Three-dimensional visualizations of the anisotropic ultrasonic and mechanical properties of unidirectional graphite/epoxy composites are generated. Mechanical moduli (Poisson's ratio, Young's and shear modulus) descriptive of the anisotropic mechanical properties of unidirectional graphite/epoxy composites are obtained from the ultrasonically determined stiffness coefficients. Fundamental constituent parameters, such as elastic stiffness coefficients (c_), are experimentally determined from ultrasonic time-of-flight measurements. We examine the physics underlying the use of ultrasound as an interrogation probe for determination of ultrasonic and mechanical properties of anisotropic materials such as fiber-reinforced composites. The desired characteristics of practical fiber -reinforced composites depend on average mechanical properties achieved by placing fibers at specific angles relative to the external surfaces of the finished part. Fiber-reinforced plastics represent a class of advanced composite materials that exhibit substantial anisotropy. Our hypothesis is that a fundamental understanding of the physics involved in the interaction of interrogating ultrasonic waves with anisotropic media will provide useful information applicable to quantitative ultrasonic measurement techniques employed for the determination of material properties. The central theme of this thesis is to contribute to the physics underlying the mechanical properties of highly anisotropic materials. Physical Principles Pertaining to Ultrasonic and Mechanical Properties of Anisotropic Media and Their Application to Nondestructive Evaluation of Fiber-Reinforced Composite Materials The material can function as an optic compass or could be used as an optic shutter that can be switched by a magnetic field, e.g., for an intensity control for waveguides in the visible range. The integration and control of light emission modes within a homogeneous particle dispersion marks a smart optical material, addressing fundamental directions for research on switchable multifunctional materials. In addition to direct switching, the optical properties can be tailored continuously between isotropic red emission and anisotropic reflection of light if the illuminating light is tuned through fractions of both UV and visible light. If illuminated by UV light, the particles exhibit isotropic luminescence while the same sample shows anisotropic optical properties when illuminated with visible light. These rotation-dependent optical properties are complemented by an isotropic luminescence resulting from the MOF shell.
Their anisotropic shape causes changes in the reflectivity and diffraction of light depending on the orientation of the composite particle. The composite particles can be rotated by an external magnet. The composite is formed as anisotropic core/shell particles by coating superparamagnetic iron oxide-silica microrods with a layer of the luminescent metal-organic framework (MOF) 3 ∞ Â♲DMFÂ♲H 2 O (BDC 2- = 1,4-benzenedicarboxylate). This combination enables switching between luminescence and angle-dependent reflectivity by changing the applied wavelength of light. Mandel, Karl Granath, Tim Wehner, Tobias Rey, Marcel Stracke, Werner Vogel, Nicolas Sextl, Gerhard Müller-Buschbaum, KlausĪ smart optical composite material with dynamic isotropic and anisotropic optical properties by combination of luminescence and high reflectivity was developed. Smart Optical Composite Materials: Dispersions of Metal-Organic Microrods for Switchable Isotropic- Anisotropic Optical Properties. Good agreements are achieved to demonstrate the accuracy of our efficient model. Numerical results are shown in comparing extracted effective parameters and orientation angle with analytical results from low frequency limit. We also derive analytical expressions for effective parameters and orientation angle with low frequency (LF) limit, which will be shown in detail.
Effective permittivity, permeability and orientation angle for a layered anisotropic composite medium are extracted with this equivalent model. In this paper, we present an efficient method to simulate multilayered anisotropic composite material with effective medium theory. Modeling of layered anisotropic composite material based on effective medium theory
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