This article presents the results of an experimental and theoretical study aimed at studying the adhesive properties of the filament – matrix interface. The experiment on pulling a filament out of a polymer matrix was carried out for materials manufactured by additive technology. The purpose of the study was to determine the limiting shear stresses at the carbon filament-polymer matrix interface, as well as the influence of the length of the “embedding” of the filament on the pulling force. For this purpose, specimens were made with different lengths of filament “embedding”. The tensile experiment was carried out on a universal testing machine and the load-displacement diagram was recorded. To estimate the displacement fields, the digital image correlation (DIC) method was used. In the process of testing, pictures of displacement and strain fields on the surface of the specimen were obtained, from which it is possible to assess the processes occurring on the surface of the filament-matrix interface. The typical fields of strain when pulling a single thread from the matrix array are shown. The length of the filament at which the load-bearing capacity of the composite is realized more efficiently and the load is close to the limit for the filament itself was determined experimentally. Based on experimental data, the minimum effective length of filament “embedding” was calculated when manufacturing composite structural elements using additive methods.

This article discusses the methodology for determining residual stresses in case-hardened material layers. It includes the joint use of the slitting method and the method of electronic pattern speckle interferometry. In the final part; experimental data are obtained from studies of samples with and without force strengthening effect.

The technologies and results of an experimental determination of residual stresses in the impeller blades of a hydraulic unit of the Krasnoyarsk hydroelectric power plant obtained through technical diagnostics beyond the projected periods of use are presented. The investigations of the residual stresses were performed by strain measurement with excision of templates and the optical method of speckle interferometry. Factual values of the components of the residual stresses in two zones of the blade with nonuniform stress fields were obtained.

Residual stress in layered composites significantly affects their mechanical properties. One of the most important tasks in the sphere of experimental mechanics is the development of effective methods for the accurate determination of residual stress values. This paper describes a modified destructive testing method implemented through layer-by-layer stitching. It differs from previous analogous methods by the use of electronic speckle pattern interferometry to measure the deformation response of a given sample. The interpretation of the initial experimental data in "stress terms" was carried out based on modeling through the use of the fmite element method (FEM).