The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Eric P. Fahrenthold - One of the best experts on this subject based on the ideXlab platform.

  • Hypervelocity Impact simulation using membrane particle elements
    International Journal of Impact Engineering, 2008
    Co-Authors: A Bohannan, Eric P. Fahrenthold
    Abstract:

    Abstract A series of three-dimensional simulations have been performed to evaluate the use of membrane particle-elements to model Hypervelocity Impact effects in fabrics. The simulations employed an improved hybrid particle-finite element method and material models recently developed for conventional Kevlar and for Kevlar treated with a shear thickening fluid. The simulation results were compared with experimental data from tests conducted by NASA Johnson Space Center. The results suggest that membrane particle-elements can provide a computationally efficient description of Hypervelocity Impact dynamics in flexible multi-layered structures.

  • an ellipsoidal particle finite element method for Hypervelocity Impact simulation
    International Journal for Numerical Methods in Engineering, 2004
    Co-Authors: Ravishankar Shivarama, Eric P. Fahrenthold
    Abstract:

    A number of coupled particle–element and hybrid particle–element methods have been developed for the simulation of Hypervelocity Impact problems to avoid certain disadvantages associated with the use of pure continuum-based or pure particle-based methods. To date these methods have employed spherical particles. In recent work a hybrid formulation has been extended to the ellipsoidal particle case. A model formulation approach based on Lagrange's equations, with particle entropies serving as generalized coordinates, avoids the angular momentum conservation problems which have been reported with ellipsoidal smooth particle hydrodynamics models. Copyright © 2003 John Wiley & Sons, Ltd.

  • an improved hybrid particle element method for Hypervelocity Impact simulation
    International Journal of Impact Engineering, 2001
    Co-Authors: Eric P. Fahrenthold, Blaise A Horban
    Abstract:

    An improved hybrid particle-finite element method has been developed for Hypervelocity Impact simulation. The method combines the general contact-Impact capabilities of particle codes with the true Lagrangian kinematics of large strain finite element formulations. Unlike some alternative schemes which couple Lagrangian finite element models with smooth particle hydrodynamics, the present formulation makes no use of slidelines or penalty forces.

  • Energy based particle hydrodynamics for Hypervelocity Impact simulation
    International Journal of Impact Engineering, 1999
    Co-Authors: Eric P. Fahrenthold
    Abstract:

    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.

Sarath Kumar Sathish Kumar - One of the best experts on this subject based on the ideXlab platform.

  • behavior of dragon skin flexible metal bumper under Hypervelocity Impact
    International Journal of Impact Engineering, 2019
    Co-Authors: Chunghyeon Choi, Sarath Kumar Sathish Kumar
    Abstract:

    Abstract The need for large space structures has been of significant interest in recent years, owing to the expansion of potential space applications. The use of flexible and inflatable shield designs is a very promising method for constructing spacious structures in space. Dragon skin or so-called fish-scale armor may provide an effective flexible bumper structure for space. This is the first study to evaluate dragon skin as a bumper against Hypervelocity Impact of micro-meteoroid and orbital debris in space. In this research, Hypervelocity Impact experiments and various numerical simulations were conducted. It was found that the deflection effect and critical Impact location factor prevailed in the dragon skin bumper; hence, fragmentation can be seriously affected by the dragon skin shape. However, a simulation work of the research showed that the shape effect can be alleviated by using a thin and dense metal material instead of aluminum. In conclusion, the dragon skin structure can be utilized as a bumper in space with consideration of several design factors that are reported in this study.

  • multi functional aramid epoxy composite for stealth space Hypervelocity Impact shielding system
    Composite Structures, 2018
    Co-Authors: Sarath Kumar Sathish Kumar, Venkat Akhil Ankem
    Abstract:

    Abstract In this study, a stealth space Hypervelocity Impact shielding system containing electromagnetic wave absorption capability and Impact shielding system was presented and verified from design to fabrication. To improve the microwave absorption performance of the proposed system, the electrical modification of aramid fabric via a RF magnetron silver-sputtering coating technique was used. The proposed thin stealth space shielding composite demonstrated excellent microwave absorption performance in the target frequency range from C-band to Ku-band (4–18 GHz) without using carbonaceous nano-conductive material in a polymer matrix (4.970-mm total thickness) while maintaining the thin total thickness. To check the Impact shielding performance, Hypervelocity Impact experiments were conducted using two-stage light-gas gun projectile velocities between 2.7 and 3.2 km/s. The average specific energy absorbed of silver-coated aramid/epoxy composites was comparable to that of pristine (uncoated) material. The type and shape of failures in the pristine and silver-coated aramid/epoxy composites were similar. In addition, interlaminar shear-strength (ILSS) tests were performed to check the mechanical performance of the proposed shielding system according to ASTM D 2344. Based on these results, our proposed stealth space shielding system proved to be a promising candidate for military satellite systems.

  • polybenzimidazole pbi film coating for improved Hypervelocity Impact energy absorption for space applications
    Composite Structures, 2018
    Co-Authors: Sarath Kumar Sathish Kumar, Chunghyeon Choi, Edwin Antonio Juradomanriquez, Abrar H Baluch
    Abstract:

    Abstract This paper deals with how the use of Polybenzimidazole (PBI) as a film coating over conventional composite designs could help improve the Hypervelocity Impact ballistic performance of the system. PBI coated composite samples were studied for resistance to Low Earth Orbit environment conditions like high vacuum, thermal cycling, Atomic Oxygen and Ultraviolet Radiation in a simulation facility. It was observed that the PBI coated composites reduced mass loss and surface erosion compared to the non-coated samples after LEO exposure. Hypervelocity Impact experiments were conducted on the PBI coated composites for Impact velocities between 2.5 to 3 km/s. The experiments showed that the PBI film coating significantly increased the energy absorption of the composite system. The effect of thickness increase as a result of the film application on energy absorption was also found to be negligible confirming the effectiveness of PBI coating as a Hypervelocity shield.

  • Hypervelocity Impact on flexible curable composites and pure fabric layer bumpers for inflatable space structures
    Composite Structures, 2017
    Co-Authors: Chunghyeon Choi, Sarath Kumar Sathish Kumar
    Abstract:

    Abstract Demands for large space structures recently increased in accordance with the growth of space applications for micro-gravity research and space travel. To satisfy growing demand, inflatable structures have been developed. For Hypervelocity Impact protection from micrometeoroid and orbital debris with enough structural flexibility to be applied to an inflatable space structure, a Multi-shock shield was developed and adopted. However, the multi-layered ceramic fabric bumper of the Multi-shock shield is inferior to the bumper of the conventional stuffed Whipple shield with respect to its Hypervelocity Impact protection performance. In this study, the applicability of directly curable carbon, Zylon and Twaron composites as a front bumper of the Hypervelocity Impact shield was examined through 22 experiments involving a pure fabric layer bumper. Through the experiments, it was found that directly curable composites can be more effectively used as a bumper of Hypervelocity shield than pure fabric layers.

F. Schäfer - One of the best experts on this subject based on the ideXlab platform.

  • TRAJECTORY BASED 3D FRAGMENT TRACKING IN Hypervelocity Impact EXPERIMENTS
    ISPRS - International Archives of the Photogrammetry Remote Sensing and Spatial Information Sciences, 2018
    Co-Authors: Erkai Watson, Hans-gerd Maas, F. Schäfer, Stefan Hiermaier
    Abstract:

    Abstract. Collisions between space debris and satellites in Earth’s orbits are not only catastrophic to the satellite, but also create thousands of new fragments, exacerbating the space debris problem. One challenge in understanding the space debris environment is the lack of data on fragmentation and breakup caused by Hypervelocity Impacts. In this paper, we present an experimental measurement technique capable of recording 3D position and velocity data of fragments produced by Hypervelocity Impact experiments in the lab. The experimental setup uses stereo high-speed cameras to record debris fragments generated by a Hypervelocity Impact. Fragments are identified and tracked by searching along trajectory lines and outliers are filtered in 4D space (3D + time) with RANSAC. The method is demonstrated on a Hypervelocity Impact experiment at 3.2 km/s and fragment velocities and positions are measured. The results demonstrate that the method is very robust in its ability to identify and track fragments from the low resolution and noisy images typical of high-speed recording.

  • theoretical prediction of dynamic composite material properties for Hypervelocity Impact simulations
    International Journal of Impact Engineering, 2009
    Co-Authors: F. Schäfer, M Wicklein, Shannon Ryan, A P Mouritz, W Riedel, Klaus Thoma
    Abstract:

    Recent advances in the description of fibre-reinforced polymer composite material behaviour under extreme loading rates provide a significant extension in capabilities for numerical simulation of Hypervelocity Impact on composite satellite structures. Given the complexity of the material model, extensive material characterisation is required, however, as the properties of composite materials are commonly tailored for a specific application, experimental characterisation is not efficient, particularly in preliminary design phases. As such, a procedure is outlined in this paper that applies a number of commonly accepted composite mechanics and shock physics theories in conjunction with generalised material properties which allows for the theoretical derivation of a complete material data set for utilisation of the new modelling capabilities. The derivation procedure has been applied to a carbon fibre/epoxy laminate, and is validated through a comparison of derived material properties with experimentally characterised values and numerical simulation of damage induced by Hypervelocity Impact on a representative space debris shielding configuration employing the CFRP laminate. For the specific structures and Impact conditions considered, application of the material property derivation procedure in place of experimental characterisation provided comparable accuracy in the prediction of damage induced by particles Impacting at Hypervelocity.

  • Hypervelocity Impact research acceleration technology and applications
    Advances in Space Research, 2001
    Co-Authors: E Schneider, F. Schäfer
    Abstract:

    Modern acceleration techniques like two- and three stage light gas guns, electrostatic and plasma accelerators, shaped charge launchers etc. will be reviewed and discussed with respect to their projectile mass and velocity ranges and their applicability for the experimental simulation of Hypervelocity collisions. Recent studies in the fields of micrometeoroid/debris shielding (e.g. COLUMBUS Orbital Facility), as well as pressure vessel behavior under Hypervelocity Impact conditions will be presented as examples of applications.

Shannon Ryan - One of the best experts on this subject based on the ideXlab platform.

  • theoretical prediction of dynamic composite material properties for Hypervelocity Impact simulations
    International Journal of Impact Engineering, 2009
    Co-Authors: F. Schäfer, M Wicklein, Shannon Ryan, A P Mouritz, W Riedel, Klaus Thoma
    Abstract:

    Recent advances in the description of fibre-reinforced polymer composite material behaviour under extreme loading rates provide a significant extension in capabilities for numerical simulation of Hypervelocity Impact on composite satellite structures. Given the complexity of the material model, extensive material characterisation is required, however, as the properties of composite materials are commonly tailored for a specific application, experimental characterisation is not efficient, particularly in preliminary design phases. As such, a procedure is outlined in this paper that applies a number of commonly accepted composite mechanics and shock physics theories in conjunction with generalised material properties which allows for the theoretical derivation of a complete material data set for utilisation of the new modelling capabilities. The derivation procedure has been applied to a carbon fibre/epoxy laminate, and is validated through a comparison of derived material properties with experimentally characterised values and numerical simulation of damage induced by Hypervelocity Impact on a representative space debris shielding configuration employing the CFRP laminate. For the specific structures and Impact conditions considered, application of the material property derivation procedure in place of experimental characterisation provided comparable accuracy in the prediction of damage induced by particles Impacting at Hypervelocity.

  • Hypervelocity Impact on cfrp testing material modelling and numerical simulation
    International Journal of Impact Engineering, 2008
    Co-Authors: M Wicklein, Shannon Ryan, D M White, R A Clegg
    Abstract:

    Abstract This paper describes the derivation and validation of a numerical material model that predicts the highly dynamic behaviour of CFRP (carbon fibre reinforced plastic) under Hypervelocity Impact. CFRP is widely used in satellites as face sheet material in CFRP-Al/HC sandwich structures (HC = honeycomb) that can be exposed to space debris. A review of CFRP-Al/HC structures typically used in space was performed. Based on this review, a representative structure in terms of materials and geometry was selected for study in the work described here. An experimental procedure for the characterisation of composite materials is documented by Riedel et al. [ADAMMO – advanced material damage models for numerical simulation codes. ESA CR(P) 4397, EMI report I 75/03, Freiburg; October 31, 2003.]. The test results from the CFRP of the current study allow for the derivation of an experimentally based orthotropic continuum material model data set that is capable of predicting the mechanical behaviour of CFRP under Hypervelocity Impact. Such a data set was not previously available. In the work by Riedel et al. [Hypervelocity Impact damage prediction in composites: part II – experimental investigations and simulations. International Journal of Impact Engineering, 2006;33:670–80.] an orthotropic material data set was used for modelling HVI on AFRP (aramid fibre reinforced plastic), which shows relatively high deformability before failure. The enhancements of the modelling approaches in previous studies [Riedel W, Harwick W, White DM, Clegg RA. ADAMMO – advanced material damage models for numerical simulation codes. ESA CR(P) 4397, EMI report I 75/03, Freiburg; October 31, 2003. Hiermaier S, Riedel W, Hayhurst C, Clegg RA, Wentzel C. AMMHIS – advanced material models for Hypervelocity Impact simulations. Final report, EMI report E 43/98, ESA CR(P) 4305, Freiburg; July 30, 1999.] necessary to model brittle CFRP are specified. An experimental Hypervelocity Impact campaign was performed at two different two-stage light gas guns which encompassed both normal and oblique Impacts for a range of Impact velocities and projectile diameters. Validation of the numerical model is provided through comparison with the experimental results. For that purpose measurements of the visible damage of the face sheets and of the HC core are conducted. In addition, the numerically predicted damage within the CFRP is compared to the delamination areas found in ultrasonic scans.

Enling Tang - One of the best experts on this subject based on the ideXlab platform.

  • Electrostatic Discharge of Plasma Created by Hypervelocity Impact 2A12 Aluminum Targets With Gradient Potential
    IEEE Transactions on Plasma Science, 2017
    Co-Authors: Ruizhi Wang, Enling Tang, Liping He, Meng Wang, Shenghai Xiang
    Abstract:

    Based on the objective reality of gradient potential existence in spacecraft surface caused by charging particles in space-plasma environment or solar wind activities, electrostatic discharge of spacecraft with surface charging or deep dielectric charging would be induced by debris or meteoroids Impact. To simulate the gradient potential on the spacecraft surface in the laboratory, spacecraft surface was segmented into different parts, which different spacing reserved in two adjacent surfaces was added resistance to create different potential surfaces, and the highest potential surface as a target in the segmented surface. Circuit system realizing different gradient potential, discharge test system, as well as ultrahigh-speed camera acquired system was built by ourselves; combining with two-stage light gas gun loading system, four set experiments have been performed about Hypervelocity Impact on 2A12 aluminum target with gradient potential. In the experiments, spacings of 2A12 aluminum target were the same among different potential parts in every experiment, and the spacings of four set experiments were 2, 5, 10, and 15 mm, and high-potential 2A12 aluminum as the target, respectively. The experiments were performed at the Impact velocity of about 3 km/s and the incidence angles of 60° (between projectile flying trajectory and target plane). Voltage probes and current probes were used to acquire discharge voltages and currents during the process of the Impact. The experimental results showed that the discharge induced by Impact plasma was generated between high- and low-potential targets by forming a plasma discharge channel, the gaps with 2-15 mm can evoke discharge among different targets, and the variations of the discharge current along the high- and low-potential targets did not obviously. However, the discharge duration decreased with an increasing of distance between high- and low-potential targets at the near collision velocities and the same incidence angle of the projectile. The whole physical process of discharge had experienced four stages in general, which created by Hypervelocity Impact 2A12 aluminum targets with gradient potential. The first stage was plasma generated by Hypervelocity Impact, the second stage was complex mixed plasma including plasma generated by Hypervelocity Impact and discharge plasma induced by split targets with gradient potential, the third stage was discharge plasma induced by Hypervelocity Impact, and the fourth stage was the discharge between charging particles due to the reciprocating motion of charging particles in the electromagnetic field.

  • Research on the Ionization Degree of the Plasma Generated by 2A12 Aluminum Target During Hypervelocity Impact
    IEEE Transactions on Plasma Science, 2016
    Co-Authors: Enling Tang, Mingyang Xu, Qingming Zhang, Shenghai Xiang, Liping He, Meng Wang, Lijiao Zhang
    Abstract:

    The theories of Impact dynamics and adiabatic temperature change were adopted to investigate the ionization degree of the plasma generated by the 2A12 aluminum target during 2A12 aluminum projectile Hypervelocity Impact, and the radiant temperature was also estimated during Hypervelocity Impact. A two-stage light gas gun combined with the plasma characteristic parameters measured by a triple Langmuir probe was applied, and then the fitting relationship between the plasma ionization degree and the theoretical Impact temperature as well as the fitting relationship between the maximum electron density and Impact velocity were obtained with the aid of the theoretical derivation of the plasma ionization degree and the electron temperature and electron density extracted from experiments.

  • the signal characteristics of light flash generated by Hypervelocity Impact natural dolomite plate
    International Journal of Applied Electromagnetics and Mechanics, 2014
    Co-Authors: Enling Tang, Qingming Zhang, Shenghai Xiang, Meng Wang, Hongjie Xu, Zhiqiu Li, Minghai Yang
    Abstract:

    To investigate light flash produced during Hypervelocity Impact in the laboratory, we have conducted a series of experiments on a two-stage light gas gun at different Impact velocities and the same Impact angle. Light flash were acquired through optical fiber pyrometer measurement system during the whole physical process in Hypervelocity Impact, Experimental results showed that the maximum light flash intensity decreases with Impact velocity increasing, and maximum light flash intensity should exist a critical Impact velocity for polycarbonate projectile Impacting natural dolomite plate, which may be between 2.52 km/s and 4.21 km/s at the wavelength of 550 nm–700 nm. In addition, the light flash intensity peak value was 0.4∼0.5 mW.cm−2.nm−1 in the experimental conditions in the paper.

  • sweep langmuir probe and triple probe diagnostics for transient plasma produced by Hypervelocity Impact
    Plasma Science & Technology, 2012
    Co-Authors: Enling Tang, Shenghai Xiang, Minghai Yang, Lexin Li
    Abstract:

    Two techniques are applied to diagnose characteristic parameters of plasma created by Hypervelocity Impact, such as electron temperature and electron density. The first technique is a sweep Langmuir probe (SLP), which is a new apparatus based on a dual channel circuit that can compensate for stray capacitance and obtain a good synchronicity, so that electrostatic turbulence with a good temporal resolution can be acquired. The second technique is a triple Langmuir probe (TLP), which is an electrostatic triple Langmuir probe diagnostic system, in which no voltage and frequency sweep is required. This technique allows to measure electron temperature, electron density as a function of time. Moreover, the triple Langmuir probe diagnostic system allows the direct display of electron temperature and semidirect display of electron density by an appropriate display system, the system permits us to eliminate almost all data processing procedures. SLP and TLP were applied to obtain fluctuations of the characteristic parameters of plasma generated by Hypervelocity Impact. As an example of their application to time-dependent plasma measurement, the electron temperature and electron density of plasmas were acquired in Hypervelocity Impact experiments. Characteristic parameters of plasma generated by Hypervelocity Impact were compared by the two kinds of diagnostic techniques mentioned above.

  • diagnosis of electromagnetic properties and light flash characteristics created by Hypervelocity Impact m 1
    International Journal of Applied Electromagnetics and Mechanics, 2012
    Co-Authors: Enling Tang, Qingming Zhang, Shenghai Xiang, Minghai Yang, Mingjian Zhang
    Abstract:

    In order to diagnose electromagnetic properties and light flash characteristics generated by Hypervelocity Impact, the diagnostic systems of sweep Langmuir probe(SLP) and triple Langmuir probe (TLP) for electron temperature and electron density in plasma were established, properties of magnetic field were obtained by using coil measurement system established, and characteristics of light flash were also acquired through optical pyrometer measurement system during the whole physical process in Hypervelocity Impact, Experimental results showed that the average electron temperature of the triple Langmuir probe was near 0.75 eV on the whole physical process, the average electron density in the experiment was about. However, the electron temperature and electron density of plasma acquired by using t he sweep Langmuir probe were lower than the values by using triple Langmuir probe. The peak value of magnetic induction intensity induced by plasma was 9.8 × 10/cm during the Hypervelocity Impacts, and light flash intensity peak value was 40–50 mW.cm−2.nm−1 in the experimental conditions in the paper.