пРИМЕНЕНИЕ МЕтОДА ОтНОшЕНИь к ОпРЕДЕДЕНИУ сОстАВльУЩЕИ σ_x НАпРьжЕНИь

Abstract

In this paper the possibility is analyzed of using the ratio method to determine the biaxial stress componentσ _x in an arbitrary direction from two photographs, one taken with the primary beam incident perpendicularly and rotating film holder and the second photograph with the primary beam incident obliquely and film holder stacionary or oscillating in a small angular range. A relation is derived for the value ofσ′ _x based on measurements of the diameters of the diffraction “circles” in the corresponding azimut, and a relation for estimating the magnitude of the percentual error of the value ofσ′ _x thus determined as compared with the real value ofσ _x .

It is shown in the case of aluminium in three typical stress states (circularly symmetrical stress distribution, unaxial state, torsional stress) that the error in determiningσ _x , caused by using the ratio method, is quite unimportant for application in technical practice and is much smaller than when applying the ratio methods to the determination of the sum of the two principal stresses from one photograph taken with the primary beam incident perpendicularly. The application of the ratio method for determiningσ _x gives simultaneously the possibility of using this method for solving the general problem, i.e. of determining the two principal stresses as to their magnitude and direction.