A Layered Notch Filter for High-Frequency Dynamic Isolation

Abstract

An efficient method of isolation from high-frequency vibrations is the use of periodically layered composites acting as a mechanical filter. This device is a periodically layered stack of alternating materials with widely different densities and stiffnesses. The working principle of the device is wave reflection, and the device becomes increasingly effective when there is a large impedance mismatch which leads to rapid attenuation of an input wave for certain frequency ranges. This filter acts only in specific frequency bands. At other frequencies, it will transmit the vibratory energy unmodified, thus acting as a mechanical notch filter. The theoretical development of the mechanical notch filter is based on the theory of waves in periodically layered media. Floquet theory is used to solve the equations for the propagation of plane waves through a laminated system of parallel plates of different materials when the direction of propagation is normal to the plates. Several experiments were conducted to prove the validity of the mechanical notch filter concept. These experiments demonstrated that the theory is correct and that the results have practical application.

The stress field due to an interfacial edge dislocation in a multi-layered medium

“…Many modern composites and advanced material systems, such as protective coatings, laminated ceramics, microelectronic devices, layered nanofilms, functionally graded materials and adhesive joints, are examples of multi-layered structures (Sackman et al 1989;Holleck et al 1990;Roeder and Sun, 2001;Chen and Pindera, 2006;Khanna and Kotousov, 2014). These structures are also prevalent in nature, ranging from the nano-scale structures, which provide unique properties to bio-materials such as nacre, tooth enamel and bone (Sellinger et al 1998;Gao et al 2003) to the large scale structures such as stratified rock formations in the earth's crust (Daneshy, 1978;Gudmundsson et al 2010;Khanna and Kotousov, 2015).…”

Development of curved beam periodic structure in broadband resonance suppression for cylindrical shell structure

“…One kind of the application forms is employing the periodic structures as isolators. Sackman et al. (1989) developed a periodic structure isolator composed of periodically layered metallic and elastomeric shear mountings to attenuate stresses at high frequencies.…”

Broadband Vibration Attenuation Using Hybrid Periodic Rods

“…Each such structure has a repeating set of stiffeners which are placed at regular intervals. Sackman, et al Sackman, et al (1999) presented a layered notch filter device that is limited only to high-frequency vibrations. Such a filter which was developed theoretically based on the Floquet theory is a periodically layered stack of two alternating materials with widely different densities and stiffnesses.…”