The healing process exhibited by biological structures has inspired the creation of engineered materials capable of mimicking this behavior, providing adaption to impeding crack propagation and subsequently healing it. Recently, a new approach to self-healing was devised in which a sensing network was combined with shape memory polymers (SMPs) to allow the controlled response of the material to damage. The system was designed such that in the presence of a crack the polymer locally modified its modulus to toughen the damaged region and arrest crack growth. This process is followed by the shape memory response, closing the crack and healing the system. This paper will study the mechanics of the toughening portion of this self-healing system and specifically develop models to predict the stress intensity factor of a crack tip in a nonhomogeneous inclusion. The models will be formulated using finite element analysis (FEA) and a single inclusion model based on Eshelby’s equivalent theory with the elastic gradient defined by a point source thermal load. It will be shown that as the temperature of the crack tip passes the glass transition temperature of the polymer, the stress intensity factor at crack tip decreases to 95% of the original material stress intensity factor. This is due to the formed elastic gradient and deflection of the stress concentration away from the crack tip into the bulk polymer.

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