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Number of results: 7
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Abstract

In this paper the influence of high power airborne ultrasound on drying biological material (Lobo apple) properties is considered. Apple samples were dried convectively at 75 ◦C and air flow of 2 m/s with and without ultrasound assist at 200W. During experiments, sun-drenched and not sun-drenched part of fruits were considered separately to show, how the maturity of the product influences dry material properties. Dried apple crisps in a size of small bars were subjected to compression tests during which acoustic emission (AE) was used. Analysis of AE and strength test results shows that correlations between received acoustic signals and sensory attributes (crispness, brittleness) of dried apples can be found. It was noted that ultrasound improved fruit brittleness in comparison with pure convective processes, where fruit maturity determines a kind of destruction and behaviour of dried apple crisps.

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Authors and Affiliations

Jacek Banaszak
Andrzej Pawłowski
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Abstract

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.

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Authors and Affiliations

Tae-Hoon Kang
Kyu-Sik Kim
Man-Ho Park
Kee-Ahn Lee
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Abstract

In this paper, the different mechanical behaviors of layered rocks with different bedding angles during uniaxial compression tests are studied. Numerical simulation models of layered rock are validated based on laboratory tests, and uniaxial compression tests are conducted by using Particle Flow Code (PFC). Using these simulations, the uniaxial compressive strength, failure patterns, development of micro-cracks, and displacement of meso particles are analyzed. When the bedding angle is similar to the failure angle, the macro failure planes develop directly along the beddings, the bedding behavior dictates the behavior of the layered rock, reducing the compressive strength.

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Authors and Affiliations

Nan Yao
Yi-Cheng Ye
Bin Hu
Wei-Qi Wang
Qi-Hu Wang
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Abstract

The article presents the results of tests of plastic shaping of magnesium alloy Mg-Li. Magnesium alloy for an extrusion process was obtained with the method of vacuum smelting and casting into graphite moulds. The materials for tests were slabs cast from magnesium alloys with symbols: Mg-4%Li-1%Ca (LX41). Before the process of deformation the castings were subject to homogenization. Conventional extrusion tests were conducted in a complex state of deformation (KoBo method). An assessment was performed of the influence of the deformation process parameters on the structure and properties of the tested alloy. Results of mechanical tests were presented both for static compression test in room temperature. On the basis of the achieved tests results, the susceptibility to plastic working for the Mg-4%Li-1%Ca alloy was determined. An analysis of the microstructure was conducted both in the initial condition and after plastic deformation with the use of light and scanning microscopy techniques. The applied deformation methods allowed the determination of the influence of process parameters on changes in the microstructure and properties of the Mg-4%Li-1%Ca alloy.
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Authors and Affiliations

Iwona Bednarczyk
ORCID: ORCID

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Abstract

In this study, the uniaxial compression test and PFC 2D numerical simulation were carried out on the artificial rock specimen with T-shaped prefabricated fractures. The effects of the lengths l1, l2 of the main fractures, the length l3 of the secondary fracture, and the angle β between the secondary fracture and the loading direction on the uniaxial compressive strength and crack evolution law of specimen were studied. The research results show that the change of l1, l2 and β has obvious effect on the compressive strength and crack growth of the specimen, but the change of l3 has little effect on the compressive strength of the specimen. When l3 = 40 mm and l1l2, the angle β influences on the crack propagation and failure mode of the specimen.
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Authors and Affiliations

Xiong Liangxiao
1
ORCID: ORCID
Haijun Chen
2
ORCID: ORCID
Zhongyuan Xu
3
ORCID: ORCID
Deye Hu
1
ORCID: ORCID

  1. School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China
  2. Geotechnical Engineering Department, Nanjing Hydraulic Research Institute, Nanjing, 210029, China
  3. Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China
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Abstract

The mechanical response of interpenetrating co-continuous composite Al-Si12/SiC3D was described for uniaxial tension and compression. The internal structure of the IPC was examined by optical microscopy and micro-CT. The apparent density and Young’s modulus were assessed theoretically and experimentally. Uniaxial tensile tests were performed using the prismatic samples of dimensions 1 mm × 2 mm × 30 mm. Cylindrical samples of diameters ϕ = 5 mm and height h = 10 mm were subjected to quasi-static uniaxial compressive loading. During tests, the side surfaces of the specimen were observed using a digital image correlation system (DIC) to find strain fields and to monitor the surface cracks development in the complex internal microstructure of the IPC.
The analyzed two-phase ICP was manufactured using ceramic foam SiC infiltrated by alloy Al-Si12. This material finds application in cosmic, airplane, or automobile industries, due to their excellent tribological, heat distribution, and ballistic properties.
Obtained results show different modes of microcracking and fracture of cylindrical and prismatic samples. They indicate the substantial influence of the ceramic skeleton on the behavior of the IPC under uniaxial states of loading. Different modes of damage related to the tension or compression loading were described in detail. The results can find application in the designing process of modern co-continuous IPCs and further development of the numerical models of degradation processes.
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Authors and Affiliations

D. Pietras
1
T. Sadowski
1
M. Boniecki
2
E. Postek
3

  1. Lublin University of Technology, 20-618 Lublin, 38D Nadbystrzycka Str., Poland
  2. Łukasiewicz Research Network, Institute of Microelectronics and Photonics , 02-668 Warsaw, Poland
  3. Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland
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Abstract

An uniaxial compression mechanical model for the roof rock-coal (RRC) composite sample was established in order to study the effects of height ratio of roof rock to coal on the structural strength of composite sample. The composite sample strengths under different height ratios were established through stress and strain analysis of the sample extracted from the interface. The coal strength near the interface is enhanced and rock strength near the interface weakened. The structural strength of composite sample is synthetically determined by the strengths of rock and coal near and far away from the interface. The area with a low strength in composite sample is destroyed firstly. An analytical model was proposed and discussed by conducting uniaxial compression tests for sandstone-coal composite samples with different height ratios, and it was found that the structural strength and elastic modulus decrease with a decrease in height ratio. The coal strengths far away from the interface determine the structural strengths of composite sample under different height ratios, which are the main control factor for the structural strength in this test. Due to its lowest strength, the rock near the interface first experienced a tensile spalling failure at the height ratio of 9:1, without causing the structural failure of composite sample. The coal failure induces the final failure of composite sample.

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Authors and Affiliations

Dawei Yin
Shaojie Chen
Xizhen Sun
Ning Jiang

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