Method of continuous non-destructive observation of profiles made of polymer fibre composite materials for the registration of crack formation

The relevance of the study is conditioned by the absence of the necessary devices and structures made of composite materials such as stingers with holes for registering cracks. The purpose of the study is to develop the design and manufacturing technology of stringer-type profiles made of composite materials with micro-holes in the cross-section or inside which hollow polymer fibres are laid, while the holes did not significantly affect the strength of the product and the specified strength properties of the product are preserved. The task of manufacturing products from a polymer composite material is solved by a method that includes pre-laying hollow longitudinal fibres or introducing bundles coated with anti-adhesive lubricant at specified cross-section points of stringers with subsequent pressing when laying pre-cut layers of composite material in a mould (polymerisation of the binder). After cooling, decompressing, removing the bundles with anti-adhesive grease (the second option) and stripping the product, special sensors are installed, a vacuum is created inside the holes or pressure is applied within 0.1-0.2 atm. At the same time, the holes do not significantly affect the strength of the product and the specified properties of the product are preserved. The study suggests a method for continuous and autonomous monitoring of the integrity of profiles made of polymer fibre composite materials for registering the formation of cracks based on the introduction of longitudinal micro-holes or hollow fibres under pressure or vacuum into their structure, followed by recording changes in the pressure value. The advantage of the proposed method is that it allows making a product from composite materials with increased physical and mechanical properties, increasing operational safety, increasing service life, and reducing the cost of routine inspections due to continuous monitoring of the occurrence and development of damage in real time. At the same time, the reliability of the design significantly increases, which leads to an improvement in the quality of the produc

HOB BACKOFF FOR GEAR MACHINING WITH NORMAL ELLIPTIC PROFILE

The equations of the hob relief, based on the earlier dependences of the section coordinates of the elliptic tooth-wheel profile, and the equations of the hob cutting profile are defined

TRIBOCHEMICAL ASPECT OF THE EFFECT HARD ALLOYS METAL ON DETERIORATION AT CUTTING

Warmth calculations of carbides and nitrides oxidation of some metals as elements of wearproof coverings define probability of formation corresponding oxide base metals under the cutting conditions. Proofness indicator (volume factor) of connections is introduced for the first time to estimate efficiency of coverings from nitrides, carbides and aluminides, formed oxides, under the cutting conditions.  Experimental data of oxidation of pure metals, double alloys, including aluminides, allow to consider that the efficiency of aluminides of Ti, Fe, Cu, Nb, Zr, Ni, correlates with their proofness indicators values.  Research of cutting firm alloys with coverings of TiC, TiN and Al2O3 in the air and in nitrogen atmosphere have confirmed  efficiency of these coverings under the  retardation (shortstop) of  tribochemical contact reactions