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Numerical aNd experimeNtal studies oN the rotatiNg rotor with three active composite blades badaNia NumeryczNe i eksperymeNtalNe wirującego wirNika z trzema aktywNymi łopatami kompozytowymi [8], but the object of the research was a thin plate with PZT actuators.The aim of this paper is to determine the relation between the dynamics of a rotor blade with MFC elements in relative motion and the rotational movement of the hub. Constant angular velocity can generate undesired changes in the natural frequencies and/or eigenmodes of the active composite blades. The aim of the experimental research was to demonstrate the possibility of using the MFC actuator for reducing these changes. The experimental setupThe experimental studies were performed using a specially designed test stand which is shown in Fig. 1. This stand was built at the Department of Applied Mechanics at the Lublin University of Technology. The rotor (Fig. 1) consisted of a hub with three composite blades which were located 120 degrees relative to each other. The rotor blades were beams with a rectangular cross-section made of glassepoxy laminate.The mechanical properties of the glass-epoxy laminate were as follows:Young's modulus in fibre direction (i.e., direction 1): 46.43 GPa • and in transverse direction of the fibers (i.e., direction 2): 14.926 GPa, respectively, Poisson's ratio in plane 1-2: 0.27, • shear modulus in plane 1-2: 5.233 GPa,Each blade was composed of six layers. The lay-up configuration of the laminate was: [±45/90] S . The geometry of the rotor blades is given in Table 1. The rotor hub was driven by a DC motor. In addition, the sensors and actuators were fixed on the opposite surfaces of the beams. The strain-gauges and piezoelectric actuators were used to measure and control the dynamics of the rotor blades in their relative motion. In our case, the Macro Fiber Composite active elements were used as actuators. They were MFC elements type M-8528-P1. In this case, the piezoelectric d 33 effect occurs [15]. Each element can be powered by electric current in the range of -500 to 1500 volts.The piezoelectric properties of the MFC element depend on its dimensions. According to the literature [16], the optimal value of the d 33 parameter for MFC M-8528-P1 elements is 1.01*10 -7 m/V. The coefficient of permittivity is 8*10 -9 F/m. The mechanical properties of the MFC element were:Young's modulus in fibre direction (i.e., direction Fig. 1(b) shows the electronic equipment which was used to control the power of the electrical motor and piezoelectric transducers. Additionally, the DSP subsystem was used. The numerical model of the rotorThe numerical model of the rotor was designed by the finite elements method using the commercial system Abaqus [1]. The FE model of the rotor is shown in Fig. 2.The model consists of a base with electric drive, the hub with a drive shaft, a blade handle, three composite blades and MFC active elements [16]. The hub and the base of the rotor were built of 10-node tetrahedral, solid elements having three transl...

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In the paper, the authors discuss the numerical and experimental modal analysis of the cantilever thin-walled beams made of a carbon-epoxy laminate. Two types of beams were considered: circumferentially asymmetric stiffness (i.e., CAS) and circumferentially uniform stiffness (i.e., CUS) beams. The layer-up configurations of the laminate were chosen to get a vibration mode coupling effect in both analysed cases. The aim of the paper was to perform the numerical and experimental modal analysis of the composite structures, when a flapwise bending with torsion coupling effect or flapwise-chordwise bending coupling effect took place. Firstly, numerical studies by the finite element method was performed. The numerical simulations were carried out by the Lanczos method in the Abaqus software package. The natural frequencies and the corresponding free vibration modes were determined. Next, the experimental modal analyses of the CAS and CUS beams were performed. The test stand was consisted of a special grip, two beams with an adhered holder, the LMS Scadas III system with a modal hammer and an acceleration sensor. Finally, the results of both methods were compared.

In this paper, the dynamical behavior of composite material is analyzed, including the energy harvesting effect. The composite is modeled by the Finite Element Method (FEM) and is made of pre-impregnate with a matrix of thermosetting epoxy resin reinforced with high-strength R-type glass fibers, and it is designed as a beam structure that is exposed to mechanical vibrations. The structure assumed the form of a beam with a substantially rectangular cross section. The couplings of motion occurring between mode shapes at properly selected fiber orientations are investigated. The beams with determined sets of composite layers and a coupling effect are used to recover electricity from the mechanical vibrations in the vicinity of the first resonance zone. The composite with a certain number of fiber glass layers has assumed an orientation relative to the beam axis. The new values found in this paper are the intensity of the coupling between the bending in the stiff and flexible directions of the beam for a chosen fiber layer stacking sequence. Additionally, the influence of layer configuration on the energy harvesting efficiency of the Macro-Fiber Composite (MFC) piezoelectric element is assessed.

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