Compressive Mechanical Behavior Research Articles

A quantitative model considering crack closure effect of rock materials

The crack closure effect of rock materials plays a key role in the evaluation of its compressive mechanical behavior. Based on the effective medium theory, an exponential model is proposed to describe the influence of the crack closure effect on the constitutive relation. The crack deformation is characterized by natural strain, and the crack propagation in the compaction phase and elastic phase can be captured by this quantitative model. Three model parameters can be determined from experimental data. The model was verified by our uniaxial compression tests on marble and other types of rocks from the published literature. The results show that the model can simulate the nonlinear phase of stress–strain curves of rocks under uniaxial and triaxial compression conditions. The crack closure behavior in the compression tests can be well reflected by this model. In addition, the microcrack volume ratio is positively correlated with the crack density parameters, and the material damage caused by microcracks can be identified and quantified by the microcrack volume ratio.

Influence of processing route on microstructure and properties of Al13.45FeCrNiCo high entropy alloys

The Al13.45FeCrNiCo high entropy alloys (HEAs) were obtained using two different processing routes, namely (i) mechanical alloying (MA) and spark plasma sintering (SPS), and (ii) vacuum induction melting – copper cast molding. A final homogenizing treatment step was applied to the as synthesized materials. Based on thermodynamic and empirical criteria for phase formation, the alloy was designed to develop a mixture of the face-centered-cubic (FCC) and body-centered-cubic (BCC) solid solution. The contribution of aluminum content on the alloy microstructure in terms of hardening of solid solution and precipitation hardening was highlighted. The influence of the processing route on the microstructure evolution and the relationship between the microstructure and properties of HEA materials were established by performing X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and high-resolution (HR) TEM analyses, as well as microindentation and compression tests. The powder metallurgy processes produced a two-phase structure consisting of at least two types of crystalline grains based on FCC and BCC solid solutions. Increasing the sintering temperature from 950 °C to 1050 °C contributed to structural changes in the materials. Lower sintering temperatures (950 °C and 1000 °C) generated a single FCC phase structure, while at 1050 °C two FCC and BCC phases were obtained without any evidence of the liquid phase sintering. The as cast route generated a hypoeutectic type structure with a very fine and preferentially oriented dendritic structure, in which the interdendritic space is occupied by a second phase arranged in a network where the microstructure appears to be the result of a eutectic transformation with precipitation of secondary phases rich in Ni and Al. All the synthesized alloys revealed high hardness and a good mechanical behavior in compression. Sintered HEA materials exhibited higher Vickers hardness than as cast HEA, even after the heat treatment process, while the as cast HEA material has better ultimate strength and deformation behavior than sintered HEAs. The processing route did not affect the nature of the FCC and BCC solid solution phases formed in the Al13.45FeCrNiCo HEA materials but was responsible for the variation of phase proportion in the HEA’s microstructure, which in turn influenced the mechanical properties.

Strain rate-temperature coupling deformation mechanism and constitutive relationship of D2 wheel steel for high-speed EMUs

<p indent="0mm">With the increasing speed of trains and the increasingly complex and changeable service conditions, higher demands are forward for the safety and reliability of train components. Wheelsets are the key components in ensuring the safe operation of high-speed trains and may be subjected to significant dynamic impact loads during service due to the existence of wheel-rail defects such as rail corrugation and wheel irregularity. Due to the geographical and climatic characteristics of wide span and large temperature difference in China and the traction/braking of trains, thermal and mechanical stress may exist and superimpose on each other in the wheel-rail contact area, which leads to a reduction in material load-bearing capacity and endangering the safety of train operation. Therefore, clarifying the internal relationship between the dynamic mechanical properties and the microstructural evolution of wheel steel, revealing the strain rate- and temperature-sensitivities and plastic deformation mechanism of the material, and constructing an accurate constitutive model to describe the dynamic mechanical response of the material are still the key problem to be solved urgently in the study of the impact dynamics of the wheel-rail system. In this paper, the compressive mechanical behavior of D2 wheel steel in the temperature range of <sc>293–873 K</sc> and the strain rate range of <sc>0.001–2400 s^–1</sc> was investigated experimentally using the Gleeble-3800 thermal simulation testing machine and the split Hopkinson pressure bar (SHPB) device, the effect of strain rate and temperature on the quasi-static and dynamic mechanical properties of the material was analyzed, the strain rate- and temperature-sensitivities of wheel steel were discussed. In addition, the compression deformation mechanism of D2 wheel steel under different strain rates and temperatures was revealed using scanning electron microscope (SEM) and transmission electron microscope (TEM) technologies. Finally, the modified Johnson-Cook model was obtained to characterize the plastic flow behavior of the material based on the compression test results. The following conclusions are made based on the experimental results: (1) The compression mechanical response of D2 wheel steel displays obvious power-hardening plastic response characteristics, and there is no obvious yield plateau in stress-strain curves. The yield strength and flow stress of wheel steel increase with increasing strain rate and decreasing temperature, which shows significant strain rate strengthening effect and temperature softening effect. The strain rate- and temperature-sensitivities of D2 wheel steel are synthetically influenced by strain rate, temperature and deformation level. (2) The microstructure of D2 wheel steel is composed of lamellar pearlite and pro-eutectoid ferrite. The increase in test temperature will promote the dynamic recrystallization of ferrite inside the material, the decomposition, melting, diffusion of carbon atoms and granular precipitation of cementite under quasi-static loading. As the strain rate increases, the cementite lamellae of pearlite inside the material are sheared, broken and spheroidized, and the ferrite produces large plastic deformation, while the temperature has less effect on the evolution of the microstructure of the material under dynamic loading. (3) By modifying the strain rate and temperature terms of the classic Johnson-Cook model based on the compressive test results of D2 wheel steel, the modified Johnson-Cook model which has higher prediction accuracy for the plastic flow behavior of D2 wheel steel in the temperature range of <sc>293–873 K</sc> and the strain rate range of <sc>10^–3–2400 s^–1</sc> is obtained. The research results can provide important technical support for accurately evaluating the service safety and developing and establishing the service safety evaluation method and standard system of the wheel-rail system.

Dynamic Compressive Mechanical Behavior and Microstructure Evolution of Rolled Fe-28Mn-10Al-1.2C Low-Density Steel.

In this study, the quasi-static and dynamic compressive mechanical behavior of a rolled Fe-28Mn-10Al-1.2C steel (low-density) was investigated. X-ray diffraction, optical microscopy, electron backscattered diffraction and transmission electron microscopy were conducted to characterize the microstructure evolution. The results displayed that the steel has remarkable strain rate sensitivity and strong strain hardenability under high strain rate compression. Most specifically, the deformation behavior was changed with the increase in the strain rate. A feasible mathematical analysis for the calculation of stacking fault energies and the critical resolve shear stresses for twinning was employed and discussed the nucleation of the twinning. The microband-induced plasticity and twinning-induced plasticity controlled the deformation under high strain rate compression and provided a strong strain hardening effect. The higher mechanical response can increase the broad use of low-density steel in automobile applications.

ABAQUS plug-in finite element tool for designing and analyzing lattice cell structures

This paper presents the development of a lattice structure design (LSD) tool for building and analyzing different configurations of 3D-printed lattice structure (LS). This tool was developed via ABAQUS graphical user interface (GUI) based on Python code. Due to the extensive research activities in the field of lattice design using experimental and computational methods, there is a high demand for finding new techniques to reduce the computational time and human effort. Also, several challenges were revealed while creating finite element models for lattices of complicated geometries. These models showed the capability for capturing the elastic and inelastic mechanical responses of LSs during the compression test. Consequently, the LSD tool was designed not only to build lattice structures in a short time and simple way, but also to analyze the associated compressive mechanical behavior that goes beyond initial yielding to cover the entire crushing behavior. This paper examined many challenges involved in generating and decomposing the lattice geometry, creating hexahedron elements and optimizing the mesh density, assigning and inserting the material type, activating the face recognition to define the boundary and loading conditions, and conducting linear and polar patterns. Finally, to demonstrate the effectiveness of the new approach in designing and analyzing LSs, finite element results were validated with the previous experimental findings.

Effect of Curing Condition on the Compressive Mechanical Behavior of Clayey Soil Stabilized with Liquid Polymer

This study investigates the potential use of polyvinyl acetate emulsion in soil strengthening with emphasis on curing condition. Molded clay specimens treated with three polymer contents of 1%, 2%, and 3% (by the weight of dry soil) are cured in dry and humid environment, respectively. Unconfined compression tests are performed on the specimens after 1, 3, and 9 days of curing, and the results are compared with that for the untreated clay specimens. This comparison shows that polyvinyl acetate polymer can enhance soil mechanical properties. It was found that the compressive strength of soil-polymer composite increases significantly with the increase of polymer content and curing time in air-drying condition, which is 24% higher than that of plain soil after 9-day curing. The role of polymer treatment is to provide soil interparticle binding, which becomes particularly important in humid environments. In curing environments of high moisture, polymer-treated soils always have greater strength, but the effectiveness of polymer treatment decreases with polymer content. The scanning electron microscopies indicate that soil structure is reinforced mostly by three-dimensional interparticle polymeric bridges. The tension in polymeric threads and textiles provides the interparticle bonding that prevents the development of cracks.

Development of polycarbonate urethane-based materials with controlled diclofenac release for cartilage replacement.

Hydrogels are very promising human cartilage replacement materials since they are able to mimic its structure and properties. Besides, they can be used as platforms for drug delivery to reduce inflammatory postsurgical reactions. Polycarbonate urethane (PCU) has been used in orthopedic applications due to its long-term biocompatibility and bio-durability. In this work, PCU-based hydrogels with the ability to release an anti-inflammatory (diclofenac) were developed, for the first time, for such purpose. The materials were reinforced with different amounts of cellulose acetate (CA, 10%, 15%, and 25% w/w) or carbon nanotubes (CNT, 1% and 2% w/w) in order to improve their mechanical properties. Samples were characterized in terms of compressive and tensile mechanical behavior. It was found that 15% CA and 2% CNT reinforcement led to the best mechanical properties. Thus, these materials were further characterized in terms of morphology, wettability, and friction coefficient (CoF). Contrarily to CNTs, the addition of CA significantly increased the material's porosity. Both materials became more hydrophilic, and the CoF slightly increased for PCU + 15%CA. The materials were loaded by soaking with diclofenac, and drug release experiments were conducted. PCU, PCU + 15%CA and PCU + 2%CNT presented similar release profiles, being able to ensure a controlled release of DFN for at least 4 days. Finally, in vitro cytotoxicity tests using human chondrocytes were also performed and confirmed a high biocompatibility for the three studied materials.

Spent Coffee Grounds as Building Material for Non-Load-Bearing Structures.

The gradual development of government policies for ecological transition in the modern construction sector leads researchers to explore new alternative and low environmental impact materials with a particular focus on bio-sourced materials. In this perspective, the mechanical, thermal insulation, and the sound absorption performances of a spent coffee grounds/potato starch bio-based composite were analyzed for potential application in buildings. Based on thermal conductivity and diffusivity tests, the coffee grounds waste biocomposite was characterized as an insulating material comparable with conventional thermal insulation materials of plant origin. Acoustical tests revealed absorption coefficients in the same range as other conventional materials used in building acoustical comfort. This bio-sourced material presented a sufficient compressive mechanical behavior for non-load-bearing structures and a sufficient mechanical capacity to be shaped into building bricks. Mechanical, thermal, and acoustic performances depend on the moisture environment. The groundwork was laid for an initial reflection on how this composite would behave in two opposite climates: the continental climate of Reims in France and the tropical climate of Belém in Brazil.

Study of the mechanical properties and constitutive model of the roadbed rehabilitation polyurethane grouting materials under uniaxial compression

AbstractPolyurethane grouting materials are increasingly used in the non‐excavation rehabilitation of roadbeds. The compressive strength of roadbed rehabilitation polyurethane (RHPU) grouting materials is the key to achieving the desirable repair effect, whereas the constitutive model of RHPU grouting materials is not yet understood. Here, the mechanical properties of RHPU grouting materials under compression were experimentally investigated, followed by establishing the hyperfoam constitutive model. The variation laws of the critical parameters in the model with density were function fitted, and then the constitutive model was simplified as an equation of density as the single independent variable. The comparisons between the theoretical and experimental mechanical behavior of RHPU grouting materials were discussed to illustrate the applicability of the hyperfoam constitutive model. Results show that with the increasing density, both the yield strength (σ1), elastic modulus (E1), and secant modulus (Es) increases exponentially, and the Poisson's ratio (v) increases logarithmically. The maximum increase in σ1, E1, Es, and v are about 750%, 720%, 940%, and 50%, respectively. Compared to the effects of density on the mechanical properties, the effect of loading rate is much smaller, and the side length has no effect. For RHPU samples with a density not exceeding 0.35 g/cm3, the hyperfoam model can well describe the uniaxial compression mechanical behavior, but for those whose density exceeds 0.35 g/cm3, the model can only describe the mechanical behavior before yielding. The theoretical yield strength of the RHPU samples obtained from the model is close to the experimental value (with differences of about 0.1%–14.4%). This study provides a base to evaluate the compressive strength of the practically used RHPU grouting materials based on the density.

Influencing Factors on the Longitudinal Compression Properties of Pultruded Unidirectional Fiber Composites

Unidirectional fiber composites produced by pultrusion have good mechanical properties. We conducted compression experiments to investigate the factors that influenced the compression of pultruded unidirectional carbon fiber-reinforced plastics (CFRPs) under static axial loads. The CFRPS were composed of carbon fiber or carbon fiber cloth as reinforcement material, resin, ceramic, metal, cement, carbon or rubber as matrix. The modulus and compressive strength were measured. The experimental data were compared with the theoretical values obtained from the rule of mixtures. Moreover, the effects of the components, dispersion, interface states, and other factors on the compressive mechanical behaviors of the composites were studied. Scanning electron microscopy revealed the microstructure and fracture of the material. The results showed that the modulus and compressive strength of the CFRPs with a higher carbon fiber modulus decreased with the modulus and resin strength. The compressive modulus and compressive strength of CFRPs with the same resin increased with the modulus and strength of the carbon fibers. Upon increasing the modulus and strength of the carbon fibers, the compressive modulus and compressive strength of the CFRPs decreased with the modulus and strength of the resin. Moreover, glass fiber-reinforced plastics (GFRPs) were used to compare the difference between CFRPs, C/GFRP, and GFRP. The relationship between the the microstructure and promperties of these composites was systematically revealed. These research results are valuable for the design and synthesis of low-cost pultruded unidirectional fiber composites with excellent mechanical properties.

Mechanical characteristics of epoxy nanocomposites derived through reinforcing carbonaceous fillers

Epoxy nanocomposites (ENCs) were fabricated through reinforcing various carbonaceous fillers (CFs, 3.0 wt%) into epoxy resin followed by curing with polyamine hardener. For this purpose, nanographite (NG), pine needle cone derived biochar (BC), and related graphene oxide (GO) were used as fillers for epoxy modification. Test specimens were fabricated and investigated for their tensile (ASTM D 638-02a), compressive (ASTM D 695-02a) and dynamic mechanical (ASTM E1820-01) behavior with reference to cure epoxy. Effect of chemical identity of CFs on morphology and average roughness of ENCs was investigated through atomic force microscopy. Study reveals that ENCs derived from GO exhibited maximum tensile strength (84.75 MPa) as compare to the other NG and BC derived analogues. ENCs derived through reinforcing NG has exhibited maximum elastic modulus (1307.72 MPa) in compare to their GO and BC derived analogues. ENCs derived through reinforcing BC have exhibited maximum compressive strength (46.93 MPa) and modulus (102.98 MPa) in comparision to their NG and GO analogues. Dynamic mechanical analysis reveals moderate shift in glass transition temperature (Tg, °C) of ENCs derived from GO (77.73) and NG (81.75) ranging to over cured epoxy (66.67).However, reinforcing BC into epoxy has raised the Tg of ENCs to 95.46 °C.

Compressive mechanical behavior and model of composite elastic-porous metal materials

This work presents the experimental characterization and theoretical modeling of composite elastic-porous metal materials (C-EPMM). C-EPMM is a novel porous metallic damping material made of wire mesh and wire helix. A series of quasi-static compressive experiments were carried out to investigate the stiffness and energy absorption ability of the C-EPMM with different mass ratios. The experimental results show that the mass ratios can significantly affect the stiffness and loss factor of C-EPMM. To efficiently predict the nonlinear mechanical properties of the C-EPMM a theoretical model of C-EPMM was proposed for the first time, the model was based on the manufacturing process. A comparison between the predicted data and the experimental data was conducted. The results show that the theoretical model can accurately predict the mechanical performance of C-EPMM. The conclusions derived from this work can provide a new method for adjusting the mechanical performance of EPMM in applications.

β‐Cyclodextrin‐based macroporous monoliths: One‐pot oil‐in‐oil emulsion templating and adsorption

AbstractThe ability of β‐cyclodextrin (β‐CD) to form a host–guest complex with relatively hydrophobic molecules such as bisphenol A (BPA), a common wastewater contaminant, has inspired the development of β‐CD‐containing polymers for adsorption applications. For the most part, these polymers are powders, which can limit their applicability. Here, low‐density (~0.1 g cm−3), macroporous monoliths based on unmodified β‐CD were synthesized using emulsion templating. The relatively simple, one‐pot, polyurethane synthesis took place within the external phase of oil‐in‐oil (o/o) high internal phase emulsions (HIPEs) that contained β‐CD and a diisocyanate. The combination of o/o emulsions and a polyurethane reaction enabled the incorporation of relatively high β‐CD contents (up to 63 wt%) and limited the occurrence of the water–isocyanate urea reaction. The resulting open‐cell porous structures varied from an average pore size of 5.0 μm (lower surfactant content) to the typical structure associated with polyHIPEs (higher surfactant content), voids of ~50 μm and interconnecting holes ranging from submicrometer to ~2 μm. The compressive mechanical behaviors of the easily handled monoliths were similar to those of flexible foams, reaching strains of 70% without failure. The BPA adsorption capacities, up to 117.7 mg g−1, may make these monoliths advantageous for adsorption applications.

Porous structure and compressive failure mechanism of additively manufactured cubic-lattice tantalum scaffolds

Additively manufactured tantalum scaffolds have attracted increased attention for their high potential for bone tissue reconstruction and other industrial applications. Porous structure designs, mechanical property evaluation, and material failure investigation are needed for this new structural and functional material. In this study, cubic lattice tantalum scaffolds with porosities of 65%, 75%, and 85% were designed and fabricated by selective laser melting, and the porous architecture and microstructure were characterized. The compressive mechanical behavior and material failure mechanism were explored by experimental compression tests and finite element analysis (FEA). The designed scaffold porous structure parameters included the following: side length of unit cell 880 μm, 1020 μm, and 1220 μm; pore size 380 μm, 520 μm, and 720 μm; and strut diameter 250 μm. The pore parameters of fabricated scaffolds matched well with those of the designed scaffolds. Struts were dense without macro/microscopic cracks and other microstructure defects resulting from laser melting. Porosity significantly affected the compressive mechanical properties. As the porosity decreased from 85% to 65%, the compressive strength and elastic modulus increased from 17.6±0.5 MPa and 0.7±0.2 GPa to 40.5±0.8 MPa and 1.5±0.6 GPa, respectively. Compression testing results indicated that additively manufactured cubic lattice tantalum scaffolds show ductile deformation behavior and excellent mechanical reliability. When the strain was as high as 50%, the scaffolds with different porosities exhibited plastic failure with progressive layer-by-layer collapse behavior determined by the coupling of buckling and bending deformation, demonstrating their high ductility. Collapse initially occurred in the upper and lower lattice layers of the scaffolds. Large deformation resulted in strut fracturing with micro crack propagation. Most of the fracturing sites were at the vertical struts and conjunctions, not the horizontal struts. FEA revealed that the stress was primarily concentrated on the vertical struts, and the struts in the upper and lower layers withstood greater stress than the struts in the middle layers. The stress in the vertical struts was distributed along the inclination angle of 45° with respect to the loading direction. Stress was not concentrated at the horizontal struts. The results of the FEA were consistent with the experimental results of the compression tests and showed that the load-bearing capability of cubic lattice tantalum scaffolds can be enhanced by increasing the diameter of the vertical struts.

Static Compressive Behavior and Material Failure Mechanism of Trabecular Tantalum Scaffolds Fabricated by Laser Powder Bed Fusion-based Additive Manufacturing.

Additively manufactured trabecular tantalum (Ta) scaffolds are promising bone repair materials for load-bearing applications due to their good pore interconnectivity. However, a thorough mechanical behavior evaluation is required before conducting animal studies and clinical research using these scaffolds. In this study, we revealed the compressive mechanical behavior and material failure mechanism of trabecular tantalum scaffolds by compression testing, finite element analysis (FEA), and scanning electron microscopy (SEM). Trabecular tantalum scaffolds with porosities of 65%, 75%, and 85% were fabricated by laser powder bed fusion-based additive manufacturing. Porosity has a significant effect on their compressive mechanical properties. As the porosity decreased from 85% to 65%, the compressive yield strength and elastic modulus increased from 11.9 MPa to 35.7 MPa and 1.1 GPa to 3.0 GPa, respectively. Compression testing results indicate that trabecular tantalum scaffolds demonstrate ductile deformation and excellent mechanical reliability. No macroscopic cracks were found when they were subjected to strain up to 50%. SEM observations showed that material failure results from tantalum strut deformation and fracture. Most microcracks occurred at conjunctions, whereas few of them appear on the struts. FEA-generated compressive stress distribution and material deformation were consistent with experimental results. Stress concentrates at strut conjunctions and vertical struts, where fractures occur during compression testing, indicating that the load-bearing capability of trabecular tantalum scaffolds can be enhanced by strengthening strut conjunctions and vertical struts. Therefore, additively manufactured trabecular tantalum scaffolds can be used in bone tissue reconstruction applications.

Compressive mechanical behavior for surface auxetic structures

Auxetic structure is a typical metamaterial, whose mechanical behaviors of two-dimensional and three-dimensional structures are widely studied. However, reports on surface auxetic structure (SAS) are rare. As a consequence, two types of SAS were designed by reversing and crimping the concave hexagonal plane auxetic structure (PAS) composed of double arrows, which were known as RAS and CAS, respectively. The theoretical equations to calculate the deformation of the representative volume cell structure (RVCS) were derived, and the relationships between energy and work were established based on the plastic wrinkle. The compressive simulations of the plane and surface auxetic structures were conducted through the use of finite element method (FEM) verified by experiment, and the mechanical behaviors and energy absorption characteristics were obtained. By comparing the simulation results of different structures, it was found that RAS not only realized the auxetic effect of compression shrinkage but also realized the supermechanical effect of compression twist. The auxetic effects of these structures were realized by the deformation of beams. The auxetic effect only appeared in the local positions of these structures, and other positions still belonged to the positive Poisson’s ratio effect. The crimped CAS had the biggest maximum load peak, and PAS possessed the highest specific energy absorption (SEA). The supermechanical effects of compression shrinkage and compression twist in RAS have great potential in some distinctive engineering applications.

Mechanical behavior of a typical polymer bonded explosive under compressive loads

ABSTRACT The compressive mechanical behavior and damage mode of polymer bonded explosives (PBXs) based on hexahydro-1, 3, 5-trinitro-1, 3, 5-s-triazine (RDX) were systematically investigated via experiments and simulations. The strength sensitivity on strain rate of PBX–JH14C was studied using quasi-static and dynamic uniaxial compressive tests. The axial and radial stress history curves were measured using a passive confining experiment, and characterizations of the behavior of PBX–JH14C were studied under dynamic multi-axial loads. The results showed that the dynamic stress-strain curves of PBX–JH14C exhibited an evident strain rate effect. Combining theoretical and meso analyses, the damage characteristics of PBX–JH14C under low speed impacts were studied. A constitutive theory was developed for modeling the dynamic mechanical response of PBX–JH14C by using the Boltzmann superposition principle with a Prony series representation. Mathematical presentation of the relaxation modulus can be obtained by fitting the modulus master curve. The model was verified by comparing the finite element simulations with experimental results. Furthermore, it was observed that the theoretical prediction coincided with experimental results. The damage mode and mechanisms of PBX–JH14C were discussed based on the experimental and theoretical studies. In the absence of confinement, interface debonding and matrix cavitation were the predominant failure mechanisms under low speed impact.

Numerical simulation of crack growth process in Brazilian disk test using finite element method

Accurately simulating the compressive and tensile mechanical behavior of rock is one of the challenges faced by numerical simulation. In this paper, the rock’s triaxial compression experiment and the Brazilian disk simulation were simulated, and the propagation process of the rock crack was simulated in Brazilian disk test in the finite element method. According to the experimental data, the KCC model was completely modified and the triaxial compression experiment was carried out with the modified model. The modified model was applied to the Brazilian disk test simulation, and the crack propagation in Brazilian disk test was simulated by inducing the erosion algorithm, which verifies the applicability of the erosion algorithm in the finite element method of material continuity loss.

Effect of open fire on dynamic compression mechanical behavior of granite under different strain rates

Effect of open fire on dynamic compression mechanical behavior of granite under different strain rates

Experimental Study of Compressive Mechanical Behavior of Red Sandstone after Heating-Cooling Treatment

Investigation of compressive mechanical property of rock materials after heating-cooling treatment is of great significance for deep geothermal energy exploitation. This study conducted a series of uniaxial compressive experiments on red sandstone subjected to different heating-cooling treatments, i.e., heating temperature 25, 200, 400, 600, 800, and 1000°C and cooling temperature of 10°C. The experimental results showed that with an increase in the heating temperature, the peak strength of red sandstone after heating-cooling treatments attained a maximum value under the heating temperature of 400°C. Furthermore, the variations of instantaneous elastic modulus of treated samples are the same as that of primary wave velocity. To futher reveal the failure characteristics of heating-cooling treated red sandstone, related scanning electron microscopy tests were also carried out to analyze the microstructure of red sandstone samples after various heating-cooling treatments, to provide a valuable reference for studying the mechanical properties of rock materials after heating-cooling treatments.