Non-destructive techniques of identification using the maximum load acoustic emissions (AE) Lthwithout exceeding thereof a product's defect does not propagate and the maximum load Lfat which a product still survives at continuous loading until a destruction occurs were developed. It was proved experimentally that at stationary loading L the product's life is R¥(Lth/L)n. The value n does not depend on the stress state, overall dimensions of the product and could be identified accurately and timely using the AE on the material samples at a specified temperature T. The value Lthdoes not depend on T, it defines the initial condition of a product at a specified loading circuit but it can vary more than once at its changing, e. g. at changing of the core bending direction. The Lthcontrol at likely loading circuits of the product allows to opt for an optimum circuit, to orient the product correctly at its operation and to use its strength to a full extent. The product's life prediction at specified L and T requires n to be identified on samples with Lthidentified at a selected circuit of the product loading. At such evaluation of R, a 3 to 5-fold error is likely to occur. Though the scatter of R at the same loading conditions for products manufactured of the same material and using the same process is not below 2/10th of the orders. When carrying-out a screening of the weakest products using R, not above 20% of them would prove to be in a good state. At the same time, screening, e. g. of 13% of the weakest ferrite cores (using R or Lth) will lead to 106-fold increase in the trouble-free operation time. The products intended for an one-fold quick loading should be inspected using Lf. The techniques have been verified using metal turbine blades, soldered and welded joints, ceramics (ranging from optically transparent to coarse construction ones and concrete) but they are unfit for materials which durability is identified not on the basis of the time of degradational development until a critical size but on the basis of time of onset of a defect. When implementing the techniques, both mechanical loading and electric one, with ceramic heaters control and polymeric insulation of the cables were utilized. In the latter case the microcavitation was recorded by AE in the insulation submicrocracks under action of the alternating stress.
