Influence of hygrothermal conditioning on strength and stiffness of rigid foam core glass/epoxy skin sandwich composites

High-performance metal/polymer/metal hybrid sandwich composites are attractive materials for lightweight constructions in automotive, aerospace and naval engineering world-wide. Due to the excellent combination of mechanical, thermal and elastic properties and, as a result of high forming potential, they can be used in areas of high vibration, where high damping properties of the polymer are demanded and at the same time high strength and stiffness are given by the metal. Disadvantages can be given in case of mechanical or thermal joining of these polymer-based sandwiches because of the elastic behaviour as well as low melting temperature of the polymer. Local metal plate insertions in the soft core at the place of joining can be a solution for such kind of problems. But forming behaviour of sandwich materials with and without local inlays differs strongly. Sandwich composites of that type were produced by roll-bonding. Their quality and their position were controlled by Lockin thermography. The forming behaviour of sandwiches with different geometry, size, type and the position of the inlays was tested by deep drawing and bending and analysed with the help of digital photogrammetry and compared to experimentally obtained mechanical properties. As a result, the local inlays, as well as their geometry, size and type strongly influence the forming limit conditions. The differences in flow behaviour of non-reinforced and reinforced sandwich regions after deep drawing and bending will be presented, as well as the influence of the position of the inlays.

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Effect of processing conditions and material properties on the debond fracture toughness of foam-core sandwich composites: experimental optimization

Composites Part A Applied Science and Manufacturing ◽

10.1016/s1359-835x(03)00207-0 ◽

2003 ◽

Vol 34 (11) ◽

pp. 1097-1104 ◽

Cited By ~ 23

Author(s):

Prasun Majumdar ◽

Deepak Srinivasagupta ◽

Hassan Mahfuz ◽

Babu Joseph ◽

Matthew M. Thomas ◽

...

Keyword(s):

Fracture Toughness ◽

Material Properties ◽

Foam Core ◽

Processing Conditions ◽

Sandwich Composites ◽

Experimental Optimization

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Creep relaxation and fully reversible creep of foam core sandwich composites in seawater

Journal of the Mechanical Behavior of Materials ◽

10.1515/jmbm-2015-0019 ◽

2015 ◽

Vol 24 (5-6) ◽

pp. 187-194

Author(s):

Ismael de la Paz ◽

Basir Shafiq

Keyword(s):

Strong Dependence ◽

Cyclic Creep ◽

Foam Core ◽

Sandwich Composites ◽

Creep Tests ◽

Modes Of Failure ◽

Service Lifetime ◽

Interface Cell ◽

Reversed Loading ◽

Creep Loading

AbstractFoam core sandwich composites were subjected to (i) creep to failure, (ii) cyclic creep-relaxation and (iii) fully reversible cyclic creep loading in seawater in order to mimic an actual ship hull’s service lifetime scenario. The results indicate a strong dependence of lifetime on the mode of loading. A significant reduction in the overall life was observed under cyclic creep as compared with the conventional creep to failure. Creep relaxation (R=1) tests were performed at loading-relaxation periods of 24/24, 24/12, 24/6, 12/12 and 6/6 h, while the fully reversible (R=-1) creep tests were conducted at loading-reversed loading times of 36/36, 24/24, 12/12, 6/6, and 3/3 h. The results suggest that creep-relaxation lifetime characteristics depend predominantly on the relaxation time as opposed to loading times, i.e. longer relaxation periods lead to shorter life. Whereas, fully reversible creep appears to be dependent upon the number of reversals whereby, life is observed to reduce as the number of reversals increase. These significant observations are explained in terms of various possible paths to interface cell wall collapse. Modes of failure were predominantly indentation and core compression in the vicinity of the loading site.

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