Mechanical tests - calculations and methods.

First, let's take the section of the bar as separate figures. Let us determine the moments of torsional inertia of the elements Jcr and the section as a whole Jcr. Since the main material is wood, the torsional rigidity of the element is equal to Gwood*Jcr. When bending, you need to indicate the center of gravity of an individual figure. We obtain the calculation of the moment of inertia during bending, and then the stiffness of the element Etree*J. Let's calculate the stiffness characteristics as follows: let's reduce the existing structure to the standard diagram of a three-layer plate, the rigidity of which is defined as the rigidity of the three-layer package relative to the neutral plane. After this, we will calculate the door deflection under the action of a concentrated load RI, the maximum load RP and the maximum stress. The final decision is made based on the worst result. Drawing conclusions, we see that the value of corner movements under the action of a concentrated load must be entered into the parameters of the strength class of the door block. The safety factor should also be taken into account. Calculations show that not all external doors meet the requirements of DIN 18103. To increase the strength class, careful selection of cladding materials and an increase in its thickness is necessary. In addition, a more durable structure of the core and the canvas frame should be used. The method for calculating the strength characteristics makes it possible to produce a sample ready for all the necessary tests; for this buy a heat and cold chamber . As a result, the calculation results are reflected in the regulatory and technical documentation. An editorial error in GOST 30109 requires immediate correction. Also, the data on the deflections of the free corner of the door leaf needs to be finalized. In addition to this correction, the data from the GOST 31173 table is required. To ensure safety during the design, production and operation of buildings and structures, the best solution would be the urgent development of standards “Doors. Mechanical testing methods" and "Doors. General specifications. garden houses made of timber, cheap wooden houses, houses made of timber, frame projects of two-story country houses.