Oblique Hypervelocity Impact Research Articles

Jetting and shock wave during oblique hypervelocity impact of spherical projectile

Abstract Space debris impacts on whipped shields are dominantly non-vertical. During the initial impact stage of a projectile on a target, wave propagation and evolution occur in their interior with co-dominant material fragmentation. In this study, the effects of the impact conditions (impact velocity and attack angle) on the critical conditions for jet generation were examined based on the asymmetric jetting theory. In the geometric propagation model (GPM), the effect of the attack angle was considered, and a wave front deflection angle parameter was introduced. The modified GPM could describe the geometric features and position of a wave front during an oblique impact. Combined with smoothed particle hydrodynamics numerical simulations, the interior of projectiles, fragmentation features and pressure attenuation were studied. It was found that in large attack angle cases, the projectile material is more likely to reach the critical conditions for jet generation. The modified GPM is an oblique elliptic equation that is a function of the equivalent speed, impact velocity, attack angle, time and deflection angle. It may be applicable to hypervelocity events involving any monolithic material as long as the equivalent speed and deflection angle can be provided from numerical simulations. The impact conditions exhibit a quantitative relationship with the pressure attenuation in a projectile, among which the impact velocity has a more significant effect. This study established a quantitative analysis method for the initial impact stage of the oblique hypervelocity impact of a spherical projectile on a flat plate.

Numerical analysis of oblique hypervelocity impact damage to space structural materials by ice particles in cryogenic environment

A phase-aware constitutive model is developed and integrated with the meshfree simulations to study the failure mechanisms of space structural materials under the oblique hypervelocity impact of ice. The proposed constitutive model covers material’s dynamic behavior in a wide range of temperature, pressure, and strain rates. The numerical analysis combines the Hot Optimal Transportation Meshfree method with the EigenErosion algorithm to explicitly account for large deformation, brittle and ductile failure, phase transition, and debris cloud formation in the target materials and ice projectile. Specifically, the surface erosion and crater formation in the target under different impact speeds and angles are characterized by the damage’s shapes, depth, and length. The predicted crater depths in the Al6061 targets are validated by the Cour-Palais empirical model. It is evident that the damage to the space structural material by ice particles results from the competition between fracture, plasticity, and phase transition in the materials. The impact angle and velocity determine the crater deformation and the potential thread of the ejected debris.

Predicting the damage on a target plate produced by hypervelocity impact using a decoupled finite particle method

Hypervelocity impact (HVI) is associated with large deformations of structures, phase transitions of materials and scattered debris cloud. It is a great challenge to accurately model the HVI process and predict the damage produced by HVI for conventional numerical methods. In this paper, a recently developed corrective smoothed particle hydrodynamics (SPH) method, decoupled finite particle method (DFPM), is extended to model HVI problems. Validation examples show that DFPM is as flexible as SPH while having much better performance in improving accuracy and removing tensile instability. DFPM is also very attractive for modeling problems with extremely disordered particle distribution (e.g., HVI) as no matrix inversion is required. DFPM is then applied to model the penetration of a sphere on a target plate at various impact velocities and impact angles. It is found that as the impact velocity increases, the hole size increases accordingly and maintains basically constant in a steady state after the impact velocity reaches a critical value. Based on extensive DFPM simulation results, novel formulae are given for predicting the hole size produced by normal and oblique HVIs, which can reproduce experimental data and shows better performance than existing empirical formulae in a wider range of impact velocity.

Numerical Simulation of Projectile Oblique Impact on Microspacecraft Structure

In the present study, the microspacecraft bulkhead was reduced to the double honeycomb panel, and the projectile oblique hypervelocity impact on the double honeycomb panel was simulated. The distribution of the debris cloud and the damage of a honeycomb sandwich panel were investigated when the incident angles were set to be 60°, 45°, and 30°. The results showed that as incident angle decreased, the distribution of debris cloud was increased gradually, while the maximum perforation size of the rear face sheet was firstly increased with the decrease of the incident angle and then decreased. On the other hand, the damage area and the damage degree of the front face sheet of the second honeycomb panel layer were increased with the decrease of the incident angle. Finally, the critical angle of front and rear face sheets of the honeycomb sandwich panel was obtained under oblique hypervelocity impact.

The Expansion Model of Debris Cloud Induced by Oblique Hypervelocity Impact

Abstract For describing the dynamic evolution of debris cloud formed in oblique hypervelocity impact, a model (expressed in polar coordinates) for the shape, the velocity distribution and the mass distribution is developed according to the results of experiments and numerical simulation, and parameters of the Model are identified by nonlinear integral equations which are derived from mass conservation law and energy conservation law. Afterwards, the model has been verified by another simulation code.

OS0116 超高速斜め衝突時のクレータおよびエジェクタ形状(OS1-4 材料特性評価,OS-1 実験力学と計測技術2)

OS0116 超高速斜め衝突時のクレータおよびエジェクタ形状(OS1-4 材料特性評価,OS-1 実験力学と計測技術2)

Numerical Analysis for the Expansion of Debris Cloud Induced by Oblique Hypervelocity Impact

Article Numerical Analysis for the Expansion of Debris Cloud Induced by Oblique Hypervelocity Impact was published on January 1, 2009 in the journal International Journal of Nonlinear Sciences and Numerical Simulation (volume 10, issue 1).

Experimental study on expansion characteristics of debris clouds produced by oblique hypervelocity impact of LY12 aluminum projectiles with thin LY12 aluminum plates

Abstract Tests of hypervelocity projectile impacts to a double-wall structure made of LY12 aluminum were performed using a two-stage light gas gun. In the bumper plate hole analysis, empirical equations that relate hole dimensions to impact parameters such as velocity, angle of obliquity and bumper plate thickness are obtained. The laser shadowgraphs in order to get the expansion of debris clouds were taken and the characteristic parameters obtained. The damage effects of the back wall varying with impact parameters were studied. The expansion of debris clouds was determined.

Characterizing Debris Clouds Created in Oblique Orbital Debris Particle Impact

The problem of pollution within Earth’s orbital environment has gained considerable recognition over the past decades. Determining adequate passive protection schemes is an unending process that attempts to meet different objectives for widely varying types of missions. Significant amounts of resources have been expended toward development of numerical and analytical models that model the response of a variety of target systems under high-speed orbital debris impacts. The objective of the study whose results are presented herein was to improve upon an existing oblique hypervelocity impact model that characterizes the various secondary debris clouds created in such an impact. This was accomplished by reducing the model’s dependence on empirical user-defined parameters and by correcting an error in one of its equations. Predictions of the improved model are compared with numerical simulations generated during previous impact studies under comparable conditions. It is found that the improved model does a reasonable job of predicting the characteristics of the secondary debris clouds created in an oblique hypervelocity impact.

Normal and oblique hypervelocity impacts on carbon fibre/peek composites

A series of normal and oblique hypervelocity impact tests were performed on carbon fibre/PEEK composite specimens using the Light Gas Gun facilities at the University of Kent at Canterbury. The tests were conducted on 16 ply and 24 ply targets, using 1 mm and 2 mm aluminum projectiles, at velocities of approximately 5 km/s, and at impact angles of 0, 30 and 45 degrees. The primary objective of this investigation was to add oblique impact data to the University of Toronto Institute for Aerospace Studies (UTIAS) database on hypervelocity impact damage to composites. The parameters investigated in this study were debris cloud (primary and secondary) dispersion cone angles, (equivalent) entry and exit crater diameters, and front and rear surface delamination damage zones. The results of the analysis showed that the cone angles were not symmetric about the projectile velocity vector, maxima for both angles occurring at a normalized energy of approximately 55 J, followed by an asymptotic decrease. The results obtained for the entry crater diameter and equivalent entry damage diameter were found to be in good agreement with the existing UTIAS database. For a given impact energy, the damage area in the 24 ply targets was found to be nearly twice that of the damage in the 16 ply targets. Results were found to be in good agreement when compared, using an empirical equation, to predictions of impact damage of Al projectiles on aluminum targets (when a scaling factor of 0.9 was applied to the PEEK data to account for the greater damage in composites).

Energy based particle hydrodynamics for hypervelocity impact simulation

Hamiltonian mechanics provides a simple, systematic, energy based approach to the formulation of particle models for hypervelocity impact simulation. The methodology may be applied to particle models based either on mass points which define moving interpolations or on physical particles described by Lagrangian control volumes. Implementation of the method in a three dimensional computer code allows for the simulation of oblique hypervelocity impact on multi-plate orbital debris shield designs.

Ricochet of deforming projectiles from deforming plates

Ricochet means rebound of a striker from the impacted surface (or penetration into a medium along a curved trajectory emerging through the impacted surface with a residual velocity). Changes in direction, velocity and rotational motion of the penetrator are due to several mechanisms. These include release of stored elastic impact energy; influence of surfaces, material interfaces and impact deformations in the target on the magnitude and direction of the resisting force during impact; resistance to motion due to drag and friction. The subject is of interest due to the need to establish safety zones and to design containment structures to guard against failure of rapidly moving machine parts, to protect outer components of space vehicles from the energetic debris spray resulting from oblique hypervelocity impact and to reconstruct bullet trajectories in forensic engineering. This paper contrasts two-dimensional plane strain calculations of ricochet with fully three-dimensional simulations performed with Apollo, a three-dimensional Lagrangian finite element code for impact and explosive loading problems set up exclusively on personal computers and workstations. While some useful information can be extracted from plane strain calculations regarding the early stages of impact, the use of two-dimensional calculations to simulate fully three-dimensional phenomena with long response times (up to the millisecond regime) results in gross overestimation of deflections and is inherently dangerous.

Analysis of the Solwind Fragmentation Event Using Theory and Computations

The planned fragmentation of the Solwind satellite in an antisatellite experiment is analyzed from the radar data on the fragments obtained following the experiment. The orthogonal components of the velocity perturbations received by the fragments are calculated, and the angular distributions of the fragments obtained. Groups of three or four fragments having similar velocity changes most likely originated from adjacent parts of Solwind or the antisatellite, and this episode may be an example of sequential fragmentation in space. The angular distribution of the fragments shows a primary and a secondary area of concentration of the fragments, the former possibly indicating the exit area of the antisatellite fragments. Three fragments thrown out with extremely large velocity boosts in the forward direction were objects of much speculation. The possibility that these represented ricochet ejecta resulting from oblique hypervelocity impact between Solwind and the antisatellite is discussed. The velocity of the antisatellite at the moment of impact is estimated to have been near 1 km/s. The angles of encounter, impact, and ricochet are defined and determined. The observed angle between the antisatellite and the ricochet fragments suggests that incidence near 45 deg was possible. The significantly higher ricochet speeds compared with the relative speed between the target and the projectile are consistent with computational results obtained from Lagrangian and Eulerian hydrocodes. The evidence strongly points to the possibility that the three objects were actually ricochet material produced by oblique hypervelocity impact in space.

Oblique hypervelocity impact simulation for whipple shield-protected structures

Three dimensional simulation of hypervelocity impacts on space structures places extreme demands on even supercomputer resources. This is due in large part to the fact that conventional Eulerian and Lagrangian codes are ill-suited to model debris cloud evolution. To reduce the computer time and memory requirements of oblique impact simulations, a three-dimensional elastic-plastic particle dynamics model of debris cloud evolution has been developed. This numerical model has been linked to an Eulerian hydrocode and a Lagrangian structural code, and applied in the simulation of oblique hypervelocity impacts on Whipple shield-protected structures.

Debris fragment characterization in oblique hypervelocity impacts

A case history in debris characterization is presented for oblique impacts of chunky tungsten projectiles against thin plates. The integrated approach of scaled experiments and hydrocode simulations led to a semi-analytic model of behind the plate debris fragment distributions. This debris distribution model agreed quite well with the experimental fragment distributions derived from witness plate measurements. The 1 4 scale test program included three projectile masses, two target geometries (single and dual plates), a velocity range of 4–7 km/s and a strike angle range of 15–55 degrees. Close correlation of measured and predicted fragment distributions encouraged the extension of the model to higher velocities not currently obtainable in the laboratory. The paper also includes discussions of critical features of debris in oblique hypervelocity impact, the scalability of fragment data, and the utilization of the derived fragment models in semi-analytic damage assessment codes.

An analytical model of hole size in finite plates for both normal and oblique hypervelocity impact for all target thicknesses up to the ballistic limit

This paper presents, for the first time, a single comprehensive analytical model for the hole size produced by hypervelocity impact into finite plates. This model is based on experimental data for 2017 aluminum spheres impacting 2014, 2024 and 6061 aluminum plates. The significance of this model is that it spans the entire range of target thickness from very thin to very thick, which makes it possible to determine when the impact conditions are those of thin target behavior (where the hole size increases with increasing target thickness and debris formation and damage is important) and when the impact conditions are those of thick target behavior (where the hole size decreased with increasing target thickness and the debris formation is significantly decreased). The model makes it clear that the target thickness that divides the thin target regime from the thick target regime is a function of velocity. This means that an impact configuration which exhibits thick target behavior at common experimental velocities could actually exhibit thin target behavior at velocities in the tens of kilometers per second such as that of meteroid impacts. This hole size model also includes the effects of oblique impact and computes both the major and the minor diameters of the hole. This paper also raises, for the first time, the possibility that the commonly accepted models for crater diameter (and by implication those for penetration depth as well), which are taken to be a power function of velocity, might be wrong. Only a linear dependence on velocity for the crater diameter is consistent with the linear velocity dependence of this and all other accepted models of hole diameter in finite plates. If this is correct, it would raise questions about the validity of using any target damage computer models, that are based on the old crater modeling equations, to extrapolate to higher velocities.

Spacecraft wall design for increased protection against penetration by orbital debris impacts

All orbiting spacecraft are susceptible to impacts by meteoroids and pieces of orbital 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. The design of a spacecraft for a long-duration mission into the meteoroid and space debris environment must include adequate protection against perforation of pressurized components by such impacts. This paper presents the results of an investigation into the perforation resistance of dual-wall structural systems fabricated with monolithic bumper plates and with corrugated bumper plates of equal weight. A comparative analysis of the impact damage in dual-wall systems with corrugated bumper specimens and that in dual-wall specimens with monolithic bumpers of similar weight is performed to determine the advantages and disadvantages of employing corrugated bumpers in structural wall systems for long-duration spacecraft. The analysis indicates that a significant increase in perforation protection can be achieved if a monolithic bumper is replaced by a corrugated bumper of equal weight. The parameters of the corrugations in the corrugated bumper plates are optimized in a manner that minimizes the potential for the creation of ricochet debris in the event of an oblique hypervelocity impact. Several design examples using the optimization scheme are presented and discussed.

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.

Penetration and ricochet phenomena in oblique hypervelocity impact

An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectile on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.