Fig. 1: Multi-physical characterisation of FFF samples with different printing orientations.

a Diagram of the printing directions used. b Experimental results isolating physics by pairs: b.1 Electro-thermal characterisation analysing the Joule effect under an electric field (\({\mathbb{E}}\)) of 250 V m⁻¹. The temperature evolution is presented on the left and the effective resistivity (ρ_eff) is presented on the right. b.2 Mechano-electrical characterisation analysing the effective resistivity (ρ_eff) variation with tensile deformation. b.3 Thermo-mechanical characterisation analysing the effect of the temperature (θ) in the mechanical response under uniaxial tensile loading. c Experimental results of a fully-coupled test performed on longitudinal samples. An electric field (\({\mathbb{E}}\)) of 187.5 V m⁻¹ is imposed leading to a Joule heating for 5 min and, then, a tensile stretch ramp is imposed. The average surface temperature (θ), the effective resistivity (ρ_eff) and the mechanical stress (σ) are measured over time. Three replicates were used per testing condition. The lines represent the average response whereas the shaded areas represent the experimental deviation To provide fair comparisons between experimental and modelling data, as the voltage at reference configuration is kept constant during the tests, the effective resistivity and electric field are calculated in the reference configuration too.