FATIGUE TESTS OF METAL MATERIALS (review) Part 1. Main definitions, loading parameters, representation of results of tests

The article gives the review of techniques of fatigue tests of metal materials and presents the results of such tests . It has been shown that the low-cyclic fatigue occurs in conditions of elastoplastic deformation in material microvolume from the first cycles of loading. Its distinctive feature is influence on durability of the size and form of a mechanical hysteresis loop . Nucleation of fatigue microcracks and formation of the main crack occurs on the surface and in near-surface layers of a sample.

MICROSTRUCTURE RESEARCH OF THE UNIDIRECTIONAL ORGANOPLASTIC BASED ON RUSAR-NT ARAMID FIBERS AND EPOXY-POLYSULFONE BINDER

This paper studies a polymer composite material - a unidirectional organoplastic based on Rusar-NT aramid fiber and a melt epoxy-polysulfone binder. Organoplastic has the following mechanical properties: tensile strength 2060 MPa, Young's modulus 101 GPa. The microstructure of the fiber and the polymer matrix in the organoplastic samples was studied before and after tensile tests. The features of the formation of the binder structure depending on the packing density of the fibers in organoplastics have been determined. The nature of the destruction of fibers and polymer matrix caused by the uniaxial tension has been studied.

CONTINUOUS FIBERS BASED ON ALUMINA (review)

The article provides an overview of the continuous alumina-based fibers currently produced as well as their production technologies, major manufacturers and applications. Ceramic fibers are relatively new species and are of particular interest at the modern stage of technology development, since their advantages make them promising in the creation of new types of composite materials. A large number of polycrystalline oxide fibers have been developed, both for refractory insulation and for reinforcing composites.

MATHEMATICAL MODELING OF DESTRUCTION OF FIBERGLASS-BASED THERMAL-PROTECTION MATERIAL

The paper proposes physical and mathematical models of heat and mass transfer in fiberglass used as a destructive heat-shielding material for capsule type descent vehicles. To provide the mathematical model with the initial data, experimental studies of the thermophysical characteristics of the material and the kinetic parameters of destruction have been carried out. There has been made a simulation of the destruction of a material sample during descent in the Earth's atmosphere along a typical trajectory for various areas of the heat shield; as a result, the dependences of temperatures on the flight time and the depth of the coked layer have been determined.