Experimental identification of the dynamic piezoresistivity of fused-filament-fabricated structures

Abstract

Fused-filament-fabrication (FFF) technology is promising for the production of fully embedded piezoresistive dynamic sensors. However, the lack of experimental identification of the dynamic piezoresistivity limits the scientific and applied progress. Dynamic piezoresistivity of 3D printed structures is hard to research due to: structural anisotropy and heterogeneity, the large number of process parameters in 3D printing, the nonhomogenous electric/stress/strain fields. Additionally, the piezoresistivity can be dependent on the frequency of the mechanical load and also on the temperature. This research proposes an experimental method to identify the dynamic piezoresistivity of unidirectionally printed specimens. The method is based on the Bridgman model of piezoresistivity and is extended to the dynamic conditions. With a single measurement, the stress in the specimen, the initial resistivity and the piezoresistive coefficient in the frequency domain are identified. The applicability of the method is experimentally tested on three specimens with different orientations of the mechanical and electrical loads. The identified piezoresistive coefficients identified using the proposed method can be used in analytical and numerical models in embedded, FFF dynamic sensors and similar applications.