Placement Of Piezoelectric Sensors Research Articles

Optimisation of active SHM system based on optimal number and placement of piezoelectric transducers

This paper concerns optimal placement and number of discrete piezoelectric macro fibre composite (MFC) sensors to optimise SHM systems. Its novelty lies in a two-stage placement methodology for discrete piezoelectric transducers, with fitness and objective functions to optimise the location and number of discrete piezoelectric sensors in order to reduce the cost and complexity of data processing and increase the effectiveness in damage detection. The maximisation of sensor voltage amplitude at multiple modes of vibration and the average of sensor normal damage index [Formula: see text] measured for several plates artificially cracked at different positions and orientations are proposed as objective functions to optimise the locations and the number of efficient piezoelectric sensors. A non-normalised root-mean-square deviation [Formula: see text] is introduced in this study in place of the conventional normalised [Formula: see text] to assess the degree of damage and sensor effectiveness. Furthermore, normal damage indices [Formula: see text] and [Formula: see text] normalised to 100% are proposed as the fitness functions. The placement methodology is utilised and verified for stiffened and unstiffened plates; stiffeners are used to break the dynamic symmetry and increase plate complexity. The performance of the placement methodology is tested for a healthy and 12 damaged plates to optimise SHM system based on the maximisation of sensor voltage and average normal damage index [Formula: see text] as objective functions. The results show that the placement methodology is efficient in determining the optimum number and placement of piezoelectric sensors at a low computational effort. The optimum placement of two piezoelectric sensors can efficiently monitor the crack’s initiation at different positions and multiple modes of vibration. The optimal placement and number of sensors have a positive impact on the cost, data acquisition and processing of the active SHM system

Noninvasive Swallowing Test for Young Healthy Adults: Finding the Best Location to Monitor Thyroid Cartilage Movements

Noninvasive electrophysiological swallowing monitoring has become commonly used for swallowing studies due to its accuracy and lack of radiation exposure. Excursion of the thyroid cartilage plays a crucial role in airway protection during oropharyngeal swallowing. Therefore, monitoring this excursion is essential in swallowing studies. The level of the thyroid cartilage and the level at which cricothyroidotomy is performed are two locations at which piezoelectric sensors can be placed to measure excursion activities. This study aimed to find the best location for the placement of piezoelectric sensors for detecting thyroid cartilage excursion movements during noninvasive swallowing tests. Nineteen healthy young adults (9 men, 10 women), aged 20 to 32 years (mean: 24.5 ± 4.0 years), were recruited for the analysis of swallowing signals while drinking six different bolus volumes of water. The quantitative excursion signals of the thyroid cartilage integrated with the activities of the submental muscles were compared between the two piezoelectrical sensor placement locations and between men and women. Recording at the thyroid cartilage level showed higher excursion amplitude, earlier onset latency, and longer excursion duration under most bolus conditions compared to those recorded at the cricothyroidotomy level, although some conditions did not reach statistical significance. Earlier onset latency makes detecting the delayed latency in dysphagia easier, and higher amplitude facilitates signal detection on the skin surface. Thyroid cartilage recordings did not differ significantly between men and women. The data suggest that the thyroid cartilage level is more suitable for piezoelectric sensor placement for recording swallowing signals than the cricothyroidotomy level.

Multi-objective optimization of piezo actuator placement and sizing using genetic algorithm

Sizing and placement of piezoelectric sensors and actuators (S/As) for active vibration control of flexible structures is commonly based on maximum control effectiveness. Mounting of piezos changes the natural frequencies of existing structure, which would have been designed to have a certain natural frequency spectrum in relation to the disturbance excitation. In the event of failure of the active system, natural frequencies of the structure with piezos (now rendered passive) become significant. Therefore minimal change in natural frequency along with good controllability should be design consideration while deciding sizing and placement of actuators. Multi-objective genetic algorithm is shown to be useful for optimization of placement and sizing of piezo actuators for such problems. Optimal S/As sizing and locations have been found out for stationary and rotating cantilever beams with multiple sensors/actuators.

Vibration Control for Flexible Smart Cantilever Plate Based on Characteristic Model

The vibration problem of spacecrafts' flexible appendages shaped as cantilever plate will be unavoidable when external disturbance excitation happens,including bending and torsional mode vibration and which will affect the stability and control accuracy of the system.Especially the lower amplitude modal residual vibration near the equilibrium point is hard to be suppressed. To solve this problem,nonlinear golden section adaptive control based on characteristic model and combined with non-linear switched logic integral damping algorithm is adopted to suppress the said vibration of cantilever plate quickly.Firstly,decoupling of bending and torsional modes is realized by optimal placement of piezoelectric sensors and actuators.Secondly,the piezoelectric smart cantilever plate is designed and built up,and the modal frequencies and frequency responses of bending and torsional modes are obtained by experimental identifications.Finally,several control methods are used to develop the experimental comparison researches for attenuating the bending and torsional mode vibration of the plate.The experimental results demonstrate that the adopted methods can suppress the vibration of cantilever plate quickly.

Optimal placement of piezoelectric sensors and actuators for vibration control of a composite plate using genetic algorithms

In this paper, the placement of piezoelectric sensors and actuators has been studied. Genetic algorithms have been used to find efficient locations of piezoelectric sensors and actuators of a smart composite place. Locations of both sensors and actuators have been determined with consideration of controllability, observability and spillover prevention. The composite specimen with piezoelectric sensors and actuators has been prepared according to the optimization result. The experimental vibration control shows significant vibration reduction for the controlled modes with little effect on the residual modes. In addition, the closed loop system is observed to be robust with respect to system parameter variations.