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Active washer for smart mechanical linkage
9 December 2017
Bolted connection is the most common way to assemble mechanism. It is widely used in transport domains, such as aerospace, rail, aircrafts… Ensuring that the minimum torque value is always present in the assembly is one of the main maintenance tasks for those components. A possible way to carry out those actions is to implement active component in the bolted assembly. A solution is proposed in this document. Construction, potentialities, performances (based on lap-joint demonstrator) and limitations are identified and confronted to other techniques.
Semi-passive vibration control technique via shunting of Amplified Piezoelectric Actuators
12 January 2016
The objective of this paper is to provide results of an experimental and analytical investigation of Amplified Piezoelectric Actuators (APA) as vibrational isolator in a configuration of a mechanical Single Degree of Freedom system. The investigation is aimed at assessment of the mechanical properties modification ability via shunting techniques. The investigation consist of a phenomenological modelling of the APAs considered as generators and experimental verification of the vibrational energy dissipation ability in frequency domain. The results obtained during this investigation reveal that it is feasible to receive more than 20 dB reduction of the displacement amplification in the resonant range. Moreover, three tested examples of APA reveal up to 9 % of resonant frequency shift due to proper adjustment of the electronic shunting circuit, which is an encouragement for further analyses towards application of the APAs in semi-passive vibration control applications.
Potentialities of APA® composite shell actuators and SA75D amplifier for new dynamic applications
11 January 2016
The piloting of APA’s composite shell by SA75D power amplifier offers new opportunities for dynamic new applications. Two in particular were received and are being studied: the design of a compact table tensile micro machine for characterizing stress-strain laws at high strain rate of wires, fibers, strands and textile samples that will usefully complete the fleet of dynamic testing machines available, the generation of synthetic jets of air pulsed also studied at ONERA. The energy capacity (displacement, force) without or with an external linear load were modeled versus the rise time using the Simulink code and experimentally measured using a very light device. Other identified improvements remain to be implemented both at the APA’s actuators as the Amplifier SA75D to get some gains.
Module Stepping Piezoelectric Actuator: A versatil way of micro-positioning actuation
10 January 2016
Stepping Piezoelectric Actuators (SPA’s) – based on the Piezoelectric Friction-Inertial Actuation (PFIA) principle – are made from Cedrat Technologies Amplified Piezoelectric Actuators (APA). They use the stickslip principle to couple high resolution positioning (cm) and low volume (10cm), allowing easier multi-DoF mechanism developments and miniaturization possibilities – is presented. Results obtained on three innovative engineering models – linear long stroke, rotary and three-DoF actuators – are presented, giving the reader actual benefits of this concept and allow addressing new applications such as consumer goods and medical devices.
Encapsulated Piezo Actuators for use at high power levels and/or within harsh environmental conditions
9 January 2016
Traditionally piezo ceramic actuators have not been able to operate within harsh/humid environments. Furthermore, two temperature-related problems have limited the number of applications for piezo actuators. Firstly, internal heating of the ceramic from use at high frequency, for extended periods. Secondly, external environmental conditions. Encapsulation of the actuator offers an opportunity to overcome all of these problems by allowing the environment directly in contact with the ceramic to be controlled. This paper presents R&D work done on encapsulated actuators, design work, and thermal simulation calculations with an emphasis on experimental results.
Amplified Piezo Actuator APA® with viscoelastic material for machine tool semi active damping system
8 January 2016
Modern machine tools must achieve a high precision for a better surface texture and higher flexibility for wide range of machining requirements. To fulfill these requirements, a semi-active damping system for a new generation of machine tools is proposed. The new concept is partially based on the Amplified Piezo Actuators APA® from CEDRAT Technologies. With these actuators, the dynamic behavior (stiffness and damping) of structural body components of machine tools can be controlled and adjusted to the optimum parameters. To reduce the transfer of vibrations through the active elements, a viscoelastic material was used. This article presents test results performed on the APA® with viscoelastic material. A significant reduction of the vibrational amplitude at resonance frequency was observed with additional material. The optimized quantity of viscoelastic
material reduces the full stroke of the actuator only by 10 percent. At the same time, the viscoelastic material has reduced the amplitude at resonance frequency by more than double. The designed actuator obtains a blocking force of 8.5kN. Results obtained from the tests performed on the machine tool showed significant surface texture improvement with use of the amplified piezoelectric actuator.
