Flexural behaviors and local failure analyses of EPS foam-filled GFRC truss-core sandwich panels

The ANSYS/Autodyn software was employed to investigate the dynamic responses of foam-filled corrugated core sandwich panels under air blast loading. The panels were assembled from metallic face sheets and corrugated webs, and PVC foam inserts with different filling strategies. To calibrate the proposed numerical model, the simulation results were compared with experimental data reported previously. The response of the panels was also compared with that of the empty (unfilled) sandwich panels. Numerical results show that the fluid–structure interaction effect was dominated by front face regardless of the foam fillers. Foam filling would reduce the level of deformation/failure of front face, but did not always decrease the one of back face. It is found that the blast performance in terms of the plastic deflections of the face sheets can be sorted as the following sequence: fully filled hybrid panel, front side filled hybrid panel, back side filled hybrid panel, and the empty sandwich panel. Investigation into energy absorption characteristic revealed that the front face and core web provided the most contribution on total energy absorption. A reverse order of panels was obtained when the maximization of total energy dissipation was used as the criteria of blast performance.

Download Full-text

Closure to “Local Failure of Plastic-Foam Core Sandwich Panels”

Journal of the Structural Division ◽

10.1061/jsdeag.0002665 ◽

1970 ◽

Vol 96 (8) ◽

pp. 1803-1805

Author(s):

Billy J. Harris ◽

Gene M. Nordby

Keyword(s):

Sandwich Panels ◽

Local Failure ◽

Foam Core ◽

Plastic Foam

Download Full-text

Local Failure of Plastic-Foam Core Sandwich Panels

Journal of the Structural Division ◽

10.1061/jsdeag.0002239 ◽

1969 ◽

Vol 95 (4) ◽

pp. 585-610

Author(s):

Billy J. Harris ◽

Gene M. Nordby

Keyword(s):

Sandwich Panels ◽

Local Failure ◽

Foam Core ◽

Plastic Foam

Download Full-text

Mechanical performance of polyester pin-reinforced foam filled honeycomb sandwich panels

Science and Engineering of Composite Materials ◽

10.1515/secm-2017-0039 ◽

2018 ◽

Vol 25 (4) ◽

pp. 797-805 ◽

Cited By ~ 4

Author(s):

R.S. Jayaram ◽

V.A. Nagarajan ◽

K.P. Vinod Kumar

Keyword(s):

Mechanical Properties ◽

Mechanical Performance ◽

Flexural Rigidity ◽

Sandwich Panels ◽

Interfacial Strength ◽

Structural Performance ◽

Experimental Investigations ◽

Honeycomb Sandwich ◽

Foam Filled ◽

Pin Reinforcement

Abstract Honeycomb sandwich panels entice continuously enhanced attention due to its excellent mechanical properties and multi-functional applications. However, the principal problem of sandwich panels is failure by face/core debond. Novel lightweight sandwich panels with hybrid core made of honeycomb, foam and through-thickness pin was developed. Reinforcing polyester pins between faces and core is an effectual way to strengthen the core and enhance the interfacial strength between the face/core to improve the structural performance of sandwich panels. To provide feasibility for pin reinforcement, honeycomb core was pre-filled with foam. Mechanical properties enhancement due to polyester pinning were investigated experimentally under flatwise compression, edgewise compression and flexural test. The experimental investigations were carried out for both “foam filled honeycomb sandwich panels” (FHS) and “polyester pin-reinforced foam filled honeycomb sandwich panels” (PFHS). The results show that polyester pin reinforcement in foam filled honeycomb sandwich panel enhanced the flatwise, edgewise compression and flexural properties considerably. Moreover, increasing the pin diameter has a larger effect on the flexural rigidity of PFHS panels. PFHS panels have inconsequential increase in weight but appreciably improved their structural performance.

Download Full-text

Buckling of sandwich panels with transversely flexible core: Correction of the equivalent single-layer model using thick-faces effect

Journal of Sandwich Structures & Materials ◽

10.1177/1099636218789604 ◽

2018 ◽

Vol 22 (5) ◽

pp. 1612-1634 ◽

Cited By ~ 6

Author(s):

J Jelovica ◽

J Romanoff

Keyword(s):

Finite Element ◽

Transverse Shear ◽

Sandwich Panels ◽

Shear Deformation Theory ◽

Single Layer ◽

Element Model ◽

Layer Model ◽

The Core ◽

Truss Core ◽

Single Layer Model

Modeling a periodic structure as a homogeneous continuum allows for an effective structural analysis. This approach represents a sandwich panel as a two-dimensional plate of equivalent stiffness. Known as the equivalent single-layer, the method is used here to analyze bifurcation buckling of three types of sandwich panels with unidirectional stiffeners in the core: truss-core, web-core and corrugated-core panels made of an isotropic material. The transverse shear stiffnesses of these panels can differ by several orders of magnitude, which cause incorrect buckling analysis when using the equivalent single-layer model with the first-order shear deformation theory. Analytical solution of the problem predicts critical buckling loads that feature infinite number of half-waves in the direction perpendicular to the stiffeners. Finite element model also predicts buckling modes that have non-physical, saw-tooth shape with infinite curvature at nodes. However, such unrealistic behavior is not observed when using detailed three-dimensional finite element models. The error in the prediction of the critical buckling load is up to 85% for the cases considered here. The correction of the equivalent single-layer model is proposed by modeling the thick-faces effect to ensure finite curvature. This is performed in the finite element setting by introducing an additional plate with tied deflections to the equivalent single-layer plate. The extra plate is represented with bending and transverse shear stiffness of the face plates. As a result, global buckling is predicted accurately. Guidelines are proposed to identify the sandwich panels where ordinary model is incorrect. Truss-core and web-core sandwich panels need the correction. Corrugated-core panels without a gap between plates in the core have smaller shear orthotropy and do not need the correction. Modeling the thick-faces effect ensures correct results for all cases considered in this study, and thus one should resort to this approach in case of uncertainty whether the ordinary equivalent single-layer model is valid.

Download Full-text

Bending and free vibration analysis of foam-filled truss core sandwich panel

Journal of Sandwich Structures & Materials ◽

10.1177/1099636216670612 ◽

2016 ◽

Vol 20 (5) ◽

pp. 617-638 ◽

Cited By ~ 11

Author(s):

MP Arunkumar ◽

Jeyaraj Pitchaimani ◽

KV Gangadharan

Keyword(s):

Free Vibration ◽

Vibration Analysis ◽

Sandwich Panel ◽

Closed Form Solution ◽

Free Vibration Analysis ◽

Element Model ◽

Form Solution ◽

Numerical Comparison ◽

Truss Core ◽

Foam Filled

This paper presents the studies carried out on bending and free vibration behavior of truss core sandwich panel filled with foam typically used in aerospace applications. Equivalent stiffness properties for foam-filled truss core sandwich panel are derived by idealizing 3D foam-filled sandwich panel to an equivalent 2D orthotropic thick plate continuum. The accuracy of the derived elastic property is ensured by the numerical comparison of free vibration response of 3D and its equivalent 2D finite element model. The derived stiffness constants were used in closed form solution to evaluate the maximum deflection of the continuum. The results show that the free vibration and static behavior of the sandwich panel can be enhanced in due consideration to the space constraint by filling foam in the empty space of core. The results also reveal that triangular core foam-filled sandwich panel deflects less compared to other cores. From the free vibration analysis, effect of filling foam is effective in cellular and trapezoidal core.

Download Full-text