A method for evaluating damage extent in polymer composites
Andrzej Bałzowski Politechnika Wrocławska, Wydział Mechaniczny, ul. Wybrzeże Wyspiańskiego 27, 50-370 Wrocław
Annals 2 No. 4, 2002 pages 253-258
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abstract Processes of mechanical degradation occurring in polymer composites under the influence of long-lasting static and dynamic loads have a detrimental effect on their structural properties (Fig. 1). The presently used methods for evaluating the extent of damage in material are mainly based on monitoring gradual decrease of the longitudinal elastic modulus value (Fig. 3). The paper presents a new measure of the damage extent that accounts for relative changes in the residual strength determined at a stipulated confidence level (Fig. 6). The presented approach is therefore capable of allowing for changes in both the mean value of strength and its statistical characteristics. Presented are example graphs of the damage parameter varying under fatigue conditions in unidirectional composite (Figs 4, 7, 8). Due to its sound physical basis the method may be considered a reliable tool in evaluating the extent of damage in composite components or in calibrating other existing techniques that, though convenient in use, lack a sound theoretical basis.