FIELD: quality inspection of ferroconcrete articles. SUBSTANCE: load corresponding to start of crack formation is determined by registered dependence of resonance frequency of longitudinal or lateral oscillations excited in article on intensity of uniformly distributed load on article. Measurement of resonance frequency is performed with sequential increase of load. On specified dependence values of intensity of load at which sign of derivative changes from positive to negative and from negative to positive are registered. Dependence of decrement of oscillations on intensity of load is also registered within interval fixed by values. If there is maximum on last dependence then first of specified fixed values is taken as intensity of load corresponding to start of crank formation. Measurements are first conducted under mode of forced oscillations and then under mode of free oscillations. EFFECT: enhanced reliability of method. 4 cl, 3 dwg
