Title: Determining Mode I Fracture Toughness of Adhesive Composite Joints: Autonomous Crack Tracking Using MATLAB Developed Program

Authors: Peter E. Caltagirone, Dr. Dylan Cousins, David Snowberg and Dr. Aaron P. Stebner

DOI: 10.33599/nasampe/s.20.0048

Abstract: Characterizing the fracture toughness of composite material joints is essential to informing design safety factors. ASTM D5528 defines how to calculate the Mode I fracture toughness of an adhesive using a double cantilever beam peel test. The standard specifies visual markers on the sample be inspected during the experiment to measure the crack length, which is needed to calculate the fracture toughness. While this method allows one to determine the fracture toughness, the process is extremely time consuming, tedious, and prone to human error when marking the sample and again when visually inspecting the crack growth relative to those markers. A MATLAB toolbox was written to automatically analyze crack propagation from digital images, create compliance plots, and export the fracture toughness using the modified beam theory method, the compliance calibration method, and the modified compliance calibration method. Rather than using 18 points of data as defined in the traditional method, the program computes the fracture toughness using hundreds of points, reducing noise and error. Different test types are compared i.e. ductile adhesive, brittle adhesive, crack jumping, inhomogeneous surface, etc.; and the results calculated using the ASTM standard method are compared to those exported by the MATLAB program.

References: [1] G. I. Barenblatt, “The Mathematical Theory of Equilibrium Cracks in Brittle Fracture,” Adv. Appl. Mech., 1962. [2] Y. Mi, M. A. Crisfield, G. A. O. Davies, and H. B. Hellweg, “Progressive delamination using interface elements,” J. Compos. Mater., 1998. [3] W. Xu and A. M. Waas, “Multiple solutions in cohesive zone models of fracture,” Eng. Fract. Mech., 2017. [4] E. F. Rybicki and M. F. Kanninen, “A finite element calculation of stress intensity factors by a modified crack closure integral,” Eng. Fract. Mech., 1977. [5] N. E. Dowling, K. Siva Prasad, and R. Narayanasamy, Mechanical behavior of materials : engineering methods for deformation, fracture, and fatigue. Pearson, 2013. [6] “ASTM D5528-13. Standard test method for Mode I interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites,” West Conshohocken, PA, 2013. [7] A. Brunner, B. Blackman, and P. Davies, “A status report on delamination resistance testing of polymer–matrix composites,” Eng Frac Mech, vol. 75, no. 9, pp. 2279–2794, 2008. [8] J. G. Williams, “End corrections for orthotropic DCB specimens,” Compos. Sci. Technol., 1989. [9] P. Qiao and J. Wang, “Novel joint deformation models and their application to delamination fracture analysis,” Compos. Sci. Technol., 2005. [10] M. M. Shokrieh, M. Heidari-Rarani, and M. R. Ayatollahi, “Interlaminar fracture toughness of unidirectional DCB specimens: A novel theoretical approach,” Polym. Test., 2012. [11] S. Wang and C. Harvey, “A theory of one-dimensional fracture,” Compos. Struct., 2012. [12] Z. Suo, G. Bao, B. Fan, and T. C. Wang, “Orthotropy rescaling and implications for fracture in composites,” Int. J. Solids Struct., 1991. [13] M. G. Andrews and R. Massabò, “The effects of shear and near tip deformations on energy release rate and mode mixity of edge-cracked orthotropic layers,” Eng. Fract. Mech., 2007. [14] J. Xie, A. M. Waas, and M. Rassaian, “Closed-form solutions for cohesive zone modeling of delamination toughness tests,” Int. J. Solids Struct., 2016. [15] S. Hashemi, A. J. Kinloch, and J. G. Williams, “Corrections needed in double-cantilever beam tests for assessing the interlaminar failure of fibre-composites,” J. Mater. Sci. Lett., 1989. [16] J. P. Berry, “Determination of fracture surface energies by the cleavage technique,” J. Appl. Phys., 1963. [17] K. Kageyama and M. Hojo, “Proposed methods for interlaminar fracture toughness tests of composite laminates,” in 5th U.S./Japan Conference on Composite materials, 1990, pp. 227–234.

Conference: SAMPE 2020 | Virtual Series

Publication Date: 2020/06/01

SKU: TP20-0000000048

Pages: 12

Price: FREE