The Stephenson - Kapitsa pendulum: Area of the Attraction of the Upper Positions of the Balance

Here we consider the behavior of a pendulum with a vibrating axis of suspension which differs from the classical one by the presence of an additional degree of freedom: the pendulum contains some mass, fixed on a spring, which can be displaced with respect to the main mass in two mutually perpendicular directions. Experimental investigations have been performed to determine the stable equilibrium positions of the pendulum. The results of the experiment were in good agreement with those of the numerical solution of the complete equations of motions of the system. Both of them were in good agreement with the rough analytical solution, obtained before by I.I. Blekhman and L. Sperling. It has been confirmed that the presence of the inner degree of freedom of the additional mass in the “radial” direction results in an essential widening of the range of attraction of the upper vertical quasi-equilibrium position of the pendulum

Research of strength of gluing of wood

Abstract Wood is widely used in industrial and civil engineering. It has many valuable physical, mechanical and other operational properties that make it widely possible to use it not only in construction, but also in other sectors of the economy. Many scientists studied the problems of studying the processes of mechanical processing of wood and the development of rational technological conditions and modes of gluing wood, allowing to obtain products with the required physical and mechanical properties. One of the ways to increase the efficiency of production of glued building materials from wood is gluing lumber along the length of the toothed spike. The strength of glued beams during operation depends on many factors, including the quality of the formation of adhesive joints. The main ones are the properties of wood, mainly density and humidity, and the type of glue. The surface relief, the type of surfaces to be glued, the dimensions and the shape of the ten on also have an effect. The results of a study of the bonding strength of wood in glued beams and the strength of finger jointing are presented in this article.</jats:p

Modification of urea- and phenol-formaldehyde adhesives by natural fillers for the production of plywood

Abstract For the manufacture of plywood and chipboard are used urea-formaldehyde and phenol-formaldehyde hot curing adhesives. When it is necessary to reduce the content of toxic substances, to increase the strength and reliability of gluing, other properties of adhesive bonding heat urea and phenol-formaldehyde resins are modified. Urea-formaldehyde and phenol-formaldehyde resins were used for research. Urea-formaldehyde resin was modified with technical lignosulfonates with particle sizes of 0.01-0.2 mm, shungites with particle sizes of 0.2-0.8 mm, black shales with particle sizes of 0.005-0.2 mm and aluminosilicates with particle sizes of 0.2 - 0.8 mm. Phenol-formaldehyde resin was modified with pectol, black shales with particle sizes of 0.005-0.2, technical lignosulfonates with particle sizes of 0.01-0.2, and cold sludge from aluminum production with particle sizes of 0.01-0.2. A comparative analysis revealed that all the modifiers under study improve the physicochemical parameters of urea-formaldehyde and phenol-formaldehyde resins, increase the performance properties of glued materials from wood. Plywood was tested for shear strength over the adhesive layer and for the content of free formaldehyde in accordance with Russian standards. Modification of urea and phenol-formaldehyde resins with the proposed substances increases the strength of plywood, at the same time reducing the free formaldehyde content in products.</jats:p

Effect of the structure of wood on the results of ultrasound

Abstract In article defined the influence of wood density and angle of annual rings on the deviation angle of the ultrasonic (US) signal (beam) by using the through transmission method of sounding wood. For achieving most-reliable control of glued structures, the requirements for the size of transducers were formulated.</jats:p