Authors:

Nathan Miles

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About Paper:

Cracks are unavoidable features of any engineering or biological material. Thus, understanding fracture toughness is central to ensuring structural integrity of mechanically loaded systems. Fracture mechanics provides a framework to investigate such problems. The quantity stress intensity factor is a key parameter. It combines information of stress perpendicular to the crack, the crack length, and structure geometry. Recently, Bazant et al. have demonstrated that fracture behavior can also be dependent on stress parallel to the crack. General knowledge on the effect of crack parallel stress on fracture toughness is not yet available. For concrete, an isotropic, heterogeneous solid, crack parallel stress was found to increase fracture toughness while for carbon fiber composites, an anisotropic, strongly heterogeneous solid, it was found to decrease fracture toughness. Here a mildly elastic anisotropic, mildly heterogeneous 3D printed polymer is selected to investigate the effect of crack parallel stress on fracture toughness. This choice of material is motivated by the ultimate objective to investigate the effect of crack parallel stress in cortical bone, which shares the characteristics of mild elastic anisotropy, heterogeneity, and quasi-brittle response with the material considered here. It is predicted that crack parallel stress will increase the measured toughness of the 3D printed samples due to the microstructure induced by the printing process. Evaluation of quasi-brittle materials, like bone, is important to further the development of effective treatment for bone-related disease.

Source:

Purdue University / 2023

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Co-authors:

Nathan Miles