No abstract

No abstract

No abstract

Honeycomb sandwich panels are widely used in marine, aerospace, automotive and shipbuilding industries. High strength to weight and excellent energy absorption are features that make these structures unique. Foam filling the honeycomb core enhances the mechanical properties of sandwich panels considerably. In the present study, the buckling behavior of Nomex honeycomb core/glass-epoxy face sheet sandwich panel for both bare and foam-filled honeycomb core is investigated numerically and experimentally, considering the viscoelastic properties of the sandwich panel. Indeed, the viscoelastic properties of the composite face sheet and foam are determined by relaxation test and are implemented in ABAQUS using VUmat code. The finite element method is also performed using ABAQUS to model the buckling behavior of the sandwich panel incorporating both elastic and viscoelastic material behaviour. The effects of composite face sheet lay-up, core thickness, core cell size, and foam filling are also evaluated. The experimental and numerical results show that the foam increases the critical buckling load and energy absorption.

This paper presents an experimental and numerical study of the low-velocity impact on foam core sandwich panels reinforced using hybrid short fibers. The foam cores were reinforced with carbon, aramid and carbon-aramid hybrid short fibers. The face-sheets were made of two layers of glass/epoxy, and foam cores were made of two-part polyurethane. In order to acquire the appropriate weight ratio between foam and short fibers, the weight percentage of 10% was chosen for short fibers. Comparing the experimental results proved that carbon, aramid, and carbon-aramid respectively had a better effect on increasing Young modulus by around 100 to 180 per cent. Before performing impact tests, indentation tests were conducted and based on the results for the parameter of impact energy, the value of 6  J was chosen. According to the results of impact tests and the maximum contact force, hybrid reinforced foam, aramid short fiber reinforced foam and carbon short fiber reinforced foam improved the properties respectively by 18 to 30 per cent in comparison to non-reinforced foam. Furthermore, numerical simulations were conducted via ABAQUS. After modeling face-sheet and foam separately, and verifying the results with experiments, the sandwich panel was modeled entirely while the simulation difference of 9.1% on average with the experiment results was concluded.