The shear modulus of a composite material with a transversely isotropic matrix and a fibre

2014 ◽  
Vol 78 (2) ◽  
pp. 187-191 ◽  
Author(s):  
S.N. Grebenyuk
Keyword(s):  
Composite Material ◽  
Shear Modulus ◽  
Transversely Isotropic ◽  
Isotropic Matrix

Wave Propagation and Parametric Instability in Materials Reinforced by Fibers With Periodically Varying Directions

1975 ◽  
Vol 42 (4) ◽  
pp. 825-831 ◽  
Author(s):  
M. Schoenberg ◽  
Y. Weitsman
Keyword(s):  
Composite Material ◽  
Wave Propagation ◽  
Elastic Medium ◽  
Parametric Instability ◽  
Transversely Isotropic ◽  
Harmonic Waves ◽  
Fiber Reinforced ◽  
Frequency Bands ◽  
Structural Periodicity ◽  
Dominant Direction

This paper concerns the propagation of plane harmonic waves in an infinite fiber-reinforced elastic medium. The composite material is represented by an equivalent homogeneous transversely isotropic matter whose preferred directions coincide with the orientations of the fibers. The fibers are assumed to wobble periodically about a dominant direction, all fibers being parallel to each other. This wobbliness endows the material with a structural periodicity which generates dispersion at all frequencies and instability for various frequency bands. The zones of instability are analyzed in some detail.

Weak elastic anisotropy and the tube wave

Geophysics ◽  
1993 ◽  
Vol 58 (8) ◽  
pp. 1091-1098 ◽  
Author(s):  
Andrew N. Norris ◽  
Bikash K. Sinha
Keyword(s):  
Shear Modulus ◽  
Elastic Moduli ◽  
Wave Speed ◽  
Elastic Anisotropy ◽  
Transversely Isotropic ◽  
Anisotropic Formation ◽  
Inversion Procedure ◽  
Anisotropy Parameters ◽  
Tube Wave ◽  
Simple Inversion

Tube‐wave speed in the presence of a weakly anisotropic formation can be expressed in terms of an effective shear modulus for an equivalent isotropic formation. When combined with expressions for the speeds of the SH‐ and quasi‐SV‐waves along the borehole axis, a simple inversion procedure can be obtained to determine three of the five elasticities of a transversely isotropic (TI) formation tilted at some known angle with respect to the borehole axis. Subsequently, a fourth combination of elastic moduli can be estimated from the expression for the qP‐wave speed along the borehole axis. The possibility of determining all five elasticities of a TI formation based on an assumed correlation between two anisotropy parameters is discussed.

scholarly journals Structural features of composite materials made of hydrolyzed birch wood

2021 ◽  
Vol 25 (4) ◽  
pp. 89-98
Author(s):  
Yu.G. Skurydin ◽  
◽  
E.M. Skurydina ◽  
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Shear Modulus ◽  
Bending Strength ◽  
Structural Features ◽  
Dynamic Shear Modulus ◽  
Birch Wood ◽  
Dynamic Shear ◽  
Amorphous Component ◽  
Wood Processing

Structural features and physical and mechanical characteristics of plate composite materials are investigated. The materials are obtained from hydrolyzed birch wood by hot pressing without the addition of binding components. Wood processing is carried out by the method of explosive autohydrolysis without chemical reagents. The influence of pre-moistening of wood on the structure and properties of the composite material is studied. The structural features of the amorphous and crystalline components of the composite material are studied. It was found that the composite material obtained from pre-dried and pre-moistened wood retains the crystalline phase that is present in the original wood. Changes in the structure of wood when obtaining composite materials based on it occur in the amorphous component. Based on the temperature dependences of the dynamic shear modulus and the tangent of the angle of mechanical losses, information on the glass transition temperature of a complex of amorphous components of a composite material is obtained. It was found that the region of transition of lignin and hemicellulose macrochains from a glassy to a highly elastic state in the composite material is shifted towards low temperatures in comparison with the original wood. The offset is more than 70K. It is assumed that structural plasticization is the main cause of the detected effect. Pre-moistening of wood does not affect the position of the temperature transition in the amorphous component of the composite material. The study of the diffusion and sorption of water vapor in the samples of the material shows the presence of large structural inhomogeneities. Diffusion processes obey Fick’s second law and correlate with the density of samples. Data on density, static bending strength, water absorption and swelling characteristics of composite material samples were obtained. It is shown that the use of pre-moistening of wood before barothermal treatment significantly improves the structural uniformity of the resulting material. The value of the dynamic shear modulus at room temperature in comparison with the same indicator for the material obtained on the basis of dry wood increases three times. Mechanical losses are reduced, mechanical strength increases.

A translated rigid ellipsoidal inclusion in an elastic medium

1991 ◽  
Vol 434 (1892) ◽  
pp. 571-585 ◽  
Keyword(s):  
Elastic Medium ◽  
Elastic Field ◽  
Transversely Isotropic ◽  
Ellipsoidal Inclusion ◽  
Arbitrary Orientation ◽  
Isotropic Matrix ◽  
The Matrix ◽  
Ellipsoidal Surface ◽  
Axis Of Symmetry ◽  
Anisotropic Elastic

A rigid ellipsoidal inclusion is embedded at arbitrary orientation in a homogeneous, arbitrarily anisotropic, elastic matrix and is translated infinitesimally by an externally imposed force. We find directly the relation between the force and translation vectors, and the stress, strain and rotation concentrations over the ellipsoidal surface, without having to solve the equations of equilibrium in the matrix, or the fundamental ones of a point force. We refer particularly then to a spheroid aligned along the axis of symmetry of a transversely isotropic matrix, and subsequently to the full elastic field of a general ellipsoid in an isotropic matrix.

A Different Approach for Obtaining the Shear Moduliof a Composite Material

2020 ◽  
Vol 70 (12) ◽  
pp. 4470-4476
Keyword(s):  
Finite Element ◽  
Composite Material ◽  
Elastic Modulus ◽  
Shear Modulus ◽  
Finite Element Model ◽  
Element Model ◽  
Layered Composite ◽  
Element Analysis ◽  
Shear Elastic Modulus ◽  
Elastic Characteristics

In recent years the composites materials gained a major importance in all fields of engineering, because they offer a successful replacement for classical materials conferring similar elastic-mechanical properties to metal or non-metal alloys presenting several advantages such as reduced mass, chemical resistance etc. Considering this, during the design, dull knowledge of the elastic-mechanical characteristics is of high importance. The present paper aims to create a finite element model able to predict the shear elastic modulus of a double-layered composite material based on the elastic characteristics of its constituents. For this, once the elastic characteristics of the constituents determined, they could be used in the finite element analysis obtaining consequently the shear modulus for the composite material. Also, the shear elastic modulus of the resultant composite was determined experimentally. The results of the finite element model were compared to the experimental values in order to validate the finite element analyses results. Keywords: composites, fiberglass, shear modulus, FEM

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