Experimental investigation of Basalt S glass Epoxy PVC H 130 hybrid sandwich composite for aircraft secondary structures

Abstract

Sandwich structures are used as secondary structures in the aircraft and they become an integral part of the primary structure of the aircraft. The lower density possessed favors the use of sandwich composites in the aircraft. It has been pointed out that multitudinous forces act on the structural members of the aircraft which leads to the development of stresses. When the aircraft is stationed on the ground the entire weight of the aircraft is born by the landing gear, further, the landing gears of the aircraft assimilate the forces developed during the takeoff and landing of the aircraft. During the navigation of the aircraft an effort to increase or decrease the speed magnifies the forces and stresses which act on the wings of the aircraft. Stresses such as tensile, compressive, flexural, torsional loads are developed in the structural members of the aircraft; these stresses are later transmitted to the fuselage of the aircraft. During the service of the aircraft, this is exposed to varying ranges of temperature ranging from extreme cold to extremely hot, rain and hailstone. The various structures in the aircraft are joined using by rivets; water ingress into the secondary structures of the aircraft through the minute clearance available between the rivets, besides this water used in the toilets, water spilt by the passengers, rainwater entering through the door also leads to the ingression of the water in the secondary structures. The water ingress in the secondary structures undergoes freeze and thaw cycle which reduces the strength bearing ability of the composite structures, besides this, the exposure of the aircraft for a prolonged period of time to extreme hot to extreme cold conditions also reduces the strength of the secondary structures and in turn airworthiness of the aircraft. There are earlier precedents where aircraft have failed catastrophically due to the hydrothermal effects; hence it becomes crucial to study the effect of hydrothermal aging on the properties of the sandwich composite.