Determination of corrugated core sandwich panels elastic from buzai232's blog

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.Get more news about Bh-sandwich Panel Series,you can vist our website!

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]. High specific flexural stiffness and strength are among the main features of sandwich panels. The core can be composed of miscellaneous materials such as foam, honeycomb, and corrugated sheets. Corrugated cores in comparison with foam or honeycomb are superior as far as factors such as shear strength in the transverse direction of corrugation, strength to weight ratio, structural integrity, and fluid storage capacity are concerned. The core geometry in the corrugated core sandwich panels is more than often trapezoidal (hat-type), rectangular, triangular, circular, and sinusoidal [3, 4]. An additional bonding operation using adhesive is used in the production of the laminated composite where core and skins have to be prepared separately. Poor mechanical performance of adhesive, complexity associated with predication, and determination of joints strength as well as small contact surface area between the core and the skins are among the disadvantages associated with the adhesively bonded corrugated core sandwich panels. The stated disadvantages may lead to the poor mechanical performance of the resultant composite structures or their delamination [5,6,7,8,9,10]. 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. Blingardi et al. [8] investigated the mechanical properties of the foam core sandwich panel composites using 4-point bending tests. It was found that skin–core delamination due to shear failure is the principle cause of structural failure of the sample. It was also established that the addition of a resin network perpendicular to the skins enhances flexural strength and impact resistance of the structure. 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 not only failure occurs in the bond length but also specific flexural strength at a given corrugation angle and core-sheet thickness is reduced due to an increase in the bond length.

When 3-D fabrics are used as reinforcement in composites, the presence of Z-yarn along the thickness eliminates the poor bonding of the laminated layers [5, 12]. The integrated composites reinforced with 3-D fabrics have higher inter-laminar shear load-carrying capacity than the non-integrated version. The integrated composites possess higher delamination resistance. Additionally, strength along the thickness in the integrated structures is higher than those of the non-integrated version. The mechanical and thermal stability of the integrated structures along principle directions is unique [5, 13]. Karahan et al. [14] compared conventional foam core sandwich panel composites with 3-D integrated sandwich panel composites in which the connection of the skins to each other was made using pile yarns. It was concluded that the use of pile yarns significantly improves the compression behavior of the 3-D integrated sandwiched panel. Ivanov et al. [15] and Lomov et al. [16] compared conventional non-integrated 2-D woven laminated composite with integrated non-crimp 3-D orthogonal woven composite. It was found that as far as in-plane strength, failure strain, and damage initiation thresholds were concerned, the integrated composite was significantly superior in comparison with the non-integrated.