scholarly journals Applicability of Mechanical Tests for Biomass Pellet Characterisation for Bioenergy Applications

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1329 ◽  
Author(s):  
Orla Williams ◽  
Simon Taylor ◽  
Edward Lester ◽  
Sam Kingman ◽  
Donald Giddings ◽  
...  
Keyword(s):  
Strain Rate ◽  
Young’S Modulus ◽  
High Strain ◽  
Young's Modulus ◽  
Mechanical Tests ◽  
Strain Rates ◽  
High Strain Rates ◽  
Dynamic Mechanical ◽  
Pellet Strength ◽  
Biomass Pellet

In this paper, the applicability of mechanical tests for biomass pellet characterisation was investigated. Pellet durability, quasi-static (low strain rate), and dynamic (high strain rate) mechanical tests were applied to mixed wood, eucalyptus, sunflower, miscanthus, and steam exploded and microwaved pellets, and compared to their Hardgrove Grindability Index (HGI), and milling energies for knife and ring-roller mills. The dynamic mechanical response of biomass pellets was obtained using a novel application of the Split Hopkinson pressure bar. Similar mechanical properties were obtained for all pellets, apart from steam-exploded pellets, which were significantly higher. The quasi-static rigidity (Young’s modulus) was highest in the axial orientation and lowest in flexure. The dynamic mechanical strength and rigidity were highest in the diametral orientation. Pellet strength was found to be greater at high strain rates. The diametral Young’s Modulus was virtually identical at low and high strain rates for eucalyptus, mixed wood, sunflower, and microwave pellets, while the axial Young’s Modulus was lower at high strain rates. Correlations were derived between the milling energy in knife and ring roller mills for pellet durability, and quasi-static and dynamic pellet strength. Pellet durability and diametral quasistatic strain was correlated with HGI. In summary, pellet durability and mechanical tests at low and high strain rates can provide an indication of how a pellet will break down in a mill.

Measurement of Young’s Modulus of Human Tympanic Membrane at High Strain Rates

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Huiyang Luo ◽  
Chenkai Dai ◽  
Rong Z. Gan ◽  
Hongbing Lu
Keyword(s):  
Mechanical Behavior ◽  
Tympanic Membrane ◽  
Young’S Modulus ◽  
High Strain ◽  
Young's Modulus ◽  
Strong Dependence ◽  
Strain Rates ◽  
Loading Conditions ◽  
High Strain Rates ◽  
Human Tympanic Membrane

The mechanical behavior of human tympanic membrane (TM) has been investigated extensively under quasistatic loading conditions in the past. The results, however, are sparse for the mechanical properties (e.g., Young's modulus) of the TM at high strain rates, which are critical input for modeling the mechanical response under blast wave. The property data at high strain rates can also potentially be converted into complex modulus in frequency domain to model acoustic transmission in the human ear. In this study, we developed a new miniature split Hopkinson tension bar to investigate the mechanical behavior of human TM at high strain rates so that a force of up to half of a newton can be measured accurately under dynamic loading conditions. Young’s modulus of a normal human TM is reported as 45.2–58.9 MPa in the radial direction, and 34.1–56.8 MPa in the circumferential direction at strain rates 300–2000 s−1. The results indicate that Young’s modulus has a strong dependence on strain rate at these high strain rates.

scholarly journals Strain Rate and Temperature Effects on Tensile Properties of Polycrystalline Cu6Sn5 by Molecular Dynamic Simulation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1415
Author(s):  
Wei Huang ◽  
Kailin Pan ◽  
Jian Zhang ◽  
Yubing Gong
Keyword(s):  
Strain Rate ◽  
Tensile Properties ◽  
Young’S Modulus ◽  
Temperature Effects ◽  
High Strain ◽  
Young's Modulus ◽  
Voronoi Tessellation ◽  
Strain Rates ◽  
Electronic Products ◽  
Electrical Connections

Intermetallic compounds (IMCs) are essential in the soldering of electronic products and are composed mainly of Cu6Sn5 and Cu3Sn. They must maintain reliable mechanical and electrical connections. As they are usually only a few microns thick, and it is difficult to study their mechanical properties by traditional methods. In this study, a 100 Å × 100 Å × 100 Å polycrystal with 10 grains was created by Atomsk through Voronoi tessellation based on a Cu6Sn5 unit cell. The effects of the temperature and strain rate on the tensile properties of the polycrystalline Cu6Sn5 were analyzed based on MEAM potential function using a molecular dynamics (MD) method. The results show that Young’s modulus and ultimate tensile strength (UTS) of the polycrystalline Cu6Sn5 decrease approximately linearly with an increase in temperature. At high strain rates (0.001–100 ps−1), Young’s modulus and UTS of the Cu6Sn5 are logarithmic with respect to the strain rate, and both increase with an increase in strain rate. In addition, at low strain rates (0.00001–0.0005 ps−1), the UTS has a quadratic increase as the strain rate increases.

A Dynamic Mechanical Analysis of T2 Copper at High Strain Rates

2019 ◽  
Vol 812 ◽  
pp. 38-44
Author(s):  
Shuai Chen ◽  
Wen Bin Li ◽  
Xiao Ming Wang ◽  
Wen Jin Yao
Keyword(s):  
Yield Strength ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Pure Copper ◽  
Dislocation Slip ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Shpb Test

This work compares the pure copper (T2 copper)’s stress-strain relationship at different strain rates in the uni-axial tension test and Split Hopkinson Pressure Bar (SHPB) test. Small samples were utilized in the high strain rate SHPB test in which the accuracy was modified by numerical simulation. The experimental results showed that the T2 copper’s yield strength at high strain rates largely outweighed the quasi static yield strength. The flow stress in the stress-strain curves at different strain rates appeared to be divergent and increased with the increase in strain rates, showing great strain strengthening and strain rate hardening effects. Metallographic observation showed that the microstructure of T2 copper changed from equiaxed grains to twins and the interaction between the dislocation slip zone grain boundary and twins promoted the super plasticity distortion in T2 copper.

Tensile behaviors of co-woven-knitted fabric reinforced composites under various strain rates

2011 ◽  
Vol 45 (24) ◽  
pp. 2495-2506 ◽  
Author(s):  
Pibo Ma ◽  
Hong Hu ◽  
Lvtao Zhu ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Strain Rate ◽  
Failure Modes ◽  
Shear Failure ◽  
High Strain ◽  
Tensile Failure ◽  
Knitted Fabric ◽  
Strain Rates ◽  
High Strain Rates ◽  
Textile Composite ◽  
Interface Failure

This article reports the tensile behaviors of a novel kind of 3D textile composite, named as co-woven-knitted fabric (CWKF) reinforced composite, under quasi-static and high strain rates. The tensile tests were conducted along the warp direction (0°), bias direction (45°), and weft direction (90°) at quasi-static strain rate of 0.001/s and high strain rates ranging from 1589/s to 2586/s. The results indicate that the tensile strength, failure strain, tensile stiffness, energy absorption, and resilient energy are strain rate sensitive along all the three directions. The relationships between the mechanical parameters and the strain rate were also analyzed. The fractograph of the CWKF composite demonstrate that the tensile failure modes are matrix shear failure and fibers breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.

Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions

2019 ◽  
Author(s):  
Adewale Olasumboye ◽  
Gbadebo Owolabi ◽  
Olufemi Koya ◽  
Horace Whitworth ◽  
Nadir Yilmaz
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Stress Response ◽  
Flow Stress ◽  
Yield Strength ◽  
Strain Rate ◽  
High Strain ◽  
Second Phase ◽  
Strain Rates ◽  
High Strain Rates

Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.

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