Longitudinal vibration wave in the composite elastic metamaterials containing Bragg structure and local resonator

2020 ◽  
Vol 34 (26) ◽  
pp. 2050232
Author(s):  
Xiaofei Lei ◽  
Peng Chen ◽  
Heping Hou ◽  
Shanhui Liu ◽  
Peng Liu
Keyword(s):  
Mathematical Model ◽  
Young’S Modulus ◽  
Transmission Spectrum ◽  
Strain Energy ◽  
Young's Modulus ◽  
Dynamic Properties ◽  
Longitudinal Vibration ◽  
Total Width ◽  
Bragg Structure ◽  
Vibration Wave

In this paper, a novel composite acoustical hyperstructure of Bragg structure with local resonator is investigated theoretically for discussing the scattering performance of longitudinal vibration wave, its bandgaps are calculated using the established mathematical model. For confirming the veritable existence of bandgap and verifying the correctness of established mathematical model, the transmission spectrum of composite acoustical hyperstructure is also studied using finite-element method, and comparing the vibration transmission spectrum with bandgaps, the results indicate that the established theoretical model can correctly predict longitudinal wave bandgaps. Moreover, the bandgaps and modes shapes are calculated and compared with an unalloyed Bragg structure for probing the dispersion mechanics of composite acoustical hyperstructure, it turned out that local resonator can add one bandgap at the base of Bragg structure and the total bandgaps can be broadened. Further, for discussing the effect of spring of local resonator on bandgaps, bandgap of local resonator with different spring is calculated, the results showed that the total width of BG is larger when Young’s modulus is 1E and 16E, the total width are 772.48 and 774.30 Hz, respectively; as Young’s modulus is 0.5E and 2E, the width of BG are lower, 753.79 and 754.23 Hz, respectively. In view of longitudinal vibration wave inducing structural distortion and vibration energy conversion, the dynamic properties of composite acoustical hyperstructure are studied via strain energy density, the results indicate that reaction formation of local resonator can dissipate strain energy, when the local resonator is not activated (or waveless along with Bragg structure), un-dissipation strain energy.

Correlation Analysis between Dynamic Young’s Modulus and Static MOE of the Poplar LVL Reinforced with Multilayer Fiberglass Mesh

2010 ◽  
Vol 26-28 ◽  
pp. 936-939
Author(s):  
Li Zhang ◽  
Ying Cheng Hu
Keyword(s):  
Correlation Analysis ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Dynamic Properties ◽  
Longitudinal Vibration ◽  
Flexural Vibration ◽  
Transmission Method ◽  
Vibration Method ◽  
Dynamic Young’S Modulus ◽  
Dynamic Young's Modulus

In this paper, the poplar LVL was reinforced with multilayer fiberglass mesh. The reinforcing effect of adding position of fiberglass mesh on improving the static MOE was studied. And three different nondestructive testing (NDT) methods, such as the longitudinal transmission method, longitudinal vibration method and flexural vibration method (out-plane and in-plane), were used to test the dynamic properties of the reinforced poplar LVL. The correlation analysis was implemented between the dynamic Young’s modulus and the static MOE of the reinforced poplar LVL. It can be concluded that the three NDT methods are useful for predicting the MOE of reinforced LVL, but the flexural and longitudinal vibration methods had better accuracy to estimate the MOE.

scholarly journals Phase Stability and Mechanical Properties of Al8Fe4RE via First-Principle Calculations

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 701
Author(s):  
Rongcheng Wang ◽  
Xiaoma Tao ◽  
Hongmei Chen ◽  
Yifang Ouyang
Keyword(s):  
Young’S Modulus ◽  
Phase Stability ◽  
Young's Modulus ◽  
Dynamic Properties ◽  
First Principle ◽  
Lattice Constants ◽  
First Principle Calculations ◽  
Phonon Spectra ◽  
Calculated Enthalpy ◽  
3D Surfaces

We report on the phase stability, elastic, electronic, and lattice dynamic properties of 17 Al8Fe4RE (RE = Sc, Y, La–Lu) intermetallic compounds (IMCs) using first-principle calculations. The calculated lattice constants coincided with the experimental results. The calculated enthalpy formation indicated that all the 17 IMCs are stable. The elastic constants and various moduli indicated that Al8Fe4RE can be used as a strengthening phase due to its high Young’s modulus and shear modulus. The 3D surfaces of Young’s modulus for Al8Fe4RE showed anisotropic behavior, and the values of hardness for the IMCs were high (about 14 GPa). The phonon spectra showed that only Al8Fe4Y had a soft mode, which means the other IMCs are all dynamically stable.

Study on Regeneration Pre-Sensitized Offset Plate Based on the Nondestructive Testing Method

2011 ◽  
Vol 380 ◽  
pp. 348-351 ◽  
Author(s):  
Jiang Chang ◽  
Xue Gong ◽  
Zhi Hui Sun
Keyword(s):  
Nondestructive Testing ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Longitudinal Vibration ◽  
Flexural Vibration ◽  
Vibration Method ◽  
Testing Method ◽  
Dynamic Young’S Modulus ◽  
Dynamic Young's Modulus ◽  
Nondestructive Testing Method

In this paper the vibration testing and Fast Fourier Transform(FFT) analysis detection on the basis of nondestructive testing method were analyzed. The dynamic Young’s modulus of the regeneration pre-sensitized offset plate were obtained by using the nondestructive testing methods, including the dynamic Young’s modulus by longitudinal vibration method, the dynamic Young’s modulus by out-plane flexural vibration method, and the dynamic Young’s modulus by in-plane flexural vibration method. The linear correlativity was investigated between the dynamic Young’s modulus and the modulus of elasticity(MOE) for the regeneration pre-sensitized offset plate.The linear correlations between the dynamic Young’s modulus and the MOE were good. So it is feasible to predict and analyze the plate mechanical properties put forward the nondestructive testing method of key mechanical performance parameters.

scholarly journals Inverse Identification Of Elastic Moduli For 3D Printed PLA, Using Impulse Excitation Technique (IET)

2021 ◽  
Author(s):  
Afridi Mohsin
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Bulk Material ◽  
Dynamic Properties ◽  
Test Results ◽  
Young’S Moduli ◽  
Vibration Experiment ◽  
3D Printed ◽  
Printed Materials

3D Printing has recently undergone extensive development due to its lower cost and flexibility. A number of studies have been carried out to determine 3D printed material properties. This study focuses on the determination of the dynamic properties for PLA. The PLA material is processed through the popular FDM method with three different build orientations. A vibration experiment is conducted to evaluate the first modal frequency and Young’s modulus. The results are then compared to the FEM modal analysis and finally the traditional tensile testing results. The anisotropy of the 3D printed components, mainly due to the density changes caused by voids and filament alignment, result in the variation of the Young’s modulus which is different than the homogenous bulk material. The calculated Young’s moduli values are very slightly higher than the tensile test results which is in conformance with the trend documented by earlier studies on similar printed materials using the same techniques

Determination of Young's modulus and shear modulus by means of deflection curves for wood beams obtained in static bending tests

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 589-594 ◽  
Author(s):  
Koji Murata ◽  
Tsubasa Kanazawa
Keyword(s):  
Shear Modulus ◽  
Young’S Modulus ◽  
Polynomial Regression ◽  
Young's Modulus ◽  
Dynamic Properties ◽  
Flexural Vibration ◽  
Bending Test ◽  
Deflection Curve ◽  
Element Analysis ◽  
Static Young’S Modulus

Abstract Young's modulus and shear modulus were simultaneously obtained in a three-point bending test based on Timoshenko's bending theory. Deflection curves of a bent beam were measured by image analysis, and the mechanical properties of the wood were calculated by polynomial regression analysis after excluding the singular region. When beam specimens of spruce (Picea sp.) and mizunara (Quercus crispula) wood were tested, static Young's modulus (E s) and static shear modulus (G s) values could be obtained from the deflection curve using finite element analysis. By comparing the dynamic properties (E d and G d) obtained by a flexural vibration test, it was estimated that E s was greater than E d, while G s was less than G d. However, we suppose that the G s values calculated from the deflection curve are more plausible than those obtained from a conventional bending test.

Elastic Strain Energy of a Nanowire in Three-Point Bending Test with the Consideration of Surface Effects

2011 ◽  
Vol 268-270 ◽  
pp. 67-71
Author(s):  
Xian Wei Zeng ◽  
Jia Quan Deng
Keyword(s):  
Young’S Modulus ◽  
Elastic Strain ◽  
Strain Energy ◽  
Young's Modulus ◽  
Elastic Strain Energy ◽  
Theoretical Models ◽  
Bending Test ◽  
Three Point Bending ◽  
Force Microscopy ◽  
Atomic Force

Three-point bending tests of nanowires with Contact atomic force microscopy reveal that the Young’s modulus of a nanowire is size-dependent. The modulus changes with the diameter of a nanowire. This size dependency can be explained within the framework of classical continuum mechanics by including the effects of surface stress. In this study, an analytical solution has been derived for the elastic strain energy of a nanowire with both ends clamped and contacted by an AFM tip at its midpoint. Different from previous theoretical models, the present model can handle the case of large deflection, where the displacement of the nanowire is in the same order of the diameter. Based on the equivalence of elastic strain energy, the apparent Young’s modulus of a nanowire is expressed as a function of the elastic modulus of the bulk and that of the surface, and the dimensions of a nanowire.

Effect of Temperature on Elasticity of Silicon Nanowires

2011 ◽  
Vol 483 ◽  
pp. 526-531
Author(s):  
Jing Wang
Keyword(s):  
Young’S Modulus ◽  
Silicon Nanowires ◽  
Strain Energy ◽  
Young's Modulus ◽  
Silicon Nanowire ◽  
Negative Temperature ◽  
Lattice Parameter ◽  
Mechanical Analysis ◽  
Effect Of Temperature ◽  
Continuum Approach

A semi-continuum approach is developed for mechanical analysis of a silicon nanowire, which captures the atomistic physics and retains the efficiency of continuum models. By using the Keating model, the strain energy of the nanowire required in the semi-continuum approach is obtained. Young’s modulus of the silicon (001) nanowire along [100] direction is obtained by the developed semi-continuum approach. Young’s modulus decreases dramatically as the size of a silicon nanowire width and thickness scaling down, especially at several nanometers, which is different from its bulk counterpart. The semi-continuum approach is extended to perform a mechanical analysis of the silicon nanowire at finite temperature. Taking into account the variations of the lattice parameter and the bond length with the temperature, the strain energy of the system is computed by using Keating anharmonic model. The dependence of young’s modulus of the nanowire on temperature is predicted, and it exhibits a negative temperature coefficient.

Relationships between Dynamic Young’s Modulus and Static MOE of the Reinforced Poplar LVL

2010 ◽  
Vol 129-131 ◽  
pp. 588-591
Author(s):  
Li Zhang ◽  
Ying Cheng Hu
Keyword(s):  
Nondestructive Testing ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Longitudinal Vibration ◽  
Flexural Vibration ◽  
Transmission Method ◽  
Reinforcing Effect ◽  
Vibration Method ◽  
Dynamic Young’S Modulus ◽  
Dynamic Young's Modulus

In this paper, the poplar LVL was reinforced with monolayer fiberglass mesh. The reinforcing effect of lay angle between the weft of fiberglass mesh and the veneer grain was studied. And three different nondestructive testing (NDT) methods, such as the longitudinal transmission method, longitudinal vibration method and flexural vibration method (out-plane and in-plane), were used to test the dynamic Young’s modulus of the reinforced poplar LVL. The correlativity was investigated between the dynamic Young’s modulus and the static MOE of the reinforced poplar LVL. The reinforcing effect was best when the lay angle of fiberglass mesh was 30°. And the flexural vibration method and longitudinal vibration method had better accuracy to estimate the static MOE.

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