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1

Biomechanical behavior of customized splint for the patient with temporomandibular disorders: A three-dimensional finite element analysis

Zhu Yunfan, Zheng Fangjie, Gong Yanji, Yin Deqiang, Liu Yang

Biocybernetics and Biomedical Engineering

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2024

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Vol. 44, no. 1

83--94

EN

The mechanical overloading of temporomandibular joint (TMJ) is generally linked to temporomandibular disorders (TMD). However, in patients with a typical combination of maxillofacial morphology and occlusal features, the reduction of joint load and treatment with general occlusal splints are often ineffective. This study investigates the biomechanical behavior of the stomatognathic system in a TMD patient with personalized splints by finite element analysis. The therapeutic position, determined based on the intercuspal position, served as the basis for designing personalized customized splints. The design of occlusal contact and splint structure was evaluated in terms of their impact on the maximum stress level in the TMJ and the biting forces on the dentition. The relationship between joint stress and biting force was further examined during treatment with different customized splints. In preoperative case, there was a significant increase in stress level and stress concentration in the medial to posterior band of the articular disc. However, in all customized splint cases, the highest stress area shifted to the intermediate zone and exhibited a decrease. Notably, the bi-splints demonstrated superior ability in relieving overloading and balancing the occlusal force on both sides of the dentition, as verified by clinical treatment. The predictable simulated results offer valuable interactive information regarding TMJ overload, aiding doctors in making better-informed clinical decisions in future.

2

Activation of quartz flotation by Cu2+, Ni2+ in the sodium ethylxanthogenate (EX) system

Liu Yang, Tong Xiong, Xie Rui-Qi, Xie Xian, Song Qiang, Fan Pei-Qiang

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 2

art. no. 166368

EN

During the flotation of metal sulfide minerals, due to the interference of unavoidable ions, the quartz also partially floats in some cases. The studies on the mechanism of quartz being activated and floating up are still insufficient. In this study, the influence of the Cu2+ and Ni2+ unavoidable ions on the floatation of quartz was studied by micro-flotation experiments, adsorption detection, zeta potential measurement, solution composition calculation, infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses, and atomic force microscopy (AFM) observation. This provides a theoretical reference for further understanding the mechanism of sodium ethylxanthogenate and quartz surface, as well as the development of a new quartz depressant. The results of flotation showed that after activation by Cu2+ (1×10-4 mol/dm3) and Ni2+ (5×10-5 mol/dm3), the quartz was captured by sodium ethylxanthogenate (EX: 1.4×10-4 mol/dm3) under alkaline conditions (pH=10), while the best recoveries were obtained as 80% and 43%, respectively. The results of adsorption and zeta potential measurements showed that the precipitation rate of Cu2+ was greater than that of Ni2+ under alkaline conditions. Additionally, both Cu2+ and Ni2+ electrostatically adsorbed on the quartz surface and changed the zeta potential of quartz. The solution composition calculation further showed that Cu(OH)+, Cu(OH)2(s), and Ni(OH)+, Ni(OH)2(s) were the main components in the solution under alkaline conditions. The FT-IR and XPS analyses and AFM observations demonstrated that Cu and Ni species adsorbed on O atoms on the quartz surface, providing active sites for EX adsorption, and EX combines with Cu and Ni species on the quartz surface to generate -O-Cu-EX and -O-Ni-EX complexes. Finally, the quartz floated up due to the formation of hydrophobic products and firm adsorption.

3

Study of triaxial compression mechanical properties and pore-fracture characteristics of coal rocks in the Yili Basin, Xinjiang

Shen Cheng, Yue Ling, Liu Yang

Journal of Theoretical and Applied Mechanics

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2023

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Vol. 61 nr 2

207--218

EN

Compressive mechanical properties and pore-fissure characteristics of coal rock specimens from three stably developed coal seams M1, M8 and M12 in the Xinjiang Yili Basin were investigated in detail by a series of tests. The results show that the compressive mechanical properties of coal rocks in the Yili Basin are significantly affected by the confining pressure. The peak axial stress increases and the peak modulus of elasticity decreases as the confining pressure increases. The peak axial strain increases and then remains constant, while the peak circumferential strain and peak volumetric strain increase and then decrease. The confining pressure has almost no effect on Poisson’s ratio of the coal rock specimens. In addition, electron microscopy tests show that the microscopic fraction of the coal rock specimens is predominantly vitrinite, accounting for 83.1%-89.2%, while the percentage of the inertinite group is relatively small, at 10.3%-16.1%. The throat radius of the coal rock is mainly concentrated around 1-2μm, while the pore radius of the coal rock is between 150-200μm. The coal rock has an overall fine throat and low permeability, and the coal rock in the Yili Basin of Xinjiang is a typical low-permeability coal rock.

4

Columnar Dendrite Morphology and Solute Concentration of GH3039 Nickel-Based Superalloys during Wire and Laser Additive Manufacturing: Insights from Phase Field Simulations

Zong Nanfu, Wang Zheng, Liu Yang, Liang Xinghong, Jing Tao

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

387--393

EN

Wire and laser additive manufacturing (WLAM) can produce outstanding mechanical properties of GH3039 nickel-based superalloys. A quantitative rapid phase field model with solute trapping kinetics has been developed during the rapid solidification process, where a range of process conditions are considered in terms of thermal gradients and pulling speeds. Intergranular hot cracking is found to occur at boundaries of tilted columnar dendrite in the GH3039 nickel-based superalloys. The simulations demonstrate that the phase field model considering the interface deflection can represent the dendrite growth during additive manufacturing more realistically. With the aid of numerical simulations, it is determined that dendrite growth morphologies transform from symmetrical columnar dendrite to tilted columnar dendrite as the interface crystallographic deflection is increased, while increasing the deflection angle can lead to uneven composition of material matrix, especially at the columnar dendrite interface. Solute concentrations at the columnar dendrite interface tend to promote hot cracking in additively manufactured Ni-based superalloy.

5

Quantitative characterization of seepage behavior in rough fracture considering hydromechanical coupling effect: an experimental study

Yu Xiang, Zhang Tong, Yang Ke, Yu Fei, Liu Yang, Tang Ming

Acta Geophysica

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2023

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Vol. 71, no. 5

2245--2264

EN

To study the effect of fracture morphology and in situ stress on the seepage behavior of rough fractures, hydraulic–mechanical experiments with different confining stresses, pore pressures and fracture geometry were carried out. The dimensionless parameter non-Darcy coefficient factor K and K-based critical Reynolds number model (KCRN) was proposed to characterize the behavior of rough-wall fracture and fluid seepage. The results show that the seepage flow of rough-wall fracture can be well described by Forchheimer equation. As the confining pressure increases from 1 to 31 MPa, the two walls of the rough fracture are compressed, and the fluid flow capacity is weakened, resulting in an increase of 2–3 orders of magnitude in Forchheimer viscosity coefficient A. Also affected by the increase in the confining pressure, the contact area between the two walls of the rough fracture increases, which makes the fluid channel become curved, increases the dissipation of water pressure in the inertial process and causes the inertial term coefficient B to increase by 2–3 orders of magnitude in general. In the whole range of test confining pressure (1 MPa–31 MPa), the flow state of rough fracture fluid is divided into zones based on the critical Reynolds number. The average hydraulic aperture decreases with the increase in the confining pressure, which can be perfectly fitted by hyperbolic function. The calculated critical Reynolds number of six rough fracture samples varies from 0.0196 to 1.0424. According to the experimental data, the K-based critical Reynolds number model (KCRN) is validated, and the validation results prove the accuracy and reliability of the model.

6

An improved dynamic surface sliding mode method for autonomous cooperative formation control of underactuated USVS with complex marine environment disturbances

Dong Zaopeng, Qi Shijie, Yu Min, Zhang Zhengqi, Zhang Haisheng, Li Jiakang, Liu Yang

Polish Maritime Research

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2022

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nr 3

47--60

EN

In this paper, a novel dynamic surface sliding mode control (DSSMC) method, combined with a lateral velocity tracking differentiator (LVTD), is proposed for the cooperative formation control of underactuated unmanned surface vehicles (USVs) exposed to complex marine environment disturbances. Firstly, in view of the kinematic and dynamic models of USVs and the design idea of a virtual control law in a backstepping approach, the trajectory tracking control problem of USVs’ cooperative formation is transformed into a stabilisation problem of the virtual control law of longitudinal and lateral velocities. Then, aiming at the problem of differential explosion caused by repeated derivation in the process of backstepping design, the first-order low-pass filter about the virtual longitudinal velocity and intermediate state quantity of position is constructed to replace differential calculations during the design of the control law, respectively. In order to reduce the steady-state error when stabilising the virtual lateral velocity control law, the integral term is introduced into the design of the sliding mode surface with a lateral velocity error, and then the second-order sliding mode surface with an integral is structured. In addition, due to the problem of controller oscillation and the role of the tracking differentiator (TD) in active disturbance rejection control (ADRC), the LVTD is designed to smooth the state quantity of lateral velocity. Subsequently, based on the dynamic model of USV under complex marine environment disturbances, the nonlinear disturbance observer is designed to observe the disturbances and compensate the control law. Finally, the whole cooperative formation system is proved to be uniformly and ultimately bounded, according to the Lyapunov stability theory, and the stability and validity of the method is also verified by the simulation results.

7

Exponential decay of solutions to a class of fourth-order nonlinear hyperbolic equations modeling the oscillations of suspension bridges

Liu Yang, Yang Chao

Opuscula Mathematica

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2022

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Vol. 42, no. 2

239--255

EN

This paper is concerned with a class of fourth-order nonlinear hyperbolic equations subject to free boundary conditions that can be used to describe the nonlinear dynamics of suspension bridges.

8

Effect of silane coating surface treatment on friction and wear properties of carbon fiber/PI composites

Liu Yang, Li Bin, He Yichuan, Dong Yuncheng, Wang Shiguo

Materials Science Poland

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2022

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Vol. 40, No. 2

214--222

EN

PAN-based carbon fiber was surface-modified with silane coating, and a composite material was prepared using a PI resin as a matrix. The structure and surface properties of carbon fibers were studied by means of X-ray photoelectron spectroscopy (XPS) and SEM. The tensile strength of the composite was measured by a tensile tester, and the friction properties of the composite were measured by a micro-nano mechanics comprehensive test system. The results show that treatment with silane coating can improve the surface roughness and chemical activity of carbon fiber, improve the interface between carbon fiber and PI resin matrix, and improve the tensile strength and wear rate of the composite.

9

Study of Molecular Perovskite (H2dabco)[NH4(ClO4)3]/Carbon Nanotubes Energetic Composite

Hu Li-shuang, Liu Yang, He Dan, Yang Yajun, Gong Shida, Guang Chunyu, Deng Peng, Hu Shuangqi

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 1

91--105

EN

An ammonium perchlorate (AP, NH4(ClO4)3)-based molecular perovskite energetic material (H2dabco)[NH4(ClO4)3]/carbon nanotubes (DAP/CNTs) composite was prepared and characterized. Molecular perovskite DAP samples were synthesized by a facile one-pot reaction of triethylenediamine, perchloric acid (PCA, HClO4), and AP via a molecular assembly strategy. The results showed that the mechanical sensitivity (impact and friction sensitivities: >120 cm and 20%) and electrostatic spark sensitivity (8.90 J) of the DAP/CNTs energetic composite with 10 wt.% CNTs exhibited less sensitivity than that of DAP (impact, friction and electrostatic spark sensitivities: 112.3 cm, 45%, and 5.39 J, respectively), because of the mixing desensitization mechanism of CNTs. Compared with the pure DAP, the DAP/CNTs energetic composite has better performance with respect to thermal stability, exothermic capacity, and excellent continuous combustion properties. The DAP/CNTs energetic composite has potential application in a weapons system.

10

Numerical Modelling of Chamfer Billet of High Carbon Steel During Continuous Casting

Zong Nanfu, Ma Sida, Sun Weizhao, Liu Yang, Jing Tao

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 3

967--974

EN

The formation of internal cracks in as-cast billet is mainly attributed to the stress and strain states near the solidifying front. This study investigates the effect of chamfer configuration of as-cast billet on the maximal principal stress and the tensile stress during soft reduction process. The LIT and ZDT of GCr15 bearing steel are calculated by the solidification phase transformation model. What’s more, the 3D finite element models is established to investigate stress and strain states in the brittle temperature range. The relationships between chamfer angle and maximal principal stress, internal crack, as well as equivalent plastic strain are analyzed. Numerical results reveal that a chamfer configuration of as-cast billet is much more effective than a rectangular one on decreasing the risk of internal cracks.

11

Influence of Internal Cracking on Carbide Precipitation in Continuous Casting Bloom Induced by Soft Reduction Technology and the Resulting Segregated Band in Hot-Rolled Wire Rods

Zong Nanfu, Jing Tao, Liu Yang

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

73--82

EN

Internal cracking surrounding primary carbides in high carbon steel as-cast blooms induced by soft reduction is investigated to elucidate their influence of internal cracking on carbide precipitation and the resulting segregated band in hot-rolled wire rods. The primary carbides precipitation in high carbon steel has been investigated using both experimental observations and finite element simulations for as-cast blooms induced by soft reduction. It is found that the carbides precipitation in the vicinity of existing internal cracks is often located midway between the surface and centreline of the bloom, further increases the occurrence of the segregated bands in the hot-rolled wire rods. In addition, the growth of primary carbides surrounding the internal cracking are based on the chemical driving force and high density precipitate zones have been clarified in continuous casting bloom induced by soft reduction. It clearly shows that the spatial distribution of internal cracking surrounding primary carbides that play a key role in the formation of the segregated bands in the final steel products.

12

Method of cooperative formation control for underactuated USVs based on nonlinear backstepping and cascade system theory

Dong Zaopeng, Liu Yang, Wang Hao, Qin Tao

Polish Maritime Research

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2021

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nr 1

149--162

EN

This paper presents a method for the cooperative formation control of a group of underactuated USVs. The problem of formation control is first converted to one of stabilisation control of the tracking errors of the follower USVs using system state transformation design. The followers must keep a fixed distance from the leader USV and a specific heading angle in order to maintain a certain type of formation. A global differential homeomorphism transformation is then designed to create a tracking error system for the follower USVs, in order to simplify the description of the control system. This makes the complex formation control system easy to analyse, and allows it to be decomposed into a cascaded system. In addition, several intermediate state variables and virtual control laws are designed based on nonlinear backstepping, and actual control algorithms for the follower USVs to control the surge force and yaw moment are presented. A global system that can ensure uniform asymptotic stability of the USVs’ cooperative formation control is achieved by combining Lyapunov stability theory and cascade system theory. Finally, several simulation experiments are carried out to verify the validity, stability and reliability of our cooperative formation control method.

13

Green Fabrication of Nanoscale Energetic Molecular Perovskite (H2dabco)[Na(ClO4)3] with Reduced Mechanical Sensitivity

Hu Li-shuang, Du Zelin, Liu Yang, Gong Shida, Guang Chunyu, Li Xin, Yang Zhi, Jia Qi, Liang Kaili

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 3

369--384

EN

High-energy-density molecular perovskite energetic materials with high detonation performance have attracted much attention, but poor safety performance has limited their potential applications. In this paper, nano sodium perchlorate-based molecular perovskite (H2dabco)[Na(ClO4)3] (nano DAP-1) was fabricated by green ball-milling technology. The structure and morphology of the samples were characterized and the results showed that nano DAP-1 with nearly spherical morphology has a narrow particle size distribution, < 1 μm. The thermal decomposition properties were investigated by differential scanning calorimetry (DSC). The exothermic peak of nano DAP-1 thermal decomposition was 330.0 °C, a decrease of 51.7 °C compared with that of raw DAP (381.7 °C). The apparent activation energy (Ea) of nano DAP-1 was calculated to be 160.9 kJ·mol–1, which is lower than that of raw DAP-1 (168.6 kJ·mol–1). Mechanical sensitivity studies showed that nano DAP-1 (H50: 64 cm) exhibited a lower impact sensitivity than that of the raw DAP-1 (H50: 51 cm). This work provides a simple and effective way for improving the thermal decomposition properties and safety performance of molecular perovskite energetic materials.

14

Comparative Studies on a Chamfer Technology and a Convex Roll Technology During the Soft Reduction Process

Zong Nanfu, Jing Tao, Liu Yang

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 3

819--829

EN

To comprehensively investigate the diversity of a chamfer technology and a convex roll technology under the same soft reduction process (i.e., section size, reduction amount, casting speed and solid fraction), a three-dimensional mechanical model was developed to investigate the effect of the chamfer profile and roll surface profile on the deformation behavior, cracking risk, stress concentration and reduction force of as-cast bloom during the soft reduction process. It was found that a chamfer bloom and a convex roll can both avoid the thicker corner of the as-cast bloom solidified shell, and significantly reduce reduction force of the withdrawal and straightening units. The convex profile of roll limits lateral spread along bloom width direction, therefore it forms a greater deformation to the mushy zone of as-cast bloom along the casting direction, the tensile strain in the brittleness temperature range (BTR) can obviously increase to form internal cracks. The chamfer bloom is much more effective in compensating the solidification shrinkage of mushy zone. In addition, chamfer bloom has a significant decrease of tensile strain in the brittleness temperature range (BTR) areas, which is expected to greatly reduce the risk of internal cracks.

15

Seismic performance of circular reinforced concrete columns subjected to compression, bending and torsion with low and moderate shear span ratio

Jiao Chiyu, Liu Yang, Wei Biao, Li Jianzhon, Hu Zhangliang, Zhu Gexi

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

836--851

EN

Under the action of an earthquake, the piers of urban curved bridges are usually subjected to compression, bending and torsion due to the geometric irregularity and with low and moderate shear-span ratio. To explore the seismic performance of piers under combined actions, this paper made a theoretical analysis on the seismic performance of four circular RC columns under combined action with low and moderate shear-span ratio through experimental research. Taking the shear-span ratio and torsion-bending ratio as the main variables, cyclic bending loading and combined cyclic bending and torsion loading were carried out on the columns, respectively. The results showed that the increase of torsional effect and shear effect will increase the failure height of the piers and weaken the energy dissipation capacity and bearing capacity. Through the extraction of characteristic points in the test data, the relationship between force, displacement and torsion-bending ratio of columns with shear-span ratio below 4 was fitted. The bending and shear restoring force models of columns with spiral stirrups and small torsion-bending ratio were established. Moreover, based on the variable angle truss theory, the concrete improvement coefficient β was introduced, and the formula of torsional bearing capacity of columns under combined actions with low and moderate shear-span ratio was deduced. Compared with the test data, when the value of β was taken as 1.1, the proposed formula could be well applied to the calculation of bearing capacity of piers with torsion-bending ratio below 0.2 under combined actions with low and moderate shear-span ratio.

16

Mechanical and thermal insulate behaviors of pultruded GFRP truss-core sandwich panels filled with EPS mortar

Li Sensen, Zhang Bei, Yang Dapeng, Wang He, Liu Yang, He Huguang, Fan Hualin

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

593--604

EN

Pultruded sandwich panel (PSP) usually has light weight, but its flexural performance is limited by the weak shear strength. Filling into expanded polystyrene (EPS) mortar can effectively improve the mechanical properties. The bending performance and failure mode of the EPS mortar-filled PSP were investigated by flexural testing. The ultimate bearing capacity improved from 49.562 kN for unfilled PSP to 72.065 kN for EPS mortar-filled PSP. The equivalent shear modulus is increased from 140.068 to 354.685 MPa. Increasing the EPS mortar’s density, the failure of EPS mortar-filled PSP would change from core shear failure, local indentation failure to overall shear failure. According to the thermal insulation tests, which shows EPS mortar-filled PSPs have excellent thermal insulation, the thermal insulation performance of different types of filler PSPs are obtained. The research on the mechanical and thermal insulation properties of EPS mortar-filled PSP can provide technical support for its application in engineering.

17

Blast responses of polyurea-coated concrete arches

Liu Yang, Wang Peng, Jin Fengnian, He Huguang, Zhou Jiannan, Wang Bo, Fan Hualin

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

503--517

EN

The effects of polyurea coating on anti-explosion performances of reinforced concrete arches were studied through explosion experiments. Three coating schemes were proposed and investigated, including intrados coating, enclosed coating and fiber-grid/polyurea hybrid coating. The arches exhibit cracking, spalling and crashing failure modes in succession accompanying with reducing the scaled distance. The damage degree of the exploded arch is evaluated quantitatively by the residual load carrying capacity under quasi-static mid-span concentrated loading experiments. It is revealed that polyurea coatings have excellent anti-spalling ability than carbon fiber-reinforced polymer (CFRP) strengthening method and greatly increase the blast-resistance of the concrete arch and enclosed polyurea coating is the most efficient.

18

Infuence of CO2–water–rock interactions on the fracture properties of sandstone from the Triassic Xujiahe Formation, Sichuan Basin

Li Hongfei, Xie Lingzhi, Ren Li, He Bo, Liu Yang, Liu Jun

Acta Geophysica

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2021

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Vol. 69, no. 1

135--147

EN

Carbon dioxide (CO2) storage in deep saline aquifers has been lauded as one of the most efective techniques to mitigate greenhouse efects globally. Nevertheless, despite many investigations, clarifying the infuence of CO2–water–rock inter actions on the fracture characteristics of sandstone remains a challenge. In this work, the fracture properties of sandstone collected from the Triassic Xujiahe Formation are systematically studied in tests simulating CO2 sequestration. The results indicate that the water–rock interactions occur in a system of sandstone and CO2 solution. Due to the interactions, the poros ity of sandstone specimens slightly increases from 8.24 to 8.45% when immersed in CO2 solution and from 8.20 to 8.40% in pure water after 28 days. In addition, the parameters of fracture toughness, tensile strength, uniaxial compressive strength and elastic modulus are reduced by 24.12%, 27.16%, 31.78% and 33.21% after immersion in pure water, while they are reduced by 24.05%, 29.72%, 30.75% and 25.79% after immersion in CO2 solution, respectively. These results suggest that the mechanical properties of the Xujiahe sandstone deteriorate after soaking. The results also show that the critical fracture energy of sandstone specimens after immersion in the CO2 solution is 10.4% lower than that in pure water and 24.1% lower than that under natural drying conditions. These research results have great signifcance for understanding the dissolution processes during CO2 sequestration and their infuence on the fracture properties of sandstone, which may be theoretically instructive for CO2 storage in the Xujiahe Formation in the Sichuan Basin.

19

Study of Ammonium Perchlorate-based Molecular Perovskite (H2DABCO)[NH4(ClO4)3]/Graphene Energetic Composite with Insensitive Performance

Liu Yang, Hu Li-shuang, Gong Shida, Guang Chunyu, Li Lianqiang, Hu Shuangqi, Deng Peng

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 3

451--469

EN

In order to improve the safety properties of molecular perovskite energetic materials, ammonium perchlorate-based molecular perovskite ((H2DABCO)[NH4(ClO4)3], DAP)/graphene composite was prepared and characterized. Molecular perovskite DAP was prepared via a molecular assembly strategy by the facile one-pot reaction of triethylenediamine (TEDA, DABCO), perchloric acid, and ammonium perchlorate, and the DAP/graphene composite was fabricated by mechanical mixing with 10 wt.% graphene. The results demonstrated that impact sensitivity (>120 cm), friction sensitivity (25%) and electrostatic spark sensitivity (7.04 J) of the DAP/graphene composite was less sensitive than raw DAP (impact, friction and electrostatic spark sensitivity: 112.3 cm, 45%, and 5.39 J, respectively), due to the composite desensitization mechanism of graphene. This work may offer new ideas for the design and fabrication of insensitive molecular perovskite-based energetic composites.