![]() When the host fluid is epoxy, the assembled materials can be cured and the composite sample extracted from the sacrificial frame. This device is used to assemble a variety of microscopic particles differing in size, shape, and material into simple patterns within several host fluids. ![]() The results of the study will be used for an application for fibrillation of cellulose fibers to further improve energy efficiency in paper pulp industry.Īn ultrasonic assembly device exhibiting broadband behavior and a sacrificial plastic frame is described. The electric power input required to achieve high cavitation intensity is relatively low and resulted in high energy efficiency. The results of the development process show that high cavitation intensity can be achieved by ultrasound induced power. In this application, the resonance amplification is mainly used to generate and control cavitation at a frequency that corresponds to a range of beaker natural frequencies. The aim of this feedback loop is to keep the resonance phenomena stable with respect to an adaptable frequency. The characteristic control parameters (excitation frequency and amplitude) can be adjusted to the fluid condition in the beaker (reactor) by a feedback control from a pressure sensor inside the beaker. The secondary aspect is to numerically model and experimentally evaluate a prototype beaker, where the adaptive control scheme is implemented to attain high and stable cavitation intensity. The primary objective is to keep a system of coupled and tuned resonances stable, and by that obtain high cavitation intensity in a water filled beaker. The proposed thesis work focuses on an application of acoustic cavitation and on adaptive control of resonance amplification to be used in the paper pulp industry. Ultrasound excitation has found recent application in terms of replacing the existing dynamic mechanical systems that use high energy with low levels of efficiency. The need for high-intensity focused ultrasound (sound with frequencies between 20 kHz to 10 MHz) and modeling of such systems has drawn great attention in engineering. KEY WORDS:Phononic Crystals, FEM, Eigenfrequencies, Frequency Response Analysis, Band Gap, Euler-Bernoulli Beam, Spring Resonator.Īcoustic cavitation in fluids using high powered ultrasound has been of great interest in industries and biomedical engineering. In the thesis, I give the steps for two kind of simulations in COMSOL Multiphysics. COMSOL Multiphysics is a very suitable tool for analysis of wave propagation in phononic crystals. All the simulation works have been done in COMSOL Multiphysics. Two methods also shows us the range of band gaps. And the second one is finding band gaps through frequency response analysis. The first one is finding flexural bandgaps through Eigenfrequencies. I have done two analysis to find bandgaps. ![]() In the bandgaps of the frequency ranges, flexural wave cannot propagate in the structures. My research topic of the thesis is about vibration reduction of beams connected to spring resonators with one degree of freedom, with the ultimate purpose to find bandgaps. In this thesis there is a brief introduction to phononic crystals. Understanding and controlling the phononic properties of the phononic crystals provides opportunities to reduce environmental noise. For past few decades the study about phononic crystals are getting more popular. ![]()
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