Anisotropic Mechanical Characteristics Research Articles

Understanding mechanotransduction in the distal colon and rectum via multiscale and multimodal computational modeling

Visceral pain in the large bowel is a defining symptom of irritable bowel syndrome (IBS) and the primary reason that patients visit gastroenterologists. This pain is reliably triggered by mechanical distension of the distal colon and rectum (colorectum). Consequently, the process of mechanotransduction by sensory afferents, responsible for translating mechanical colorectal stimuli into neural action potentials, plays a central role in IBS-related bowel pain. In this study, we aim to enhance our understanding of colorectal mechanotransduction by combining experimental findings in colorectal biomechanics and afferent neural encoding within a comprehensive computational simulation framework. To achieve this, we implemented a three-layered, fiber-reinforced finite element model that accurately replicates the nonlinear, heterogeneous, and anisotropic mechanical characteristics of the mouse colorectum. This model facilitates the computation of local mechanical stresses and strains around individual afferent endings, which have diameters on the micron-scale. We then integrated a neural membrane model to simulate the encoding of action potentials by afferent nerves in response to microscopic stresses and strains along the afferent endings. Our multiscale simulation framework enables the assessment of three hypotheses regarding the mechanical gating of action potential generation: (1) axial stress dominates mechanical gating of mechanosensitive channels, (2) both axial and circumferential stresses contribute, and (3) membrane shear stress dominates. Additionally, we explore how the orientation of afferent endings impacts neural encoding properties. This computational framework not only allows for the virtual investigation of colorectal mechanotransduction in the context of prolonged visceral hypersensitivity but can also guide the development of new experimental studies aimed at uncovering the neural and biomechanical mechanisms underlying IBS-related bowel pain.

Anisotropic behavior and mechanical characteristics of the Montney Formation

This study investigates the rock mechanics and anisotropic properties of the Montney Formation, Alberta, through two sets of experiments: unconfined compressive strength tests and triaxial compression tests, supplemented by ultrasonic wave velocity measurements. These tests enabled the calculation of dynamic and static stiffness properties and Thomsen anisotropy parameters (ε, δ, γ). Our findings reveal that the Montney Formation exhibits weak anisotropy, with ε values generally below 0.10, contrasting with other strongly anisotropic shale formations. Specimens exhibiting higher clay content and total organic carbon levels show more pronounced anisotropy. Static measurements exhibit a higher degree of anisotropy compared to dynamic measurements. The investigation also explored loading and unloading stiffness parameters, noting a higher E loading-to-unloading ratio for rock specimens with lower elastic properties. This provides important information on the rock's response to stress path effects during stimulation and exploitation. The study also discusses other rock mechanics parameters including Poisson's ratio, tensile strength, and brittleness. The research contributes to a more comprehensive understanding of the geomechanical and petrophysical behavior of the Montney Formation, aiding reservoir characterization and hydrocarbon exploration and production.

Anisotropic Mechanical Properties and Fracture Mechanism of Transversely Isotropic Rocks under Uniaxial Cyclic Loading

Transversely isotropic rocks, which are special anisotropic materials, are widely encountered in civil, mining, petroleum, geothermal, and radioactive waste-disposal engineering. Rock is frequently subject to cyclic loads resulting from natural and human-caused events. However, to date, the fracture mechanism of transversely isotropic rocks under cyclic loading remains poorly understood. To address this gap, uniaxial monotonic-loading and cyclic-loading tests were performed on slate specimens by the MTS815 system, during which acoustic emission (AE) signals inside the rock were monitored, and finally the fracture surfaces of the tested rock were scanned by scanning electron microscopy (SEM). Through these tests, the anisotropic mechanical properties, damage evolution, AE characteristics and fracture pattern of slate as a transversely isotropic rock were studied. The results show that the peak strength of specimens varies with the loading–foliation angle under monotonic and cyclic loading, following a U-shaped trend. The deformation modulus during unloading is more capable of characterizing the damage inside the specimen than that during loading. By defining the damage degree based on dissipation energy, it is found that the damage variable is influenced by the loading–foliation angle and the cyclic stress step. The AE characteristics of specimens exhibit significant anisotropy, closely correlated to the loading condition and loading–foliation angle. Regardless of cyclic stress step, the AE counts of specimens with a loading–foliation angle of 0° are mainly distributed near the peak region, whereas those of specimens with other loading–foliation angles occur primarily in the early stage of each cyclic loading. Finally, it is revealed that the fracture mechanism of slate specimens is determined by the loading–foliation angle, loading condition, and cyclic stress step.

Spin–orbit coupling tunable electronic properties of [formula omitted]-MoS[formula omitted] and ternary Janus [formula omitted]-MoSSe monolayers: Theoretical prediction

MoS2 can exist in many different polytypes, such as trigonal prismatic, distorted octahedral, or octahedral. The 2H-phase of MoS2 has been extensively studied in recent times, but there are very few studies focusing on the remaining phases, especially the distorted octahedral T′)-phase. Here, we design the MoS2 monolayer and Janus MoSSe structure in the 1T′ phase and study their electronic properties within the framework of first-principles calculations. Both 1T′-MoS2 and 1T′-MoSSe monolayers are confirmed to have structural stability and anisotropic mechanical characteristics. Interestingly, while the 1T′-MoS2 monolayer exhibits metallic characteristics, Janus MoSSe in the 1T′ phase is a semiconductor with a small band gap of 0.04 eV. More interestingly, a tiny bandgap of 0.05 eV has opened up in the 1T′-MoS2 monolayer due to the spin–orbit coupling effect. We also study the mobility of carriers in the semiconductor Janus 1T′-MoSSe monolayer. 1T′-MoSSe monolayer exhibits a high anisotropic carrier mobility due to its high anisotropic crystal structure. Surprisingly, 1T′-MoSSe monolayer possesses extremely high electron mobility, up to 4.58×103 cm2 V−1 s−1. Our findings give a deeper insight into the 1T′-phase of transition metal dichalcogenide and its Janus structure.

Additive Manufacturing of Nanocellulose Aerogels with Structure-Oriented Thermal, Mechanical, and Biological Properties.

Additive manufacturing (AM) is widely recognized as a versatile tool for achieving complex geometries and customized functionalities in designed materials. However, the challenge lies in selecting an appropriate AM method that simultaneously realizes desired microstructures and macroscopic geometrical designs in a single sample. This study presents a direct ink writing method for 3D printing intricate, high-fidelity macroscopic cellulose aerogel forms. The resulting aerogels exhibit tunable anisotropic mechanical and thermal characteristics by incorporating fibers of different length scales into the hydrogel inks. The alignment of nanofibers significantly enhances mechanical strength and thermal resistance, leading to higher thermal conductivities in the longitudinal direction (65mWm-1K-1) compared to the transverse direction (24mWm-1K-1). Moreover, the rehydration of printed cellulose aerogels for biomedical applications preserves their high surface area (≈300m2g-1) while significantly improving mechanical properties in the transverse direction. These printed cellulose aerogels demonstrate excellent cellular viability (>90% for NIH/3T3 fibroblasts) and exhibit robust antibacterial activity through in situ-grown silver nanoparticles.

Processing and Analysis of Hybrid Fiber-Reinforced Polyamide Composite Structures Made by Fused Granular Fabrication and Automated Tape Laying

Fused granular fabrication (FGF) is a large format additive manufacturing (LFAM) technology and focuses on cost-effective granulate-based manufacturing by eliminating the need for semifinished filaments. This allows a faster production time and a broader range of usable materials for tailored composites. In this study, the mechanical and morphological properties of FGF test structures made of polyamid 6 reinforced with 40% of short carbon fibers were investigated. For this purpose, FGF test structures with three different parameter settings were produced. The FGF printed structures show generally significant anisotropic mechanical characteristics, caused by the layer-by-layer building process. To enhance the mechanical properties and reduce the anisotropic behavior of FGF structures, continuous unidirectional fiber-reinforced tapes (UD tapes), employing automated tape laying (ATL), were subsequently applied. Thus, a significant improvement in the flexural stiffness and strength of the manufactured FGF structures was observed by hybridization with 60% glass fiber-reinforced polyamide 6 UD tapes. Since the effectiveness of UD-tape reinforcement depends mainly on the quality of the bond between the UD tape and the FGF structure, the surface quality of the FGF structure, the interface morphology, and the tape-laying process parameters were investigated.

First-principles study on the optoelectronic and photocatalytic properties of the C2h-Janus Al2XY(X/Y[dbnd]S, Se and Te) monolayers

Recently, two-dimensional (2D) new C2h phase of group III monochalcogenides have exhibited great potentials for applications in the field of photoelectric devices because of their outstanding optoelectronic properties. Here, we theoretically predict the C2h phase of aluminum monochalcogenide (C2h-Al2XY) (X/YS, Se and Te; X≠Y) compounds with Janus structure via first-principles calculations. Janus C2h-Al2XY monolayers are found to be thermodynamically, dynamically, energetically, and mechanically stable. The entire Janus C2h-Al2XY monolayers exhibit semiconducting properties, with a band gap ranging from 2.25 to 2.57 eV, as calculated using the HSE06 method. The obvious anisotropic mechanical and optical characteristics are observed. All Janus C2h-Al2XY monolayers present high optical absorption in the ultraviolet and visible regions, suggesting that these monolayers have a favorable efficiency for absorbing solar light. These significant results imply that Janus C2h-Al2XY monolayers can be used in the fields such as nano-electronics and optoelectronics. Specifically, it has been found that the band edge position of Janus C2h-Al2SSe is capable of meeting the redox potential requirements for photocatalytic water splitting. Furthermore, biaxial strain can significantly adjust the band gap of the C2h-Al2SSe and enhance its visible light absorption. Most importantly, within the biaxial strain range of −6%–6 %, the band edge positions of Janus C2h-Al2SSe consistently satisfy the redox potentials required for photocatalytic water splitting. These findings indicate that the Janus C2h-Al2SSe monolayer is promising for photocatalytic water splitting due to its moderate band gap and suitable band edge positions as well as good absorption in the visible region.

Anisotropic Deformation Behavior and Indentation Size Effect of Monocrystalline BaF2 Using Nanoindentation.

In this study, our objective is to investigate the anisotropic deformation behavior and the indentation size effect (ISE) of monocrystalline barium fluoride (BaF2) using nanoindentation experiments with a diamond Berkovich indenter. BaF2 is known for its anisotropy, which results in significant variations in its mechanical properties. This anisotropy poses challenges in achieving high processing quality in ultra-precision machining. Through our experiments, we observed numerous pop-in events in the load-displacement curves, indicating the occurrence of plastic deformation in BaF2 crystals, specifically in the (100), (110), and (111) orientations; these pop-in events were observed as the indentation depth increased to 56.9 nm, 58.2 nm, and 57.8 nm, respectively. The hardness-displacement and elastic modulus-displacement curves were obtained from the tests exhibiting the ISE. The nanoindentation hardness of BaF2 is found to be highly dependent on its crystallographic orientation. Similarly, for BaF2 in the (100) orientation, the range is from 2.43 ± 0.74 and 1.24 ± 0.12 GPa. For BaF2 in the (110) orientation, the values range from 2.15 ± 0.66 to 1.18 ± 0.15 GPa. For BaF2 in the (111) orientation, the values range from 2.12 ± 0.53 GPa to 1.19 ± 0.12 GPa. These results highlight the significant influence of crystallographic orientation on the mechanical properties of BaF2. To better understand the ISE, we employed several models including Meyer's law, the Nix-Gao model, the proportional specimen resistance (PSR) model, and the modified PSR (mPSR) model, and compared them with our experimental results. Among these models, the mPSR model demonstrated the best level of correlation (R2>0.9999) with the experimental measurements, providing a reliable description of the ISE observed in BaF2. Our reports provide valuable insights into the anisotropic mechanical characteristics of BaF2 materials and serve as a theoretical guide for the ultra-precision machining of BaF2.

Anisotropic Crystal Structure and High Electron Mobility of Novel Ternary Janus P6XY Monolayers (X/Y = S, Se, Te): First‐Principles Examinations

AbstractRecently, by forming a P‐rich P–S system, the P3S monolayer has been predicted to have good resistance to air oxidation, large band gap, high absorption, and superior mobility. Inheriting this prediction, a series of ternary Janus P6XY (X/Y = S, Se, and Te; X ≠ Y) monolayers based on P3X nanosheet are designed and studied. The structures of P6XY monolayers are confirmed to be stable based on the evaluation of calculated results for phonon spectra, ab initio molecular dynamic simulations. It is also found that P6XY compounds possess anisotropic mechanical characteristics. All Janus structures are indirect semiconductors with large energy gaps varying from 2.12 to 2.60 eV calculated by the hybrid functional. Besides, biaxial strain significantly affects the electronic properties of the P6XY monolayers. In particular, the biaxial strains can induce a transition from indirect to direct bandgap in all three P6XY structures. The carrier mobility in the three proposed structures exhibits directional anisotropy and high electron mobility value, up to 1.27 × 103 cm2 V−1 s−1, which are suitable for applications in high‐performance and direction‐dependent nanoelectronic devices.

Experimental Study on Permeability and Deformation Characteristics of Bedding Shale under Triaxial Shear-Seepage Coupling

The bedding structure of shale is generated during the deposition and formation, which results in shales with prominent anisotropic characteristics. It depends on stability, control of oil and gas storage, and deep exploitation. In addition, the mechanical and permeability parts of bedding shale are very complex when it is under deep underground space with coupled high stress and high seepage. In this study, the black bedding shale was used as the research object, and a series of triaxial shear-seepage coupling tests were carried out. Firstly, the triaxial shear stress-shear strain curves and permeability-shear stress curves of different bedding shales under other triaxial shear-seepage coupling conditions were obtained. Secondly, the failure characteristics and shear deformation characteristics of shale under the shear-seepage coupling effect were explored. The shear stress threshold and permeability evolution law at each stage of shear failure were discussed. Thirdly, the shear strength, failure mode, and mechanism parameters of the black bedding shale under different normal stress and seepage pressure were studied. Fourthly, the linear M-C criterion, Ramamurthy criterion, and Hoek-Brown criterion characterize the variation of damage strength of shale with bedding orientation under triaxial shear-seepage coupling. Those results provide an experimental basis for exploring the anisotropic mechanical characteristics and failure mechanism of bedding shale under shear-seepage coupling.

Anisotropic mechanical behavior and failure characteristics of multi-jointed rock mass

Anisotropic mechanical behavior and failure characteristics of multi-jointed rock mass

Effects of interval time and interfacial agents on the mechanical characteristics of ultra-high toughnessnn cementitious composites under 3D-printed technology

Anisotropic mechanical characteristics are crucial to the application of the printed structure. This study is aimed to investigate the effects of interval time and interfacial agents on the anisotropic mechanical strength of ultra-high toughness cementitious composite under 3D-printed technology. The bending capacity of ultra-high toughness cementitious composite under 3D-printed technology was compared with mould-casting ultra-high toughness cementitious composite. The compressive strength, flexural strength and splitting tensile strength were measured to represent mechanical properties in different directions and the microstructure of ultra-high toughness cementitious composite under 3D-printed technology with different interval time and interfacial agents were characterized using nanoindentation, scanning electron microscopy, and X-ray computed tomography. The experimental results indicated that the ultimate bending strength and bending toughness of ultra-high toughness cementitious composite under 3D-printed technology were 13.6% and 3.3% to 13.3% higher than those of mould-casting ultra-high toughness cementitious composite at 28 d, respectively. As the interval time increased, the mechanical properties showed differential development patterns. Specifically, compressive strength and splitting tensile strength had a higher rate of decline in the X direction (parallel to the printing path) than in the Y and Z directions but flexural strength was the opposite. A 3-h interval time reduced the 28-d compressive strength and splitting tensile strength in the X direction by 24.02% and 49.64% but the strength only decreased by 10.57% and 26.59% in the Z-direction. The addition of interfacial agents reduced anisotropy in compressive strength and splitting tensile strength but increased the anisotropy of flexural strength. When the interval time was 3 h, the increase rate of the 28-d flexural strength in the X direction, in which the flexural strength was weakest, was 22%–29% lower than that in the Y and Z directions under the effects of interfacial agents. A microstructure analysis showed that the filling effect and high moisture content of interfacial agents counteracted the negative impact of interval time on the width of the interface between layers and the porosity of ultra-high toughness cementitious composite under 3D-printed technology, which can enhance the interlayer bonding. These results can promote the application of ultra-high toughness cementitious composite under 3D-printed technology in additive manufacturing.

Miniaturized multi-modality field-ready sensing system for defect detection of CFRP materials

As infrastructure decays rapidly due to structural and material aging and failures, the development of new improved, and efficient nondestructive evaluation (NDE) techniques is vital for system health monitoring and preventive maintenance. Composite material, such as carbon fiber reinforced polymer (CFRP) plays a significant role in energy and transportation infrastructure due to the advantages of corrosion resistance, durability, and lightweight, which contributes to minimal maintenance and long service life. However, due to their unique anisotropic dielectric and mechanical characteristics, detecting composite material defects by NDE techniques is still challenging. This paper presents a novel, low-cost miniaturized multi-modality imaging system combining low-frequency capacitive shortwave and high-frequency microwave NDE technologies to detect various types of defects in CFRP materials. Based on the governing electromagnetic theory behind multi-modality electromagnetic NDE methods, the merit of combining low-frequency shortwave and near-field microwave imaging for dielectric characterization of composite materials is thoroughly investigated and demonstrated. Then, a miniaturized imaging system is developed to operate at ultra-wide bands: 10 kHz to 200 MHz for the capacitive shortwave probes and 1 GHz to 9 GHz for the microwave probes. Customized multi-material joining samples of CFRP and steel with different defect types, locations, depths, and sizes are tested by the developed imaging system, and the experimental results of the miniaturized system are compared with the existing table-top systems, which demonstrates comparatively accurate results for the developed multi-modality imaging system. The compact and practical nature of the presented imaging system makes it an optimal tool that can be utilized in field conditions with constrained operational spaces and NDE uncertainties.

Crystal orientations of 1,3,5-triamino-2,4,6-trinitrobenzene-based polymer bonded explosives during the pressing process by neutron diffraction

Hot-pressed 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based polymer bonded explosives (PBX) will show significant anisotropic and irreversible expansion properties, resulting in both the deterioration of their performance and weapon reliability issues. The anisotropic mechanical and irreversible expansion characteristics of TATB-based PBX have shown to be closely related to the crystal orientation. In this work, the orientations of TATB crystals in PBX under different thermal–mechanical coupling loading conditions were studied by neutron diffraction measurement technology. The microstructures were observed by computed tomography (CT) and scanning electron microscopy (SEM), and the effects of hot pressing parameters (temperature and pressure) on the TATB crystal orientation were systematically analyzed. Combining the density and compression strength of the formed samples, the optimal hot pressing parameters were determined. The results showed that during the in-situ compression process, the TATB crystals would be reoriented. The rotation angle of the (002) plane was mainly concentrated within a 35° angle from the perpendicular pressing direction. After hot compaction, the rotation angle moved from 35° to 52°, and the orientation of the TATB crystals had obvious rebound phenomenon. The (002) plane orientation degree was related to the deformation, fragmentation, and reorientation of the TATB crystals, as well as the phase transition, thermal softening, and gap filling of the binder, and the interfacial interactions. In order to obtain higher detonation energy, better mechanical properties and better shape stability of the formed samples, (120 °C, 140 MPa) was selected as the optimal hot pressing parameters for TATB-based PBX. • Neutron diffraction was developed for the TATB crystal orientation measurement. • The TATB crystal reorientation during pressing process was obtained. • The effect of the temperature and pressure on the reorientation was quantified. • The mechanism of the crystal reorientation during pressing process was analyzed.

Recrystallization Texture Analysis of FeCoNiCrMnAl0.5 High-Entropy Alloy Investigated by High-Energy X-ray Diffraction

In small volume fractions, the bcc phase plays an important role in the properties of FeCoNiCrMnAl0.5 multiple-phase high-entropy alloys (HEAs). Since the small volume fraction of the bcc phase limits the detection of its texture, its texture evolution during mechanical processing is still unclear. In the current research, high-energy X-ray diffraction was used to investigate the crystallographic textures of cold-rolled and annealed FeCoNiCrMnAl0.5 dual-phase HEA with fcc and bcc phases. During cold-rolling deformation, multi-pass symmetry under isothermal conditions leads to asymmetric {200}bcc and {211}bcc peaks; the asymmetry disappears after annealing treatment, with the evolution of prominent texture components and the release of internal residual stress. The Goss texture component and {112}<110> and {111}<112> texture components were intensified after cold-rolling in the fcc and bcc phases, respectively, with orientation relationships of {110}bcc<111>bcc//{111}fcc<110>fcc recognized in the cold-rolled HEA. Based on this relationship, the yield strength (YS) and engineering ultimate tensile strength (UTS) of the sample reached 570 MPa and 920 MPa, respectively, which shows a fracture elongation of 27%. The study provides deeper insight into the anisotropic mechanical characteristics of the investigated HEA and demonstrates the great potential of dual-phase HEAs for mechanical applications in industry.

Anisotropy and Directivity Effects on Uniaxial Compression of Carbonaceous Slate Form Jinman Mine

To determine the anisotropic mechanical characteristics of carbonaceous slate at the Jinman Mine located in Lancang River Gorge, China, uniaxial compression, acoustic emission (AE) monitoring, and scanning electron microscopy (SEM) tests were conducted. The results show that stress loading directions and bedding effects have a significant impact on strain characteristics. The deformation of slate undergoes compaction, elastic, damage accumulation, and failure stages, and there are significant differences in strain paths. The mechanical properties of grey and carbonaceous slate have significant features, and variations of these properties of carbonaceous slate are more than that of grey slate. The discrete degree is significantly related to the direction of stress loading and different types of slate structures. The AE response intensity is related to the loading mode and slate type. A sudden increase in the AE cumulative ring number near peak stress indicates instability and rupture and is a precursor of rock rupture. The failure patterns and fracture characteristics are significantly correlated to the layered structure of the slate. Slates subjected to vertical loading and parallel loading conditions are dominated by shear fracture and tensile fracture, respectively. The peak strains of gray and carbonaceous slate correspond to brittle failure. The SEM tests indicate that slate samples subjected to parallel loading primarily show a tensile failure compared with slate samples subjected to vertical loading, with fractured sections being of lesser roughness, and scattered fractures and sections being smooth without obvious protrusions or cracks.

Anisotropic mechanical characteristics and energy evolution of artificial columnar jointed rock masses subjected to multi-level cyclic loading

Columnar jointed rock masses (CJRM) are natural geological structures with regular and irregular polygons. Because of the joints throughout, the rock mass mechanical properties are severely degraded. This study focused on the effect of joint dip angle, fatigue effect, and stress level on the anisotropic strength, deformation behavior, energy evolution characteristics, and failure mode of CJRM specimens. Triaxial compression and multi-level cyclic loading tests were performed on artificial CJRM specimens with a similar geological structure under a 7 MPa confining pressure. Energy dispersive spectroscopy (EDS) tests were performed on the hexagonal prism and joint structure to investigate the failure mechanism of the CJRM specimens. The experimental results show that the relationship between the characteristic stress and the joint dip angle is a typical U-shaped pattern. The anisotropy of characteristic stresses decreases gradually under triaxial compression. The fatigue effect increases peak strength's anisotropy and decreases residual strength's anisotropy. The plastic strain and strain energy depend on stress level, fatigue effect, and joint dip angle. Three failure modes were observed. Disintegration and fracture of hexagonal prisms, and joint cracking result in the failure of CJRM specimens. Overall, the fatigue effect increases the number and distribution of cracks in CJRM specimens.

Experimental and Numerical Studies on the Anisotropic Mechanical Characteristics of Rock-Like Material with Bedding Planes and Voids

Experimental and Numerical Studies on the Anisotropic Mechanical Characteristics of Rock-Like Material with Bedding Planes and Voids

2D Graphene-Like Pb-Free Perovskite Semiconductor CsSb(Br1-xIx)4 with Quasi-linear Electronic Dispersion and Direct Bandgap Close to Germanium.

Thanks to its ultrahigh carrier mobility (∼104-105 cm2 V-1 s-1), graphene shows tremendous application potential in nanoelectronics, but it cannot be applied in effective field-effect transistors (FETs) because of its intrinsic gapless band structure. Thus, introducing a bandgap for graphene is a prerequisite to realize an FET for logic applications. Herein, through first-principles GW calculations, we have predicted a series of novel Dion-Jacobson (DJ) phase halide perovskite semiconductors CsSb(Br1-xIx)4 (x = 0, 0.5, 1) with the quasi-linear (graphene-like) band edge dispersion; as the best one of which, CsSbBr2I2 exhibits a direct bandgap (0.52 eV) as well as a quasi-linear electronic dispersion, yielding an ultrasmall carrier effective mass (0.03 m0) and a high estimated carrier mobility (5 × 103 cm2 V-1 s-1). This gives a significant reference to the exploration of semiconductors with excellent transport properties. Moreover, our calculations also implicate that the DJ perovskites CsSb(Br1-xIx)4 (x = 0, 0.25, 0.5, 0.75, 1) show soft and anisotropic mechanical characteristics as well as excellent electronic, transport, and optical properties, which demonstrate their multifunctional application in infrared optoelectronic, high-speed electronics, and photovoltaics.

Fracture Characteristics and Anisotropic Strength Criterion of Bedded Sandstone

Bedded sandstone is classified as sedimentary rock, which is a typical bedded rock with obvious layered structure characteristics. Bedded rocks formed different bedding orientations in the long and complicated geological tectonic evolution and thus have anisotropic mechanical characteristics. Therefore, the strength anisotropy of bedded sandstone depends on the bedding dip angles. In this study, the fracture characteristics and strength criterion of bedded sandstone were studied by triaxial compression tests on rock specimens with different bedding dip angles under different confining pressure. The test results show that the failure mode and strength of the bedded sandstone are related to the bedding dip angles, showing obvious anisotropy. The experimental data are broadly in line with the Jaeger’s surface of weakness (JPW) model. However, considering the difference in the strength of sandstone specimens with horizontal bedding dip (β = 0°) and vertical bedding dip (β = 90°), an improved JPW model is proposed to distinguish the strength criteria for the aforementioned differences. On the basis of considering the nonlinear relationship between confining pressure and rock strength, the JPW model is improved accordingly to make it suitable for predicting the strength behavior of bedded rocks.