Abstract

Parameters of the honeycomb core (such as cell size and foil thickness), as well as the material of the core, influence the ballistic performance of honeycomb-core sandwich panels in cases of hypervelocity impact (HVI) by orbital debris. Two predictive models capable of accounting for this influence have been developed in this study: one utilized a conventional approach based on a dedicated ballistic limit equation, while the other employed an artificial neural network trained to predict the outcomes of HVI on HCSP. BLE fitting and ANN training were conducted using a database composed of 46 numerical experiments, performed with a validated numerical model and ten physical tests derived from the literature. The new ballistic limit equation is based on the Whipple shield BLE, in which the standoff distance between the facesheets was replaced by a function of the honeycomb cell size, foil thickness, and yield strength of the HC material. The corresponding fit factors were determined by minimizing the sum of squared errors between the BLE predictions and the results of HVI tests listed in the database. The BLE was then tested against a new set of simulation data and demonstrated an excellent predictive accuracy, with the discrepancy ranging from 1.13% to 5.58% only. The artificial neural network was developed using MATLAB's Deep Learning Toolbox framework and was trained utilizing the same HCSP HVI database as was employed for the BLE fitting. The ANN demonstrated a very good predictive accuracy, when tested against a set of simulation data not previously used in the training of the network, with the discrepancy ranging from 0.67% to 7.27%. Both of the developed predictive models (the BLE and the ANN) are recommended for use in the design of orbital debris shielding for spacecraft, involving honeycomb-core sandwich panels.

Abstract

Spacecraft must be analyzed for their ability to survive hypervelocity impacts (HVI) by orbital debris, as collision of a space vehicle with even a millimeter-sized object traveling at a typical orbital speed (7 km/s and higher) can be detrimental for both the spacecraft and the orbital environment. Due to the high cost of the physical HVI experiments, numerical modeling plays a significant role in conducting such analyses. In particular, the smoothed particles hydrodynamics technique (SPH) was previously found applicable for simulating scenarios involving extreme deformations and fragmentation, including hypervelocity impact. With the extensive use of advanced lightweight materials in space structures, it is important to find a rational way of representing them using the SPH framework. This study reports the results of SPH modeling of two distinct types of lightweight materials often employed in space structures: open-cell foams and fiber-reinforced composites. For foams, explicit representation of their complex mesoscopic architecture was achieved by filling the STL exteriors (generated using X-ray computed tomography) with SPH particles. For laminated composites, ply-wise representation was obtained using finite elements that could locally and adaptively transform to SPH particles when the elements become highly distorted and inefficient. Results of HVI simulations involving foams and composites were compared with available experimental data. The advantages and limitations of the modeling techniques are discussed. Spacecraft must be analyzed for their ability to survive hypervelocity impacts (HVI) by orbital debris, as collision of a space vehicle with even a millimeter-sized object traveling at a typical orbital speed (7 km/s and higher) can be detrimental for both the spacecraft and the orbital environment. Due to the high cost of the physical HVI experiments, numerical modeling plays a significant role in conducting such analyses. In particular, the smoothed particles hydrodynamics technique (SPH) was previously found applicable for simulating scenarios involving extreme deformations and fragmentation, including hypervelocity impact. With the extensive use of advanced lightweight materials in space structures, it is important to find a rational way of representing them using the SPH framework. This study reports the results of SPH modeling of two distinct types of lightweight materials often employed in space structures: open-cell foams and fiber-reinforced composites. For foams, explicit representation of their complex mesoscopic architecture was achieved by filling the STL exteriors (generated using X-ray computed tomography) with SPH particles. For laminated composites, ply-wise representation was obtained using finite elements that could locally and adaptively transform to SPH particles when the elements become highly distorted and inefficient. Results of HVI simulations involving foams and composites were compared with available experimental data. The advantages and limitations of the modeling techniques are discussed. Spacecraft must be analyzed for their ability to survive hypervelocity impacts (HVI) by orbital debris, as collision of a space vehicle with even a millimeter-sized object traveling at a typical orbital speed (7 km/s and higher) can be detrimental for both the spacecraft and the orbital environment. Due to the high cost of the physical HVI experiments, numerical modeling plays a significant role in conducting such analyses. In particular, the smoothed particles hydrodynamics technique (SPH) was previously found applicable for simulating scenarios involving extreme deformations and fragmentation, including hypervelocity impact. With the extensive use of advanced lightweight materials in space structures, it is important to find a rational way of representing them using the SPH framework. This study reports the results of SPH modeling of two distinct types of lightweight materials often employed in space structures: open-cell foams and fiber-reinforced composites. For foams, explicit representation of their complex mesoscopic architecture was achieved by filling the STL exteriors (generated using X-ray computed tomography) with SPH particles. For laminated composites, ply-wise representation was obtained using finite elements that could locally and adaptively transform to SPH particles when the elements become highly distorted and inefficient. Results of HVI simulations involving foams and composites were compared with available experimental data. The advantages and limitations of the modeling techniques are discussed.