METHOD OF DETERMINATION OF STRENGTH PROPERTIES OF FILM MATERIALS Russian patent published in 2002 - IPC

FIELD: methods of study of loading materials for strength by loading them by internal pressure. SUBSTANCE: proposed method consists in cutting round specimen from film material in each cycle of tests, placing this specimen in die and pressing by punch; in the course of loading the specimen, present magnitudes of pressures, vertical motion of vertex of dome relative to initial position and change of thickness of specimen in area of dome vertex are measured from beginning of loading till break of specimen; testing procedure is repeated for several specimens. Making use of expression obtained on base of non-linear theory of thin films at large displacements and deformation and relationship of plasticity theory, results of measurements are processed to obtain family of analytical curves "deflection - pressure" for various magnitude of coefficient k, characterizing the material properties, then experimental curve "deflection - pressure" is compared with these magnitudes, coefficient "k" is defined more accurately by experimental and analytical curves aligning to maximum degree, after which "stress intensity - deformation intensity" diagram is drawn up and conclusion relative to strength of film material is made. EFFECT: enhanced accuracy of determination of strength of film materials at minor number of measurements; possibility of observation of change in strength in the course of loading. 5 dwg, 1 tbl