Author: Vijay Kumar BadagiPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Dynamic Response of Width- and Thickness-tapered Composite Beams Using Rayleigh-Ritz Method and Modal Testing
Author: Vijay Kumar BadagiAmerican Society for Composites
Author: Michael HyerPublisher: DEStech Publications, Inc
ISBN: 1605950513
Category : Technology & Engineering
Languages : en
Pages : 2760
Book Description
Dynamic Response of Doubly-Tapered Laminated Composite Beams Under Periodic and Non-Periodic Loadings
Author: Pramod KumarPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Doubly-tapered laminated composite beams provide a great opportunity to enhance capabilities such as high strength-to-weight ratio, high modulus-to-weight ratio, and design flexibility. Due to design tailoring capabilities, the use of doubly-tapered composite beams has increased in the automobile industry and aerospace industry. In the present thesis, the free and forced vibration analyses of the width-and-thickness-tapered, called herein as doubly-tapered, laminated composite beams are conducted considering different boundary conditions, taper configurations, and loadings. The exact and closed-form solutions for the mode shapes and natural frequencies of doubly-tapered composite beams could not be acquired because of the complexity of the corresponding partial differential equations. Therefore, the classical laminate theory and the one-dimensional laminated beam theory in combination with the Ritz method are used in evaluating the stiffness and mass matrices of the composite beam. The natural frequencies and the corresponding mode shapes are determined by solving the eigenvalue problem obtained using the Ritz method. The forced vibration analysis of the doubly-tapered composite beams subjected to the transverse periodic and non-periodic loadings is carried out by representing the periodic loading as the superposition of the harmonic components of various frequencies using the Fourier series expansion and by expressing the non-periodic pulse excitation as the superposition of two or more simpler functions for which solutions are easier to determine. The maximum deflection of the doubly-tapered composite beam in spatial and time coordinates is determined. Numerical and symbolic computations have been performed using MATLAB® software. The solutions to the free and forced vibration analyses of the composite beams are compared, with the solution available in the literature and with the solution based on the Finite Element Method obtained using ANSYS®, to demonstrate solution accuracy. The Rayleigh damping is considered to model the viscous damping of the composite beam. A detailed parametric study is carried out to investigate the influences of the loading components in the Fourier series expansion, loading type, period of the periodic loading, the rise and fall times of the non-periodic loadings, taper angle, width ratio, thickness ratio, laminate length, stacking sequence, and taper configuration on the forced response of the doubly-tapered composite beam considering different boundary conditions.
Vibration Analysis of Thickness- and Width-Tapered Laminated Composite Beams Using Hierarchical Finite Element Method
Author: Mohammad Amin FaziliVibrations of Thickness-and-width Tapered Laminated Composite Beams with Rigid and Elastic Supports
Author: Pooya SalajeghehFree Vibration Analysis of Tapered Composite Beams Using Hierarchical Finite Element Method
Author: Lin ChenApplied mechanics reviews
Author: Free and Forced Vibrations of Tapered Composite Beams Including the Effects of Axial Force and Damping
Author: Hasnet Eftakher Uddin AhmedPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Tapered composite beams formed by terminating or dropping-off some of the plies from primary structure are being used in various engineering applications since the mid-1980s. Because of their structural tailoring capabilities, damage tolerance and potential for creating significant weight savings in engineering applications such as helicopter yoke, robot arms and turbine blades, tapered composite beams have received much attention from engineers and researchers. Design of mechanical components using tapered composite beams requires a better understanding of their behavior on free and forced vibrations. In the present thesis, free and forced vibration analysis including the effects of axial force and damping of tapered composite beams is conducted using conventional, and higher-order finite elements and the Rayleigh-Ritz method. Composite beam samples are manufactured and tested for the determination of mechanical properties and damping loss factor. Conventional and higher- order finite element formulations are established based on classical laminate theory. Since conventional finite element has limitation in obtaining accurate results with fewer elements, higher-order finite element formulation is developed considering four degrees of freedom per node (deflection, rotation, curvature and gradient of curvature) to overcome that problem. Rayleigh-Ritz method is used to obtain solutions for different boundary conditions to validate the results obtained by finite element methods. A detailed parametric study is conducted to investigate the effects of boundary conditions, laminate configurations, taper configurations, taper angle, the ratio of the length of the thick section to the length of thin section, axial force, and damping. The NCT-301 graphite-epoxy composite material is used in the experimental work, analysis, and in the parametric study.
Vibration Analysis of Composite Beams Using Hierarchical Finite Element Method
Author: Amit K. NigamPublisher:
ISBN:
Category : Composite construction
Languages : en
Pages : 0
Book Description
The conventional finite element formulation has limitations in performing the dynamic analysis of composite beams. The discretization necessary for obtaining solutions with acceptable accuracy in the determination of dynamic response parameters leads to discontinuities in stress and strain distributions. The hierarchical finite element formulation provides us with the advantages of using fewer elements and obtaining better accuracy in the calculation of natural frequencies, displacements and stresses. The hierarchical finite element formulation for uniform and variable-thickness composite beams is developed in the present work. Two sub-formulations of hierarchical finite element method viz. polynomial and trigonometric sub-formulations have been developed. The efficiency and accuracy of the developed formulation are established in comparison with closed-form solutions for uniform composite beams. The static response of uniform composite beams is evaluated using the hierarchical finite element method. The dynamic response of variable-thickness composite beams is calculated based on the developed formulation. A detailed parametric study encompassing the influences of boundary conditions, laminate configuration, taper angle and the type of taper on the dynamic response of the beam is performed. The NCT-301 graphite-epoxy composite material is considered in the analysis and in the parametric study.
Free Vibration Analyses of Stationary and Rotating Tapered Composite Beams with Delamination
Author: Puneet JagpaulPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
ABSTRACT Free Vibration Analyses of Stationary and Rotating Tapered Composite Beams with Delamination Puneet Jagpaul The exceptional engineering properties and customizability of the laminated composites have enabled their use in the design of the stationary and rotating tapered structures in the aerospace and energy sectors. The tailoring capabilities of the composite material can be used to stiffen the structure at one location while being flexible at other location and consequently reduce the weight, as required in specific applications such as helicopter rotor blade, windmill blade and turbine blade. The vibration characteristics (natural frequencies and mode shapes) of the stationary and rotating structures differ substantially and must be well identified in the design stage. The composite structures are prone to failures such as delamination and fiber-matrix debonding caused during their fabrication or in service, especially when used as blades and beams in various stationary and rotating applications. Delamination reduces the overall stiffness and the strength of the laminates, which may lead to local or sudden structural failures. The delaminated structure has reduced natural frequencies and exhibits different mode shapes than that of the intact structure. In the present thesis, the free vibration analyses of stationary and rotating tapered composite beams with delamination are conducted. The influence of the delamination on the vibration characteristics of the stationary and rotating tapered composite beams is comprehensively studied. The Finite Element Analysis tool ANSYS® is used to develop three-dimensional models of the intact and delaminated composite beams. The natural frequencies of the stationary and rotating intact cantilever composite beams are determined for uniform, thickness-tapered and doubly tapered beam profiles using modal analysis and the results are compared with the results available in the literature. The Mode-I and Mode-II delamination tests are performed on the numerical models of the double cantilever beam and end notch flexure test samples based on cohesive zone modeling and the results of the tests are verified with the available results. The critically stressed locations prone to delamination in the stationary and rotating composite beams are determined using the first-ply failure analyses based on Tsai-Wu failure criterion. The free vibration responses of the stationary and rotating composite beams with end and mid-span delaminations of different lengths and with different stacking sequences are obtained and they are verified wherever possible. The delamination length that has minimal effect on the first three natural frequencies of the uniform and thickness-tapered composite beams is determined and is found to be 5% of the total beam length. Higher modes should be investigated for the composite structures with smaller delamination. A basis for the non-destructive evaluation is suggested for the stationary thickness-tapered simply supported composite beams with end and mid-span delaminations. The influences of the delamination length, delamination location, fiber orientation angle, thickness-tapering, double tapering, layer reduction and taper angle on the free vibration response of the stationary and rotating delaminated composite beams are investigated for uniform, thickness-tapered and doubly tapered beam profiles through various parametric studies. The influences of the rotational velocity and hub radius on the natural frequencies of the rotating doubly tapered composite beams with delamination are thoroughly examined. The present thesis contributes towards the safe design of the composite structures. The studies performed are helpful for developing delamination detection techniques based on the free vibration response of tapered composite beams and can aid designers to model optimised tapered composite structures by considering the influences of delamination on their vibrational characteristics.