Composite materials have become an integral part of our lives: they are used in aviation and space technologies, as well as the automobile and mining industries. However, there has been a problem of internal stress assessment with composite material designs since their inception.
“Scientists from the National University of Science and Technology (NUST) MISIS Center of Composite Materials, led by Professor Sergey Kaloshkin, have proposed a non-contact method of internal voltage control in polymer composites. It is now possible to more effectively assess the degree of internal damages during the operation of aircraft parts, oil pipelines, ship hulls, and other industrial and transport facilities”, said Alevtina Chernikova, Rector of NUST MISIS.
Andrey Stepashkin, Candidate of Technical Sciences and Senior Research Associate at the NUST MISIS Center of Composite Materials, discussed why the problem of assessment is so critical. “There are composite materials in which the internal stress reaches 95% of the tensile strength after fabrication. It will crack if we add even a little more pressure. For example, a number of composite materials, processing excellent heat and thermal resistance and created for the ‘Buran’ spacecraft, had a high level of internal stresses due to the characteristics of their manufacturing. This has become a huge problem: to get one [functioning] piece of ‘Gravina’ material (which was used for the ship’s black plating) 50 had to be thrown out”.
There is no such level of internal stress in carbon plastics, fiberglass, or hybrid composite materials after manufacturing. Instead, stresses arise and accumulate under the influence of operating loads, the external environment, and weather, which can lead to damage in the material and reduce its load-bearing capacity. Such changes affect operational safety and must be identified in a timely manner.