The paper parametrically explores the design sensitivity of a fiber optic pressure sensor (FOPS), based on the potential
failure mechanisms expected in the sensor diaphragm. The product under study is a miniature FOPS that can be
embedded in, or installed on, a structure for pressure monitoring applications. The field operating conditions are defined
in terms of temperature, pressure, and vibration loading. The FOPS probe has a Fabry-Perot cavity, with the fiber tip and
a miniature diaphragm acting as the two mirrors. The cavity length changes when the diaphragm deflects under
pressure. However, due to field operating conditions, several failure mechanisms may affect the structural and optical
characteristics of the sensor, such as cracks in the diaphragm and/or high residual stresses in the optical fiber. With the
aid of finite element analysis, this article investigates conflicting design constraints due to structural failure mechanisms
in the diaphragm and elaborates on the severity of each one by parametric design sensitivity studies.
In this article, the modeling and control of enclosed sound fields using shunted piezoelectric circuit is investigated. A
spherical wave, which is generated by a noise source located in the near field, is transmitted into a rectangular enclosure
through a flexible panel. Piezoelectric patches, which are bonded symmetrically to the top and bottom surfaces of the
panel, are either shunted through electric shunt circuits, and hence acting as energy dissipaters, or used as sensors for
vibration measurements. Microphone sensors are used inside and outside the enclosure for acoustic pressure
measurements. The shunted circuits are developed such that the acoustical effects of two dominant vibration modes can
be attenuated, and this feature makes it appealing for noise control schemes for multiple tones. The numerical
predictions of the noise attenuation levels are found to be in good agreement with the corresponding experimental
In designing a controller, one way to avoid an energy spillover is to use what is called the zero spillover scheme. However, practical limitations may make such a controller impossible to realize, and one will need to implement a relaxed version of this controller called a relaxed zero spillover controller (RZSC). Here, analytical and experimental investigations into a RZSC scheme are presented. This controller has been used for active structural acoustic control (ASAC) of sound transmission into an enclosure. Noise is transmitted through the flexible boundary of the enclosure, and piezoceramic patches, mounted on the flexible boundary, are used as actuators. Polyvinylidene fluoride sensors are used on the flexible boundary and condenser microphone sensors are used inside and outside the enclosure. The stability of the chosen RZSC scheme for a single input, single output system and the extension to multiple input, multiple output systems are discussed along with other issues.
In this paper, analytical and experimental investigations conducted into the design and use of fiber-tip based Fabry-Perot sensors for control of structural acoustics are presented. Noise is transmitted into the enclosure through a flexible boundary, and the fiber-tip sensors are designed for acoustic pressure and air particle velocity measurements inside and outside the enclosure as well as panel acceleration measurements. The benefits of these sensors for realizing zero spillover control schemes and other schemes are discussed.
In designing a controller, one way to avoid energy spillover is to use what is called the zero spillover control scheme. Here, this scheme is studied for actively controlling sound fields inside an enclosure with a flexible boundary. Noise is transmitted into the enclosure through the flexible boundary, and piezoceramic patches, which are mounted on the flexible boundary, are used as actuators. Polyvinylidene fluoride sensors are used on the flexible boundary and microphone sensors are used inside and outside the enclosure. The locations of the sensors needed to construct a zero spillover controller are discussed along with other issues.