grade combination, water saturation status, and stress loading method (i.e., continuous loading or cyclic loading and unloading), on the compressive deformation of crushed sandstone was analyzed from four perspectives including stress-strain, bulking coefficient, deformation mechanism and energy dissipation. The results indicate that the stress-strain relations of crushed sandstone are closely associated with all factors considered, and are well represented by exponential functions. The strain observed for a given applied stress increased with increasing crushed rock grade throughout the loading period. Crushed sandstone grades were combined according to a grading index (n), where the proportion of large-grade rocks in the sample increased with increasing n. The bearing capacity of a water-saturated crushed sandstone sample with n = 0.2 was less than that of an equivalent dry sample for a given applied stress. The stress-strain curve of a water-saturated crushed sandstone sample with n = 0.2 under cyclic loading and unloading was similar to that obtained under continuous loading. Observation and discovery, the deformation mechanism of crushed sandstone was mainly divided into four stages, including crushing, rupture, corner detachment and corner wear. And 20% of the work done by testing machine is used for friction between the crushed sandstone with the inner wall of the test chamber, and 80% is used for the closing of the void between the crushed sandstone, friction sliding, crushing damage.

Compressive Deformation Behavior of an Ultrafine/Nano Grained AZ31 Magnesium Processed by Accumulative Back Extrusion

Fatemi S. M., Zarei-Hanzaki A., Paul H.

Archives of Metallurgy and Materials

2016

Vol. 61, iss. 3

1593--1600

An AZ31magneium alloy was processed through accumulative back extrusion (ABE) process at 280 °C up to six passes. Compressive deformation behavior of the processed materials was studied by employing uniaxial compression tests at room temperature. The results indicated that grains of 80 nm to 1 µm size were formed during accumulative back extrusion, where the mean grain size of the experimental material was reduced by applying successive ABE passes. A deformation texture characterizing with the basal plane mainly lie inclined to the deformation axis was developed. Compressive yield and maximum compressive strengths were measured to increase by applying successive extrusion passes, while the strain-to-fracture dropped. The evolution of mechanical properties was explained relying on the grain refinement effect as well as texture change. It was described that the share of different deformation mechanisms and developing of shearing regions near the grain boundaries may influence the deformation behavior of the ultrafine/nano grained AZ31 alloy.

Absorpcja energii przy odkształceniach ściskających pian aluminiowych

Koza E., Leonowicz M., Wojciechowski S., Pakieła Z.

Inżynieria Materiałowa

2003

R. XXIV, nr 6

322-324

Piany aluminiowe wytworzono metodą metalurgii proszków ze stopu AlSi10 z dodatkiem środka spieniającego w ilości 0,9 % wag. TiH2. Otrzymane piany poddano pomiarom gęstości i jednoosiowej próbie ściskania, z różną szybkością odkształcania w zakresie 3,3x10 do potęgi -3 /s - 1,66x10 do potęgi -1 /s i 5/s - 55/s. Oceniono wpływ szybkości odkształcenia na zaabsorbowaną energię i wytrzymałość na ściskanie. Przeprowadzone badania wykazały, że zwiększanie szybkości odkształcania w badanym zakresie powoduje wzrost zaabsorbowanej przez piany energii, a także nieznaczne zmniejszenie wytrzymałości na ściskanie sigma c. Zaabsorbowaną energię obliczono przy zastosowaniu dwóch różnych metod wyznaczania odkształcenia, przy którym rozpoczyna się zagęszczanie piany (epsilon D). Zmierzona wartość epsilon D maleje ze wzrostem gęstości pian i szybkości ich odkształcania.

Aluminium foams were produced by powder metallurgy method from AlSi10 alloy with addition of 0,9 wt. % of foaming agent (TiH2). The foams were subjected to density measurements and uniaxial compressive tests with different strain rates in the ranges of 3,3x10 to the -3 /s - 1,66x10 to the -1 /s and 5/s - 55/s. The influence of strain rate on the absorbed energy and compressive strength were investigated. The results showed that increase of strain rate, in the investigated range, leads to increase of the absorbed energy, as well as to slight decrease of compressive strength, sigma c. Absorbed energy was calculated using two different methods for determination of the strain values at which foam densification starts (epsilon D). The epsilon D values measured from the stress-strain curves decrease with increase of the foam density and strain rate.