Theory of the physical properties of porous and composite materials and the principles for control of their microstructure in manufacturing processes

The formation of internal boundaries in a unidirectional fiber strand during isostatic and uniaxial pressing in plastic state is studied. The process is modeled using the finite-element method (FEM). An ideal contact elastoplastic problem for a hexagonal fiber strand undergoing plane deformation is solved taking into account friction at the boundaries. For angles of 0°, 30°, 60°, and 90° between the normal to the contact area and the pressing direction, the contact area width, change in the contact area slope, and the radius vector of the cross-sectional boundary of the fiber inside the pore channel as functions of density are determined for the friction coefficient at the boundaries of fibers equal to 0 and 0.5.

Section: Introductionmentioning

confidence: 99%

Modeling the formation of internal boundaries in an unidirectional fiber strand compacted in plastic state

Borovik

2009

“…The properties of composites as a heterophase system are determined not only by the properties of individual phases (taking into account the size effect), but also by the geometry of the system [2]. In this regard, matrix systems (they have the main, continuous matrix phase and the phase of isolated inclusions) and statistical systems (they consist of structural elements with similar geometries) are differentiated.…”

Section: Structural Hierarchic Levels and Structural Engineering Of Cmentioning

confidence: 99%

“…That is why the stochastic behavior of a structure under various external impacts becomes critical and requires new process-control systems based on monitoring principles [2].…”

mentioning

confidence: 99%

Hierarchic concept of structural levels and structural engineering of inorganic materials

Скороход

2009

Self Cite

The paper considers the hierarchic concept of structural levels in inorganic materials. On the one hand, it reflects the hierarchic structure of matter and, on the other hand, plays a significant part in the well-known materials-science triad: chemical composition-structure-properties. It is the hierarchic concept of structure that may underlie the structural engineering of materials. Special significance of the concept in nanostructured materials science is emphasized.Inorganic materials have certain chemical composition and structure, which determine their properties needed to perform a specific function.The structure of a material qualitatively characterizes the mutual arrangement and interrelation of its components⎯structural elements. Depending on scale, each material has different structural levels that form a sequence or hierarchy.As applied to inorganic materials, the hierarchy of structural levels should be considered a particular case of the hierarchy of the structural levels of matter as a whole. This aspect was most fully and clearly treated by Weisskopf [1] in describing the so-called quantum ladder in the structure of matter. The quantum ladder is a sequence of structural states of matter occurring as its energy is gradually increased (or decreased).Atoms with fixed internal structure, which can exchange only kinetic energy during elastic collisions, can be selected as the ground state of matter. At higher energies, atoms will be ionized and split into electrons and nuclei. Up to certain energies, the nuclei will remain integral and indivisible but will disintegrate into protons and neutrons with further increase in external energy. Matter will become an unstructured mixture of elementary particles. Each rung of the quantum ladder is associated with a threshold of energy that disturbs the stability of the structure; the smaller the linear scale, the higher the threshold (Table 1).Moving down the quantum ladder from the ground state toward lower energies and, hence, a larger scale, we will see atoms combine into molecules or crystals with specific internal structure. The larger the molecules, the

“…The polarization of a dielectric ellipsoid in a uniform external field was detailed in [13]. The obtained solutions were used in [16] to derive formulas for the effective generalized conductivity of matrix structures with ellipsoidal inclusions.…”

Section: Elastic Moduli Of Some Matrix Systems With Nonspherical Inclmentioning

confidence: 99%

Approximate methods for numerical evaluation of the elastic moduli of composite and microheterogeneous materials

Скороход

2011

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Approximate methods for calculating the effective elastic moduli of microheterogeneous materials, including multiphase ones, are considered. These methods are based on the analogy between the electrostatic field in dielectrics and the field of elastic stresses and strains in solids. Formulas are derived for the quantitative evaluation, with accuracy sufficient for materials science practices, of the effective elastic moduli of composites with different structures as a function of the elastic moduli, morphology, and volume fraction of the phases. The method is validated by calculating the elastic characteristics of bodies with plane slit-like defects, including powder compacts.