Numerical Simulation of Hypervelocity Impact on Mesh Bumper Causing Fragmentation and Ejection

With the continuous increase of centimeter-scale space debris, the exploration and design of new high-performance shields has become an urgent need. Based on the shield of active materials, the hypervelocity impact experiments with different projectile sizes and impact velocities were carried out by using a two-stage light gas gun. The image characteristics of debris clouds under different impact conditions were obtained and analyzed by laser shadowgraph photography. The damage characteristics of the rear wall of the active Whipple shield were studied. Through the statistical analysis of the number of craters, the influences of active materials on the fragmentation of projectiles under different impact velocities were obtained. Compared with the classical Christiansen ballistic limit equation, the protective performance of energetic active material shield was obtained, and the ballistic limit curve of the new shield was fitted. Analysis suggests that shock initiation characteristics of active materials under impact enhanced the shield performance. When impacted by the space debris, active material shield firstly uses its mechanical strength for primary crushing. During this process, the energetic material shield has an explosive reaction with an instantaneous temperature being as high as 3 800 K, which can promote fragmentation, melting and reduce the size of the space debris. At the same time, the explosion products with high temperature, pressure and high speed motion produce a negative acceleration to the projectile fragments, reducing the axial kinetic energy. The explosion products of the active materials are mostly gaseous, which greatly reduce the number of the fragments with penetration ability in the debris cloud. The penetration failure of the rear plate only comes from the fragments generated by the fragmentation of the projectile. Under the combined action of impact and explosion, the active materials shield can not only fully break and decelerate space debris, but also greatly reduce the number of solid debris in debris cloud, thereby produce a sharp rise in the spacecraft protection ability, and the maximum protection ability can be increased by 45% when the velocity is 2.31 km/s.

Numerical study on debris cloud and channeling effect of honeycomb sandwich shields under hypervelocity impact

Finite element-smoothed particle hydrodynamics adaptive method in simulating debris cloud

Hypervelocity impact response of monolithic UHMWPE and HDPE plates

Imaging Ejecta and Debris Cloud Behavior Using Laser Side-lighting

Flash x-ray radiography was conducted using imaging plates (IP) to observe high-speed thermal spray jets and debris clouds produced from hypervelocity impact. The radiographs of the spray jets or debris cloud shadows on the IPs were analyzed to estimate the distribution of mass per unit area, i.e., Areal mass density, due to the distribution of the intensities of stimulated emissions from the IPs. The wide dynamic range of the IPs led to the detection of an Areal mass density one hundred times as large as the minimum Areal mass density and the very detailed densities. The availability of the IPs for the flash x-ray radiography of a high-speed thermal spray jet and a hypervelocity-impact-produced debris cloud was demonstrated.

We have measured debris cloud generated by oblique impact. And in order to evaluate effect of oblique impact of aluminum spheres against a thin laminated target, hypervelocity impact test have been conducted. Impact velocity was approximately 2km/s. Impact angle was 0[deg] and 30[deg]. The experiments were performed to take images of the generated debris clouds behind target using three flash x-rays and to capture them softly using a stack of polystyrene sheets. And then, the images were analyzed to measure the velocity of each fragment. And the mass of recovered fragments were measured. As a result, it is found that at the impact obliquity of 30[deg], heavier and faster fragments were generated with a spray angle ranging from 20[deg] to 30[deg].

<p><strong>Introduction</strong>: Scheduled to be performed in September 2022, the DART (Double Asteroid Redirection Test, NASA) mission will be the first-ever space mission to demonstrate asteroid deflection by crashing an impactor spacecraft into a binary NEA target: the moon of (65803) Didymos, called Dimorphos. In the frame of the studies related to the EC-H2020 NEO-MAPP project, we perform numerical simulations of the collision event on Dimorphos without the presence of Didymos by using the N-body numerical code, PKDGRAV [1] with an implementation of the soft-sphere discrete element method [2], under the assumption that it is a spherical gravitational aggregate produced in the formation of the binary system [3, 4]. The very structure of the target is unknown; therefore, we model it by (a) 100550 mono-dispersed spherical particles in a close hexagonal packing (hereafter mono-CHP) configuration, with particle radii of 1.5 m; (b) multi-dispersed distribution of 100000 spherical particles in a random packing (hereafter multi-RP) configuration, with particle radii ranging from 1 to 2.5 m.</p> <p><strong>Method</strong>: The real DART impact should be a hyper-speed cratering event where most impact kinetic energy goes into the shattering phase including asteroid local material damage like vaporization, melting, rock deformation, heat transfer, and so on. However, due to the fact that PKDGRAV is not able to simulate the shattering phase, we instead concentrate on the effect of the collision on the target, once the shattering phase is over. Therefore, our synthetic projectile needs to deliver the same nominal linear momentum to Dimorphos as the DART spacecraft will do, but it delivers to the target only a small fraction of kinetic energy expected to survive once the shattering phase has dissipated most of the impact kinetic energy (non-elastic collision). According to the cratering experiments [5], only a small fraction of impact energy will go into the kinetic energy of the target after the shattering phase. This residual kinetic energy is about 0.25% of the initial impact energy.</p> <p>For the multi-RP case, we also account for different centre and off-centre impact geometry compatible with DART nominal impact angle (20º) with respect to the target orbital plane, considering the possibility that the real DART spacecraft may not impact exactly toward the centre of Dimorphos.</p> <p><strong>Results</strong>: From all of our cases, we find that none of the cases can transmit the impact kinetic energy to the other side of the impact point. However, particle movements in the antipodal hemisphere of the impact are possible even without impact energy reaching there because the aggregate tries to reach a new equilibrium shape after the relatively large crater and deformation were generated by the DART impact. As a result, the surface particles in the antipodal hemisphere move toward the crater, causing the particles to sink into the ground. <br />In the antipodal hemisphere, we found all the particles have negative vertical displacements typically around -1 m and can be up to around -2 m. The center of the surface depression is very close to a longitude and latitude of 0° and 20° because the center of the crater is at 180° and 20° longitude and latitude, which is the antipodal point.<br /><br />The surface particle movements have both vertical and horizontal components. We found many particles in the northern region have horizontal displacements larger than 1 m and can be up to 3.2 m. It takes tens of minutes or a few hours for the particles to settle down and reach their final locations. On the other hand, at about 3 mins after the impact, LICIACube will be able to take images on the antipodal side of the impact, with a resolution of about 1.5 m. None of the surface particles can have horizontal displacements larger than 1.5 m at that time, therefore LICIACube will be essentially taking images of the original locations of the boulders on the antipodal side of the impact.<br /><br />We therefore predict that by comparing the LICIACube and Hera observations, it is possible to obtain the real horizontal displacements of the boulders. The exact displacements caused by this resurfacing process depend on several internal material parameters and also on the level of deformation of Dimorphos by the real impact, and thus the observation may give information about the internal structure of Dimorphos.</p> <p> </p> <p><strong>References</strong>:</p> <p>[1] D. C. Richardson et al. (2000). Icarus, 143, 45.</p> <p>[2] S. R. Schwartz et al. (2012) Granular Matter 14, 363.</p> <p>[3] A. Campo Bagatin et al. (2001) Icarus, 149-1, 198. </p> <p>[4] A. Campo Bagatin et al. (2018) Icarus, Volume 302, 343.</p> <p>[5] D. W. Walker (2013) Int. J. of Impact Engin. 56, 12.<br /><br /></p>

Hyper velocity impact is a well-known problem due to micro meteoroid coincidence with space structures. Hence, hyper velocity impact behavior of materials is an interesting topic for researchers. Despite this fact, experimental studies require heavy costs to install hyper velocity impact systems. For this reason, numerical efforts come into prominence to understand hyper velocity impact events in a cost-effective way. In this work, a numerical model was built to simulate hyper velocity impacts on metallic plates. The model was validated by using the experimental results of a previous paper. Two different factors were investigated in impact conditions. The first one was target plate material and the other one was impact angle. Aluminum alloy Al 6061-T6 and A36 steel were used as the plate material due to their applications in space structure components. Impact angle was varied as 30°, 60° and 90° in the simulations. According to the results, plate material leads to a variation in fragmentation especially in normal impacts. Impact angle effect is observed in damage size on plates. Impact hole on target plates turn from circular to elliptical form by reducing impact angle.

Behavior of impact and explosion is complicated and usually involves large deformation and multi- material interaction of different phases. Failure and fragmentation of structure caused by impact or explosion also need to be considered. Simulation of impact and explosion problem requires a powerful numerical tool. The material point method, MPM, combines the advantages of Eulerian and Lagrangian description of motion. It eliminates the drawbacks of numerical difficulties associated with mesh distortion and element entanglement in Lagrangian and with the advected quantities in Eulerian description. Therefore the MPM is well suitable to the impact and explosive problems, which involves large deformation and interaction of different materials. A three dimensional material point method code, MPM3D, is developed. The linear hardening plasticity, Johnson-Cook plasticity and high explosive material model are implemented. Three kinds of equation of state (EOS) are implemented to calculate the pressure of different materials under extreme load. They are Gruneisen EOS for solid material, JWL EOS for explosive products, linear polynomial EOS for air. Numerical examples including Taylor bar impact, debris cloud and cylinder test are given to investigate the performance of MPM3D, which show that MPM is much more efficient than FEM and SPH in simulating hypervelocity impact and explosion problems, especially in large scale problems.

The hypervelocity impact resistance behaviors of NbC/Al2024 ceramic-metal composites

first_page settings Order Article Reprints Font Type: Arial Georgia Verdana Font Size: Aa Aa Aa Line Spacing:    Column Width:    Background: Open AccessConference Report Numerical Simulation of Drop Impact on Wetted and Dry Surfaces by M. GATTRINGER and H. STEINER * Institute of Fluid mechanics and Heat transfer, Graz University of Technology, Graz, Austria * Author to whom correspondence should be addressed. Sci. Pharm. 2010, 78(3), 568; https://doi.org/10.3797/scipharm.cespt.8.LPES07 Received: 12 July 2010 / Accepted: 12 July 2010 / Published: 12 July 2010 Download Download PDF Versions Notes Abstract The impact of liquid drops on wetted and dry surfaces is a complex two-phase flow phenomenon with high technical relevance especially in surface coating. [...] Share and Cite MDPI and ACS Style GATTRINGER, M.; STEINER, H. Numerical Simulation of Drop Impact on Wetted and Dry Surfaces. Sci. Pharm. 2010, 78, 568. https://doi.org/10.3797/scipharm.cespt.8.LPES07 AMA Style GATTRINGER M, STEINER H. Numerical Simulation of Drop Impact on Wetted and Dry Surfaces. Scientia Pharmaceutica. 2010; 78(3):568. https://doi.org/10.3797/scipharm.cespt.8.LPES07 Chicago/Turabian Style GATTRINGER, M., and H. STEINER. 2010. "Numerical Simulation of Drop Impact on Wetted and Dry Surfaces" Scientia Pharmaceutica 78, no. 3: 568. https://doi.org/10.3797/scipharm.cespt.8.LPES07 Find Other Styles Article Metrics No No Article Access Statistics For more information on the journal statistics, click here. Multiple requests from the same IP address are counted as one view.

The numerical simulations of different head shape semi-armor-piercing warheads penetrating thin steel target are done using the finite element software ANSYS/LS-DYNA, and the whole process of different nose shape semi-armor-piercing warheads vertically penetrating the thin steel plate is compared. Besides, the influence of impact angle on penetration performance of three different nose shape projectiles is researched. The analysis results indicate that the nose shape has a significant influence on semi-armor-piercing warhead penetration performance. The effect of impact angle on the three kinds of projectiles’ residual kinetic energy and deflection is different. The research results provide references for designing of warhead and battlefield damage assessment.

In the present analysis, we have focused on the emission characteristics of the projectile and target fragments produced from the interaction of [Formula: see text]Kr with nuclear emulsion at 1 A GeV. We have studied the variation of the fragmentation parameter for singly charged [Formula: see text], doubly charged [Formula: see text], lower multiple-charged [Formula: see text]–[Formula: see text], medium multiple-charged [Formula: see text]–[Formula: see text] and higher multiple-charged [Formula: see text], projectile fragments with respect to mass of the projectile and found that they are showing the different behaviors for different projectile fragments. We have also studied the emission behavior of shower particles, with respect to the black and gray particles. The present studies show that the production of shower particles strongly depends on the incident kinetic energy of the projectile and also depending on the interaction of the different types of target nuclei of nuclear emulsion.

Dynamic stress concentration and energy evolution of deep-buried tunnels under blasting loads