Constitutive model of MWCNTs/PDMS composites considering volume change and electromechanical response characteristics under impact load.

Multi-walled carbon nanotubes/polydimethylsiloxane (MWCNTs/PDMS) composites have excellent electromechanical conversion ability which can be applied in the field of intelligent sensing. However, the volume changes and electromechanical response mechanism of MWCNTs/PDMS under dynamic load remain unclear. In this paper, the electromechanical response of MWCNTs/PDMS with different mass ratio of MWCNTs are studied by quasi-static compression, SHPB experiment and finite element numerical simulation. The quasi-static compression results show that volume ratios of MWCNTs/PDMS are decreased with compression strain (0.845 when strain is 0.5), then, the Yeoh hyperelastic constitutive model is established considering volume change. When the mass ratio of MWCNTs is 1 wt%, MWCNTs/PDMS shows the best mechanical properties. The stationary phases of strain rate of MWCNTs/PDMS decrease with increasing of impact velocity, showing obvious viscoelastic mechanical properties. The impact induced voltages of MWCNTs/PDMS are generally larger than PDMS (10∼15 m/s). The flexoelectric effect of MWCNTs/PDMS under impact is further studied based on numerical simulations. The results show that the strain gradients are within 10−2∼10−1 m−1, the related flexoelectric coefficients are within 10−10–10−9 C/m. In summary, this study can further expand the application of MWCNTs/PDMS in the field of intelligent sensing. • The constitutive model of MWCNTs/PDMS composites considering volume change is established. • The impact induced flexoelectric effect of MWCNTs/PDMS is mainly related to strain gradient ∂ ε z z / ∂ x z. • CNTs 1wt% /PDMS composite has the largest flexoelectric coefficients: μ zzzz = 6.447 × 10−9 C/m, μ xxzz = −6.04 × 10−10 C/m, μ xzxz = 1.23 × 10−10 C/m. [ABSTRACT FROM AUTHOR]