Multipurpose software-hardware systems for active electromagnetic testing as a trend

The instability of the results of passive (in "geomagnetic" fields) magnetic testing under action of uncontrolled inhomogeneous fields is demonstrated. The zero crossing of the normal magnetic-field component that is suggested as a diagnostic sign of a stress-deformed state is formed independently of the structural-phase or stress-deformed state of a ferromagnet, and the position of such crossing alters even by small inhomogeneous fields. It is shown that the frequently encountered necessity for a multiparameter testing can be due to both the nonlinearity of relationships between controlled and measured parameters of testing and the necessity of taking into consideration measurement conditions. The main criteria are formulated that should be met by promising multipurpose systems of active (i.e., involving deliberate action upon test objects by quasistatic or variable field) electromagnetic testing.