Abstract: An aerodynamic component such as a helicopter rotor blade has an aerodynamic flow profile, a free end and a mounting end forming a blade root for attachment to a rotor mast. A blade section between the root and the free end has a leading edge and a trailing edge as viewed in the flow or chord direction. The blade is enclosed on its suction side and its pressure side with a respective skin. A nose flap or leading edge flap is secured to the leading edge by a bearing or hinge. The blade tilting angle is adjustable by piezo-drive elements arranged in at least one pair forming an actuator for each nose flap. The piezo-elements of a pair are arranged in the chord direction one behind the other and the pair is secured to the body of the blade by a fixed point positioned between the elements of a pair. The expansion and contraction from the piezo-element closer to the trailing edge is transmitted to the flap by a push rod.

Abstract: A piezoelectric actuating drive is calibrated so that displacements or movements of its actuator output beam (4) become independent of environmental operating conditions and of piezoelectric instabilities. For this purpose an automatic determination and correlating of energizing signal values and respective displacement positions of an actuator beam (4) are performed on the basis of first sensing or measuring striking times (t1, t2) when the actuator beam (4) encounters at least one, preferably two limit stops which limit the beam displacement caused by piezoelectric action. The change of the electric capacitance of a piezostack (3) that displaces the actuator output beam (4) is measured when the beam (4) strikes a limit stop. Instead of measuring a change in the electric capacitance of the piezostack (3), electric charge impulses may be measured at the time (t1, t2) and evaluated for the correlation between the energizing control or input signal and the corresponding output beam displacement.

Abstract: A ligand layer on a metal surface is capable of being reversibly switched between adhesion and deadhesion.

Abstract: An actuator device (2) includes a piezoelectric or electro-strictive solid state actuator element (6) that is elongated upon application of an electric voltage thereto, and a transmission mechanism (8) that amplifies the stroke displacement of the actuator element. The transmission mechanism (8) includes a plurality of rigid frame members (12), including unitary frame members (12.1, 12.2) and divided frame members (12.3), and elastically flexible joints (10) that respectively interconnect the frame members. Each one of the divided frame members (12.3) is made up of a plurality of separate parallel link rods (16). Each flexible joint (10) is made up of a plurality of individual parallel hinge members (18) that respectively connect an end of each one of the link rods (16) to the adjacent unitary frame member (12.1, 12.2).

Abstract: A method for reversibly switchable cross-linking of monomers includes cross-linking the monomers by adding complexable metal ions to form a polymer, and bond-breaking the polymer formed by applying a direct voltage, by changing the pH value or by changing the temperature.

Abstract: A piezoelectric actuator has at least two piezoelectric actuator elements connected in series with each other mechanically and electrically and form a half bridge in an amplifier bridge circuit having a further half bridge formed by two series connected electronic switches which are operated or clocked by a control circuit such as a pulse modulator circuit for periodically energizing the piezoelectric actuators in push-pull fashion. A choke (22) is connected between the junction point (JP1) of the two piezoelectric actuators and the junction point (JP2) between the two electronic switches (23, 24) for assuring a loss free reverse charging of the two piezoelectric actuators functioning as electrical capacitors in the energizing bridge circuit (21). The choke 22 functions as an energy storage and the stored energy is used in the push-pull charging of the capacitors (19, 20) formed by the piezoelectric elements.

Abstract: An airfoil member, especially a rotor blade for a helicopter, includes an airfoil body and a servo-actuated flap tiltably connected to the airfoil body so as to form at least a portion of the trailing edge of the airfoil member. At least one piezoelectric actuator is arranged inside the airfoil member, and connected to the servo-flap via a transmission mechanism and a connecting rod linkage so as to tiltingly deflect the servo-flap as needed. Preferably, two counter-acting piezoelectric actuators are connected to the flap via respective transmission mechanisms and connecting rod linkages. An elongation of the piezoelectric actuators in the span width direction of the airfoil member is converted or redirected into an actuating motion in the chord length direction of the airfoil member by the transmission mechanisms.

Abstract: A mechanical resonator has an electronically adjustable resonance frequency and is especially adapted to be used as a tunable vibration absorber. The mechanical resonator includes an inertial mass mounted on a free end of a spring, which is secured at its other end to the structure that is to be vibrationally damped. In order to vary the resonant frequency of the resonator, an electromechanical converter such as a piezoelectric element is connected to the spring and/or the inertial mass, and a displacement and/or acceleration sensor provides a sensor signal that is dependent on the respective displacement and/or acceleration of the spring and/or the inertial mass. An electronic control circuit generates an actuating signal based on the sensor signal. The actuating signal is applied to the electro-mechanical converter, which responsively exerts an adjusting force onto the spring and/or the inertial mass.

Abstract: A piezoelectric actuator or sensor includes a solid state body made of a monolithic piezoelectric material, a plurality of actuating electrodes formed as closed-loop electrodes entirely around the perimeter of the solid state body, and a support plate with two contact electrodes respectively having interdigitally intermeshing contact fingers arranged thereon. The intermeshing or alternating contact fingers of the two contact electrodes respectively contact alternating ones of the actuating electrodes, preferably through an adhesive layer having conducting particles dispersed therein. The energized actuating electrodes effectively form virtual piezoelectric layers in the solid state body.

Abstract: An electrostrictive or piezoelectric actuator device includes a solid state actuator element (4) that is elongated in the lengthwise direction (L) and contracted in the transverse direction (T) upon application of an electric voltage thereto. The actuator element (4) is clampingly held between a housing floor and an actuator output pin (6) in a housing (2). A protective interlayer (12) is respectively arranged between the lengthwise end faces of the actuator element (4) and the housing floor and the actuator pin respectively, to protect the actuator element against transverse stress peaks. The interlayer (12) provides a soft or elastic coupling in the transverse direction and a substantially rigid, force and stroke transmitting coupling in the lengthwise direction.

Abstract: The invention relates to an electro-hydraulic actuator, especially for an antilock brake system, which directly converts electrical input energy into hydraulic useful energy and has an especially simple and problem-free design as well as very rapid adjustability. A working chamber of the actuator according to the invention is filled with an electrostrictive fluid and provided with an electrically controlled electrode system to generate an electrical field that causes a change in pressure and/or volume in the electrostrictive fluid.