Conventional piezoelectric ceramics lose their piezoelectric properties near the Curie temperature (Tc), which limits their application at high temperatures. One approach to resolving this issue is to design flexoelectric piezoelectric composites or piezoelectric metamaterials by exploiting the flexoelectric effect of the ferroelectric materials. In this work, an experimental study on two designs of flexoelectric metamaterials is demonstrated. When a ferroelectric ceramic wafer is placed on a metal ring or has a domed shape, which is produced through the diffusion between two pieces of ferroelectric ceramic of different compositions at high temperatures, an apparent piezoelectric response originating from the flexoelectric effect can be measured under a stress. The apparent piezoelectric response of the materials based on the designs can be sustained well above Tc. This study provides an approach to designing materials for high-temperature electromechanical applications.

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The newly developed flexure mode flexoelectric composites have extremely high direct piezoelectric response around mechanical resonant frequency. Methods of tuning the resonant frequencies of the composites were studied in this paper. The resonant frequencies can be adjusted by changing dimensions of ferroelectric ceramic bars in the composites or by adding an additional mass on the composites. Design of flexure mode composites with multiple resonant frequencies was also studied.

Abstract：Assembled shear wall built with precast two-way hollow slab is a new-typed shear wall built with precast concrete. In order to study its mechanical property, a quasi-static experiment is conducted with 1 reinforced concrete shear wall and 2 new type shear walls as the study objects. It was found that the internal and vertical joints of the wall body were vulnerable parts so that the new-typed shear wall experienced the loading process from the whole wall to the portioned wall. So, brittle shear failure can be avoided, deformability and anti-collapse performance are greatly improved, and shear capacity of wall body is reduced. The new-typed shear wall is reasonably structured, with convenient and reliable horizontal and vertical reinforcement, which leads to satisfactory vertical joint force-bearing capacity. Thus, it can be applied in practical construction.