Vibrations of straight and curved composite beams: A review

Rotating composite beams and blades have a wide range of applications in various engineering structures such as wind turbines, industrial fans, and steam turbines. Therefore, proper understanding of such structures is of a great importance. As a result, the behavior of rotating composite beam structures has received a lot of attention. This paper presents a comprehensive review of scholarly articles about rotating composite beams as published in the past decades. The review addresses analytical, semi-analytical and numerical studies dealing with dynamical problems involving adaptive/smart/intelligent materials (e.g. piezoelectric materials, electrorheological fluids, shape memory alloys, etc.), damping and vibration control, advanced composite materials (e.g. functionally graded materials and nanocomposites), complicating effects and loadings (e.g. added mass, tapered beams, initial curve and twist, etc.), and experimental methods. Moreover, the influence of Vlasov or restrained warping, out-of-plane warping, transverse shear, arbitrary cross-sectional geometry, trapeze phenomena, swept tip, size-dependent effect, as well as other areas that have been considered in research, are reviewed in depth. The review concludes with a presentation of the remaining challenges and future research needs.

Dynamics, vibration and control of rotating composite beams and blades: A critical review

Active aeroelastic flutter analysis and vibration control of supersonic composite laminated plate

OTORCRAFT engineering is highly interdisciplinary because the flexibility of the main rotor blades couples with the aerodynamics, dynamics, and control system. In addition, interaction between the rotor and fuselage further complicates helicopter system predictions. The multidisciplinary nature of the helicopter engineering problems has led researchers to investigate formal optimization methods for the design process. Applications of formal optimization methods for helicopter problems started in the early 1980s. Miura 1 provided a review of some of the early work on application of numerical optimization to helicopters. Friedmann, 2 Adelman and Mantay, 3 and Celi 4 provide further reviews of helicopter optimization. Sobieszczanski-Sobieski and Haftka 5 give a review of recent developments in multidisciplinary design optimization for aerospace problems and Gieseng and Barthelemy 6 provide an industrial perspective of multidisciplinary optimization research. Whereas considerable studies have been conducted on helicopter design optimization, several issues have prevented it from becoming as popular or successful as structural optimization. Many finite element-based design packages today have builtin optimization capacity. However, the predictive capacity of even the most sophisticated helicopter aeroelastic analysis codes remains quite poor, as evidenced in a recent study by Hansford and Vorwald, 7 where hub load predictions from several codes are compared with flight-test data. In addition, because of the nature of helicopter problems, comprehensive aeroelastic codes are highly multidisciplinary and very difficult to understand and alter except by domain experts. This is because of the complexity of the physical modeling. For example, as the blade moves over one revolution, it encounters transonic flow, reverse flow, stall, and unsteady effects including dynamic stall. Large azimuthal variations in lift result from changes in dynamic pressure

Survey of Recent Developments in Rotorcraft Design Optimization

........................................................................................................... .ii Acknowledgements ...................................................................................... iii Acknowledgement of Funding .................................................................. iv Table of

Nonlinear Mechanical and Actuation Characterization of Piezoceramic Fiber Composites

A new smart composite box beam model is developed to investigate the behavior of helicopter rotor blades built around the active box beam. Piezoelectric actuators and sensors are surface bonded on the walls of the composite box beam. The new theory, based on a refined higher order displacement field of a plate with eccentricity, is a three-dimensional model which approximates the elasticity solution so that the box beam cross-sectional properties are not reduced to one-dimensional beam parameters. Both in-plane and out-of-plane warpings are included automatically in the formulation. The formulations also include nonlinear induced strain effects of piezoelectric actuators. The procedure is implemented using finite element method. The developed theory is used to model the load carrying member of helicopter rotor blades with moderately thick-walled sections. Static analysis of the smart box beam under varying degrees of actuation has been performed. Very good overall agreement is observed with available experimental data for thin-walled sections without embedded actuators. The results show that piezoelectric actuation significantly reduces the deflection along the box beam span and therefore can be used to control the magnitude of rotor blade vibrations. The nonlinear actuation effect is found to be closely related to the material stiffness of the primary structure.

Modeling of smart composite box beams with nonlinear induced strain

The vibratory load reduction at a rotor hub using smart materials and closed-loop control is investigated. The principal load-carrying member in the blade is represented by a composite box beam, of arbitrary thickness, with surface bonded self-sensing actuators. A comprehensive theory is used to model the smart box beam. The theory, whichisbasedonaree neddisplacemente eld,isathree-dimensionalmodelthatapproximatestheelasticitysolution so that the beam cross-sectional properties are not reduced to one-dimensional beam parameters. Both in-plane and out-of-plane warpings are included automatically in the formulation. Next, an integrated rotor vibratory load analysis procedure is developed by coupling an unsteady aerodynamic model with the rotor blade dynamic model based on the smart composite box beam theory. The dynamic deformations of the blade in all three directions, e ap, lead lag, and torsion, are included in the analysis. The e nite-state, induced-e ow model is used for predicting the dynamic loads. The procedure results in signie cant reductions in the amplitudes of rotor dynamic loads with closed-loop control. Detailed parametric studies are presented to assess the ine uence of number of actuators and their locations in vibratory hub load reduction.

Vibration reduction in rotor blades using active composite box beam

The use of segmented constrained layer damping treatment and closed loop control is investigated for improved rotor aeromechanical stability. The rotor blade load-carrying member is modeled using a composite box beam with arbitrary wall thickness. The ACLs are bonded to the upper and lower surfaces of the box beam to provide active and passive damping in the aeromechanical stability analysis. A finite element model based on a hybrid displacement theory is used to accurately capture the transverse shear effects in the composite primary structure, the viscoelastic and the piezoelectric layers within the ACL. The Pitt-Peters dynamic inflow model is used in the air resonance analysis under hover conditions. Rigid body pitch and roll degrees of freedom and fundamental flap and lead-lag modes are considered in this analysis. A transformation matrix is introduced to transform the time-variant system to a time-invariant system. A LQG controller is designed for the transformed system based on the available measure...

Aeromechanical stability analysis and control of smart composite rotor blades

The use of a special type of smart material, known as segmented constrained layer (SCL) damping, is investigated for improved rotor aeromechanical stability. The rotor blade load-carrying member is modeled using a composite box beam with arbitrary wall thickness. The SCLs are bonded to the upper and lower surfaces of the box beam to provide passive damping. A finite-element model based on a hybrid displacement theory is used to accurately capture the transverse shear effects in the composite primary structure and the viscoelastic and the piezoelectric layers within the SCL. Detailed numerical studies are presented to assess the influence of the number of actuators and their locations for improved aeromechanical stability. Ground and air resonance analysis models are implemented in the rotor blade built around the composite box beam with segmented SCLs. A classic ground resonance model and an air resonance model are used in the rotor-body coupled stability analysis. The Pitt dynamic inflow model is used in the air resonance analysis under hover condition. Results indicate that the surface bonded SCLs significantly increase rotor lead-lag regressive modal damping in the coupled rotor-body system.

https://iopscience.iop.org/article/10.1088/0964-1726/9/4/316/pdf

Use of segmented constrained layer damping treatment for improved helicopter aeromechanical stability

Aeromechanical stability plays a critical role in helicopter design and lead-lag damping is crucial to this design. In this paper, the use of segmented constrained damping layer (SCL) treatment and composite tailoring is investigated for improved rotor aeromechanical stability using formal optimization technique. The principal load-carrying member in the rotor blade is represented by a composite box beam, of arbitrary thickness, with surface bonded SCLs. A comprehensive theory is used to model the smart box beam. A ground resonance analysis model and an air resonance analysis model are implemented in the rotor blade built around the composite box beam with SCLs. The Pitt-Peters dynamic inflow model is used in air resonance analysis under hover condition. A hybrid optimization technique is used to investigate the optimum design of the composite box beam with surface bonded SCLs for improved damping characteristics. Parameters such as stacking sequence of the composite laminates and placement of SCLs are us...

Qiang Liu

Papers

Modeling of smart composite box beams with nonlinear induced strain

Vibration reduction in rotor blades using active composite box beam

Aeromechanical stability analysis and control of smart composite rotor blades

Use of segmented constrained layer damping treatment for improved helicopter aeromechanical stability

Improved Helicopter Aeromechanical Stability Analysis Using Segmented Constrained Layer Damping and Hybrid Optimization