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This paper focuses on the loading of small spacecraft induced by the triggering of separation systems. The article presents the experimental results for the shock loading level of small spacecraft manufactured by Lavochkin Association and analyses the causes of its observed increase. Recommendations are given for changing the testing techniques for the response to shock-impulse loading for similar objects.

A bistable nonlinear energy sink conceived to mitigate the vibrations of host structural systems is considered in this paper. The hosting structure consists of two coupled symmetric linear oscillators (LOs), and the nonlinear energy sink (NES) is connected to one of them. The peculiar nonlinear dynamics of the resulting three-degree-of-freedom system is analytically described by means of its slow invariant manifold derived from a suitable rescaling, coupled with a harmonic balance procedure, applied to the governing equations transformed in modal coordinates. On the basis of the first-order reduced model, the absorber is tuned and optimized to mitigate both modes for a broad range of impulsive load magnitudes applied to the LOs. On the one hand, for low-amplitude, in-well, oscillations, the parameters governing the bistable NES are tuned in order to make it functioning as a linear tuned mass damper (TMD); on the other, for high-amplitude, cross-well, oscillations, the absorber is optimized on the basis of the invariant manifolds features. The analytically predicted performance of the resulting tuned bistable nonlinear energy sink (TBNES) is numerically validated in terms of dissipation time; the absorption capabilities are eventually compared with either a TMD and a purely cubic NES. It is shown that, for a wide range of impulse amplitudes, the TBNES allows the most efficient absorption even for the detuned mode, where a single TMD cannot be effective.

Reinforced concrete structures and structural members used in strategic infrastructures such as highway bridges, high-rise buildings, etc. are inherently subjected to lateral impact loads arising from the collision of vehicles, vessels, falling rocks, and rigid objects having different impact geometries, weights, and velocities. Due to the brittle nature of concrete materials, both localized and overall failure modes are very likely to occur in concrete structures under dynamic and impulsive loads. Hence, many attempts have been carried out in the literature to recognize the failure behaviors and to assess the vulnerability of concrete structure under lateral impact loads. This paper presents a comprehensive state-of-the-art review on the responses and failure behaviors of various types of concrete structures and structural members subjected to lateral impact loads based on analytical, numerical, and experimental studies carried out by the previous research works. In addition, the influences of various structural- and load-related parameters on the impact resistance and failure behaviors of different concrete structures under lateral impact loads are reviewed.

Overhead cranes are machines designed to lift and transport heavy equipment and materials. For this reason, their design is regulated by rigorous standards (for example, the series EN13000 in Europe). However, the standards do not take into account the effect of cyclic loading due to, for example, rapid successions of short commands to place heavy machines and structures in a required position. Therefore, the aim of this research is to study the structural effect of rapid successions of command impulses. The preliminary results show that the displacement of the structure over time increases when the command impulses have a frequency equal or close to the natural frequency of the structure.

Structures comprising elements with markedly distinct physical and mechanical properties are ubiquitously employed in engineering applications. The paper considers the motion of an elastic half-strip interacting unilaterally with an absolutely rigid foundation, caused by a longitudinal edge mechanical fast impulse load. Dynamic equations of elasticity theory are used to describe the motion of the half-strip. The method of spatial characteristics is used to model the wave dynamics and dynamic failure of a piecewise homogeneous structure. This method allows to take into account variable conditions at the contact surface of the half-strip and the foundation, and consider delamination processes. The connection of the half-strip to the foundation is modeled by a nonlinear strength function of normal and tangential stresses, taking into account the mechanism of the connection, including its separation. The propagation of elastic waves caused by a non-stationary mechanical action is studied. The calculation results are analyzed to identify the areas of the contact surface that are most susceptible to damage. In order to study the shape of the main and reflected wave fronts at the contact boundary distributions of the values of the velocity components and stresses for different moments in time were obtained. Applications such as non-destructive testing and energy-efficient designs benefit from wave research techniques. The focus on propagation of waves in compound structures could further bridge theoretical advancements with practical implementations, enhancing the structural reliability and functionality of dynamic systems. The proposed method of direct numerical solution allows us to give practical recommendations for the identification of emerging local stress concentrations zones at the mating points.

The developed dynamic calculation schemes for the horizontal and vertical dynamics of the bogie carriages of the TEP70 BS passenger diesel locomotive under an impulsive load on its body are presented. Equations of oscillations of the components of the undercarriage of the specified diesel locomotive are obtained, describing the energy state of the diagnosed system with the subsequent substantiation of the equations of coupled mass oscillations in the horizontal and vertical planes of the diagnosed diesel locomotive using Lagrange equations of the 2nd kind.

Metallic thin-walled circular rings are widely employed as energy-absorption components in impact protection systems. However, the dynamic deformation mechanisms under impact loads remain incompletely understood. In this study, we develop a rigid-perfectly plastic model to analyze a simply supported circular ring subjected to impulsive loads. We present a theoretical survey of the incipient deformation under step loading, establishing the relation between the applied load magnitude and the number and location of the stationary plastic hinges. Our analytical findings reveal that as load magnitude increases, the number of stationary hinges grows, with newly formed hinges progressing closer to the point of loading. We validate these theoretical predictions against finite element analyses, demonstrating the model’s accuracy. Additionally, we investigate the complex deformation mechanisms involving both stationary and traveling hinges under rectangular pulse loading. This study provides fundamental insights into the dynamic plastic response of thin-walled structures, offering theoretical guidance for optimizing impact protection systems.

Relevance is due to insufficient knowledge and development of models of dynamics of complex heterostructures. Modern mechatronic systems include hybrid components consisting of complex heterogeneous structures: mechanical, electrical, electronic, etc. Heterostructures function in extreme conditions due to kinematic, dynamic, temperature, vibration and other external factors and are exposed to external influences. To create a reliable system for protecting complex heterostructures, it is necessary to build appropriate mathematical models that allow you to adequately describe the processes occurring in complex heterostructures. The purpose of the work is to study and develop heterostructural models based on the equations of point dynamics, plate and multilayer structures under the action of force and impulse loads in the presence or absence of internal friction in heterostructures. Particular attention is paid to the study of models of heterostructures with dissipation, with many degrees of freedom under the action of impulse loads.

Spacecraft shall be subjected to mechanical environments such as mechanical shocks during loading, unloading and transportation, and the shocks shall be transmitted to the circuit boards inside. There are plenty of tin-lead spots on the circuit board as there are a large number inside the spacecraft. The dynamic behaviour of tin-lead welding spot determines the anti-impact and anti-fatigue properties of the circuit board, and therefore, it is essential to investigate the dynamic behaviour of tin-lead welding spot based on sufficient experiments and accurate simulation. In this research work, the dynamic uniaxial tension at five different strain rates (0.1/s, 1/s, 10/s, 100/s and 1000/s) were performed, the morphology of the fracture surface was examined and the alloy ingredient was analyzed. Furthermore, the finite element models (FEM) of both the tensile sample and the circuit board were developed based on the modified Darveaux model and the cohesive zone method. According to the experiments and the simulation of the uniaxial tensile samples, it was the mass ratio of the tin to the lead that govern the micro mechanical properties, and the modified Darveaux model could precisely describe the stress-strain response of the welding spot. As a result, the calculated results of the impacting dynamical behaviour of the circuit board are reasonable and helpful. The modified Darveaux model and the developed simulation approach could also be applied to other welding structures experiencing impulsive loads. The investigation shall provide research support for the mechanical environment analysis of spacecraft and other mechanical impact.

The paper presents the results of numerical simulation of the dynamic behaviour of the post-tensioned beams subjected to a constant force impulse load over time and a short-term force impulse load varying over time. Abaqus programme was used for numerical analysis, introducing necessary and detailed modifications to the modelling and calibration parameters. The numerical dynamics models were calibrated using results previously obtained from our own experimental and numerical static analysis. To estimate the dynamic strength of structural materials, the dynamic strength coefficient was applied in the concrete damage plasticity model, and the Johnson-Cook model was used to describe the evolution of the dynamic yield strength of steel elements. An explicit procedure was used to solve the dynamic equilibrium equations. The selection of the Rayleigh damping parameter and the methodology for determining the external load in a dynamic problem are discussed. The study presents new results on the influence of the type of force impulse loading and variable prestressing eccentricity in numerical simulations of post-tensioned beams. The results of the simulation show that the post-tensioned beams achieved a lower dynamic load capacity under a constant force impulse load of approximately 5% compared to the static load capacity achieved in the experimental static tests, regardless of the assumed prestressing eccentricity. A dynamic load capacity significantly exceeded the static load capacity under short-term time-varying force impulse loading. The beam with the larger prestressing eccentricity achieved a dynamic load capacity of 211% of the static load capacity, while the beam with the smaller prestressing eccentricity achieved a dynamic load capacity of 198% of the static load capacity.