Narayanan, K P; Pradeep, K R; Anju, Mohanan(IJSER, May , 2013)
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Abstract:
A sandwich construction is a special form of the laminated composite consisting of light weight core, sandwiched between two stiff thin
face sheets. Due to high stiffness to weight ratio, sandwich construction is widely adopted in aerospace industries. As a process dependent bonded
structure, the most severe defects associated with sandwich construction are debond (skin core bond failure) and dent (locally deformed skin
associated with core crushing). Reasons for debond may be attributed to initial manufacturing flaws or in service loads and dent can be caused by
tool drops or impacts by foreign objects. This paper presents an evaluation on the performance of honeycomb sandwich cantilever beam with the
presence of debond or dent, using layered finite element models. Dent is idealized by accounting core crushing in the core thickness along with the
eccentricity of the skin. Debond is idealized using multilaminate modeling at debond location with contact element between the laminates.
Vibration and buckling behavior of metallic honeycomb sandwich beam with and without damage are carried out. Buckling load factor, natural
frequency, mode shape and modal strain energy are evaluated using finite element package ANSYS 13.0. Study shows that debond affect the
performance of the structure more severely than dent. Reduction in the fundamental frequencies due to the presence of dent or debond is not
significant for the case considered. But the debond reduces the buckling load factor significantly. Dent of size 8-20% of core thickness shows 13%
reduction in buckling load capacity of the sandwich column. But debond of the same size reduced the buckling load capacity by about 90%. This
underscores the importance of detecting these damages in the initiation level itself to avoid catastrophic failures. Influence of the damages on
fundamental frequencies, mode shape and modal strain energy are examined. Effectiveness of these parameters as a damage detection tool for
sandwich structure is also assessed
Description:
International Journal Of Scientific & Engineering Research Volume 4, Issue 5, May-2013