Expanding the Conceptual Approach to the Concept of “Witness Sample”

The analysis of normative and scientific sources using the concept of a witness sample is carried out. It is shown that a witness sample is currently understood to be a sample made of the same material and processed by the same methods as the structure under study. The witness sample is being moved or is already in the laboratory for examination. Such witness samples are used to control the parameters of various materials (steels, carbon materials, reinforced polyethylene). According to the condition of the witness samples, various characteristics are determined (residual stresses and endurance limit, exposure temperature, rate and type of corrosion in different environments, exposure to radionuclides). The authors propose to expand the conceptual approach to the concept of a witness sample by expanding the scope of witness samples for the study of the residual life of non-ferromagnetic materials. The fundamental differences include that the witness sample and the main structure are made of different materials, while the witness sample and the main structure work and deform together due to the adhesive bond between them. The witness sample is not separated from the structure under study, and the necessary parameters are determined directly on the object in the field. For the designed critical structures made of non-ferromagnetic materials, it is proposed to provide for the attachment of witness samples made of ferromagnetic materials to the most potentially destructive structural elements. © 2025 Elsevier B.V., All rights reserved.