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We propose an architecture for dramatically enhancing the stress bearing and energy absorption capacities of a polymer based composite. Different weight fractions of iron oxide nano-particles (NPs) are mixed in a poly(dimethylesiloxane) (PDMS) matrix either uniformly or into several vertically aligned cylindrical pillars.These composites are compressed up to a strain of 60% at a strain rate of 0.01 s À1 following which they are fully unloaded at the same rate. Load bearing and energy absorption capacities of the composite with uniform distribution of NPs increase by $50% upon addition of 5 wt% of NPs; however, these properties monotonically decrease with further addition of NPs so much so that the load bearing capacity of the composite becomes 1/6 th of PDMS upon addition of 20 wt% of NPs. On the contrary, stress at a strain of 60% and energy absorption capacity of the composites with pillar configuration monotonically increase with the weight fraction of NPs in the pillars wherein the load bearing capacity becomes 1.5 times of PDMS when the pillars consisted of 20 wt% of NPs. In situ mechanical testing of composites with pillars reveals outward bending of the pillars wherein the pillars and the PDMS in between two pillars, located along a radius, are significantly compressed. Reasoning based on effects of compressive hydrostatic stress and shape of fillers is developed to explain the observed anomalous strengthening of the composite with pillar architecture.

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Evolution in bending modulus and accompanying microstructure of free‐standing air plasma‐sprayed Y2O3‐stabilized ZrO2 subjected to thermal exposure, from 800°C to 1300°C, has been studied. The bending modulus was measured using custom‐made miniaturized cantilevers, which was loaded using a nanoindenter. Variation in the bending modulus was compared with the density change. The coating shows two domains of behavior of modulus variation with density: the low temperature/time domain wherein the bending modulus doubles without measurable change in the density and the high‐temperature domain where modulus increases monotonically with density. Finite element (FE) analysis was carried out using cross‐sectional micrographs of coatings to measure the elastic modulus of the actual coating and compared with experimentally observed values. The modulus values predicted by FE analysis are 70%‐80% higher than the experimentally observed values. An analytical model has been proposed to corelate the microcracks density and elastic modulus, which is in reasonable agreement with the experimentally measured values.

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