Mechanical properties and fault plane features of Shidara sandstone in uniaxial compression tests

Construction applications sometimes require use of a material other than construction steel or concrete – mainly in cases, where strength to weight ratio needs to be considered. A suitable solution to this problem are structures manufactured using the 3D printing process, as they have a very good strength to weight ratio (i.e.: Ti-6Al-4V – σ<sub>ult</sub> = 900 MPa and ρ = 4500 kg/m<sup>3</sup>). Trabecular structures are porous structures with local material characteristics identical to their commonly manufactured counterparts, but due to their geometry, they have different global mechanical properties and are suited for special applications. We designed and manufactured six variants of these structures and subjected them to uniaxial compression tests, nanoindentation tests and subsequently evaluated their differences and elastic moduli. The values of global moduli E are in the range of 2.55 GPa – 3.55 GPa for all specimens.

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Rice Husk Shredding as a Means of Increasing the Long-Term Mechanical Properties of Earthen Mixtures for 3D Printing

10.20944/preprints202112.0360.v2 ◽

2022 ◽

Author(s):

Elena Ferretti ◽

Massimo Moretti ◽

Alberto Chiusoli ◽

Lapo Naldoni ◽

Francesco De Fabritiis ◽

...

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Uniaxial Compression ◽

Rice Husk ◽

Brittle Material ◽

Strict Sense ◽

Compression Tests ◽

Vegetable Fiber ◽

Natural Way

This paper is part of a study of earthen mixtures for 3D printing of buildings. To meet the ever-growing environmental needs, the focus of the paper is on a particular type of biocomposite for the stabilization of earthen mixtures—the rice husk-lime biocomposite—and on how to enhance its effect on the long-term mechanical properties of the hardened product. Having assumed that the shredding of the vegetable fiber is precisely one of the possible ways to improve the mechanical properties, we compared the results of uniaxial compression tests performed on cubic specimens made with both shredded and unaltered vegetable fiber, for three curing periods. The results showed that the hardened earthen mixture is not a brittle material in the strict sense, because it exhibits some peculiar behaviors, anomalous for a brittle material. However, being a “designable” material, its properties can be varied with a certain flexibility to get as close as possible to the desired ones. One of the peculiar properties of the hardened earthen mixture deserves further investigation, rather than corrections. This is the vulcanization that occurs (in a completely natural way) in the long term, thanks to the mineralization of the vegetable fiber by carbonation of the lime.

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Dual role of microcracks: toughening and degradation

Canadian Geotechnical Journal ◽

10.1139/t00-105 ◽

2001 ◽

Vol 38 (2) ◽

pp. 427-440 ◽

Cited By ~ 12

Author(s):

G M Nagaraja Rao ◽

C RL Murthy

Keyword(s):

Mechanical Properties ◽

Acoustic Emission ◽

Uniaxial Compression ◽

Inelastic Strain ◽

Dual Role ◽

Compression Tests ◽

Defective Structure ◽

Heating And Cooling ◽

Thermally Treated

One of the methods of improving the mechanical properties of ceramics is to introduce a defective structure that acts as a restraint for the propagation of cracks. In the present study a detailed investigation was carried out by introducing a defective structure in rock to determine if there is any improvement in properties similar to ceramics. Granite was chosen for the investigation, and the microcracks were introduced by a heating and cooling cycle. Uniaxial compression tests have shown that granite thermally treated to 200°C shows the highest strength, and the strength of granite treated to 400°C is comparable to that of unheated granite. Both ultrasonic images and acoustic-emission monitoring show that for thermally treated samples the stress-induced microcrack and macrocrack nucleation and their growth are retarded. The variations in mechanical properties are explained based on the concept of toughening and degradation. Uniaxial compression tests on unheated and thermally treated granite samples have clearly established the dual role of microcracks, which operate in the toughening and degradation mechanisms.Key words: thermal treatment, microcrack, inelastic strain, ultrasonic C-scan imaging, acoustic emission, toughening.

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Evaluation of remodeling and geometry on the biomechanical properties of nacreous bivalve shells

Scientific Reports ◽

10.1038/s41598-021-04414-1 ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Estefano Muñoz-Moya ◽

Claudio M. García-Herrera ◽

Nelson A. Lagos ◽

Aldo F. Abarca-Ortega ◽

Antonio G. Checa ◽

...

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Uniaxial Compression ◽

Shell Length ◽

Biomechanical Properties ◽

Material Behavior ◽

Stress And Strain ◽

Wave Forces ◽

Compression Tests ◽

Shell Size

AbstractMollusks have developed a broad diversity of shelled structures to protect against challenges imposed by biological interactions(e.g., predation) and constraints (e.g., $$pCO_2$$ p C O 2 -induced ocean acidification and wave-forces). Although the study of shell biomechanical properties with nacreous microstructure has provided understanding about the role of shell integrity and functionality on mollusk performance and survival, there are no studies, to our knowledge, that delve into the variability of these properties during the mollusk ontogeny, between both shells of bivalves or across the shell length. In this study, using as a model the intertidal mussel Perumytilus purpuratus to obtain, for the first time, the mechanical properties of its shells with nacreous microstructure; we perform uniaxial compression tests oriented in three orthogonal axes corresponding to the orthotropic directions of the shell material behavior (thickness, longitudinal, and transversal). Thus, we evaluated whether the shell material’s stress and strain strength and elastic modulus showed differences in mechanical behavior in mussels of different sizes, between valves, and across the shell length. Our results showed that the biomechanical properties of the material building the P. purpuratus shells are symmetrical in both valves and homogeneous across the shell length. However, uniaxial compression tests performed across the shell thickness showed that biomechanical performance depends on the shell size (aging); and that mechanical properties such as the elastic modulus, maximum stress, and strain become degraded during ontogeny. SEM observations evidenced that compression induced a tortuous fracture with a delamination effect on the aragonite mineralogical structure of the shell. Findings suggest that P. purpuratus may become vulnerable to durophagous predators and wave forces in older stages, with implications in mussel beds ecology and biodiversity of intertidal habitats.

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Experimental Study on the Calibration of Microparameters of Dolomite in the Barun Open-Pit Mine on the Basis of the Parallel Bond Model

Advances in Civil Engineering ◽

10.1155/2021/1267536 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Zhiheng Dang ◽

Zuoming Yin ◽

Desheng Wang ◽

Mingyu Fu ◽

Qi Yin

Keyword(s):

Mechanical Properties ◽

Numerical Simulation ◽

Uniaxial Compression ◽

Open Pit Mine ◽

Particle Flow ◽

Open Pit ◽

Test Results ◽

Compression Tests ◽

Simulation Test ◽

Bond Model

The microparameter calibration of the particle flow parallel bond model (PBM) is mostly based on a uniaxial compression test. The microparameters calibrated only by uniaxial compression tests cannot be directly used to study the mechanical properties of rocks with surrounding pressure conditions. To analyze the relationship between the macroparameters and microparameters in the model and select appropriate particle flow model parameters, this study conducted a particle flow numerical simulation experiment based on the basic test principles of the uniaxial compression, Brazilian splitting, and triaxial compression tests. An orthogonal experimental design was performed for the calibration of the microparameters of the particle flow PBM, and multifactor analysis of variance was used to screen out the factors that have a considerable influence on the experimental indicators. Regression analysis was performed on the significant influencing factors and test indicators, and the corresponding linear and nonlinear relationships between the macroparameters and microparameters were obtained. Lastly, the microparameters of the model were determined in accordance with the macroparameters of the mechanical test of the Barun open-pit mine dolomite, and a numerical simulation test was conducted. Simulation test results were consistent with the actual test results, thus providing a basis for a subsequent numerical simulation study on the mechanical properties of dolomite.

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Rice Husk Shredding as a Means of Increasing the Long-Term Mechanical Properties of Earthen Mixtures for 3D Printing

10.20944/preprints202112.0360.v1 ◽

2021 ◽

Author(s):

Elena Ferretti ◽

Massimo Moretti ◽

Alberto Chiusoli ◽

Lapo Naldoni ◽

Francesco De Fabritiis ◽

...

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Uniaxial Compression ◽

Rice Husk ◽

Brittle Material ◽

Strict Sense ◽

Compression Tests ◽

Vegetable Fiber ◽

Natural Way

This paper is part of a study of earthen mixtures for 3D printing of buildings. To meet the ever-growing environmental needs, the focus of the paper is on a particular type of bio-composite for the stabilization of earthen mixtures – the rice husk-lime bio-composite – and on how to enhance its effect on the long-term mechanical properties of the hardened product. Having assumed that the shredding of the vegetable fiber is precisely one of the possible ways to improve the mechanical properties, we compared the results of uniaxial compression tests performed on cubic specimens made with both shredded and raw vegetable fiber, for three curing periods. The results showed that the hardened earthen mixture is not a brittle material in the strict sense, because it exhibits some peculiar behaviors, anomalous for a brittle material. However, being a “designable” material, its properties can be varied with a certain flexibility to get as close as possible to the desired ones. One of the peculiar properties of the hardened earthen mixture deserves further investigation, rather than corrections. This is the vulcanization that occurs (in a completely natural way) in the long term, thanks to the mineralization of the vegetable fiber by carbonation of the lime.

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Experimental study on the influence of locked-in stress on the uniaxial compressive strength and elastic modulus of rocks

Scientific Reports ◽

10.1038/s41598-020-74556-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Xin Liu ◽

Hansheng Geng ◽

Hongfa Xu ◽

Yinhao Yang ◽

Linjian Ma ◽

...

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Uniaxial Compression ◽

Testing Machine ◽

Peak Strength ◽

Test Block ◽

Compression Tests ◽

Inclusion Content ◽

Rubber Particles ◽

Ground Stress

Abstract The rock contains many inclusions which produce high locked-in stress under the ground stress. In order to study the influence of locked-in stress on the mechanical properties of rocks, the rock-like materials and nitrile rubber particles are used to make a test block of the rock-like model which contains inclusions. The rubber particles will expand as the test block is heated, which creates locked-in stress in the inclusions. Uniaxial compression tests of similar model blocks with different locked-in stresses and different inclusion contents were performed by using a water bath and MTS-5T uniaxial compression testing machine. The results show that the peak strength and elastic modulus decreased with the increasement of locked-in stress and inclusion content. In the meantime, the relationship among the peak strength, the elastic modulus of the test piece, the locked-in stress and the inclusion content were obtained with the help of a mathematical fitting analysis of the quantitative formula. Furthermore, the expression and value curve of the joint impact factor are calculated. This paper evaluates the importance of the locked-in stress in the mechanical properties of the rock-like material and provide a guide for other researchers to further investigate the locked-in stress in rocks.

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Effect of Thermal Environment on the Mechanical Behaviors of Building Marble

Advances in Civil Engineering ◽

10.1155/2018/1326503 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Haijian Su ◽

Hongwen Jing ◽

Qian Yin ◽

Liyuan Yu

Keyword(s):

Mechanical Properties ◽

Uniaxial Compression ◽

Building Materials ◽

Elasticity Modulus ◽

Thermal Environment ◽

Peak Stress ◽

Compression Tests ◽

Mechanical Behaviors ◽

Thermal Environments ◽

Concrete Building

High temperature and thermal environment can influence the mechanical properties of building materials worked in the civil engineering, for example, concrete, building rock, and steel. This paper examines standard cylindrical building marble specimens (Φ50 × 100 mm) that were treated with high temperatures in two different thermal environments: vacuum (VE) and airiness (AE). Uniaxial compression tests were also carried out on those specimens after heat treatment to study the effect that the thermal environment has on mechanical behaviors. With an increase in temperature, the mechanical behavior of marble in this study indicates a critical temperature of 600°C. Both the peak stress and elasticity modulus were larger for the VE than they were for the AE. The thermal environment has an obvious influence on the mechanical properties, especially at temperatures of 450∼750°C. The failure mode of marble specimens under uniaxial compression is mainly affected by the thermal environment at 600°C.

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Investigation of mechanical properties of fractured marbles by uniaxial compression tests

Journal of Rock Mechanics and Geotechnical Engineering ◽

10.3724/sp.j.1235.2011.00302 ◽

2011 ◽

Vol 3 (4) ◽

pp. 302-313 ◽

Cited By ~ 11

Author(s):

Heping Xie ◽

Jianliang Pei ◽

Jianping Zuo ◽

Ru Zhang

Keyword(s):

Mechanical Properties ◽

Uniaxial Compression ◽

Compression Tests

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Mechanical properties of cryolite from Ivigtut, South Greenland

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-1984-33-31 ◽

1985 ◽

Vol 33 ◽

pp. 401-413

Author(s):

Hans Pauly

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

Uniaxial Compression ◽

Atmospheric Pressure ◽

Major Part ◽

Room Temperature ◽

Compression Tests ◽

Plastic Deformations ◽

Load Axis ◽

Formed Part

Cryolite made up about 75 per cent of the deposit in Ivigtut, South Greenland. Its mechanical properties seem important for the shaping and for the internal build-up of the deposit of which a major part, sideritecryolite with about 15 per cent siderite and a few per cent of sulphides, quartz etc., consolidated between 500 and 600'C. Thermal expansion, by volume, of cryolite is shown to be two to five times greater than the expansion of the accompanying minerals and rocks. The elastic constants of cryolite are found to be: E = 6.8 • 1()5 bars, G = 2.7 • 10' bars and Poisson's No. = 0.24. Compressive strength at room temperature 919 bars. Uniaxial compression tests at atmospheric pressure showed strength to increase to 1360 bars at 200"C and strain rate 0.05 mm per minute. Cryolite behaved in the tests up to 300"C as a brittle substance. Ductility was noted at temperatures from 400"C and, depending on strain rate, cryolite was found to exhibit unrestricted plastic deformations above 450"C. Ductility of cryolite around 500°C was found to be about the same as found for halite, tested in the same instrument, at 150-200°C. It is to be noted that the plastic deformation observed in these uniaxial compression tests dominantly appeared as bending of lamellae developed parallel to the load axis both in cryolite and in halite. In the siderite-cryolite, representing the earliest formed part of the deposit, siderite exhibits a pronounced cataclastic structure. This is attributed to the high ductility of cryolite at temperatures around 500°C. The contraction on cooling of cryolite appears important in judging joint patterns of the intrusion as well as macro- and microfissures within the deposit.

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