Perforation Of Sandwich Panels Research Articles

A numerical study of the impact perforation of sandwich panels with graded hollow sphere cores

In this study, we numerically investigate the impact perforation of sandwich panels made of 0.8 mm 2024-T3 aluminum alloy skin sheets and graded polymeric hollow sphere cores with four different gradient profiles. A suitable numerical model was conducted using the LS-DYNA code, calibrated with an inverse perforation test, instrumented with a Hopkinson bar, and validated using experimental data from the literature. Moreover, the effects of quasi-static loading, landing rates, and boundary conditions on the perforation resistance of the studied graded core sandwich panels were discussed. The simulation results showed that the piercing force–displacement response of the graded core sandwich panels is affected by the core density gradient profiles. Besides, the energy absorption capability can be effectively enhanced by modifying the arrangement of the core layers with unclumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions.

Impact perforation of sandwich panels with graded hollow sphere cores: Numerical and Analytical investigations

In this study, we numerically and analytically investigate the impact perforation of sandwich panels made of 0.8 mm 2024-T3 aluminum alloy skin sheets and graded polymeric hollow sphere cores with four different gradient profiles. A suitable numerical model was conducted using the LS-DYNA code, calibrated with an inverse perforation test, instrumented with a Hopkinson bar, and validated using experimental data from the literature. Moreover, the effect of boundary conditions on the perforation resistance of the studied graded core sandwich panels was discussed. The simulation results showed that the piercing force– displacement response of the graded core sandwich panels is affected by the core density gradient profiles. Besides, the energy absorption capability can be effectively enhanced by modifying the arrangement of the core layers with un-clumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions. Finally, an analytical model, taken account only gradient in the quasi-static plateau stress, is developed to predict the top skin pic peak load of the graded sandwich panel.

Deformation and perforation of sandwich panels with aluminum-foam core at elevated temperatures

Quasi-static perforation and low-velocity impact tests at different temperatures were carried out for sandwich panels with aluminum face sheets and a closed-cell aluminum foam core. The deformation and failure behaviors, load carrying capacity and energy absorption capability of sandwich panels were explored and compared at different temperatures. In the experiments, effects of several key parameters, i.e. soaking time, boundary condition, and geometrical size of the indenter, on the load carrying capacity and energy absorption of the sandwich panels during perforation were discussed. The differences of the perforation behavior of sandwich panels at elevated temperatures under quasi-static and low velocity impact tests were also studied.

Analytical modeling for perforation of foam-composite sandwich panels under high-velocity impact

In this paper, a new simple analytical model for perforation process of composite sandwich panels subjected to high-velocity impact of flat-ended projectile is presented. The panels consist of foam core sandwiched between two composite skins. In the analytical model, global deformation, plug shearing or localized tensile fracture, delamination of front and back-up composite skins, and the absorbed energy during the perforation of the sandwich panel are calculated considering the local indentation and also the energy balancing equation is employed to determine the ballistic limit and residual velocity of projectile. The results of current new model are compared with the experimental results available in the open literature and the finite element simulation results obtained by the LS-Dyna code. A good agreement is observed between the analytical and numerical model results and the experimental results.

Perforation of aluminium foam core sandwich panels under impact loading: A numerical and analytical study

This paper reports the numerical results of the inversed perforation test instrumented with Split Hopkinson Pressure Bar SHPB with an instrumented pressure bar on the AlSi7Mg0.5 aluminium foam core sandwich panels with 0.8 mm thick 2024 T3 aluminium top and bottom skin. The numerical models are developed in order to understand the origin of the enhancement of the top skin loads found under impact loading (paper published by [1]). Numerical predicted piercing force vs displacement curves are compared with experimental measurements (tests at impact velocities at 27 and 44 m/s). The simulation catches all process of the perforation of the sandwich panels (top skin, foam core, and bottom skin). Within experimental scatter, there is a good agreement between numerical predictions and experimental measurements. Virtual tests with different impact velocities up 200 m/s are presented and showed a significant enhancement of the piercing force under impact loading (top skin peak and foam core plateau loads). In order to understand the origin of these force enhancements, any difference of detailed local information between static and dynamic loading is studied and showed that a shock front effect is responsible for the enhancement piercing force. An analytical model using an improved RPPL shock model based a power law densification assumption is proposed to calculate the top skin piercing force. The improved RPPL shock model agrees with the FE results for small velocities and gives better prediction of the piercing force than the RPPL shock model for large velocities (>100 m/s).

Impact perforation of sandwich panels with Coremat®

Analytical solutions for the quasi-static and low-velocity perforation of sandwich panels with woven roving E-glass/vinyl ester facesheets and Coremat were derived. A multi-stage perforation process involving delamination, debonding, core shear fracture and facesheet fracture was used to predict the quasi-static failure load and ballistic resistance of the panel. The high core-crushing resistance and damping of the Coremat resulted in rupture of the distal facesheet before the incident facesheet during panel perforation because they limited the amount of local indentation compared with global panel deformation. Analytical predictions of the quasi-static load-deflection response and the dynamic contact force history were within 10% of the test results.

Perforation of Sandwich Panels with Honeycomb Cores by Hemispherical Nose Projectiles

Analytical models for the static and low-velocity perforation of composite sandwich panel with woven E-glass/epoxy prepreg facesheets and aluminum honeycomb core are developed. The analytical models are based on a set of experimental results. A three-stage perforation process involving consecutive failures of top facesheet, core, and bottom facesheet is proposed. The analytical predictions of static failure loads and deformation are within 10 and 8% of the test data, respectively. The predicted ballistic limit is within 10% of the test data, while the total energy dissipated at the ballistic limit is within 18% of the test results.