Extremum principles for elastic heterogenous media with imperfect interfaces and their application to bounding of effective moduli

1992 ◽  
Vol 40 (4) ◽  
pp. 767-781 ◽  
Author(s):  
Zvi Hashin
Keyword(s):  
Effective Moduli ◽  
Imperfect Interfaces ◽  
Heterogenous Media

Anisotropic Effective Moduli of Cracked Short-Fiber Reinforced Composites

1999 ◽  
Vol 66 (3) ◽  
pp. 709-713 ◽  
Author(s):  
R. S. Feltman ◽  
M. H. Santare
Keyword(s):  
Short Fiber ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Effective Moduli ◽  
Fiber Reinforced ◽  
Fiber Fracture ◽  
Composite Systems ◽  
Reinforced Composite ◽  
Anisotropic Elastic ◽  
Energy Dissipated

A model is presented to analyze the effect of fiber fracture on the anisotropic elastic properties of short-fiber reinforced composite materials. The effective moduli of the material are modeled using a self-consistent scheme which includes the calculated energy dissipated through the opening of a crack in an arbitrarily oriented elliptical inclusion. The model is an extension of previous works which have modeled isotropic properties of short-fiber reinforced composites with fiber breakage and anisotropic properties of monolithic materials with microcracks. Two-dimensional planar composite systems are considered. The model allows for the calculation of moduli under varying degrees of fiber alignment and damage orientation. In the results, both aligned fiber systems and randomly oriented fiber systems with damage-induced anisotropy are examined.

scholarly journals Spectroscopy in heterogenous media and applications for bioprocess and environmental monitoring

2002 ◽  
Vol 4 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Frank Schael ◽  
Oliver Reich ◽  
Sonja Engelhard
Keyword(s):  
Diffuse Reflectance ◽  
Near Infrared ◽  
Transport Theory ◽  
Radiation Transport ◽  
Diffusion Theory ◽  
Nile Blue ◽  
Milk Powder ◽  
Photon Migration ◽  
Heterogenous Media ◽  
Reflectance Measurements

Diffuse reflectance measurements and photon migration studies with near infrared (NIR) diode lasers were employed to elucidate experimental methods for determining absorption and scattering coefficients and species concentrations in heterogenous media. Measurements were performed at a number of wavelengths utilizing several laser sources some of which were widely tunable. In order to establish the applicability of simple photon migration models derived from radiation transport theory and to check the experimental boundary conditions of our measurements, simple light scattering solutions (such as suspensions of titanium dioxide, latex particles, and solutions of milk powder) containing dyes (such as nile blue, isosulfan blue) were investigated. The results obtained from diffuse-reflectance studies at different sourcedetector distances were in accordance with predictions from simple photon diffusion theory. Applications of reflectance measurements for monitoring of cell growth during fermentation processes and forin-situinvestigations of soils are presented.

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