Cracks in fiber composites: Determination of the stress intensity factor by the polarization-optical method

1996 ◽  
Vol 31 (6) ◽  
pp. 544-548
Author(s):  
V. P. Netrebko
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Optical Method ◽  
Fiber Composites ◽  
Polarization Optical Method

The Importance of the Mode II Term on the Analysis of Angled Cracks in Unidirectional Carbon Fiber Composites

2021 ◽  
Author(s):  
Jacob Biddlecom ◽  
Garrett J. Pataky
Keyword(s):  
Stress Intensity Factor ◽  
Regression Analysis ◽  
Stress Intensity ◽  
Carbon Fiber ◽  
Intensity Factor ◽  
Fiber Composites ◽  
Shear Loading ◽  
Mode Ii ◽  
Carbon Fiber Composites ◽  
Displacement Fields

Abstract Carbon fiber reinforced polymers (CFRP) have been used in many high-performance applications where strength to weight ratio is an important characteristic. The goal of this research was to analyze the effects of Mode II, also known as shear loading, on the displacement fields surrounding a crack for unidirectional carbon fiber composites. Tensile and fatigue experiments were conducted on angled unidirectional CFRP coupled with digital image correlation (DIC) to analyze the full field displacement. Angled CFRP cracks experienced mixed mode loading which required addition insight due to the complex stresses on the fiber/matrix interface. The experimental displacement fields acquired from DIC were used as inputs for an anisotropic regression analysis to determine the mode I and mode II stress intensity factor ranges. The results from the regression analysis were used to predict the displacement fields around a crack. When comparing the experimental results with the predicted results, the inclusion of Mode II increased the agreement between predicted and experimental displacement fields around a crack tip for two different fiber orientation angles. Crack growth rate analysis and analytical stress intensity factor ranges were used to expand on the agreement of the results as well as bring to light CFRP specific fracture mechanisms that lead to disagreements.

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