DYNAMICS OF CHANGE OF REQUIREMENTS OF STANDARDS TO DURABILITY OF WOOD-SHAVING PLATES: REASONS AND CONSEQUENCE

Drevesno – chip plates are widely used in production of case furniture. The volume of their production constantly grows in Russia. If in 2013 it has been made 7270, then in 2017 – 8370, in 2018 – 9789, in 2019 – 9986 thousand m3 of plates. However, one of the main shortcomings of plates of the plates released by the industry is their low durability. It especially concerns one of the main strength performances of plates – ultimate strength at bend. So, in comparison with requirements of GOST 10632-77 durability of plates at bend of the most widespread thickness (13-20 mm) in accordance with GOST 10632-89 has decreased on 9 and 21, in accordance with GOST 10632-2007 on 21 and 29, and by current GOST 10632-2014 – by 38 and 43% depending on brand of plates. Decrease in durability at stretching perpendicular to plate face less noticeable. One of the main reasons of such decrease, use in technology of plates of low-toxic carboamidoformaldehyde (KFS) pitches the content of free formaldehyde in which generally is makes about 0,15%. It is known, than more free formaldehyde is in pitch of subjects bond quality of wood and wood-base materials, with use of this pitch, above. However such big decrease in durability of plates for furniture makers is big shortcoming. It is necessary to change approaches to designing of furniture from such plates. Manufacturers of plates, using low requirements of the present standard, sometimes manipulate due to decrease in density of plates that results in friability of plates, problem of fastening of plates in furniture designs. The purpose of our work was studying of dynamics of decrease in durability of plates according to requirements of standards, since 1977 till present, establishment of the reasons and possible consequences from such decrease.

A new method of highly accurate orientation of single crystals on a standard powder diffractometer

A new method of obtaining high accuracy in a diffractometer refinement of a single-crystal orientation is presented in this paper. The primary errors in goniometer orientations are caused by the fact that, whereas the measurement required is the angle between the atomic plane and the plate face, goniometers in general measure the angle between the atomic plane and a plane defined by the goniometer, which is not necessarily parallel to the plate face. The methods of correcting for these inaccuracies associated with the goniometer orientations that have been used and cited so far are based on the laser-assisted system described by Vig [Proc. 29th Annual Symposium on Frequency Control (1975), pp. 240–247]. The method described in this paper allows one to eliminate these errors by a specially invented method of measurements and calculations without a laser-assisted system or any other additional instruments.

Transverse Vibrations of a Free Circular Plate Carrying Concentrated Mass

The plate under consideration carries a concentrated mass at its center, which is struck impulsively in a direction perpendicular to the undisturbed plate face. Only circularly symmetric vibrations are considered. The solution is carried out by the use of the Laplace transform method, treating the concentrated mass as a plate-density impulse. The first four natural frequencies are displayed as functions of mass ratio, and the first mode shape is displayed for three mass ratios. The natural frequencies, particularly the higher, are shown to be very sensitive to changes in mass ratio at small values of the concentrated mass.