Abstract
Location of delamination is a triggering parameter for structural instability of laminated composites. In this paper, a finite element method is employed to determine the effects of location of delamination on free vibration characteristics of graphite-epoxy cross-ply composite pre-twisted shallow conical shells. The generalized dynamic equilibrium equation is derived from Lagrange's equation of motion neglecting Coriolis effect for moderate rotational speeds. The formulation is exercised by using an eight noded isoparametric plate bending element based on Mindlin's theory. Multi-point constraint algorithm is utilized to ensure the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front. The standard eigen value problem is solved by applying the QR iteration algorithm. Finite element codes are developed to obtain the numerical results concerning the effects of location of delamination, twist angle and rotational speed on the natural frequencies of cross-ply composite shallow conical shells. The mode shapes are also depicted for a typical laminate configuration. Numerical results obtained from parametric studies of both symmetric and anti-symmetric cross-ply laminates are the first known non-dimensional natural frequencies for the type of analyses carried out here.
Highlights
Extensive uses of composite laminated structures can be found in weight-sensitive applications such as turbomachinery engines
This paper presents a finite element based numerical approach to determine the effect of location of delamination on non-dimensional natural frequencies of graphite-epoxy pretwisted shallow cross-ply composite conical shells neglecting effect of dynamic contact between delaminated layers
For any number of layer and at a particular relative position of the delamination across the thickness of the conical shell, it is observed that the non-dimensional fundamental and second natural frequencies are found to decrease with the increase of twist angle from 0◦ to 45◦, with an exception for non-dimensional second natural frequencies wherein ψ = 15◦ corresponds to maximum value (e.g. Fig. 4 with n = 4)
Summary
Extensive uses of composite laminated structures can be found in weight-sensitive applications such as turbomachinery engines. Two worth mentioning investigations were carried out It included analytical and experimental determination of natural frequencies of delaminated composite beam by Shen and Grady [13] and the second one dealt with finite element treatment of the delaminated composite cantilever beam and plate by Krawczuk et al [14] for free vibration analyses. To the best of the authors’ knowledge, there is no literature available, which deals with delaminated pretwisted rotating composite cross-ply conical shells To fill up this apparent void, the present analyses employed a finite-element based approach to investigate the effect of location of delamination on free vibration characteristics of graphite-epoxy pretwisted shallow cross-ply composite conical shells. This paper presents a finite element based numerical approach to determine the effect of location of delamination on non-dimensional natural frequencies of graphite-epoxy pretwisted shallow cross-ply composite conical shells neglecting effect of dynamic contact between delaminated layers
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
