Momentum Enhancement Simulations for Hypervelocity Impacts on Sandstone

2020 ◽  
Author(s):  
Sidney Chocron ◽  
James Walker ◽  
Donald Grosch ◽  
Stephen Beissel ◽  
Daniel Durda ◽  
...  

<p>Two NASA missions that will be launched in 2022 have spun renewed interest in hypervelocity impact of  rocks and metals. This work focuses on the prediction of the momentum enhancement effect, i.e. the extra momentum acquired by the target due to the ejecta flying off the target in the direction of the impactor. Predicting the momentum enhancement with simulations has been elusive, probably because the target material is rarely well characterized. This presentation shows that, given a good knowledge of the properties of the target material and, by adding two essential pieces of the physics (strength of failed material and bulking after failure), the computer simulations can provide good predictions of the momentum enhancement for hypervelocity impact tests performed at Southwest Research Institute.</p>

Author(s):  
M. Ganser ◽  
B. van der Linden ◽  
C. G. Giannopapa

Hypervelocity impacts occur in outer space where debris and micrometeorites with a velocity of 2 km/s endanger spacecraft and satellites. A proper shield design, e.g. a laminated structure, is necessary to increase the protection capabilities. High velocities result in massive damages. The resulting large deformations can hardly be tackled with mesh based discretization methods. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless scheme, can resolve large topological changes whereas it still follows the continuous formulation. Derived by variational principles, SPH is able to capture large density fluctuations associated with hypervelocity impacts correctly. Although the impact region is locally limited, a much bigger domain has to be discretized because of strong outgoing pressure waves. A truncation of the computational domain is preferable to save computational power, but this leads to artificial reflections which influence the real physics. In this paper, hypervelocity impact (HVI) is modelled by means of basic conservation assumptions leading to the Euler equations of fluid dynamics accompanied by the Mie-Grueneisen equation of state. The newly developed simulation tool SPHlab presented in this work utilizes the discretization method smoothed particle hydrodynamics (SPH) to capture large deformations. The model is validated through a number of test cases. Different approaches are presented for non-reflecting boundaries in order to tackle artificial reflections on a computational truncated domain. To simulate an HVI, the leading continuous equations are derived and the simulation tool SPHlab is developed. The method of characteristics allows to define proper boundary fluxes by removing the inwards travelling information. One- and two-dimensional model problems are examined which show excellent absorption behaviour. An hypervelocity impact into a laminated shield is simulated and analysed and a simple damage model is introduced to model a spallation failure mode.


Author(s):  
Alfred E. Crouch ◽  
G. Graham Chell

The only in-line inspection technology commercially available for quantitative evaluation of gouged dents is the geometry pig which cannot discriminate between gouged and smooth dents and has no sensitivity to re-rounded dents. Southwest Research Institute® (SwRI®), has been funded by the US Pipeline and Hazardous Materials Safety Administration (PHMSA) and the Gas Research Institute (GRI) through the Pipeline Research Council International (PRCI), to determine the capability of the nonlinear harmonic (NLH) method to characterize the severity of gouged dents, including those that have been re-rounded by internal pressure. This paper describes the NLH method and presents a summary of results from previous work involving burst tests of gouged dents in 24” pipe as a precursor to the current work that involves experiments with four pressure chambers made from 12-inch line pipe under cyclic pressure changes. In each case, internal scanner hardware, driven from outside the pipe, deployed NLH probes against the pipe inner surface, the gouges being on the outer surface. Analysis of the mapped NLH signals on the inner pipe surface revealed residual strain patterns in the pipe and the strain anomalies produced by gouging. The strain anomalies clearly indicated the presence of the gouges on the outside surface, even when they had re-rounded. The signal maps also indicated the length and width of the gouges whereas the signal strength indicated the residual depth. Data are presented showing that the NLH method is capable of ranking the severity of pipeline gouged dents and their propensity for failure under cyclic loading.


2012 ◽  
Author(s):  
Erik Wilkinson ◽  
Michael Vincent ◽  
Christopher Kofoed ◽  
John Andrews ◽  
Judith Brownsberger ◽  
...  

2013 ◽  
Vol 834-836 ◽  
pp. 825-828
Author(s):  
Jun Yin ◽  
Yu Wang Yang ◽  
Xia Yun Hu ◽  
Cheng Cheng Yong

For almost all materials the hypervelocity regime has been reached when the impact speed above 2 km/s. A double-barreled two-stage light gas gun (TSLGG) system used for the hypervelocity impact tests is described. The proposed TSLGG can accelerate 50 g projectile masses up to velocities of 2.2 km/s. The craters produced with this equipment reach a diameter of up to 20 cm, a size unique in laboratory cratering research. The experiment results show our TSLGG system work effectively, velocity of the projectile mass is measured highly accurate by means of the proposed optical method.


1995 ◽  
Vol 1995 (1) ◽  
pp. 279-285
Author(s):  
David L. Gray ◽  
Johan H. de Jong

ABSTRACT The second part of the Prince William Sound Disabled Tanker Towing Study was undertaken to evaluate, using computer simulations, the capability of existing escort vessels in Prince William Sound, Alaska, and to examine alternatives that could enhance escort and rescue towing capabilities. The study was undertaken by The Glosten Associates, Inc., the Maritime Simulation Centre the Netherlands, and the Maritime Research Institute Netherlands on behalf of the Disabled Tanker Towing Study Group. A brief discussion of the project background, methodology, and results is contained herein.


Author(s):  
Andrew Thurber ◽  
Javid Bayandor

The increased frequency of exploration into space has caused a dramatic rise in the density of debris in orbit. Orbital debris, both natural and man-made, poses an extreme impact risk to satellites and spacecraft. The relative velocities between orbital components and debris can exceed thousands of meters per second, giving rise to immense kinetic energies even for small objects. In such a hypervelocity impact event, the shock pressures exceed the strength of common aerospace materials, and brief shock-induced temperature rises cause melting and vaporization of most structural bodies. Under these extreme conditions, the failure and deformation of solids can resemble fluid flow. By using meshless Lagrangian models in an explicit computational framework, this work identifies analogous fluidic interactions and further quantifies the role of shear and inertial forces in hypervelocity impacts (HVI).


2008 ◽  
Vol 385-387 ◽  
pp. 201-204
Author(s):  
Gong Shun Guan ◽  
Bao Jun Pang ◽  
Run Qiang Chi ◽  
Nai Gang Cui

In order to study the hypervelocity impact of space debris on spacecraft through hypervelocity impact on aluminum alloy multi-wall structure, a two-stage light gas gun was used to launch 2017-T4 aluminum alloy sphere projectiles. The projectile diameters ranged from 2.74mm to 6.35mm and impact velocities ranged from 1.91km/s to 5.58km/s. Firstly, the advanced method of multi-wall shield resisting hypervelocity impacts from space debris was investigated, and the effect of amount and thickness of wall on shield performance was discussed. Finally, by regression analyzing of experiment data, the experience equations for forecasting the diameter of the penetration hole on the first wall and the diameter of the damaged area on the second wall of aluminum multi-wall shield under hypervelocity normal impact of Al-spheres were obtained. The results indicated that the performance of multi-wall shield with more amount of wall is excellent when area density is constant. At the same time, intensity of the first wall and protecting space play the important roles.


Author(s):  
Andrew Thurber ◽  
Javid Bayandor

Satellites and spacecraft in orbit can impact micrometeorites and other debris at velocities exceeding thousands of meters per second. The shock pressures and temperatures created by these hypervelocity impacts greatly surpass standard material strengths, and deform structures in unconventional failure modes. Under these extreme conditions and strain rates, plastic deformation of a solid can resemble viscous fluidic motion. Using meshless finite element analysis methods, the present research attempts to quantify this fluidic structural response and identify analogous interactions in fluid dynamics.


Sign in / Sign up

Export Citation Format

Share Document