If you have had an eyeglass frame break, it likely did so at the point where the temple is screwed to a hinge. The holes in the frame create local stress concentrations that can initiate cracks that limit the durability of the material. Local reinforcements can be a cost-effective solution against fracture at sites such as bolt holes, where the performance of the material is challenged by additional stresses. This approach can be simple to implement in isotropic materials such as metals, but simple ways to reinforce such materials as fiber-polymer composites have been lacking. On page 199 of this issue, Erb et al. (1) propose a new method to align fibers or platelets in a polymer for the near-surface reinforcement of polymeric composites. In their approach, these inclusions are decorated with magnetic nanoparticles and oriented by a magnetic field in the production process in which the solution polymerizes to form a solid composite.
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