There are complex flow phenomena in the inlets of the air-breathing hypersonic vehicles, such as boundary layer transition, flow separation, and shock/boundary layer interference. Deep understanding and effective control of these complex flow phenomena are the key to realizing effective operation and performance improvement of hypersonic vehicles. The current research progress of shock/boundary layer flow control technology in supersonic inlets is first reviewed from two aspects:passive control and active control；their effectiveness and drawbacks are described. Meanwhile, with the development of hypersonic vehicle towards the direction of wide velocity domain, large airspace and high Mach number, the previous flow control technology based on active and passive control cannot meet the requirements of hypersonic vehicle follow-up control. As a result, the multi-field control methods represented by plasma have become the focus of supersonic inlets flow control. However, the existing experimental research methods are difficult to carry out detailed research on flow control mechanisms, and there are still many places worth exploring. In this paper, relevant suggestions are put forward for the next step of research in addition to summarizing.

In the past decade, approximately one-third of civil aviation safety incidents have been related to landing, with hard landings comprising one-fifth of these landing-related incidents. Hard landings not only damage aircraft structures but also can lead to aircraft destruction or loss of life in severe cases. However, statistical data on hard landings remain limited. This paper systematically analyzes hard landing criteria through a review of quantitative standards, simulation analysis, and machine learning techniques. It also conducts a statistical examination of 53 typical hard landing incidents of mainstream aircraft such as Boeing-737 and Airbus-A320 over the past decade, offering a detailed exploration of common structural damage patterns associated with hard landings. Results show that heavy landing incidents often cause damage of different degrees to the aircraft's landing gear, fuselage, wings, and other key components. Moreover, the extent of damage differs significantly among various types of heavy landing incidents.

With the development of civil aircraft design technology, the focus of today's passenger aircraft design transits from structural safety to cabin comfort, of which the vibration comfort is a key factor. From the perspective of passenger vibration comfort, We carried out the vibration transfer path test of a certain type of passenger aircraft under three working conditions, namely, the cruising condition, the low-altitude flight condition, and the runway running condition. Based on the test data of these conditions, the Vibration Transfer Path models were built, and the key factors affecting the vibration comfort were studied. The following conclusions are drawn:Under the cruising and low-altitude flight condition, the cabin vibration response mainly comes from the coupling of engine rotor excitation and the structure at the fundamental frequency and the double frequency；under the runway running condition, the vibration response in the cabin comes from the coupling of the main landing gear excitation and the structure in the low frequency range（especially 50 Hz）. This test not only provides a basis for the vibration reduction and isolation design of passenger cabins, but also fills the gap of the vibration comfort test and verification platform for all passenger aircraft in China.

Large flexible appendages of flexible spacecraft are characterised by their large scale and low stiffness, resulting in vibration of large flexible appendages that can seriously affect the attitude precision of the spacecraft. Information fusion preview control is combined with fuzzy control to construct the attitude controller. According to the information fusion theory, the spacecraft's desired trajectory and system dynamics information are fused, the optimal preview control law is derived. The optimal preview control law can be easily obtained due to the information fusion control has a simple design process and low computational burden. In real engineering, the control torque generated by the actuator is limited. The fuzzy controller is employed to adjust the parameters of the control law on-line in order to satisfy the requirements of limitation. Simulation results show that the designed control strategy with high control performance can effectively suppress the vibration of the flexible appendages, and the attitude angle can reach the desired value accurately and quickly. The proposed control strategy can be served as a reference for the engineering application of large flexible spacecraft attitude control.

Hypersonic aircraft face extremely high aerodynamic resistance and heating during flight, posing a threat to flight safety and stability. Taguchi-gray correlation method is utilized to study the impact of size on the resistance and heat reduction performance of hypersonic aircraft. An orthogonal test is conducted, wherein design factors such as spike length-diameter ratio, airway diameter ratio, pneumatic disk diameter ratio, and lateral jet angle are considered. The response targets comprise total flight resistance, peak pressure coefficient, and Stanton number. Test results are obtained through numerical simulation. The findings indicate that the flight resistance is most significantly affected by the length-diameter ratio of the spike，while the lateral jet angle has the least effect. In regard to the peak pressure coefficient and Stanton number，the size factors exhibit a similar rank of influence. Among these factors，the length-diameter ratio of the pneumatic disk exerts the most significant impact. Increasing the length-diameter ratio of the spike and the diameter ratio of the pneumatic disk can effectively improve overall resistance and heat reduction performance. However，it should be noted that as the size increases，the lifting efficiency gradually diminishes. In comparison to the optimal group of orthogonal design，the optimized configuration demonstrates an overall performance improvement of 4.6%，thus indicating a favorable optimization effect.

In order to investigate a structure with better mechanical properties, this paper proposes a square honeycomb lattice sandwich cylindrical shell structure, which combines metal thin-walled tubes and honeycomb structures. The mechanical behavior of the sandwich cylindrical shell structure with a square honeycomb as the core under radial compressive loads is studied by experimental and numerical methods. By comparing the results of two research methods, the accuracy of the finite element model is verified, and the deformation mode of the structure under radial compressive loads is analyzed, and the reinforcement mechanism of the structure is discussed. The results show that the rectangular honeycomb lattice sandwich cylin-drical shell structure will undergo three deformation stages:elastic stage, plastic stage and collapsibility stage under radial compression load. Compared with the simple superposition of single-layer cylindrical shells and cores, the load-bearing and energy absorption of the square honeycomb lattice sandwich cylindrical shell are greatly improved. The structure is mainly coupled and reinforced by the formation of plastic hinges and the debonding between the square honeycomb core and the inner and outer cylindrical shells.

Aiming at the demand for torsional capacity of high-power offshore wind power supporting structure, the full-range torsional mechanism of tapered concrete-filled double skin steel tubular（TCFDST）members was examined under the large hollow ratio, high taper degree, and out-of-code diameter-to-thickness（D/t）ratio. The characteristics of torque-angle curve could be divided into the elastic stage, elasticplastic, plastic strengthening stage, and failure stage. Influence of key parameters on ultimate bearing capacity and stiffness was revealed. The hollow ratio and strengths of steel and concrete were positively correlated with the ultimate torque and stiffness；D/t ratios of outer or inner tubes had negative relationship to it；the axial compression ratios had positive relationship within the limited value，and inversely，it was negatively correlative. A method based on laminated tube theory was proposed to calculate the torque-angle curves of TCFDST members. Subsequently，the hierarchical integration method was established and verified based on the Chinese code and relevant literature，for calculating the ultimate torsional capacity of concrete-filled double skin steel tubular members，and the difference of various methods in determining N-T curve was also analyzed. The research results in this paper can provide valuable reference for the application of TCFDST members with large hollow ratios，large taper degree，and out-of-code D/t ratios in wind power projects.

A large number of fission pores are generated in ceramic fuel under high burnup conditions, and the fission gas released into the crack cavity has a great influence on the crack propagation behavior. In this study, a dynamic crack propagation model under variable internal pressure is developed to address the dynamic cracking technique of the coupling effect between the internal pressure and crack propagation. The internal pressure in crack cavity varies with crack propagation, while the cracking behavior is simulta-neously affected by the pressure. The presented model is successfully applied to simulate the cracking behavior of ceramic fuel particles of high burnup structure, and the mechanical effect of fission gas release on crack propagation is studied. Based on the cohesive element, the crack initiation and propagation process are simulated, and the mechanical research method of gas release on crack propagation is established here. Furthermore, the effects of gas pressure on the crack initiation and propagation process in fuel particles are analyzed. The results show that the release of gas into the crack cavity can inhibit crack propagation based on gas pressure and crack geometry characteristics. For different initial gas pressures, the larger the initial gas pressure is, the longer the crack propagation length will be. The developed dynamic cracking simulation technique provides an analytical method and numerical foundation for accurately analyzing the failure of dispersion fuel meat. It also provides a method to study the coupling of load and crack propagation.

In order to determine the influence of aggregate irregularity on the mechanical properties and failure morphology of concrete, Python programs were developed to generate randomly distributed aggregate models with different sharpness in ABAQUS, and the 0-thickness cohesive element and variable-thickness solid interface transition zone（ITZ）were established respectively. First, the reliability of model was determined by changing mesh size and friction coefficient between the loading pad and concrete compared with the experiment. Then, the quality of two ITZ modeling methods was analyzed. Finally, the uniaxial compression mechanical behavior of the three-dimensional meso-concrete model was analyzed from the aspects of stress-strain curve, fracture propagation, and energy dissipation. The simulation results show that the 0 thickness cohesive ITZ and the solid thickness ITZ model can predict the compressive strength of concrete, and the stress-strain curve and failure morphology of the ITZ model with solid thickness are more consistent with the experiment. The fracture propagation of concrete is obviously affected by the shape parameters of aggregate. The interior and surface of the spherical aggregate model are penetrating cracks. The strain energy of polyhedral aggregate model is larger, and there are many micro-cracks in the concrete, the possibility being compressed and destroyed into more fragments is higher. With the increase of aggregate irregularity, the compressive strength of concrete increases slightly, but the peak strain is not affected.

In this paper, the effects of doping elements（Re and Ru）content on the stability and occupancy orientation of a Ni-Al binary model nickel-based single-crystal superalloy are studied by using first-principles calculations. The results show that the total energy of the system decreases gradually with the increase of the content of Re and Ru elements, which suggests that the stability of the system is improved. The system using Ru to replace Ni has the lowest stability, while the stability of system is the best by using Re to replace Al. Therefore, Re and Ru are more inclined to replace Al, which is consistent with the previous experimental results. Meanwhile, compared to other contents of Re and Ru, when Re and Ru with the content of about 1.4% are used to replace Al, the substitution formation energy is the lowest. Furthermore, two different stacking fault modes are obtained by deleting a layer of atoms in the Ni-Al binary model. Research on these two stacking fault modes indicates that replacing Al with Re and Ru can improve the stability of the systems, and systems containing Re are more stable, which have lower substitution formation energy compared to replacing Al with Ru. However, for different stacking fault modes, when replacing Al with Re and Ru, the content of Re and Ru is different for the best of a stable system and the lowest of substitution formation energy and stacking fault energy. Replacing Al with Re results in a better stability in stacking fault systems, but the content of Re in the most stable system depends on the selected stacking fault mode.

Against the characteristic of large deformation for reinforced concrete（RC）frame, RC frame-frame truss composite wall（FTCW）structure was proposed, and two reinforced concrete（RC）frameframe truss composite wall（FTCW）specimens with a scale of 1∶2 were implemented for cyclic loading test. The seismic performance of bearing capacity, ductility and stiffness degradation were analyzed by the test phenomenon, hysteresis curves, backbone curves and stiffness degradation curves. The simulation of cyclic loading test was conducted by ABAQUS software, and the results were compared with the test results. The influence of the amount of infill FTCW, rebar ratio of RC frame columns, axial compression ratio, concrete strength, embedded angle steel and the layout direction of FTCW were analyzed. The test behav-iors showed that a multistage energy consuming system that FTCW worked before RC frame and the internal diagonal struts worked before the outer frame inside the FTCW, forming a multistage energy consumption system for the design purpose of earthquake resistant structures. The numerical analysis results showed that the most effective way to improve the bearing capacity of RC frame-FTCW was to increase the amount of filled FTCW, followed by increasing the rebar ratio of frame columns, and the improvement of increasing the concrete strength or adding angle steel for the internal diagonal struts were smaller. The improvement of axial compression ratio on the bearing capacity was unnoticeable. In addition, the layout direction of FTCW was significant, and the number and position of FTCW should be symmetrically arranged.

In order to enhance the seismic performance of reinforced concrete columns, a method of embedding steel wire mesh to strengthen concrete columns was proposed. A total of six specimens including reinforced concrete column, four steel mesh-reinforced columns, and one stirrup-reinforced column were designed and poured. Constant axial pressure was applied to the specimens and horizontal quasi-static cyclic loading was carried out. The failure patterns, crack distribution, hysteretic characteristics, ductility, and energy dissipation capacity of each specimen were tested. The seismic performances of steel wire mesh-reinforced specimens and stirrup-reinforced specimens with the same equivalent stirrup ratio were compared and analyzed, and the effects of steel mesh layers and configuration height range on the seismic perform-ance of members were discussed. The research results show that the proper configuration of steel mesh can effectively restrict the formation and development of column sectional crack and“diagonal crack”, and transform the bending-shear failure mode of the specimen into bending failure mode. Therefore, compared with the reference specimen and stirrup-reinforced specimen, the wire mesh-reinforced specimen shows greater initial stiffness, better ductile deformation and cumulative energy dissipation capacity. The research results preliminarily clarify the relationship between the number of wire mesh layers, height range and ductile deformation capacity, stiffness degradation, and energy dissipation capacity of specimens, and the related results can provide reference for the design of embedded wire mesh-reinforced concrete columns.

The classic fiber model based on Euler-Bernoulli beam theory overlooks the influence of shear deformation on the section of the beam. In order to establish a more accurate creep analysis method for reinforced concrete fiber beam elements, this paper proposes a fiber beam element considering shear effects based on Timoshenko beam theory. The stiffness matrix of the fiber beam element is derived, and the finite element equation for the equivalent nodal force of creep analysis based on concrete creep analysis initial strain method is obtained. Finally, a finite element method for creep analysis of reinforced concrete fiber beam elements is established. A computing program is developed in FORTRAN language, and elastic analysis for normal beam and reinforced concrete beam, and creep analysis for reinforced concrete beam are conducted. The results are compared with analytical solutions, commercial software and other literature, indicating that the proposed method can accurately consider the shear effects and clearly define the behaviors of steel and concrete in the creep performance of reinforced concrete beams. Moreover, including steel in the creep analysis model can effectively improve the accuracy of the results.

The objective of this paper is to study the mechanical characteristics of the interface between loess and geosynthetics, in hope of providing targeted suggestions for the design of reinforced loess projects. A large-scale interface shear apparatus was used to conduct direct shear tests on the geogrid-loess interface to study the effects of the moisture content and compaction degree of loess on the shear stress-shear displacement relationships, shear strength indices, and thickness of shear band of the geogrid-loess interface. The mechanism of the effects was analyzed, and the constitutive model of the geogrid-loess interface was discussed. The test results show that as the moisture content increases（not exceeding the plastic limit）, the shear stress-shear displacement curves of the geogrid-loess interface change from softening type to hardening type. The interface cohesion and friction angle significantly decrease with the increase of the moisture content, and thus the interface shear strength decreases accordingly. The thickness of shear band increases with the moisture content. The compaction degree of loess has little influence on the shear strength of the geogrid-soil interface, but it affects the thickness of shear band significantly. The thickness of shear band increases greatly when the compaction degree reaches 90%. Hence, the compaction degree of the backfill of reinforced loess engineering should not be less than 90%. The thickness of the shear band of geogrid-loess interface decreases continuously along the shear direction, with a maximum thickness of 3 cm approximately. This indicates that the shear band between the reinforcement and soil is the thinnest at the facing column in reinforced loess retaining walls. Hence, a flexible or integral facing column is recommended to be used in reinforced loess retaining walls. The hyperbolic interface constitutive model can effectively reflect the shear behavior of the geogrid-loess interface.

The anti-yaw vibration devices currently used in high-speed trains are hydraulic dampers, whose damping characteristics cannot be adjusted according to the changes in the vehicle's operating state and environmental conditions, resulting in poor ride quality and stability for the vehicle. A semi-active damper based on magnetorheological technology combined with intelligent control technology can solve this problem. In this paper, a three-coil magnetorheological damper has been developed with adjustable damping characteristics based on the technical specifications of the anti-yaw damper. The multi-physical field of the damper is simulated, and damping performance of the damper is tested under different excitation currents, amplitudes, frequencies, and coil combinations. The results show that the magnetic circuit design of the damper is reasonable and complies with the technical requirements for anti-yaw dampers, with a maximum output force of 46 kN and an adjustable dynamic coefficient of 28. In addition, an analysis is conducted on the magnetic field distribution at varying coil spacings. The findings indicate that a critical distance exists between the coils, and the critical distance of this damper is 0.69 times the width of the coil, beyond which the magnetic field distribution becomes non-uniform. The change in magnetic flux density at the effective damping channel will stop when a certain part of the magnetic circuit reaches saturation.

To study the effect of double circular holes on the mechanical properties of rocks and the crack extension process, a uniaxial compression model for rock specimens containing double circular holes was constructed, and the correctness and rationality of the numerical model were verified based on the comparison of the macroscopic mechanical parameters obtained from experiments and simulations. In addition, the crack extension process of specimens containing double circular holes and the evolution of the stress field around the circular holes were analyzed. The results show that the numerical simulation results are in good agreement with the experimental results；the initial tensile crack first sprouts at the upper and lower ends of the circular hole, and with the increase of axial stress, structural weak zones are usually formed at the left and right sides of the hole wall. The sprouting direction of the initial tensile crack is in the axial load-ing direction, independent of the orientation angle α, but the damage pattern of the specimen is influenced by the orientation angle α. The initial tensile crack is generated in the tensile stress concentration area；the tensile stress concentration area at the upper and lower ends of the circular hole moves and dissipates accordingly with the expansion of the initial tensile crack. The compressive stress concentration area of the stress component σ_yy is located on the left and right sides of the circular hole, while a shielding area of compressive stress is formed at the upper and lower ends of the circular hole, and the smaller the distance from the vertical center line of the circular hole, the stronger the shielding effect and the weaker the compressive stress.

The roughness of the interface between new and old concrete is one of the key factors that affect its shear performance. In this paper, the roughness of the new and old concrete interface is characterized and quantified based on fractal theory. Different fractal dimension interfaces of new and old concrete random aggregate geometric models are established using the Monte Carlo method and aggregate grading theory. By simulating the mechanical behavior of rough interfaces using zero-thickness cohesive elements locally embedded in the model, the effects of mesh size, random distribution of aggregates, fractal dimension, normal pressure, and interface material parameters on the shear performance of rough interfaces between new and old concrete are analyzed. The results show that the model's mesh size and random distribution of aggregates have no significant effect on the shear performance of the interface between new and old concrete. As the fractal dimension increases, the interface shear strength first increases and then decreases, and the fractal dimension corresponding to the maximum shear strength decreases as the normal pressure increases. Under the same fractal dimension, the shear strength increases linearly with the normal pressure. The normal pressure has a more significant impact on the interface shear strength compared to the fractal dimension. As the fractal dimension increases, cracks are more likely to propagate deeper into the old concrete area, and increasing the strength and fracture energy of the new and old interface can effectively improve the shear performance of the interface.

In steel-concrete composite structures, due to the existence of certain interface slip and web shear deformation, the assumption of flat section is no longer applicable. In order to scientifically study the effects of shear deformation and interface slip on the deflection and interface slip of composite beams, this paper adopts Goodman's assumption and Timoshenko beam's double generalized displacement assumption, introduces the strain relationship of composite beams and element microsegment mechanical equilibrium, and derives the elastic bending differential equation of double inverted T-shaped steel-concrete composite beams considering shear deformation and interface slip. Then based on the equivalent spring model and the equivalent rod spring model, a theoretical calculation formula for the elastic shear stiffness of the embedded web connection is derived. By using the known deformation and constraint conditions of the composite beam, we obtain the analytical solution of deflection and slip of the simply supported composite beam under concentrated load in the span and verify it through the experimental results of four double inverted T-shaped steel-concrete composite beams with different parameters. The results show that the deflection and slip values obtained from theoretical calculations are in good agreement with the measured values, and the correctness of the theoretical calculation formula for the elastic shear stiffness of the embedded web connection is verified. In the deflection deformation of double inverted T-shaped composite beams, the deflection value caused by bending accounts for about 56% of the total deflection, the deflection value caused by interface slip accounts for about 36% of the total deflection, and the deflection value caused by shear deformation accounts for about 8% of the total deflection. This article comprehensively considers the effects of shear deformation and interface slip on the deflection and slip of composite beams, and makes a significant improvement compared to the model structure that does not consider shear deformation and interface slip.

This paper develops a free vibration model of rectangular microplates including three material length scale parameters and two displacement field variables using the modified strain gradient theory and a refined higher-order shear deformation theory, and presented the related governing differential equations. The analytical vibration frequencies of a four-edge supported rectangular microplate were obtained via the Navier method. Combining the Gauss-Lobatto quadrature and differential quadrature rules, a four-node seventy-two-DOF differential quadrature finite element was constructed to solve the free vibration of rectangular microplates with general boundary conditions. Through typical numerical examples, the effectiveness of the present model was established, and the effects of boundary conditions, material length scale parameters, aspect ratio and length-thickness ratio on the vibration frequencies and mode shapes of rectangular microplates were revealed. The results indicate that the vibration frequencies and some mode shapes of rectangular microplates exhibit significant size effect, and its intensity is associated with the boundary conditions and geometric dimensions.

The modeling of the passive dynamic walker of flexible legged rimless wheel is studied, and the influence of damping coefficient on system dynamics is analyzed. According to the geometric characteristics of the walker, the independent generalized coordinates are selected to describe the position of the system, and the second kind of Lagrange equation is used to establish the dynamic model of the passive dynamic walker of flexible legged rimless wheel. By analyzing the structure and physical properties of the flexible leg, it is concluded that the impact occurs in the tangential direction of the telescopic leg and the impact force is not transmitted between the leg and the ground in the radial direction during the impact stage, and a state jump model under the assumption of partial impact is proposed. The numerical simulation of passive dynamic walking of flexible legged rimless wheels using different damping parameters verifies the effective-ness of the proposed method. When a larger damping coefficient is selected, the double-limb support period of periodic walking accounts for 77.6% of the whole walking cycle, while the single-limb support period accounts for 22.4% of the whole walking cycle. The periodic walking can be achieved when the slope angle is in the range of 0.1-0.7 rad. The slope angle of the flexible legged rimless wheel that can passively and dynamically walk on decreases as the damping coefficient decreases.

In order to characterize the distribution law of active earth pressure with depth for a circular platform foundation pit under transient infiltrations, this study derived the slip line equation for the active earth pressure of circular platform foundation pits. The derivation was based on the strength equation of generalized effective stress for unsaturated soils and matric suction under transient infiltration conditions. Subsequently, the differential iterative method was adopted to obtain the slip line solution of active earth pressure for circular platform foundation pits under transient infiltrations. Last, the accuracy of the obtained slip line solution was verified, and an influencing factor analysis was conducted. The results indicate that the obtained slip line solution, compared with the existing solutions, can reasonably account for comprehen-sive influences of transient infiltration（time, infiltration ratio, nonlinear profiles of suction stress）, soil types（sand, silt, clay）, foundation pit model parameters（wall dip angle, wall-soil friction angle）, and the circumferential stress coefficient on the active earth pressure of foundation pits. The accuracy of the obtained slip line solution of active earth pressure under specific reduced conditions is demonstrated by comparing it with the slip line solution of circular platform foundation pits in saturated soils（when suction stress is zero）, and the limit equilibrium solution of plane retaining walls under transient infiltrations（when the radius of foundation pit tends to infinity）reported in the literature. The influence of time and infiltration ratio on the value and distribution of active earth pressure is most pronounced for foundation pits in clay, followed by foundation pits in silt. However, it is negligible for foundation pits in sand, which is caused by nonlinear profiles of suction stress for different soils. The active earth pressure of foundation pits decreases significantly with the increase of wall dip angle, wall-soil friction angle and circumferential stress coefficient, while its distribution and change with depth are closely related to soil types.