This paper investigates the crashworthiness of freight vehicles under frontal impact based on the C-NCAP (China New Car Assessment Program) standard. Explicit dynamics and finite element methods were employed to conduct simulation analyses of the impact event, with the aim of offering references for improving vehicle crashworthiness. The findings indicate that the vehicle cabin remains largely intact, providing sufficient survival space for occupants. However, increased load amplifies the impact impulse and reduces crashworthiness. Additionally, the use of an enhanced anti-collision beam helps distribute impact forces and lowers the peak impact load.

To address the challenges of excessive free recoil energy and difficult buffering/braking during ultra-high kinetic energy artillery launches, this study draws inspiration from carrier-based aircraft arresting cable technology. We constructed an artillery free-recoil arresting buffer system and designed an experimental test platform. A multi-body system dynamics model was developed for the arresting cable buffering and braking process during free recoil. Experimental and simulation data comparisons validated the model: the maximum absolute relative error at characteristic points did not exceed 7

This work proposes a new offshore launch method using a semi submersible ship for single domain multi launch operations, improv-ing launch efficiency and protecting the platform from gas jet damage. Rockets and equipment are mounted on the ship, which is sub-merged to a predetermined depth so that the launch platform is covered by seawater. Results show that the water layer significantly delays impingement of the gas jet core on the platform surface, thereby reducing ablation. A theoretical model is derived to predict the time required for an overexpanded jet to penetrate the water layer, considering added mass and momentum dissipation. Through dimensionless analysis using the Buckingham p theorem, a linear empirical correlation for the dimensionless penetration time is obtained. These findings provide a valuable reference for designing effective offshore launch methods and point toward a new integrated direction for ocean engineering. (c) 2026 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Mars sample return (MSR) missions represent a frontier in planetary exploration, with the launch of the Mars Ascent Vehicle (MAV) serving as a critical enabling step. To overcome challenges including limited payload capacity, complex terrain, and stringent planetary protection constraints, a lateral cold ejection system based on a multi-stage cylindrical mechanism is proposed to enable lightweight, low-impact, and plume-free launch. A zero-dimensional internal ballistic model determines the deployment dynamics, yielding a theoretical minimum propellant mass of 67 g to achieve the required launch velocity. A rigid-flexible coupled dynamic model combines multi-body dynamics and explicit finite element analysis to capture nonlinear dynamic behaviors. Parametric studies reveal that initial platform inclination strongly affects MAV attitude: a - 10 degrees tilt produces a peak pitch angle of 9.27 degrees, below the 15 degrees requirement, while a + 10 degrees tilt causes excessive rotation (73.11 degrees). Soil bearing capacity minimally influences attitude but affects platform rebound. Adjusting the MAV center-of-mass position relative to the adapter effectively controls pitch angular velocity, enabling trajectory shaping. These results validate the feasibility and controllability of the lateral ejection concept for future MSR missions.

To address the risk of attitude instability caused by the strong coupling between propellant sloshing and rocket body motion during the cold ejection process of liquid rockets, this paper conducts a systematic study on the rigid–liquid coupling dynamics of the cold ejection process. First, combined with the structural parameters of the Long March 2C rocket, a multi-body dynamic model of the rocket body considering contact collision, ejection force loading, and other factors is established. A propellant sloshing model is constructed using the Moving Particle Semi-implicit (MPS) method, and a bidirectional coupling simulation interface is built to realize rigid–liquid strong coupling simulation. Second, the effectiveness of the modeling method is verified through the MPS method example validation, with the relative error between the simulation results and NASA experimental data ≤1.23%. Subsequently, the influence laws of thrust eccentricity angle and guide rail-adapter clearance on orbital exit performance and attitude stability are quantitatively analyzed. Finally, the optimization range of key parameters and engineering technical measures is proposed. The research shows that the thrust eccentricity angle is the core parameter affecting cold ejection performance, and the attitude stability is optimal when the eccentricity angle ≤0.25°. The guide rail clearance is recommended to be controlled within 0.5–1.0 mm to balance assembly tolerance and stability. The rigid–liquid coupling simulation method established and the nonlinear coupling mechanism revealed in this paper provide a scientific basis for the design optimization of liquid rocket cold ejection systems and have important theoretical significance and engineering application value.

The stage separation process, though often completed within one second, plays a critical role in determining the overall success and safety of the launch mission. The process of host stage separation is simulated to study the flow field evolution and the impact on the lower-stage. Overset mesh is utilized together with a novel adaptive mesh refinement sensor for the purpose of adapting to the relative motion. A third-order scheme is adopted in spatial discretization, and the simulation results fit well with the experiment data. The results show that the initial shockwave oscillated back and forth in the cavity of the lower-stage, leading to sustained oscillations in the forces of the lower-stage. Based on the monitor data, the force acting on the lower-stage exhibits five phases. Compared with former research, a longer interstage results in two more obvious oscillation phases. The pressure distribution on the forward dome of the lower-stage is also studied.

Prelaunch rolling of maritime rockets threatens the reliability of launch in rough sea conditions. In order to suppress the prelaunch rolling, this study introduces advanced smart prediction designed especially for maritime rockets. The suggested approach introduces a hybrid model that combines random forest (RF) and Adaptive boosting ( AdaBoost) methods to describe the coupling mechanism of factors affecting rocket rolling and to suppress the rolling. This combination improves forecast accuracy. Thereafter, the dimensionality reduced response surfaces are used to visually present the coupling between rocket rolling and influencing factors, which reveals the prelaunch rolling mechanism. When angle between the launch device and the ship's bow is within 80 degrees-100 degrees, the dynamic friction coefficient between adapters and guideways is 0.4, and the dynamic friction coefficient between the rocket and launchpad is within 0-0.15 or 0.5-0.7, the prelaunch rolling of rocket during one motion cycle of the ship is less than 0.065 degrees, originally 0.27 degrees, reduced by 75.93%, effectively suppressing the prelaunch rolling. This study improves the prelaunch stability of maritime rockets in rough sea conditions and establishes a mapping relationship between the factors affecting rocket rolling and the structure of the sea launch system, guiding the optimization of future sea launch systems.

In this study, a backward launch method for missiles placed on semi-recessed wings is proposed to reduce the interference effects during the missile-aircraft separation process. The feasibility of this launch strategy and the safety of missile-aircraft separation were verified using an unsteady computational fluid dynamics (CFD) modeling method. Using six-DOF rigid body dynamics equations and unstructured dynamic mesh technology, a numerical simulation of the rearward launch process of missiles mounted on semi-recessed wings was carried out. The separation flow field and missile trajectory parameters were obtained at different times. The results show that during the first separation phase, the missile has low aerodynamic interference from the carrier aircraft, its attitude changes minimally, and the missile may separate from the carrier aircraft rapidly, safely, and stably.

Machine learning-based techniques have been introduced to help enhance the performance of high-order shock-capturing schemes in recent years. In this work, a novel neural network is devised to address the accuracy reduction issue faced by previous machine learning-based schemes. By fully leveraging the features of multi-resolution strategy, optimal accuracy of the original numerical scheme can be formally preserved at all grid levels by the proposed WCNS3-MR-NN scheme. Meanwhile, the present scheme is designed to achieve high-resolution property and robust shock-capturing ability simultaneously. Analysis and numerical experiments are presented for validation. The results confirm that WCNS3-MR-NN maintains its optimal accuracy even at the presence of extreme points, and demonstrates excellent performance across a wide range of benchmark cases.

To solve the problem of excessive shock wave intensity in the channel of the launch box during the shock wave opening process, a baffle is installed at the rear end of the launch box to reduce the shock wave intensity. The effects of the baffle on the evolution of shock wave and gas flow field are investigated using computational fluid dynamics methods. Results show that the baffle effectively limits the propagation path of the shock wave and high-pressure gas, significantly reducing both the intensity and speed of the shock wave. Additionally, the baffle, as a reflective surface, increases the intensity of reflected shock wave at the rear end of the launch box. Further, a smaller baffle hole diameter leads to a weaker shock wave intensity within the launch box. By adjusting the baffle hole diameter, the shock wave intensity can be effectively controlled, ensuring that the launch box pressure meets launch requirements.

Sea-based rocket launches encounter significant challenges stemming from dynamic marine environmental interactions. During the hot launch phase, characterized by low-velocity ascent, the departure of the rocket from the oscillatory platform exhibits heightened sensitivity to external disturbances. In the development stage, assessing the launch dynamics and the clearance between the rocket and framed launcher are crucial for improving the reliability of sea-based rocket launches in rough sea conditions. This study presents a high-fidelity dynamic model of maritime hot launch system, demonstrating 3.21% prediction error through rigorous validation against experimental datasets from comprehensive modal analyses and the full-scale rocket flight test. To mitigate collision risks, we develop a computational method employing spatial vector analysis for dynamic measurement of rocket-launcher clearance during departure. Systematic investigations reveal that in rough sea conditions, optimal departure dynamics are achieved at θthrust = 270° nozzle azimuth configuration, reducing failure probability compared to conventional orientations. The developed assessment framework not only resolves critical safety challenges in current sea launch systems but also establishes foundational principles for optimizing adapter axial configuration patterns in future designs.

Multi-axle heavy-duty vehicles (MHVs) are essential for military equipment transport due to their safety and stability. However, braking dynamic responses between MHVs and pavement systems still remain underexplored, particularly regarding their complex load transfer mechanisms. This paper develops an enhanced model of a multi-axle heavy-duty vehicle (MHV) coupled with the uneven and flexible pavement. An advanced coupling iterative method is proposed to solve the highly dimensional equations of the MHV-pavement coupled system. The proposed method was validated through experimental tests, with characteristic parameters of vertical accelerations showing relative errors between 0.42% and 11.80%. The coupling effect and influence mechanism of the braking process are investigated by characteristic parameters of the dynamic responses. Additionally, the influences of braking conditions and pavement parameters are analyzed in time and frequency domains in order to reveal the vibration mechanisms of the coupled system. Moreover, this study establishes a theoretical foundation for monitoring pavement health via vehicle-mounted acceleration signals, which is necessary in military transportation.

The wave equation is an important physical partial differential equation, and in recent years, deep learning has shown promise in accelerating or replacing traditional numerical methods for solving it. However, existing deep learning methods suffer from high data acquisition costs, low training efficiency, and insufficient generalization capability for boundary conditions. To address these issues, this paper proposes an unsupervised learning method for the wave equation based on finite difference residual constraints. We construct a novel finite difference residual constraint based on structured grids and finite difference methods, as well as an unsupervised training strategy, enabling convolutional neural networks to train without data and predict the forward propagation process of waves. Experimental results show that finite difference residual constraints have advantages over physics-informed neural networks (PINNs) type physical information constraints, such as easier fitting, lower computational costs, and stronger source term generalization capability, making our method more efficient in training and potent in application.

Based on the goals of “high reliability, high frequency, rapid launch, and low cost” for space launch sites, an integrated dual-sided deflector system for convective cooling and thermal protection is presented. The interaction process between the gas jet and liquid water jet and its effect on the flow field environment are thoroughly studied using numerical calculation methods. Furthermore, considering the phase-change heat transfer issue in a compressible gas–liquid two-phase flow, and the varying distribution of different bubble shapes and sizes at the gas–liquid interface, a modified Lee model is derived. The research results show that compared to the classical Lee model, the modified Lee model can achieve a higher numerical accuracy in predicting the heat and mass transfer processes in gas–liquid two-phase flows. Through comparative analysis with the traditional dual-sided deflector and the conventional cooling system, the integrated dual-sided deflector system exhibits significant performance advantages in gas flow regulation and flow field environment improvement at the near-ground region of the space launch site. It not only achieves effective flow deflection, but also mitigates the degree of erosion caused by the gas jet on the deflector. This conclusion can provide theoretical references for the thermal protection design of commercial launch vehicle systems at space launch sites.

During the sea launch of a launch vehicle in low sea state, a rolling phenomenon of the launch vehicle has been observed. In rough sea conditions, launch may failure. This study utilizes dimensionality reduction-driven spatial system projection methods and virtual prototype modeling technology to reveal that the launch vehicle’s rolling is caused by differences in the motion paths of the center of mass. Additionally, during the prelaunch stage, the variation in the trajectory of the launch vehicle’s center of mass caused by the rolling and pitching motions of the transportation vessel has a significant impact on the roll motion of the launch vehicle. The motion in other degrees of freedom has minimal influence on the launch vehicle’s rolling. The minimum rocket rolling occurs when the dynamic coefficient of friction of the launchpad–launch vehicle contact is 0.05, and the dynamic coefficient of friction of the adapters and guideways is 0.4. The conclusions provide a theoretical foundation for optimizing the sea launch system and enhancing the reliability of sea launch in rough sea conditions.

Flow field prediction is essential for airfoil design. It is a time-consuming task to obtain the flow fields around an airfoil. Convolution neural networks (CNN) have been applied for flow field prediction in recent years. However, CNN-based methods rely heavily on convolutional kernels to process information within local neighborhoods, making it difficult to capture global information. In this paper, we propose a novel self-attention generative network referred to as SAG-FlowNet, both for original and optimization airfoil flow field prediction. We investigate the self-attention mechanism with a multi-layer convolutional generative network. We use the self-attention module to capture various information within and between flow fields, and with the help of the attention module, the CNN can utilize the information with stronger relationships regardless of their distances to achieve better flow field prediction results. Through extensive experiments, we explore the proposed SAG-FlowNet performance. The experimental results show that the method has accurate and universal performance for the reconstruction and prediction of the flow field both for original and optimized airfoils. SAG-FlowNet is promising for fast flow field prediction and has potential applications in accelerating airfoil design.

Rocket sled test avoids boundary effects in wind tunnel test and inconvenience of flight test, which is one of the feasible options for future single-stage-to-orbit. To analyze potential safety issues during payload separation and optimize the arrangement of testing sensors, different structural layouts and operating speeds of the rocket sled are conducted based on computational fluid dynamics and computational aeroacoustics. The hypersonic winged standard model is utilized as the load for these simulations. The analysis encompasses the evolution of shock waves, the forces exerted on the payload and noise propagation. Variations in flow field and aeroacoustic characteristics of rocket sled are analysed, revealing underlying physical mechanisms. It is observed that placing the payload in front of the thruster can reduce the head pressure, excessive wingspan may have an impact on the structural safety of the wingtip, and the regions of high sound pressure levels mainly exists in the middle and rear sections of the rocket sled. Moreover, as the Mach number increases, the characteristic frequency initially rises and then declines. These researches can serve as a valuable reference for the development of ground test systems and single-stage-to-orbit.

In this paper, computational fluid dynamics (CFD) and reduced order method (ROM) are developed for predicting the velocity time series during the initial stage of projectile launching. The overlapping grid technique is firstly applied to perform high accuracy CFD simulations of the underwater launch of a submarine-launched projectile under two-parameter varying working conditions (i.e., different piston velocities and pipe interface radii). After that, the proper orthogonal decomposition (POD)–based ROM is used for decomposing the launching process into several spatial dependent mode functions and the corresponding time coefficients. The prediction of the initial stage of the launching velocity (which is the most important part of the launching process) is realized by establishing the neural network between the working condition parameters and the POD basis coefficients. The analysis results show that this method of CFD and ROM can accurately predict the complex dynamic process such as projectile launching process.

为解决现有弹射器红外目标明显、能量不稳定、结构复杂等问题,进一步提升弹射效率、弹射稳定性,该研究在现有压缩空气弹射器的基础上提出一种可自主增长气缸边界的柔性气缸弹射器,实现高压气体在柔性气缸约束下的长距离做功.在显式动力学基础上,建立多工况下的大尺度柔性气缸弹射负载有限元模型,实现基于粒子法模型的大尺度柔性结构弹射负载的流固耦合数值仿真.研究结果表明在充气量一定时,柔性气缸弹射器比压缩空气弹射器弹射速度增加11.7％,火箭最大过载减小71.6％.进一步研究表明,同种织物漏气的主要影响因素为柔性气缸内外压差,针对不同材料漏气,选取三种材料,其中棉纶66C为柔性气缸织物的弹射系统的弹射指标最佳.对比不同环境压力,外界大气压越低,弹射动能越高,70 kPa环境压力下,比标准大气环境压力下,动能增加15.8％.