Volume 53, Nº 7 (2017)

A model has been developed for the interaction between plane elastic waves incident upon an interface between elastic media and the interface, with the interface possessing a singularity in the boundary conditions under a “linear slip” approximation. Changes in the angular dependences of the reflectance and transmittance on the microrougness and other parameters of the model have been determined.

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.

The magnetoresistive properties of FeMn/Fe₁₀Ni₉₀ films with unidirectional anisotropy have been studied under controlled elastic deformation. It has been shown that linear strain or compression significantly affects the magnetic anisotropy of the films and, as a consequence, leads to major changes in magnetoresistance curves. The dependences of the magnetoresistance on the relative deformation have been determined for varied external magnetic field, magnetic biasing, film thickness, and sample geometry. An optimum combination of the listed parameters has been found that corresponds to the maximum sensitivity and nearly anhysteretic type of the tensomagnetoresistive effect.

Composite materials are widely used in aerospace engineering, shipbuilding, and automobile industry due to their high durability, relatively low mass, and corrosion resistance. Composites are vulnerable to impact damages that may occur during production and service (e.g., as a result of dropped tools, bird strikes and luggage hits in aviation, hail, and other similar factors). Often unnoticeable on the affected composite surface, low-energy damages (below 20–40 J) can, however, lead to the emergence of significant flaws (such as complex combinations of cracks, exfoliations, fiber ruptures, etc.) inside the material. Results of applying ultrasonic infrared thermography to the detection of impact damages with an energy of 5–30 J in a carbon-carbon composite are presented.

The fundamentals of GOST (Intergovernmental Standard) 33514–2015, implemented on July 1, 2015, are set forth. Compliance of a nondestructive testing technique with its indicated purpose indicators, which may include numerical values of the certainty index achieved with the technique, is established during verification. Experimental research that is part of the verification procedure is carried out on test samples that contain natural and/or artificial defects as well as on flawless samples. The number of the samples is calculated depending on the prescribed value of the confidence probability of estimating the certainty index. Examples of verification tests for magnetic and ultrasonic inspection techniques are described.