Flexural behavior of stiffened syntactic foam core sandwich composites

2013 ◽  
Vol 16 (2) ◽  
pp. 195-209 ◽  
Author(s):  
SJ Amith Kumar ◽  
K Sabeel Ahmed
2005 ◽  
Vol 7 (2) ◽  
pp. 95-111 ◽  
Author(s):  
Eyassu Woldesenbet ◽  
Nikhil Gupta ◽  
H. Dwayne Jerro

Author(s):  
PETER BREUNIG ◽  
VINAY DAMODARAN ◽  
KIRAN SHAHAPURKAR ◽  
SUNIL WADDAR ◽  
MRITYUNJAY DODDAMANI ◽  
...  

2019 ◽  
Vol 54 (4) ◽  
pp. 535-547 ◽  
Author(s):  
P Breunig ◽  
V Damodaran ◽  
K Shahapurkar ◽  
S Waddar ◽  
M Doddamani ◽  
...  

Sandwich composites and syntactic foams independently have been used in many engineering applications. However, there has been minimal effort towards taking advantage of the weight saving ability of syntactic foams in the cores of sandwich composites, especially with respect to the impact response of structures. To that end, the goal of this study is to investigate the mechanical response and damage mechanisms associated with syntactic foam core sandwich composites subjected to dynamic impact loading. In particular, this study investigates the influence of varying cenosphere volume fraction in syntactic foam core sandwich composites subjected to varying dynamic impact loading and further elucidates the extent and diversity of corresponding damage mechanisms. The syntactic foam cores are first fabricated using epoxy resin as the matrix and cenospheres as the reinforcement with four cenosphere volume fractions of 0% (pure epoxy), 20%, 40%, and 60%. The sandwich composite panels are then manufactured using the vacuum assisted resin transfer molding process with carbon fiber/vinyl ester facesheets. Dynamic impact tests are performed on the sandwich composite specimens at two energy levels of 80 J and 160 J, upon which the data are post-processed to gain a quantitative understanding of the impact response and damage mechanisms incurred by the specimens. A qualitative understanding is obtained through micro-computed tomography scanning of the impacted specimens. In addition, a finite element model is developed to investigate the causes for different damage mechanisms observed in specimens with different volume fractions.


2017 ◽  
Vol 48 (1) ◽  
pp. 58-76 ◽  
Author(s):  
Mohammad Azadian ◽  
Hossein Hasani ◽  
Mahmoud Mehrdad Shokrieh

This paper undertakes to study the flexural behavior of 3D integrated weft-knitted spacer composites, under three-point bending. The integrated-knitted spacer fabrics were produced with various cross-sectional shapes on a computerized flat-knitting machine utilizing electrical grade glass (E-glass) fibers. The sandwich composites were manufactured by vacuum-assisted resin transfer molding using unsaturated polyester resin. Continuing the process, hand lay-up method was used to reinforce the face sheets of fabricated sandwich structure with glass woven fabrics. Bending performance of the produced composites was compared with polyurethane foam core sandwich composites. The results revealed that the cross-sectional shape has significant effect on the bending performance of the 3D integrated weft-knitted spacer composites. Also, the spacer reinforced composite with V-shape cross-section has the highest bending stiffness than composites with U-shape cross-section as well as polyurethane foam core sandwich composite. The failure modes of 3D integrated weft-knitted spacer composites include: core shear failure, compression failure of upper face sheet and tensile failure of lower face sheet.


2020 ◽  
pp. 109963622092666
Author(s):  
SJ Amith Kumar ◽  
SJAjith Kumar ◽  
Bharath K Nagaraja

Polymeric foam core sandwich composites are the nascent materials used in marine and aerospace structural applications for its low-density characteristics. A special class of foam called syntactic foam is one of the promising core material having high specific properties. However, these polymeric foam core sandwich composite structures may encounter problems in correlation with temperature and fire. Damages that happen due to the variation in temperature and by the catch of fire are sometimes imperceptible which may lead to the deterioration of load carrying ability or catastrophic failure of these composite structures. Present investigation is focused on the possibilities of reducing the extent of damages due to variation in temperature and by the catch of fire by enhancing its thermal stability and flame resistance characteristics. This was achieved from the development of syntactic foam by embedding hollow micro-spherical particles in phenolic resin for fire containment or fire isolation. Result of the experimentation reveals that the phenolic syntactic foam core was thermally more stable than glass/epoxy face skins up to a temperature of 450°C. The minimum concentration of oxygen required for burning was found to be 30%, in which phenolic syntactic foam core helps in flame isolation, whereas E-glass/epoxy face skins contribute to flame spread in the event of burning of sandwich composites. Improved thermal stability and fire resistance characteristics of developed sandwich composites are attributed to the phenolic syntactic foam core and by its orientation.


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