Determination of corrugated core sandwich panels elastic constant based on three different experimental methods and effect of structural integrity on flexural properties

Hamid Abedzade Atar,Hossein Hasani,Mohammad Zarrebini,Jalil Rezaeepazhand

doi:10.1007/s42452-021-04424-8

Hamid Abedzade Atar, Hossein Hasani + Show 2 more

Open Access

https://doi.org/10.1007/s42452-021-04424-8

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Abstract

This study deals with the investigation of flexural stiffness and transverse shear rigidity in the direction of corrugation of the integrated and non-integrated corrugated core sandwich panels with the rectangular core. The non-integrated sandwich panels were reinforced with conventional 2-D fabrics in which resin provides the bond between core and skins. The integrated sandwich panels were reinforced with 3-D weft knitted fabrics in which bonding of the core wall to skins was carried out by combined efforts of knitted loop and resin. Using weft knitting technical capabilities, samples of the integrated and non-integrated structures were manufactured with the uppermost degree of resemblance in terms of geometry and mass. Flexural stiffness and transverse shear rigidity of the structures based on the known and unknown facing modulus of ASTM D7250 standard and Nordstrand–Carlsson methods were calculated. The estimated elastic constants based on unknown facing modulus and the Nordstrand–Carlsson methods were found to be highly compatible. However, the unknown facing modulus method is prone to disclose the statistical significant differences between the elastic constants of the structures with fewer tests. Regarding the unknown facing modulus method, it was found that the flexural stiffness and transverse shear rigidity of the non-integrated structure in the direction of corrugation were higher than those of the integrated structure. Results also indicated that the load-carrying capacity in the direction of corrugation was significantly higher in case of the non-integrated rectangular core structure compared with that of the integrated structure.

Highlights

Sandwich panels are composed of a thick and low-density core which is sandwiched by two thin and stiff skins or face sheets [1, 2]
Taghizadeh et al [11] experimental investigation revealed that the delamination of skin–core is the principle damage mechanism that can occur in corrugated core sandwich panel composites
Since the modulus of the skin of the integrated sandwich panel which was reinforced with fabric knitted using 400 Tex yarn was known, the flexural stiffness in the direction of corrugation of this structure was calculated in accordance to ASTM D7250 standard using Eq (2)

Summary

Introduction

Sandwich panels are composed of a thick and low-density core which is sandwiched by two thin and stiff skins or face sheets [1, 2]. Taghizadeh et al [11] experimental investigation revealed that the delamination of skin–core is the principle damage mechanism that can occur in corrugated core sandwich panel composites. Zhang et al [7] investigated the effect of corrugation angle, core-sheet thickness, and core to skins bond length on the flexural strength of the corrugated core sandwich panel composites in the transverse direction of corrugation. It was found that failure occurs in the bond length and specific flexural strength at a given corrugation angle and core-sheet thickness is reduced due to an increase in the bond length

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Conclusion