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A series of numerical simulations using SPH (Smoothed Particle Hydrodynamics) method were carried out to study the hypervelocity impact of aluminum spheres on multi-plate structures. Both the morphologic characteristics of debris clouds and the damage of intermediate plates were investigated. The possible damage effects of debris cloud threat on back wall were also described qualitatively. Results showed that, comparing with single plate or double-plate structures, the multi-plate structure has higher resistance capacity to the impact from hypervelocity particles. Hence the multi-plate shield structure has a better shielding performance with a reduction in weight of the structure. It provides a promising alternative to the traditional shield in the spacecraft shield design.

The characteristics of the plasma with difference between the electron temperature and gas temperature were investigated and the relationship between the plasma ionization degree and the internal energy of a system was obtained. A group of equations included the chemical reaction equilibrium equation, the chemical reaction rate equation and the energy conservation equation were adopted to calculate the electron density, the electron temperature and the atom temperature with a given internal energy. These equations combined with Navier–Stokes (N–S) equations is solved by a smooth particle hydrodynamic (SPH) code. The charges generated in hypervelocity impacts with five different velocities are calculated and verified with the empirical formulas. The influence of a critical velocity for plasma generation is considered in the empirical formula and the parameters are fitted by the numerical results. By comparing with the results in reference, the fitted new empirical formula is verified to be reasonable and useful for a wide range of impact velocity.

With the rapid development of material science, the original aluminum alloy shield structure of spacecraft has been gradually replaced by sandwiched structure of carbon fiber reinforced resin matrix composite structure with aluminum honeycomb. In order to reveal the damage characteristics induced by debris impacting on shield structure of spacecraft and aiming at the engineering requirements that spacecraft undergo alternately high and low temperature environment during on-orbit operation, CFRPs/aluminum honeycomb core sandwich shield structure is used as the impact object. The damage characteristics of 2A12 aluminum projectile impacting on CFRPs/aluminum honeycomb sandwich structure with different aluminum honeycomb arm lengths at different impact velocities are studied by using the high and low temperature system for the target and the loading system of two-stage light gas gun. The experimental results show that the arm lengths of aluminum honeycomb have little effect on the perforation area of front and rear surfaces of CFRPs/aluminum honeycomb sandwich structure at high temperature, but the impact speed has a great effect on the perforation areas of front and rear surfaces of rear panels. The lower the impact speed is, the smaller the perforation diameter is. The deformation and ablation areas of the front and rear surfaces of the aluminum honeycomb increase with the increasing of the arm length of the aluminum honeycomb. At the same time, the physical quantities mentioned above have similar changes in low temperature environment. The fitting formulas, such as the relationships among perforations of the front and rear surfaces of CFRP and the arm lengths of aluminum honeycomb, and ablation area of aluminum honeycomb and the arm lengths of aluminum honeycomb are given at the given experimental conditions. The micro-morphology and damage characteristics of the panels and aluminum honeycomb are analyzed at the different locations near the impact point at high temperature.

Numerical investigations are conducted to examine the penetration depth of ellipsoid-shaped projectiles into semi-infinite aluminum targets under conditions of hypervelocity impact. These results are then compared against empirical equations developed by various researchers for spherical projectiles. The semi-infinite aluminum target, sized at $150\times 150\times 50$mm, is composed of Al7075-T651. The projectiles are fashioned from Al-7075-T651, steel, and boron carbide. The projectile’s shape factor was determined using the L/d ratio, specifically for the symmetrical ellipsoidal shape. Employing Ansys Autodyn, a 3-dimensional finite element model (FEM) is created and calibrated using existing experimental findings from the literature. The validation utilized the Johnson–Cook (JC) and Johnson–Holmquist (JH-2) material models for both the targets and projectiles. These validated models are subsequently employed to analyze how the ellipsoid projectile’s shape and density influenced their interaction with the semi-infinite targets. Furthermore, the investigation also encompassed an analysis of the resulting crater shapes generated by the hypervelocity impact of both metallic and nonmetallic projectiles. It is observed that for a definite SF, max${}^m$ depth of penetration is observed due to steel project as compared to boron carbide and aluminum projectile. Both the diameter of the crater and the height of the bulge ($H_c)$ are directly proportional to the impact velocity and density of projectiles, and inversely proportional to SF. However, for a particular material and impact velocity of the projectile, in the case of $H_c$, there are no clear-cut observations displayed it seems like a mixed variation.

This paper presents three-dimensional computational simulations of the hypervelocity impact (HVI) using standard smoothed particle hydrodynamics (SPH). The classic Taylor-Bar-Impact test is revisited with the focus on the variation of results corresponding to the different model parameters in the SPH implementation. The second example involves both normal and oblique HVIs of a sphere on the thin plate, producing large deformation of structures. Based on original experimental results and some numerical results reported previously, some comparisons are also made, in the hope of providing informative data on appropriate SPH implementation options for the software being developed. The results obtained show that the current SPH procedure is well suited for the HVI problems.

Driven by applications in the design of protective structure systems, the need to model high velocity impact is becoming of great importance. This paper presents a Smoothed Particle Hydrodynamics (SPH) procedure for 3D simulation of high velocity impacts where high rate hydrodynamics and material strength are of great concern. The formulations and implementations of the Johnson–Cook strength and damage model considering temperature effect, and Mie–Gruneison and Tilloton equations of state are discussed. The performance of the procedure is demonstrated through two example analyses, one modeling a cubic tungsten projectile penetrating a multi-layered target panel and the other involving a sphere perforating a thin plate. The results obtained, with comparisons made to both experimental results and other numerical solutions previously reported, show that our SPH-3D implementation is accurate and reliable for modeling the overall behavior of the high rate hydrodynamics with material strength.

In this paper, we introduce a mesh-free computational model for the simulation of high-speed impact phenomena. Within the framework of particle dynamics simulations we model a macroscopic solid ceramic tile as a network of overlapping discrete particles of microscopic size. Using potentials of the Lennard–Jones type, we integrate the classical Newtonian equations of motion and perform uni-axial, quasi-static load simulations to customize our three model parameters to the typical tensile strength, Young’s modulus and the compressive strength of a ceramic. Subsequently we perform shock load simulations in a standard experimental setup, the edge-on impact (EOI) configuration. Our obtained results concerning crack initiation and propagation through the material agree well with corresponding high-speed EOI experiments with Aluminum Oxinitride (AlON), Aluminum Oxide $({\mathrm{\text{Al}}}_2{\mathrm{\text{O}}}_3)$ and Silicon Carbide (SiC), performed at the Fraunhofer Ernst-Mach-Institute (EMI). Additionally, we present initial simulation results where we use our particle–based model to simulate a second type of high-speed impact experiments where an accelerated sphere strikes a thin aluminum plate. Such experiments are done at our institute to investigate the debris clouds arising from such impacts, which constitute a miniature model version of a generic satellite structure that is hit by debris in the earth’s orbit. Our findings are that a discrete particle based method leads to very stable, energy-conserving simulations of high–speed impact scenarios. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.

Hypervelocity impact (HVI) of materials is usually associated with large deformations of structures, big craters, phase transition of materials and scattered debris cloud. It is difficult to predict the size of damage caused by HVI while comprehensively considering all the influencing factors for both experimental and numerical approaches. In this paper, the HVI process is modeled by using the smoothed particle hydrodynamics (SPH) method with Kernel Gradient Correction (KGC) technique. The SPH method with KGC (SPH-KGC) has been demonstrated to have better accuracy and reliability for modeling the HVI problems in our recent work. In this paper, the SPH-KGC method is used to investigate the HVI of a sphere on a target plate. The sizes of the craters produced by HVI at different initial impact velocities are obtained, and the variation of the crater size over the impact velocity is studied. According to the present simulation results, a critical velocity is identified and the increase of the crater size versus the initial impact velocity can be divided into two stages, a varying stage and a steady stage. A new empirical formula is presented for predicting the crater size of the target plate produced by HVI. This formula comprehensively considers the influence of many model parameters, such as the densities of the materials of both the projectile and the target, the sound speed of the target material, the diameter of the projectile and the thickness of the target plate. The results obtained by the presented prediction formula agree well with the experimental observations as well as the present SPH simulation results.

Analysis of two spaced aluminum plates against hypervelocity impact of a spherical aluminum projectile was performed to find an optimum thickness ratio of two plates. The smooth particle hydrodynamics (SPH) scheme used here is especially effective since the major features of debris clouds between two plates are successfully captured. For systematical analysis the extent of debris clouds is first correlated as a function of sphere diameter to front plate thickness ratio, with which a potential optimum front plate thickness range is identified. Then a critical sphere diameter causing failure of rear wall is examined while keeping the total thickness of two plates constant. In fact an optimum thickness ratio exists and is examined as a function of the size combination of the sphere diameter and plate thicknesses. The debris cloud expansion correlated optimum thickness ratio study provides a good insight on the hypervelocity impact onto spaced target system.

The deformation twinning model based on Field Theory of Multiscale Plasticity (FTMP) represents the twin degrees of freedom with the incompatibility tensor, which is incorporated into the hardening law of the FTMP-based crystalline plasticity framework. The model is further implemented into a finite element code. In the present study, the model is adapted to a single slip-oriented FCC single crystal sample, and preliminary simulations are conducted under static conditions to confirm the model's basic capabilities. The simulation results exhibit nucleation and growth of twinned regions, accompanied by serrated stress response and overall softening. Simulations under hypervelocity impact conditions are also conducted to investigate the model's descriptive capabilities of induced complex substructures composing of both twins and dislocations. The simulated nucleation of twins is examined in detail by using duality diagrams in terms of the flow-evolutionary hypothesis.