Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Experimental validation of unloading compliance solutions applicable to C(T) and SE(B) specimens
Submission Author:
Gustavo Henrique Bolognesi Donato , SP
Co-Authors:
Gustavo Henrique Bolognesi Donato, Régis Barros, Joao Ferreira de Carvalho Jr
Presenter: Gustavo Henrique Bolognesi Donato
doi://10.26678/ABCM.COBEM2017.COB17-2100
Abstract
The design and maintenance of high performance structures demand structural integrity assessments considering the presence of flaws (cracks), which demands accurate properties regarding fatigue and fracture. These mechanical properties may be characterized, for example, through J-R or da/dN vs. Delta_K curves. Such measurements are highly dependent on the instantaneous crack size during the experiments, which are commonly estimated through electrical, optical or unloading compliance techniques. Unloading compliance is based on the stiffness decrease caused by crack growth. In this scenario, this work focuses on the experimental validation of recent numerical unloading compliance solutions proposed by Donato and Moreira and, predicting instantaneous crack size on C(T) and SE(B) specimens incorporating three-dimensional effects. To achieve this, C(T) and SE(B) specimens were machined according to current standards (ASTM E1820 and ASTM E647) and tested in a universal testing machine MTS 810.25. Based on load-displacement records, normalized unloading compliance (μ) could be computed and instantaneous crack sizes (a) estimated through standards and recent numerical proposals. The predicted crack sizes were compared to real measurements. The results reveal that both solutions are accurate and provided deviations below ~ ±1.6% when compared to experiments. They are comparable for C(T) specimens but Donato and Moreira’s proposals were slightly better for SE(B) geometries.
Keywords
Unloading compliance, experimental validation, ASTM compliance solutions, SE(B), C(T)
