Mechanical Compression and Crushing Properties of a Straw-Lime Material

2022 ◽  
Author(s):  
Parmo Parmo ◽  
Jean-Luc Hanus ◽  
Naima Belayachi ◽  
Patrice Bailly
Keyword(s):  
Mechanical Properties ◽  
Linear Part ◽  
Strain Curve ◽  
Image Correlation ◽  
Compression Tests ◽  
Stress Plateau ◽  
Speed Test ◽  
Binder Ratio ◽  
Parallel Direction ◽  
Strain Stress

The aim of this study was to determine the compressive mechanical properties and the energy absorption characteristics of a bio-composite material based on lime, wheat straw, and additives (protein and entraining agent). The selected samples with fiber to binder ratio of 30% were subjected to compression tests at different strain rates (1 mm/min, 10 mm/min, and 100 mm/min), in the perpendicular and parallel directions to fiber orientation. Image analysis supported with Digital Image Correlation (DIC) method is performed to follow longitudinal and lateral deformations, thus making it possible to evaluate elastic properties. The results show that the highest density and compressive strength in the parallel direction are ~349 kg/m3 and ~0.101 MPa, respectively. The perpendicular specimens at 100 mm/min of speed test showed the highest values of densification strain, stress plateau, energy efficiency, and absorbed-energy of 47.27%, 0.32 MPa, 16.98 %, and 13.84 kJ/m2, respectively. The values of Young’s modulus identified with DIC are significantly different from those determined by the slope of the linear part of the stress-strain curve. A slight influence of strain rate on mechanical properties is observed.

scholarly journals Effect of Layer Thickness on the Physical and Mechanical Properties of Sand Powder 3D Printing Specimens

2021 ◽  
Vol 9 ◽  
Author(s):  
Qing Xu ◽  
Lishuai Jiang ◽  
Changqing Ma ◽  
Qingjia Niu ◽  
Xinzhe Wang
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Layer Thickness ◽  
Uniaxial Compression ◽  
Strain Curve ◽  
Physical And Mechanical Properties ◽  
Image Correlation ◽  
Ductile Material ◽  
Compression Tests ◽  
Failure Patterns

The application of sand powder three-dimensional (3D) printing technology in the field of rock mechanics and mining engineering has tremendous potential, but it is still in the preliminary exploration stage. This study investigated the effect of printing layer thickness on the physical and mechanical properties of rock-like specimens with sand powder 3D printing. Quartz sand powder was used as the printing material, and the specimens were prepared with three different layer thicknesses of 0.2, 0.3, and 0.4 mm. Uniaxial compression tests with a combination of digital image correlation (DIC), acoustic emission (AE) and 3D microscope observations were performed to analyze the mechanical properties and failure patterns of the specimens during loading. Experimental findings showed that increasing the layer thickness from 0.2 to 0.4 mm would result in a decrease in the weight, density, uniaxial compression strength, and elastic modulus of the specimens. The stress-strain curve, deformation and failure patterns, crack growth process, and AE characteristics of the specimens with a layer thickness of 0.2 mm are similar to the AE characteristics of rock-like material, whereas the specimens with layer thicknesses of 0.3 and 0.4 mm deform like a ductile material, which is not appropriate for simulation of coal or rock mass. In future studies, rock-like specimens should be prepared with a small layer thickness.

scholarly journals Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2350 ◽  
Author(s):  
Jun Peng ◽  
Sheng-Qi Yang
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Damage ◽  
Strain Curve ◽  
Treatment Temperature ◽  
P Wave ◽  
High Temperature Treatment ◽  
High Porosity ◽  
Compression Tests

High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

Mechanical properties of UN-5100 envelope material for stratospheric airship

2020 ◽  
pp. 1-17
Author(s):  
W.-c. Xie ◽  
X.-l. Wang ◽  
D.-p. Duan ◽  
J.-w. Tang ◽  
Y. Wei
Keyword(s):  
Mechanical Properties ◽  
Significant Role ◽  
Strain Curve ◽  
Image Correlation ◽  
Membrane Structures ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Biaxial Tensile ◽  
Envelope Material ◽  
Biaxial Tensile Testing

ABSTRACT Stratospheric airships are promising aircraft, usually designed as a non-rigid airship. As an essential part of the non-rigid airship, the envelope plays a significant role in maintaining its shape and bearing the external force load. Generally, the envelope material of a flexible airship consists of plain-weave fabric, composed of warp and weft fibre yarn. At present, biaxial tensile experiments are the primary method used to study the stress–strain characteristics of such flexible airship materials. In this work, biaxial tensile testing of UN-5100 material was carried out. The strain on the material under unusual stress and the stress ratio were obtained using Digital Image Correlation (DIC) technology. Also, the stress–strain curve was corrected by polynomial fitting. The slope of the stress–strain curve at different points, the Membrane Structures Association of Japan (MSAJ) standard and the Radial Basis Function (RBF) model were compared to identify the stress–strain characteristics of the materials. Some conclusions on the mechanical properties of the flexible airship material can be drawn and will play a significant role in the design of such envelopes.

scholarly journals Impact of the reinforced metal structure on the mechanical properties foamed aluminium composites at the load

2021 ◽  
Vol 8 (1) ◽  
pp. 318-326
Author(s):  
Olga Mareeva ◽  
Vladimir Ermilov ◽  
Vera Snezhko ◽  
Dmitrii Benin ◽  
Alexander Bakshtanin
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Matrix Material ◽  
Metal Structure ◽  
Absorption Capacity ◽  
Large Contribution ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Plateau ◽  
The Matrix

Abstract This paper is an experimental study of the quasi-static mechanical compressive properties of the reinforced closed-cell aluminum alloy foams with different cell orientations at different strain rates. The reinforced foam samples were obtained via the powder metallurgical route. The results of the compression tests revealed that the deformation behavior and mechanical properties of foamed aluminum composites are highly dependent on the orientation of the reinforcing mesh. Differences in the deformation behavior of foams appear to be influenced by the mechanical properties of the matrix material, by foam deformation mechanisms, and by the mechanical properties of the reinforcement. The yield stress, plateau stress, densification stress, and energy absorption capacity of unreinforced foam samples improved linearly with increasing strain rate due to dynamic recrystallization and softening of the foam matrix material. The reinforced foam samples exhibit nonlinear deformation behavior. It was also found that the mechanical properties reduction of transverse reinforced foams was slightly lower compared to foams with longitudinal reinforcement at varying strain rates because of the large contribution of the mechanical properties of the reinforcement. The results of the present study can be employed to modelling and obtain impact-resistant fillers for complex structures in transport construction.

Experimental Determination of Mechanical Properties of Aluminium Foams Using Digital Image Correlation

2014 ◽  
Vol 601 ◽  
pp. 254-257 ◽  
Author(s):  
Tudor Voiconi ◽  
Emanoil Linul ◽  
Liviu Marsavina ◽  
Jaroslav Kováčik ◽  
Marcin Kneć
Keyword(s):  
Mechanical Properties ◽  
Digital Image Correlation ◽  
Yield Stress ◽  
Digital Image ◽  
Compressive Loading ◽  
Image Correlation ◽  
Compression Tests ◽  
Closed Cell

This paper presents an experimental characterization of three different types of closed-cell aluminium alloy foams (AlMg1Si0.6, AlSi12Mg0.6 and AlMg0.6Si0.3) under static compressive loading. This study was carried out on half-cylindrical specimens with skin. The influence of foam density on compressive behaviour was investigated for densities ranging from 430 kg/m3 to 935 kg/m3. The compression tests were performed at room temperature (23°C) with a constant crosshead speed of 0.5 mm/min. Strain distribution, yield stress and compressive modulus values were recorded using Digital Image Correlation. Experimental results show that the mechanical properties (Youngs Modulus, yield stress and plateau stress) increase with density.

scholarly journals A Study on the Mechanical Properties and Bursting Liability of Coal-Rock Composites with Seam Partings

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Dong Xu ◽  
Mingshi Gao ◽  
Yongliang He ◽  
Xin Yu
Keyword(s):  
Mechanical Properties ◽  
Crack Propagation ◽  
Shear Failure ◽  
Strain Curve ◽  
Efficient Production ◽  
Compression Tests ◽  
Linear Elastic ◽  
Splitting Failure ◽  
Coal Rock ◽  
The Stability

Geological tectonic movements, as well as complex and varying coal-forming conditions, have led to the formation of rock partings in most coal seams. Consequently, the coal in coal-rock composites is characterised by different mechanical properties than those of pure coal. Uniaxial compression tests were performed in this study to determine the mechanical properties and bursting liability of specimens of coal-rock composites (hereinafter referred to as “composites”) with rock partings with different dip angles θ and thicknesses D. The results showed that as θ increased, the failure mode of the composite changed from tensile and splitting failure to slip and shear failure, which was accompanied by a decrease in the brittleness of the composite and an increase in its ductility as well as a decrease in the extent of fragmentation of the coal in the composite. Additionally, as θ increased, the uniaxial compressive strength σu, elastic modulus E, and bursting energy index Ke of the composite decreased. The rock parting in the composite was the key area in which elastic energy accumulated. As D increased, σu, E, and Ke of the composite increased. In addition, as D increased, the ductility of the composite decreased, and the brittleness and extent of coal fragmentation in the composite increased. Notably, the curve for the cumulative acoustic emission (AE) counts of the composite corresponding to the stress-strain curve could be divided into four regimes: pore compaction and closure, a slowly ascending linear elastic section, prepeak steady crack propagation, and peak unsteady crack propagation. The experimental results were used to propose two technologies for controlling the stability of coal-rock composites to effectively ensure safe and efficient production at working faces.

scholarly journals Combined Calorimetry, Thermo-Mechanical Analysis and Tensile Test on Welded EN AW-6082 Joints

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1396 ◽  
Author(s):  
Philipp Wiechmann ◽  
Hannes Panwitt ◽  
Horst Heyer ◽  
Michael Reich ◽  
Manuela Sander ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welded Joints ◽  
Thermal Analyses ◽  
Mechanical Analysis ◽  
Image Correlation ◽  
Ex Situ ◽  
Compression Tests ◽  
Depth Analysis ◽  
Welding Processes

Wide softening zones are typical for welded joints of age hardened aluminium alloys. In this study, the microstructure evolution and distribution of mechanical properties resulting from welding processes of the aluminium alloy EN AW-6082 (AlSi1MgMn) was analysed by both in-situ and ex-situ investigations. The in-situ thermal analyses included differential scanning calorimetry (DSC), which was used to characterise the dissolution and precipitation behaviour in the heat affected zone (HAZ) of welded joints. Thermo-mechanical analysis (TMA) by means of compression tests was used to determine the mechanical properties of various states of the microstructure after the welding heat input. The necessary temperature–time courses in the HAZ for these methods were measured using thermocouples during welding. Additionally, ex-situ tensile tests were done both on specimens from the fusion zone and on welded joints, and their in-depth analysis with digital image correlation (DIC) accompanied by finite element simulations serve for the description of flow curves in different areas of the weld. The combination of these methods and the discussion of their results make an essential contribution to understand the influence of welding heat on the material properties, particularly on the softening behaviour. Furthermore, the distributed strength characteristic of the welded connections is required for an applicable estimation of the load-bearing capacity of welded aluminium structures by numerical methods.

Consideration of Yield Discontinuity in the Elastic-Plastic Fracture Analysis of Circumferentially Flawed Pipes

2017 ◽  
Author(s):  
Longjie Wang ◽  
Elvin Eren ◽  
Bin Wang ◽  
Guiyi Wu
Keyword(s):  
Driving Force ◽  
Large Scale ◽  
Strain Curve ◽  
Tensile Tests ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Stress Plateau ◽  
Crack Driving Force

This study examined the fracture behaviour of pipes containing surface flaws oriented circumferentially and made from a material that exhibits yield discontinuity (known as Lüders plateau) with the view of making recommendations for the assessment of pipes subject to high level of plasticity. Starting with the fundamental and first principles, uniaxial tensile tests were carried out with the use of digital image correlation (DIC) to observe the formation and propagation of Lüders bands quantitatively. Finite element (FE) analyses were then carried out to simulate the Lüders banding phenomenon in uniaxial tensile specimens and consequently cracked pipes. Different material models were adopted in FE analyses, including the stress-strain curve with a flat stress plateau neglecting upper yield stress, and the so-called ‘up-down-up’ (UPU) stress-strain curve for refining crack driving force predictions. The numerical analysis of tensile tests demonstrated that UPU stress-strain model satisfactorily simulated the main macroscopic features of Lüders band observed in the experiment. FE analysis of flawed pipes using both flat and UPU stress-strain curves produced a similar trend in the crack tip opening displacement (CTOD)-strain trajectory as that obtained from large-scale testing. It was seen that the shape of the UPU stress-strain curve, particularly the magnitude of softening, considerably affects the magnitude of crack driving force in the flawed pipe. However, the strain localisation associated with Lüders banding was not observed in the circumferentially flawed pipe in the case of using the flat stress-strain curve. The CTOD crack driving force obtained from simulations was lower than the CTOD obtained from experiments in the Lüders plateau regime, even with the consideration of ductile tearing. Finally, as a result of this study, recommendations on the optimum choice of material parameters were made for more accurate predictions of crack driving force in the presence of yield discontinuity.

Mechanical Properties of Nanotextiles Determined with Digital Image Correlation

2014 ◽  
Vol 606 ◽  
pp. 201-204
Author(s):  
Jiří Němeček ◽  
Ivan Jandejsek
Keyword(s):  
Mechanical Properties ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Measurement ◽  
Linear Part ◽  
Correlation Method ◽  
Local Strain ◽  
Image Correlation ◽  
Testing Device ◽  
Load Direction

The paper is devoted to the assessment of mechanical properties of nanotextiles prepared from polyvinylalcohol by electrospinning. The nanotextile is composed of a multi-layered net of cross-linked fibers with individual diameters of approx. 200-500 nm. Strips of the textiles were tested in a standard electromechanical testing device by uniaxial tension. Precise local strain measurement was provided by the digital image correlation method. The overall nanotextile Young's modulus was found to be 277±9 MPa (for strains <1%) and exhibited small variations as well as ultimate strength (10.3±0.9 MPa at ~13% strain). The deformation mechanism includes alignment and stretching of the fibers in longitudinal (load) direction (initial linear part), yielding with transversal textile smoothing and textile rupture (at strains ~13%). The progress of apparent Poisson's ratio (5.5-0.52) was also monitored with the digital image correlation.

scholarly journals Experimental Study on Mechanical Properties of Briquette Coal Samples with Different Moisture Content

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wang Haidong ◽  
Tao Yang ◽  
Wang Deyue ◽  
Sun Xin ◽  
Gao Jiahui
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Coal Seam ◽  
Mechanical Response ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Confining Pressure ◽  
Coal And Gas Outburst ◽  
Compression Tests ◽  
Gas Outburst

Coal seam water injection is an important technical method to prevent and control coal and gas outburst and other disasters. Water can soften coal and change its mechanical properties. In order to study the mechanical properties of coal samples with different moisture content, briquette coal samples with five moistures content (4%, 6%, 8%, 10%, and 12%) were selected to carry out triaxial compression tests under different confining pressures (0.1, 0.2, 0.4, 0.8, and 1.2 MPa). Then, the mechanical response mechanism of the water-bearing briquette coal was analyzed. The results show that the slope of the linear elastic stage of the stress-strain curve gradually decreases with the increase of moisture content. Water-bearing coal exhibits strain strengthening characteristics under high confining pressure, which transforms the water-bearing coal from brittle to ductile state. The peak stress under different moisture content conditions shows a linear relationship with the confining pressure. The internal friction angle decreases linearly with the increase of moisture content. The cohesion varies parabolically with the increase of moisture content and reaches the maximum value when the moisture content is 8%. The coal body with moisture content between 7% and 9% has a high bonding force, which is beneficial to the consolidation of the coal body. Therefore, ensuring a reasonable moisture content of coal through coal seam injection can provide a basis for preventing coal and gas outburst.

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