Delamination and First Ply Failure Study of Composite Conoidal Shells
Abstract
Interlaminar and intralaminar failure modes of
composite conoidal shells are investigated in this paper using
finite element as the mathematical tool. One of the
prerequisites for confidently applying the composite shells in
practical civil engineering is to have a comprehensive idea
about the shell behavior under different loading conditions.
The static bending and free vibration responses of laminated
composite conoidal shells are now well known as a good
number of technical papers have been published by different
researchers. But for these materials which are weak in
transverse shear failure may initiate at any inner lamina or
interface and may remain undetected and unattended. Such
latent damages may progress gradually and lead to a sudden
total ply failure. Due to fabrication problems or overloading,
delamination defect may occur and remain hidden within the
lamina. Hence it is imperative to have knowledge of the first
ply failure load and the load at which delamination initiates.
To explore this area, in this paper, a simply supported shell is
considered loaded by concentrated load. Lamination and the
load position are varied to investigate the first ply failure
characteristics of the composite shell. Well accepted failure
theories like maximum stress, Hoffman, Tsai-Wu and Tsai-Hill
are used in the current formulation to obtain failure loads.
While obtaining the failure loads, each lamina is considered
to be under plane stress condition i.e. no transverse stresses
are considered to act on any lamina. Comparison of failure
loads obtained from both the failure modes are also presented
to get the minimum failure load which will govern the shell
design.
Keywords Conoidal Shell, Delamination, First Ply Failure, Finite Element Method, Laminated Composite
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