Study on the Dynamic Performance of Locally Resonant Plates with Elastic Unit Cell Edges

A Floquet–Bloch approach is employed to demonstrate the stop bands for an infinite locally resonant plate. In addition, the effects of the connection stiffness of the unit cells on the band gap and dynamic performance of a locally resonant plate are analysed. The results show that the degree of inhibition of elastic waves in the band gaps increases rapidly when the connection stiffness of the unit cells increases within the scope of the transition stage stiffness. However, outside of the range of transition stage stiffness, the degree of inhibition of elastic waves in the band gaps basically remains unchanged. This discovery widens the application scope for vibration and noise control using locally resonant plates.

Construcción y caracterización de un cristal artificial elástico

In order to achieve the main objective, a design of a supercell or basic cell consisting of an array of elastic units will be made. This supercell will be obtained from a locally periodic structure of coupled blocks, whose central block will be deformed; later, the one-dimensional elastic artificial crystal will be built, which will be characterized experimentally and understood from a strong mooring model. The locally proposed system consists of a set of vibrating bars, identical, coupled together, imitating a set of " defectsin a one-dimensional periodic network and with a periodic coupling. It is expected that the acoustic wave amplitudes of this system show similar characteristics to the wave functions of an electron strongly linked in an eective potential generated by a one-dimensional network of atoms. In the locally periodic system that we propose the vibrating elastic units will be coupled together by means of locally periodic rods; since, in these we can control the resonance frequencies and the same frequency of normal resonance. Furthermore, in these rods, the lower energy vibration modes can be isolated from the rest of the excited states. When the resonance frequency of the elastic unit (defect) is in the gap of the coupler (locally periodic rod) the wave amplitude will be located. To generate the emergence of a new band in the second torsion spectrum gap, from an originally periodic system, using the transfer matrix method for torsional waves, six elastic structures formed by 1, 2, 3 and up to 6 were designed. coupled supercell The neighboring levels of the emerging band is separated to a maximum distance of 100 Hz to facilitate its detection. This band is in the frequency range of 26450 to 26650 kHz.

Analysis of Stiffness and Energy Consumption of Nonlinear Elastic Joint Legged Robot

In order to reduce the energy consumption of the legged robot in walking, this paper designs a kind of nonlinear elastic joint from the flexible variable-stiffness joint based on the mammal walking on the limb and optimizes the leg structure of the legged robot. The motor is rigidly connected to the articulated lever. When the lever is accelerated or decelerated, the elastic unit is introduced. The system can be considered as a special variable-rate elastic system. This paper will study it from theory and simulation experiments. Based on the dynamic analysis, a functional relationship between the output torque and the torsion spring stiffness and between the energy consumption and the torsion spring stiffness was established. By finding the extremum, the two optimum torsional spring stiffness that can minimize the required output average torque and the energy consumed during one cycle of motion were deduced. The results show that using this design in a reasonable position can effectively reduce the energy consumption of the system and can achieve up to a 50% reduction in energy consumption.

Theoretical Study of Memristor and \\ Time Reversal based\\ Nonlinear Elastic Wave Spectroscopy

Principle of memristor presented by Leon Chua and time reversal based non-linear elastic wave spectroscopy (TR-NEWS) which can be applied to acoustic tomography are reviewed. Correlation of acoustic or electromagnetic nonlinear waves and its time reversed wave can produce strong signal. Materials like transducer or biological skin can be assumed to be composed of a large number of small elastic unit: hysteretic elementary unit (HEU), and one can take a HEU as a memristor whose operation depends on time. Relation between TR-NEWS and solitonic wave in fluid, and relation between decomposition of time reversal operator (DORT) and chaotic oscillation are discussed.

Controlling the Thickness Uniformity in Equal Channel Angular Rolling (ECAR)

As the surface friction between feeding rolls and metal sheet generates the feeding power of ECAR, the generated feeding power is low, and the friction between the metal sheet and ECAR die should be minimized. However, for obtaining a large shear deformation by ECAR, the metal sheet should be tightly contacted with the wall of ECAR die. In this condition, the thickness of the metal sheet is continuously increased during ECAR. A new ECAR apparatus is developed for maximizing the shear deformation and obtaining sheet thickness uniformity, and succeeding continuous ECAR with such a limited feeding power. By controlling the outlet gap of the ECAR die with elastic unit, the thickness of the metal sheet is kept uniform. Detailed thickness control mechanism during the new ECAR process is analyzed. A sheet of Al 6063 alloy that is 1-pass deformed with the new ECAR apparatus shows below ±0.037 mm of thickness variation and 0.61 of shear strain.

Basement Membrane of Smooth Muscle Cell and Its Association With Elastic Tissue in Aorta

Organization and connection between smooth muscle cells and elastic tissues in aortas is not elucidated. Keech believed that the smooth muscle cells anchore on the elastic tissue. Among the fibers of the aortic connective tissue, there are collagen, elastic tissue and microfibril. This communication is to present evidence that the microfibrils which are derived from the basement membrane of the smooth muscle cells, play a role for connection between the smooth muscle cells and the elastic tissues.Thoracic aortas from new born rats were fixed with Dalton's chrom-osmium solution, embedded in Epon 812 and stained with uranyl acetate and lead citrate. Our previous work showed that the smooth muscle cell synthesized the elastic tissue during its differentiation prior to completing the process. At the actively synthesizing site of the cell, the basement membrane was replaced by numerous microfibrils (Fig. 1 MF). The microfibrils extended from the basement membrane toward the preformed elastic lamellae (EL), occasionally surrounded scallop-shaped elastic unit (EU).