Fast-condensing nanofoams: Suppressing localization of intense stress waves

We investigated the propagation of intense stress waves across silica nanofoams, with the pore size ranging from 50 nm to 1 mm and the porosity of 60%. The experimental results showed that if the pore size was relatively large, the stress wave remained localized and its energy was dissipated in narrow bands; if the pore size was below 200 nm, however, the stress wave was homogenized in a broad area and consequently, bulk distributed energy absorption was promoted and the maximum transmittedwave pressure was significantly reduced. We attribute this phenomenon to the fast condensation of the smallest pores at the wave front. The ability of nanofoams to promote widespread energy absorption may enable efficient stress-wave mitigation techniques. The classic Grady model was modified to take account for the nanopore size effect. & 2016 Elsevier B.V. All rights reserved.