Issue 46

V. E. Wildemann et alii, Frattura ed Integrità Strutturale, 46 (2018) 295-305; DOI: 10.3221/IGF-ESIS.46.27 295 Deformation and failure of carbon fiber composite specimens with embedded defects during tension-torsion test Valery E. Wildemann, Tatyana V. Tretyakova, Elena M. Strungar, Mikhail P. Tretyakov Center of Experimental Mechanics, Perm National Research Polytechnic University, Russia wildemann@pstu.ru, http://orcid.org/0000-0002-6240-4022 cem.tretyakova@gmail.com , http://orcid.org/0000-0001-9445-5185 cem.spaskova@mail.ru, http://orcid.org/0000-0002-2246-8638 cem_tretyakov@mail.ru , http://orcid.org/0000-0001-6146-6769 A BSTRACT . A need to timely reveal operational damages and technological defects requires a prompt control of states of structures made from composite materials and their consequent repairs aimed at service life extension. This work is devoted to the experimental study of inelastic deformation and fracture of specimens made from layer composite materials with prior introduced technological defects related to a possible inappropriate compacting and inappropriate bonding of material layers at a given restricted domain. The analysis is carried on the evolution of inhomogeneous deformation fields on the surface of carbon plastic specimens with an internal “delamination-type” defect under complex stress state. The method of active infrared thermography was used to identify the location and parameters of defects configurations. The obtained experimental data will be used for further tests related to sufficiency evaluation of signals received from the built- in sensors under complex loadings. K EYWORDS . Carbon fiber composite; Embedded defect; Complex stress state; Digital image correlation technique; Infrared thermography; Deformation. Citation: Wildemann, V. V., Tretyakova, T. V., Strungar, E. M., Tretyakov, M. P., Deformation and failure of carbon fiber composite specimens with embedded defects during tension-torsion test, Frattura ed Integrità Strutturale, 46 (2018) 295-305. Received: 29.07.2018 Accepted: 13.08.2018 Published: 01.10.2018 Copyright: © 2018 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION ayer composite materials are widely used to manufacture products for aviation and structural elements using woven prepregs with different technologies. Delamination, damage accumulation in polymer matrix, as well as fiber breaking of fabric (at a later stage) are major types of damages for composites of this class which are prior to the mechanical loss of load-bearing strength and operational performance of structural elements [1,2]. Delamination, inappropriate bonding, inappropriate compacting, cracks, air holes or blow holes [3] have a technology-related origin and refer to different material discontinuities. L