Hypervelocity Projectile Impact Research Articles

Impact resistance of single-layer metallic glass nanofilms to high-velocity micro-particle penetration

Macro- and microscale metallic glasses exhibit excellent protective capability under hypervelocity projectile impact conditions. However, it is formidably challenging to evaluate the ballistic performance of metallic glasses with characteristic sizes down to the nanoscale. Here, we adopt the laser-induced micro-particle impact technique to penetrate 60-nm-thick Ni60Ta40 metallic glass nanofilms with projectile velocities in the range of 186–540 m/s. Based on the ballistic analysis, the superior impact resistance of the metallic glass nanofilms is quantitatively characterized in terms of the specific penetration energy. The post-mortem observations of the penetration features reveal that shear-banding, cracking, and bending of cracking-induced petals are the main energy dissipation modes beyond the localized perforated hole, which is strongly dependent on impact velocities. This work for the first time achieves high-strain-rate loading on nanoscale metallic glasses, and extends their engineering applications as promising armor materials for high-velocity impact protection.

Ballistic performance of multi-layered aluminium and UHMWPE fibre laminate targets subjected to hypervelocity impact by tungsten alloy ball

Multi-layered structures have been widely used in defence, marine, aerospace and automotive engineering. It is radical to comprehend the dynamic response of such structures under impact loadings and to design optimal structures to resist ballistic penetration. In this study, hypervelocity projectile impact experiments were conducted to explore the penetration resistance of spaced multi-layered aluminium and ultra-high molecular weight polyethylene (UHMWPE) fibre laminate targets. Experimental results including crater diameter, depth of penetration (DOP) and energy absorption capacity of multi-layered targets were measured and then discussed, from which it was evident that the combined use of aluminium and UHMWPE fibre laminates was the most effective in resisting projectile impact considering both the dynamic performance and light weight. Based on the validated simulation models, further parametric studies were conducted to investigate the effect of air space between adjacent layers, number and order of layers on the ballistic performance of multi-layered aluminium and UHMWPE fibre laminate targets.

Atomistic damage mechanisms during hypervelocity projectile impact on AlN: A large-scale parallel molecular dynamics simulation study

Atomistic mechanisms of damage initiation during hypervelocity (15 km/s) impact on an AlN coating is investigated using parallel molecular-dynamics simulations involving 209 million atoms. On impact a strong shock wave is generated, which then splits into an elastic precursor and a structural phase transformation (SPT) waves, the latter driving a wurtzite to rocksalt structural transition. During its development, the SPT wave induces plastic processes in the intact wurtzite material, which in turn facilitate the nucleation and growth of brittle cracks. Specifically, the interface between the transformed (rocksalt) and untransformed (wurtzite) regions acts as a source of nanocavities and kink bands. They further interact with stress release waves reflected from the back surface and create cracks in mode I, from the nanocavities, and in mode II, from the kink band superdislocation boundary. Stresses are evaluated using a stoichiometric-preserving formula for virial local averages on inhomogeneous binary systems. Defects are analyzed using shortest-path ring statistics.

Dynamic expansion of a spherical cavity within a rate-dependent compressible porous material

The problem of shock expansion of cavities in geological or geologically derived media is of fundamental interest because it is closely related to the blast problem (propagation of waves from an explosion source) as well as to crater formation by hypervelocity projectile impact. Since rock and cementitious materials exhibit very strong high-rate and high-confinement sensitivities, those effects cannot be neglected in a realistic analysis of penetration events. In this paper a new model for the shock expansion of a spherical cavity in an infinite medium that displays very strong high-rate and high-confinement sensitivities is proposed. Waves are generated by an instantaneous rise of the pressure at the surface of the cavity. A complete description of the motion of the medium situated between the cavity and the shock wave as well as the distribution of stresses and deformation as functions of time and distance from the center of the cavity is obtained. Specifically, we provide a description of the dynamic compaction of the material, we determine the extent of the domain affected by the dynamic event and the moment at which the influence of the pulse on the medium ceases. A compressible zone develops as a continuation of the incompressible one. The solutions are proved to be compatible with the Rankine–Hugoniot shock conditions. We conclude with an application of the proposed model to concrete.

Quantitative analysis of debris clouds from SiC-fiber-reinforced silicon nitride bumpers

In order to investigate the dynamic response of lightweight ceramic matrix bumpers against hypervelocity projectile impact, silicon carbide continuous-fiber-reinforced silicon nitride matrix composite plates were prepared and subjected to the impact experiments using duralumin projectiles in the velocity range of 2.2 to 3.6 km/s. The debris clouds of the composites were taken by flash, soft X-ray radiography, and the fragmentation of the bumpers and the spatial distribution of the main parts of the debris clouds were quantified in mass, velocity and kinetic energy and compared with those of monolithic duralumin bumpers and monolithic silicon nitride ceramic bumpers. Almost all the average mass and kinetic energy of the in-flight fragments of the composite were smaller than those of the duralumin and monolithic ceramics. The composite provided thinner distributions of the mass and kinetic energy densities of its debris in an area extending farther from the ballistic line for higher impact velocity, while the monolithic ceramics gave massive and energetic debris distributions in a narrow area around the ballistic line. Total mass and kinetic energy of the composite debris were smaller than those of the duralumin, and for impacts over 3 km/s the volumetric energy density of the composite debris was comparable to that of the duralumin. Embedding the fibers to a ceramic matrix was thought to give the composite the heterogeneous microstructure to result in a non-uniform dynamic response of the composite, followed by the bumper fragmentation and the debris dispersion.

Measurement of stress wave asymmetries in hypervelocity projectile impact experiments

Asymmetries in both structure and ejecta are observed around a number of craters on planetary surfaces. Similar asymmetries have been documented for hypervelocity impact experiments. Such asymmetries arise from the stress front developed around oblique impacts. The onset angle for asymmetric stress distributions indicates that geologic asymmetries should be present in a significant fraction of impact structures.

Damage of aluminum borate whisker reinforced 6061 aluminum composite under impact of hypervelocity projectiles

An aluminum borate whisker reinforced 6061 aluminum composite (AlBO w/6061Al) semi-infinite target was impacted by hypervelocity projectiles with velocity of 2.1 km s −1. The results showed that a columned crater with hemispherical bottom was formed. The crater formed on the AlBO w/6061Al composite is much smaller than that on the 6061 aluminum alloy target. Spallation occurred along the edge of the crater on the composite target, and some whiskers were pulled out in the vicinity of the crater, severely compressed deformation of the composite material occurred and the whiskers were obviously smashed into smaller particles. Due to the acute damage caused by hypervelocity projectile impact, the micro-hardness is lower in the areas near crater than that far away from the crater.

Micro-damage of Ti–6Al–4V alloy under hypervelocity projectile impact

The micro-damage of Ti–6Al–4V alloy under high velocity projectile impact was studied. The results show that adiabatic shear bands are very easy to form in the target material and primarily distribute in the area adjacent to the crater. The voids and micro-cracks are formed in the adiabatic shear bands during the impact process. The formation of adiabatic shear bands is discussed.

Protecting spacecraft against orbital debris impact damage using composite materials

All earth-orbiting spacecrafts are susceptible to impacts by meteoroids and pieces of orbital debris. These impacts occur at extremely high speeds and can damage flight-critical systems, which can in turn lead to catastrophic spacecraft failure. With the advent of many new high-strength composite materials and their proliferation in aircraft applications, it is necessary to evaluate their potential for use in long-duration space and aerospace structural systems. This paper presents the results of several experimental investigations in which several different composite materials were tested for their ability to prevent the perforation of the inner walls in multi-wall systems subjected to hypervelocity projectile impact. Damage to multi-wall systems that employ composite materials is compared to damage in traditional all-aluminum multi-wall structures of similar geometry and weight under similar impact conditions. The advantages and disadvantages of using composite materials in perforation-resistant multi-wall structures are presented and discussed. The analyses performed show that the effectiveness of multi-wall systems with composite materials varies significantly depending upon the location within the multi-wall system of the composite materials. Based on the results obtained, it appears that composite materials are most effective when used as the middle wall of a triple-wall system.

Analytical hole diameter and crack length models for multi-wall systems under hypervelocity projectile impact

Summary All long-duration spacecraft in low-earth-orbit are subject to high-speed impacts by meteoroids and orbital debris. In the event of a perforation, the pressure wall of a dual-wall structure impacted by a high-speed particle can also experience cracking and petaling. If such cracking were to occur on-orbit, unstable crack growth could develop which could lead to an unzipping of the impacted spacecraft module. This paper presents a summary of the development of a first-principles-based crack length and hole size model for a spacecraft module pressure wall that has been perforated in an orbital debris particle impact Predictions of the crack length model are compared with experimental data. Modifications to the model that are required to bring its predictions in closer agreement with the experimental results are then presented and discussed.

Hole size and crack length models for spacecraft walls under oblique hypervelocity projectile impact

All long-duration spacecraft in low-earth-orbit are subject to high speed impacts by meteoroids and orbital debris. In the event of a perforation, the pressure wall of a dual-wall structure impacted by a high-speed particle can also experience cracking and petalling. If such cracking were to occur on-orbit, unstable crack growth could develop which could lead to an unzipping of the impacted spacecraft module. The analysis presented in this paper extends the applicability of a crack length and hole size model developed previously for a normally impacted spacecraft wall to the case of obliquely incident particles. Predictions of the oblique impact model are compared with experimental data and the predictions of empirical hole size and crack length models. Modifications to the model that are required to bring its predictions in closer agreement with the experimental results are then presented and discussed.

Fragmentation and dispersion of aluminum nitride ceramic plates by hypervelocity impact

The present paper describes the fragmentation and dispersion of aluminum nitride ceramic plates by a hypervelocity projectile impact. A manganese aluminide spherical magnet was used as a projectile, with a diameter of 1 mm; it was accelerated by a so-called “micro” two-stage light gas gun in the velocity range of 3–4 km/s. The fragmentation of aluminum nitride plates was evaluated by characterizing the distribution of fragments produced downrange behind the target plate. This fragmentation was then compared with that of aluminum alloy plates. In particular, ring-type distributions of fragments were found in the fragmentation of aluminum nitride ceramic plates.

Empirical hole size and crack length models for dual-wall systems under hypervelocity projectile impact

This paper presents the results of a study whose objective was to develop empirical equations to characterize the hole formation and cracking phenomena associated with the penetration of some of the multi-wall systems being considered for the International Space Station Alpha. The significance of the work performed is that these equations can be used in a survivability analysis to determine whether or not module unzipping would occur under a specific set of impact conditions and the time available for module evacuation prior to the onset of incapacitation due to air loss. The correlation coefficients for the equations obtained exceeded 0.8 in most cases; hence, it is believed that the equations developed have a rather good fit to the experimental data.

Response of space structures to orbital debris particle impact

All long-duration space and aerospace and transportation systems, such as the Space Station Freedom and the Space Shuttle, are susceptible to impacts by pieces of orbital debris. These impacts occur at high speeds and can damage the flight-critical systems of such spacecraft. Therefore, the design of a structure that will be exposed to a hazardous orbital debris environment must address the possibility of such hypervelocity impacts and their effect on the integrity of the entire structural system. A technique is developed for analyzing the response of dual-wall structures to oblique Hypervelocity projectile impact. Ballistic limit curves that predict the potential of an impacting projectiles to perform the main wall of a dual-wall strucutral system are obtained using the techniques and are compated against experimentally derived curves. Comparisons are performed for a variety of impact velocities, trajectory obliquities and projectile masses. It is shown that the results obtained using the technique developmed herein compare very well with experimetanl results.

Projectile Shape and Material Effects in Hypervelocity Impact Response of Dual‐Wall Structures

All large spacecraft are susceptible to impacts by meteoroids and pieces of orbiting space debris. These impacts occur at extremely high speeds and can damage flight‐critical systems, which can in turn lead to catastrophic failure of the spacecraft. A long‐duration spacecraft developed for a mission into this environment must include adequate protection against perforation of pressurized components by such impacts. This paper presents the results of an investigation into the effects of projectile shape and material on the perforation of aluminum dual‐wall structural systems. Impact damage is characterized according to the extent of perforation, crater, and spall damage in the structural systems as a result of hypervelocity projectile impact loadings. Analysis of the damage data shows that there are distinct differences in impact damage from cylindrical and sherical projectiles. Projectile density is also found to affect the type and extent of damage sustained by dual‐wall structural systems.

Use of composite materials in multi-wall structures to prevent perforation by hypervelocity particle impact

All earth-orbiting spacecraft are susceptible to impacts by meteoroids and pieces of orbital debris. These impacts occur at extremely high speeds and can damage flight-critical systems, which can in turn lead to catastrophic failure of the spacecraft. The design of a spacecraft for an earth-orbiting mission must take into account the possibility of such impacts and their effects on the spacecraft structure and on all of its exposed subsystem components. This paper represents the results of an experimental investigation in which several different composite materials are tested for their ability to prevent the perforation of the pressure walls in multi-wall systems subjected to hypervelocity projectile impact. The damage in the composite material specimens is also compared to the damage in aluminum specimens of similar geometry and weight caused by hypervelocity projectiles with similar impact energies. The analysis shows that using composite materials in combination with metallic materials in multi-wall structures can increase the protection afforded a spacecraft against perforation by orbital debris particles over that provided by traditional, purely metallic double-wall structures.

Response of spacecraft window materials to hypervelocity projectile impact

This paper presents the results of an investigation of the response of window materials to hypervelocity projectile impact. Window impact damage is characterized according to the nature and extent of surface and internal damage. Analysis of the test data indicates that, for single-pane specimens, the extent of the damage to the test specimens can be written as functions of the impact parameters of the original projectile and the geometric and material properties of the projectile/ window system. These functions can be used to perform parameter-sensitivity studies and to evaluate hypothetical design applications and configurations.

Hypervelocity Impact Penetration Phenomena in Aluminum Space Structures

All long‐duration spacecraft are susceptible to high‐speed impacts by meteoroids and pieces of orbiting space debris. Damage to critical spacecraft systems caused by such impacts can lead to spacecraft failure and loss of life. In order to develop adequate protection against penetration for crew compartments and other critical spacecraft systems, an aerospace design engineer must possess a full understanding of the penetration mechanics involved in the hypervelocity impact loading of a variety of structural components. This paper describes the results of an experimental investigation of the penetration phenomena associated with oblique hypervelocity projectile impact of aluminum dual‐wall structures. Equations that quantitatively describe these phenomena are obtained through a regression of hypervelocity impact test data. These equations characterize observed penetration phenomena as functions of the geometric and material properties of the impacted structure and the diameter, obliquity, and velocity of the impacting projectile. A review of the test data shows that oblique hypervelocity impact penetration phenomena are strongly dependent on impact obliquity and therefore can differ significantly from those associated with normal high‐speed impacts. It is concluded that the possibility of non‐normal impacts and their effects on structural integrity must be considered in the design of any structure that is to be exposed to the hazardous meteoroid and space debris environment.

Hypervelocity impact response of spaced composite material structures

The design of a spacecraft for a long-duration mission must take into account the possibility of high-speed impacts by meteoroids and orbiting space debris and the effects of such impacts on the spacecraft structure. With the advent of many new high-strength composite materials and their proliferation in aircraft applications, it has become necessary to evaluate their potential for use in long-duration space and aerospace structural systems. One aspect of this evaluation is the analysis of their response to hypervelocity projectile impact loadings. The analyses performed in this study indicate that the extent of damage to a dual-wall composite structure can be written as a function of the geometric and material properties of the projectile/structure system. A comparative analysis of impact damage in composite specimens and in geometrically similar aluminum specimens is also performed to determine the advantages and disadvantages of employing certain composite materials in the design of structural wall systems for long-duration spacecraft.

A simple defense conservative model for mass requirements of hypervelocity projectile impact shields for reentry vehicles

Simple analytical modeling of the physics of interaction of hypervelocity (50–100 km/s) projectiles with a bumper shield countermeasure is given. The interaction of projectile and bumper is discussed briefly. Expansion of bumper/projectile debris in the region between bumper and underlying vehicle and interaction of bumper/projectile debris cloud with vehicle are examined. Expansion of debris is treated as an expansion superimposed upon a translation with partition derived from a simple inelastic collision model. The effect of nonunity aspect ratio of compressed debris is included. Debris colliding elastically with the vehicle will impart momentum equal to twice the incident normal component. A steady-state diffusion model is used to estimate the effect of stagnation radiative loss on collision elasticity. Impulse may be reduced up to a factor of 2 by stagnation radiative losses for small projectiles and large bumper/vehicle stand-off. Stagnation radiation loss is small for larger projectiles and smaller stand-off. Impulse can be enhanced by vehicle ablation from radiative coupling, shock heating (inadequate stand-off), or liquid droplet microcratering (inadequate bumper thickness). Estimates of required bumper mass are given for a specific example.