Suppression of Lateral Vibration in Rectangular Ultrasonic Plastic Soldering Tool Based on Phononic Crystal Structure

2019 ◽  
Vol 105 (6) ◽  
pp. 953-959
Author(s):  
Tian-Tian Zhao ◽  
Shu-Yu Lin
Keyword(s):  
Band Gap ◽  
Phononic Crystal ◽  
Matrix Material ◽  
Surface Displacement ◽  
Vibration Band ◽  
Lateral Vibration ◽  
Large Size ◽  
Before And After ◽  
Practical Engineering ◽  
Scattering Material

In this paper, the design of large-size rectangular ultrasonic plastic soldering system is studied by using the band gap theory of phononic crystal and coupled vibration theory of large-size rectangular tool. In practical engineering applications, lateral vibration of the large-size rectangular tool will seriously cause the displacement of the tool's radiation surface uneven. So the lateral vibration of the tool should be suppressed. As we all know, phononic crystal materials can suppress the vibration and they are composed of two or more different materials periodically (including matrix material and scattering material). This paper uses periodic slotted structure to suppress the lateral vibration of the large-size rectangular tool. The lateral vibration band gap of the large-size rectangular tool which has periodic slotted structure in this paper is simulated. In addition, the influence of the scatterer's size on the lateral vibration band gap is also obtained. At the same time, the magnitude and uniformity of the tool's radiation surface displacement before and after slotting is compared in experiments. The research shows that by reasonably designing the periodic structure and size of the phononic crystal, the lateral vibration of the large-size rectangular tool can be effectively suppressed, and the displacement of the tool's radiation surface can be more even.

Flexural Vibration Band Gaps in a Ternary Phononic Crystal Thin Plate

2011 ◽  
Vol 675-677 ◽  
pp. 1085-1088
Author(s):  
Zong Jian Yao ◽  
Gui Lan Yu ◽  
Jian Bao Li
Keyword(s):  
Band Gap ◽  
Thin Plate ◽  
Mass Density ◽  
Phononic Crystal ◽  
Flexural Vibration ◽  
Expansion Method ◽  
Band Gaps ◽  
Physical Parameters ◽  
Vibration Band ◽  
Filling Fraction

The band structures of flexural waves in a ternary locally resonant phononic crystal thin plate are studied using the improved plane wave expansion method. And the thin concrete plate composed of a square array of steel cylinders hemmed around by rubber is considered here. Absolute band gaps of flexural vibration with low frequency are shown. The calculation results show that the band gap width is strongly dependent on the filling fraction, the radius ratio, the mass density and the Young’s modulus contrasts between the core and the coating. So by changing these physical parameters, the required band gap could be obtained.

Study on Band Gap Structure of One Dimensional Phononic Crystals

2010 ◽  
Vol 152-153 ◽  
pp. 1696-1699 ◽  
Author(s):  
Yan Lin Wang ◽  
Ming Wen Chen ◽  
Zi Dong Wang
Keyword(s):  
Band Gap ◽  
Lattice Constant ◽  
Phononic Crystal ◽  
Vibration Band ◽  
Material Density ◽  
One Dimensional ◽  
Initial Frequency ◽  
Band Gap Structure ◽  
Vibration Noise ◽  
Gap Structure

The vibration noise control is critical in engineering fields and the phononic crystal provides a new mean to control the vibration noise. The band gap structure of one dimensional phononic crystal is studied in this paper. By using the equivalent masses method we obtain the band gap structure which depends on M, m and β, the influences of initial frequency of vibration band gap via the material density, the diameter of rod and the lattice constant are analyzed. The results show that the low-frequency broadband gap characteristic is obtained by increasing M and reducing m, β. The initial frequency of vibration band gap decreases as the metal material density, the diameter of metal rod or the lattice constant increase. Some conclusions from numerical calculation are examined by the vibration experiment.

Evidence for complete low-frequency vibration band gaps in a thick elastic steel metamaterial plate

2019 ◽  
Vol 33 (04) ◽  
pp. 1950038 ◽  
Author(s):  
Suobin Li ◽  
Yihua Dou ◽  
Tianning Chen ◽  
Zhiguo Wan ◽  
Jingjing Huang ◽  
...  
Keyword(s):  
Band Gap ◽  
Steel Plate ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Crystal Plate ◽  
Band Gaps ◽  
Formation Mechanisms ◽  
Vibration Band ◽  
Low Frequency Vibration ◽  
Thick Steel

Elastic steel metamaterial plates can be used for noise- and vibration-reduction due to unique physical properties related to their vibration band gap. However, obtaining a complete low-frequency vibration band gap in a thick elastic steel metamaterial plate is difficult. In this paper, we simulate a complete low-frequency vibration band gap in a thick elastic steel metamaterial plate. The structure consists of periodic, double-sided, composite stepped resonators, which were deposited on a 2D locally resonant phononic crystal plate. The phononic crystal plate consists of an array of rubber fillers embedded in a thick steel plate. The dispersion relations, power-transmission spectra, and the displacement fields of the eigenmodes are calculated using the finite-element method. The results show that, for the proposed structure, the opening of the first complete vibration band gap is reduced by a factor of 9.5 compared to a conventional thick elastic steel metamaterial plate. This causes attenuation of low-frequency elastic waves. The formation mechanisms for the vibration band gap are also explored numerically. The results indicate that the formation mechanism for the new low-frequency vibration band gap can be attributed to coupling between a local resonance mode of the composite stepped resonators and the Lamb wave mode of the thick steel-plate. The location of the vibration band gap is determined by the resonator mode of the composite stepped resonators. The vibration band gap effects of the composite stepped resonators are also investigated in this paper. We find that the location of the complete vibration band gaps can be modulated with a relatively low frequency using different composite stepped resonators. Such an elastic steel metamaterial plate with a complete low-frequency vibration band gap can be used to reduce both vibration and noise in various commercial and research applications.

Study on Vibration Band Gap Characteristics of Phononic Crystal Consisted of Ti and Rubber

2009 ◽  
Vol 79-82 ◽  
pp. 3-6
Author(s):  
Yan Lin Wang ◽  
Zi Dong Wang ◽  
Zhuo Fei Song
Keyword(s):  
Band Gap ◽  
Volume Fraction ◽  
Phononic Crystal ◽  
Cutoff Frequency ◽  
Vibration Band ◽  
Lumped Mass ◽  
Vibration Effect ◽  
Initial Frequency ◽  
Lumped Mass Method ◽  
Gap Characteristics

The vibration band gaps of one dimensional phononic crystal of rod structure consisted of Ti and Rubber were studied using the lumped-mass method and finite element simulation, the influences of vibration band gap by the periodicity and volume fraction were discussed. The results show that the initial frequency and cutoff frequency have little influence by the periodicity, but the anti-vibration effect is more effective as the periodicity increases; the cutoff frequency gradually decreases, the initial frequency decreases first and then increases as the volume fraction increases.

Clinically Meaningful Change

Methodology ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 97-105
Author(s):  
Rodrigo Ferrer ◽  
Antonio Pardo
Keyword(s):  
Effect Size ◽  
False Negative ◽  
False Negative Rate ◽  
Point Of View ◽  
Skewed Distribution ◽  
Effect Sizes ◽  
False Negatives ◽  
Large Size ◽  
Before And After ◽  
Post Test

Abstract. In a recent paper, Ferrer and Pardo (2014) tested several distribution-based methods designed to assess when test scores obtained before and after an intervention reflect a statistically reliable change. However, we still do not know how these methods perform from the point of view of false negatives. For this purpose, we have simulated change scenarios (different effect sizes in a pre-post-test design) with distributions of different shapes and with different sample sizes. For each simulated scenario, we generated 1,000 samples. In each sample, we recorded the false-negative rate of the five distribution-based methods with the best performance from the point of view of the false positives. Our results have revealed unacceptable rates of false negatives even with effects of very large size, starting from 31.8% in an optimistic scenario (effect size of 2.0 and a normal distribution) to 99.9% in the worst scenario (effect size of 0.2 and a highly skewed distribution). Therefore, our results suggest that the widely used distribution-based methods must be applied with caution in a clinical context, because they need huge effect sizes to detect a true change. However, we made some considerations regarding the effect size and the cut-off points commonly used which allow us to be more precise in our estimates.

scholarly journals Tunable Low Frequency Band Gap and Waveguide of Phononic Crystal Plates with Different Filling Ratio

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 828
Author(s):  
Shaobo Zhang ◽  
Jiang Liu ◽  
Hongbo Zhang ◽  
Shuliang Wang
Keyword(s):  
Band Gap ◽  
Composite Structure ◽  
Structural Parameters ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Filling Ratio ◽  
Height Ratio ◽  
Road Vehicles ◽  
Aluminum Base ◽  
Gap Width

Aiming at solving the NVH problem in vehicles, a novel composite structure is proposed. The new structure uses a hollow-stub phononic-crystal with filled cylinders (HPFC) plate. Any unit in the plate consists of a lead head, a silicon rubber body, an aluminum base as outer column and an opposite arranged inner pole. The dispersion curves are investigated by numerical simulations and the influences of structural parameters are discussed, including traditional hollow radius, thickness, height ratio, and the new proposed filling ratio. Three new arrays are created and their spectrum maps are calculated. In the dispersion simulation results, new branches are observed. The new branches would move towards lower frequency zone and the band gap width enlarges as the filling ratio decreases. The transmission spectrum results show that the new design can realize three different multiplexing arrays for waveguides and also extend the locally resonant sonic band gap. In summary, the proposed HPFC structure could meet the requirement for noise guiding and filtering. Compared to a traditional phononic crystal plate, this new composite structure may be more suitable for noise reduction in rail or road vehicles.

Band gap of piezoelectric/piezomagnetic phononic crystal with graded interlayer

2013 ◽  
Vol 225 (6) ◽  
pp. 1779-1794 ◽  
Author(s):  
Man Lan ◽  
Peijun Wei
Keyword(s):  
Band Gap ◽  
Phononic Crystal ◽  
Graded Interlayer
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