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The results of a study of thermal conductivity and specific heat capacity of Zr – 1 wt.% Nb and Ti – 45 wt.% Nb alloys in coarse-grained and ultrafine-grained states are presented. The influence of the utrafinegrained state on the thermophysical properties and the processes of energy dissipation and accumulation during deformation of the alloys are estimated. It is shown that the formation of an ultrafine-grained state in a Zr – 1 wt.% Nb alloy by abc-pressing and subsequent rolling leads to a decrease in its thermal conductivity and specific heat capacity by 10 and 20%, respectively, due to substructural strengthening under severe plastic deformation. It is found out that thermal conductivity and specific heat capacity of the ultrafine-grained Ti – 45 wt.% Nb alloy increase by 7.5 and 5%, respectively, due to dispersion hardening of the ω phase by nanoparticles and formation of a new α phase. It is established that the ultrafine-grained structure has a significant influence on the energy dissipation and accumulation during plastic deformation, which in turn depend on their thermophysical characteristics and on the structural and phase states.

This paper describes research in the field of fiber optic nondestructive testing and structural health monitoring (SHM) of carbon fiber reinforced polymers (CFRP) by the use of integrated optical fiber sensors (OFS) based on fiber Bragg gratings (FBG). Basic mathematical expressions that represent optical SHM of composites are presented. Some new relationships are derived by considering the non-linear character of the FBG-sensor response and the combined effect of temperature and deformation. Both linear and non-linear coefficients of the sensor elements, as well as combined strain–temperature coefficients before and after the sensors are embedded into the composite panels, have been obtained. Experimental results on the strain state of CFRP under static and dynamic loads demonstrate the effectiveness of the proposed non-linear model for evaluating deformation in composites. It is shown that integrated OFS’s allow SHM of composite parts when mechanically loaded to failure, and that they can provide the actual level of strain in the composite parts in real time. SHM improves the operational safety of highly loaded and/or critical aerospace structures by providing real-time stress data, which would permit data-based decisions on overload conditions or imminent failure. Additionally, actual stress data from CFRP samples, or from real parts in use, could show whether the design of the parts should be changed to improve safety margins or to reduce weight.

The stage-like character of the stress-strain curves and microstructure in the fracture zone of coarse-grained and ultrafine-grained specimens of the VT1-0 and Zr–1Nb alloy specimens under quasistatic loading are investigated using the temperature curves obtained by the method of IR-imaging. New experimental data are obtained, which provide evidence on a considerable influence of the ultrafine-grained state on the evolution of plastic deformation and fracture in the VT1-0 and Zr–1Nb alloys.

It is common on space vehicles to have thermal insulation adhesively bonded to a metal structure. A typical defect in such structures is an interlayer disbond, which may occur either between the insulation and the metal substructure or between the layers of multilayer thermal insulation. One-sided thermal nondestructive testing (TNDT) using surface optical heating, such as Xenon flash or quartz tube, may detect disbonds if the thermal insulation thickness does not exceed a few millimeters and disbonds are not very small. In thicker insulation, the effectiveness of the inspection can be improved by using electrical induction to heat the metal base. In both cases, thermal excitation can be areal heating, which is heat projected over an area by a stationary heat source, or scanned linear heating (SLH), which is a linear heater scanned across the test subject. In the latter, either the linear heater is moved across a stationary test subject, or the linear heater is stationary and the test subject is moved. The SLH method usually provides a higher inspection rate (inspected area unit time). In this research, both the theoretical and experimental features of both optical and induction heating have been investigated and compared in the application to non-metallic insulation adhesively bonded to a metal structure. The effectiveness of using neural networks (NN) for characterizing defects has also been studied to demonstrate that optimal NN training should involve 4–5 points selected in defect areas close to non-defect areas, and the NN input data should be prepared by applying the known technique of Thermographic Signal Reconstruction (TSR). Since SLH provides more uniform heating, it provides higher quality IR thermograms than those obtained from areal (flash) heating and this improves the detectability of defects in thermal insulation to a depth of 4–6 mm. Other advantages of SLH for TNDT testing are (1) an inspection rate that is twice as high as an area heating technique and (2) a better potential for fully automated (robotic) testing.

The characteristics of microstructure, deformation and fracture of Zr – 1 wt% Nb and Ti – 45 wt% Nb bioinert alloys in the coarse- and ultrafine-grained states are investigated. It is shown that the ultrafine-grained structure formed in them ensures excellent mechanical properties of the alloys and affects the stages of the stress-strain curves and the behavior of the maximum temperature vs. deformation time plot. The formation of an α-phase in the Ti – 45 wt% Nb ultrafine-grained alloy suppresses the linear stage VI characterized by a constant strain hardening coefficient. In stage VII, the strain hardening coefficient rapidly becomes negative, which indicates the material softening prior to its failure.

Dynamic thermal tomography is a technique that allows the display of “slices” of solids by analyzing the evolution of surface temperature as a function of time. This paper presents the principles of one-sided thermal tomography using reference points and also introduces a technique of thermal tomography that does not require the use of reference point. The diffusion nature of heat conduction in solids causes lateral diffusion, which modifies and complicates the heat flow that is needed to detect defects. In the case of anisotropic composite materials the heat will diffuse more readily in one direction than another. Lateral diffusion can make it difficult to detect (visualize) deep defects, especially those located under shallower ones. Artifacts can be reduced by thresholding timegrams but this may hide small defects. The effectiveness of thermal tomography in detecting impact damage (cracks/delaminations) in composites has been confirmed by numerous experiments.

This study is devoted to the comparison of strength characteristics in the process of deformation and damage of axially strained VT1-0 titanium in the ultrafine-grained (UFG) and coarse-grained (CG) states. The temperature distributions on the surface of titanium specimens were recorded by means of IR thermography. The VT1-0 titanium in UFG state formed by applying severe plastic deformation is characterized by twice the yield stress and strength limit but half the deformation limit compared to CG titanium. The fracture of CG titanium is accompanied by local powerful generation of heat, while, in UFG titanium, the damage nuclei are less intense and more evenly distributed over the fracture cross-section. The titanium in UFG state, being deformed, utilizes structural channels of energy absorption more efficiently than in the CG state by involving the whole deformed volume in the fracturing process.

The regions of application of thermal imaging technique for testing the heat shielding of building structures, diagnostics of smoke pipes, boilers, cooling ponds, and thermal service lines are described.

The paper describes the technique and instrumentation for active thermal detection of water in cellular structures fabricated from aluminum, glass-enforced plastic, and carbon-fiber plastic. Results of modeling and experimental tests are given. Limiting characteristics of the method are discussed.