Interfaces in polymer-based carbon fiber composites are critical regions that are most susceptible to delamination under static and impact loads. The interface strength and fracture toughness can be improved significantly by structural micro-reinforcements using polymer additive manufacturing (PAM). A micromechanics embedded macro-model is developed for the evaluation and extraction of interface properties of laminated coupons with printed polymer reinforcements (PPRs) at ply interfaces to efficiently tailor the interface properties. Given the microstructure of the printed reinforcements, an automatic cohesive insertion module is developed to simulate the improved interface fracture toughness resulting from a wavy crack path steering around PPRs. The applicability and accuracy of the developed modeling approach are demonstrated using ENF coupons with PPRs fabricated and tested. The validated modeling approach is then applied to explore the effect of geometric configurations of PPRs through double layer printing on the enhanced Mode II energy release rate. The developed numerical model provides a digital testing tool for tailoring interface properties, optimization of PPRs, and extraction of enhanced interface properties for delamination failure prediction of a large scale composite structure.
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