Ondrej Rubes

This work examines how both the switching phase shift and the amplitude of an externally applied voltage in the Synchronized Switch Damping on Voltage (SSDV) method affect the modal characteristics of a mechanical structure fitted with piezoelectric transducers. A lumped-parameter electromechanical model was formulated and validated using a hybrid energy harvester setup. Numerical analyses were performed over a broad range of phase shifts and voltage amplitudes, showing that the phase shift—typically viewed as a factor that degrades performance—can instead be exploited as an extra control variable that strongly influences both damping efficiency and resonance frequency shift. Experimental tests carried out with a custom-built SSDV control unit corroborated the main numerical trends, especially the pronounced sensitivity of modal parameter changes to the combined effect of switching instant and applied voltage. The findings show that suitably chosen phase–voltage pairs can achieve superior vibration reduction relative to standard zero-phase SSDV, while simultaneously enabling deliberate frequency tuning. This demonstrates the potential for broader application of SSDV-based semi-active damping in systems that require adjustable vibration control under periodic excitation.

This paper explores the modal properties tuning of mechanical systems using piezoelectric transducers. The study focuses on piezoelectric shunt damping techniques, particularly Synchronous Switch Damping on Voltage (SSDV), to mitigate vibration and alter resonant frequencies. Simulations and experiments were conducted to investigate the influence of phase shifts and applied voltage on the system's dynamics. The simulation results indicate significant changes in the resonant frequency at certain phase shifts, while the experimental results showed partial alignment with the simulations, revealing challenges in electronics and the need for precise control. This research contributes to the development of adaptive vibration control technologies, enhancing the stability and lifespan of mechanical systems.

This paper deals with a development and lab testing of energy harvesting technology for autonomous sensing in railway applications. Moving trains are subjected to high levels of vibrations and rail deformations that could be converted via energy harvesting into useful electricity. Modern maintenance solutions of a rail trackside typically consist of a large number of integrated sensing systems, which greatly benefit from autonomous source of energy. Although the amount of energy provided by conventional energy harvesting devices is usually only around several milliwatts, it is sufficient as a source of electrical power for low power sensing devices. The main aim of this paper is to design and test a kinetic electromagnetic energy harvesting system that could use energy from a passing train to deliver sufficient electrical power for sensing nodes. Measured mechanical vibrations of regional and express trains were used in laboratory testing of the developed energy harvesting device with an integrated resistive load and wireless transmission system, and based on these tests the proposed technology shows a high potential for railway applications.

This paper deals with analytical modelling of piezoelectric energy harvesting systems for generating useful electricity from ambient vibrations and comparing the usefulness of materials commonly used in designing such harvesters for energy harvesting applications. The kinetic energy harvesters have the potential to be used as an autonomous source of energy for wireless applications. Here in this paper, the considered energy harvesting device is designed as a piezoelectric cantilever beam with different piezoelectric materials in both bimorph and unimorph configurations. For both these configurations a single degree-of-freedom model of a kinematically excited cantilever with a full and partial electrode length respecting the dimensions of added tip mass is derived. The analytical model is based on Euler-Bernoulli beam theory and its output is successfully verified with available experimental results of piezoelectric energy harvesters in three different configurations. The electrical output of the derived model for the three different materials (PZT-5A, PZZN-PLZT and PVDF) and design configurations is in accordance with lab measurements which are presented in the paper. Therefore, this model can be used for predicting the amount of harvested power in a particular vibratory environment. Finally, the derived analytical model was used to compare the energy harvesting effectiveness of the three considered materials for both simple harmonic excitation and random vibrations of the corresponding harvesters. The comparison revealed that both PZT-5A and PZZN-PLZT are an excellent choice for energy harvesting purposes thanks to high electrical power output, whereas PVDF should be used only for sensing applications due to low harvested electrical power output.

With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural health monitoring (SHM) of critical composite structures is increasingly expected and required. The optimized usage of this concept is subject of intensive work in the framework of the EU COST Action CA18203 “Optimising Design for Inspection” (ODIN). In this context, a thorough review of a broad range of energy harvesting (EH) technologies to be potentially used as power sources for the acoustic emission and guided wave propagation sensors of the considered SHM systems, as well as for the respective data elaboration and wireless communication modules, is provided in this work. EH devices based on the usage of kinetic energy, thermal gradients, solar radiation, airflow, and other viable energy sources, proposed so far in the literature, are thus described with a critical review of the respective specific power levels, of their potential placement on airplanes, as well as the consequently necessary power management architectures. The guidelines provided for the selection of the most appropriate EH and power management technologies create the preconditions to develop a new class of autonomous sensor nodes for the in-process, non-destructive SHM of airplane components.

Kinetic piezoelectric energy harvesters are used to power up ultra-low power devices without batteries as an alternative and eco-friendly source of energy. This paper deals with a novel design of a lead-free multilayer energy harvester based on BaTiO₃ ceramics. This material is very brittle and might be cracked in small amplitudes of oscillations. However, the main aim of our development is the design of a crack protective layered architecture that protects an energy harvesting device in very high amplitudes of oscillations. This architecture is described and optimized for chosen geometry and the resulted one degree of freedom coupled electromechanical model is derived. This model could be used in bistable configuration and the model is extended about the nonlinear stiffness produced by auxiliary magnets. The complex bistable vibration energy harvester is simulated to predict operation in a wide range of frequency excitation. It should demonstrate typical operation of designed beam and a stress intensity factor was calculated for layers. The whole system, without presence of cracks, was simulated with an excitation acceleration of amplitude up to 1g. The maximal obtained power was around 2 mW at the frequency around 40 Hz with a maximal tip displacement 7.5 mm. The maximal operating amplitude of this novel design was calculated around 10 mm which is 10-times higher than without protective layers.

The paper deals with an analysis of maximal operation amplitudes of piezoelectric energy harvesting systems generating electrical energy from ambient vibrations. Energy harvesting systems could be very interesting alternative for autonomous powering of ultra-low power electronics, sensors and wireless communication. A design of piezoelectric vibration energy harvester is based on the cantilever beam design with active piezoelectric layers. The output power is proportional to an amplitude of relative oscillation of this resonance mechanism. This paper presents an analysis based on the simulation model of multidisciplinary piezoelectric energy harvesting device, enabling an optimization of its key parameters ensuring a maximal efficiency of the system. Such analysis is also essential for development of new energy harvesting systems formed of new smart materials and structures which could be integrated in future development processes.