Sudden drop phenomena in natural frequencies of composite plates or panels with a central stiffening plate strip

Yuceoglu, U
Ozerciyes, V
The free bending vibrations of an orthotropic, composite base plate or panel reinforced by a central stiffening plate strip are considered. The orthotropic base plate and the dissimilar, orthotropic, central stiffening plate strip are bonded together with a very thin adhesive layer. The dynamic equations of the lower base plate and the upper stiffening strips are derived according to the 'Mindlin plate theory'. The governing system of partial differential equations is first reduced to a special set of first order ordinary differential equations. Following the elimination of the time variable and one of the space variables, the problem becomes a 'two-point boundary value problem'. Then, the governing system of differential equations are integrated by a 'modified version of the transfer matrix method'. The effects of the 'hard' and the 'soft' adhesive layers on the mode shapes and the natural frequencies of the composite system are investigated and presented. It was also shown that the natural frequencies of plate or panel system gradually increase at first for the increasing values of the 'bending cross stiffness ratio' of the base plate and the stiffening plate strip. Then, for certain values of the 'ratio', the natural frequencies experience a sudden sharp drop and again start going up gradually regardless of the boundary conditions. This unusual 'sudden drop phenomena' is observed for the 'hard' as well as for the 'soft' adhesive layer cases in the composite plate system. Some important conclusions in connection with the 'phenomena' are presented.


Free flexural( or bending) vibrations analysis of doubly stiffened, composite, orthotropic base plates and panels (in aero-structural systems)
Çil, Kürşad; Yüceoğlu, Umur; Department of Aerospace Engineering (2003)
In this Thesis, the problem of the أFree Vibrations Analysis of Doubly Stiffened Composite, Orthotropic and/or Isotropic, Base Plates or Panels (with Orthotropic Stiffening Plate Strips)ؤ is investigated. The composite plate or panel system is made of an أOrthotropic and/or Isotropic Base Plateؤ stiffened or reinforced by adhesively bonded أUpper and Lower Orthotropic Stiffening Plate Stripsؤ. The plates are assumed to be the أMindlin Platesؤ connected by relatively very thin adhesive layers. The general pr...
Free bending vibrations of integrally-stiffened and/or stepped-thickness rectangular plates or panels with a non-central plate stiffener
Yuceoglu, U.; GEMALMAYAN, NİHAT; Sunar, O. (2007-11-16)
The present study is primarily concerned with the "Free Bending Vibrations of Integrally-Stiffened and/or Stepped-Thickness Plates or Panels with a Non-Central Plate Stiffener". The general theoretical formulation is based on the "Mindlin Plate Theory". The plate elements of the system are considered to be made of dissimilar orthotropic materials with unequal thicknesses. The transverse shear deformations and the transverse and the rotary moments of inertia of plate elements are included in the analysis. Th...
Free bending vibrations of a centrally bonded symmetric double lap joint (or symmetric double doubler joint) with a gap in mindlin plates or panels
Yuceoglu, U.; Guvendik, O.; Ozerciyes, V. (2007-11-16)
In this present study, the "Free Bending Vibrations of a Centrally Bonded Symmetric Double Lap Joint (or Symmetric Double Doubler Joint) with a Gap in Mindlin Plates or Panels" are theoretically analyzed and are numerically solved in some detail. The "plate adherends" and the upper and lower "doubler plates" of the "Bonded Joint" system are considered as dissimilar, orthotropic "Mindlin Plates" joined through the dissimilar upper and lower very thin adhesive layers. There is a symmetrically and centrally lo...
Forced vibration analysis of generally laminated composite beams using domain boundary element method
Ahmed, Zubair; Dağ, Serkan; Department of Mechanical Engineering (2018)
Forced dynamic response of generally laminated composite beam is analyzed by boundary element method. Static fundamental solutions are used as weight functions in the weighted residual statements. The use of static fundamental solutions gives rise to a new formulation named as Domain Boundary Element Method. Displacement field of the generally laminated composite beam is written in accordance with first order shear deformation theory and equations of motion are derived using Hamilton’s principle. Developed ...
Free Vibrations of Composite Plates Stiffened by Two Adhesively Bonded Plate Strips
Javanshir, Jaber; Farsadi, Touraj; Yuceoglu, Umur (2012-07-01)
In this study, the free flexural (or bending) vibration response of composite base-plate or panel systems stiffened by two adhesively bonded plate strips are theoretically analyzed in detail and numerically solved in terms of the mode shapes with their natural frequencies. Additionally, some important parametric studies are also included in the present study. The aforementioned bonded and stiffened system is composed of an orthotropic Mindlin base plate or panel stiffened or reinforced by the dissimilar, or...
Citation Formats
U. Yuceoglu and V. Ozerciyes, “Sudden drop phenomena in natural frequencies of composite plates or panels with a central stiffening plate strip,” COMPUTERS & STRUCTURES, pp. 247–262, 2000, Accessed: 00, 2020. [Online]. Available: