Wave Propagation in Viscoelastic Laminates

1971 ◽  
Vol 38 (2) ◽  
pp. 448-454 ◽  
Author(s):  
M. Stern ◽  
A. Bedford ◽  
C. H. Yew
Keyword(s):  
Wave Propagation ◽  
Effective Modulus ◽  
Simplified Model ◽  
Structure Parameter ◽  
Longitudinal Waves ◽  
Material Parameters ◽  
Dispersion And Attenuation ◽  
Attenuation Characteristics ◽  
Representative Material ◽  
Effect Of Structure

For a simplified model of a laminated medium consisting of alternating layers of elastic and viscoelastic materials, the dispersion and attenuation characteristics for “plane,” longitudinal waves propagating in the direction of the layering are obtained. The dispersion and attenuation curves depend on a structure parameter involving the thickness of the layers and can deviate significantly from corresponding results for a continuum “effective-modulus” model. Curves are presented for a specific case with representative material parameters showing the effect of structure and of variations in the parameters of the composite.

Viscoelastic Circumferential SH Wave in Graded Hollow Cylinders

2014 ◽  
Vol 543-547 ◽  
pp. 7-11
Author(s):  
X.D. Yang ◽  
J.G. Yu
Keyword(s):  
Wave Propagation ◽  
Nondestructive Evaluation ◽  
Functionally Graded Material ◽  
Functionally Graded ◽  
Polynomial Method ◽  
Sh Wave ◽  
Graded Material ◽  
Viscoelastic Theory ◽  
Hollow Cylinders ◽  
Dispersion And Attenuation

In this article, circumferential SH wave propagation in functionally graded material (FGM) hollow cylinders is investigated. Based on the Kelvin-Voigt viscoelastic theory, the controlling differential equations in terms of displacements are deduced. By the Legendre polynomial method, the asymptotic solutions are obtained. Through the numerical results, the influences of gradient profile and the influences of the radius to thickness ratio on dispersion and attenuation are illustrated. The work is crucial for guided ultrasonic nondestructive evaluation for graded hollow cylinders.

Dynamic Fracture of 6061-T6 Aluminum Cylinders

1977 ◽  
Vol 44 (4) ◽  
pp. 643-646 ◽  
Author(s):  
D. L. Wesenberg ◽  
M. J. Sagartz
Keyword(s):  
Wave Propagation ◽  
Dynamic Fracture ◽  
Capacitor Bank ◽  
Magnetic Pressure ◽  
Strain Rates ◽  
Radial Expansion ◽  
Material Parameters ◽  
Subsequent Fracture ◽  
Thin Walled ◽  
Good Agreement

Radial expansion and subsequent fracture into segments of thin-walled cylindrical shells at large initial strain rates are studied analytically and experimentally. The theory of probability along with a description of relief wave propagation away from each fracture is used to formulate a theory which predicts the number of fractures and the distribution of fragment lengths. Eleven 6061-T6 Aluminum cylinders were expanded at strain rates of ∼104 s−1 by magnetic pressure pulses from a capacitor bank discharge, and these results are compared with predictions. Good agreement is shown between experimental results and predictions. In addition, the physical and material parameters to which the problem is sensitive are discussed.

Cavity Nucleation in AL 5083 Alloys

1999 ◽  
Vol 601 ◽  
Author(s):  
N. Chandra ◽  
Z. Chen
Keyword(s):  
Electron Microscopy ◽  
Rolling Direction ◽  
Interfacial Strength ◽  
Superplastic Forming ◽  
Simplified Model ◽  
Hard Phase ◽  
Cavity Nucleation ◽  
Material Parameters ◽  
State Of Stress ◽  
Process Material

AbstractIn this paper we address the controversial issue of nucleation of cavities in Al 5083 alloys. We focus on the origin of cavities during the manufacture of these alloys into SPF (superplastic forming) sheet form. Experimental observations on the pre-existing cavities in this alloy are made using optical and electron microscopy. The effects of rolling direction and state of stress during superplastic deformations on the formation of cavities are also discussed. Numerical simulations of the sheet manufacturing process are carried out to understand the effect of hard phase/matrix, mechanical properties and interfacial strength on the origin of cavities. Based on the numerical results, a simplified model relating the process, material parameters and the cavity nucleation is presented.

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