@article{chen_cai_zhu_liao_qian_yuan_zhang_2019, title={3D printing of electroactive PVDF thin films with high beta-phase content}, volume={28}, ISSN={["1361-665X"]}, DOI={10.1088/1361-665X/ab15b7}, abstractNote={Bi-axially oriented electroactive PVDF thin films were prepared by a 3D printing process during which multiple parameters play a critical role in enhancing β-phase and crystallinity of the thin films. The PVDF molecular chains were rotated and stretched to form orderly arrangement by the pulling of in situ strong auxiliary electric potential (voltage) and the mechanical pulling force, and the aligned PVDF molecular chains improved the crystallinity of the thin films. Doping very small amount of multi-walled carbon nanotubes (MWCNTs) or graphene (GR) as a nucleating agent significantly increased the content of the β-phase in the films. Adding GR behaved is better than the MWCNTs in improving the β-phase due to the lamellar structure of graphene can generate a large number of micro electric fields stimulating the transformation of molecular chain from trans-gauche-trans-gauche(TG+TG−) to all-trans (TTTT). The content of β-phase in the PVDF/GR(0.03 wt%) composite thin film researched at 61.52%. Under the special environment of 3D printing, the printed PVDF thin films became very dense with high β-phase after depositing layer-by-layer. It exhibited good piezoelectric properties without post-poling treatment and mechanical stretching.}, number={6}, journal={SMART MATERIALS AND STRUCTURES}, author={Chen, Caifeng and Cai, Feixiang and Zhu, Yuan and Liao, Linchen and Qian, Jilong and Yuan, Fuh-Gwo and Zhang, Ningyi}, year={2019}, month={Jun} }
 @article{huang_yang_zhang_yuan_jiang_2014, title={Cracks Monitoring and Characterization Using Ba0.64Sr0.36TiO3 Flexoelectric Strain Gradient Sensors}, volume={9061}, ISSN={["0277-786X"]}, DOI={10.1117/12.2045166}, abstractNote={This paper presents a new method for monitoring and characterizing cracks using Ba0.64Sr0.36TiO3 flexoelectric strain gradient sensors. Firstly, strain gradient field around the mixed mode asymptotic crack tip was analyzed, followed by the derivation of induced flexoelectric polarization in the strain gradient sensors attached in the vicinity of a crack tip. It was found that the flexoelectric polarization of the sensor can be expressed as a function of the stress intensity factors of crack and relative coordinates between the sensor and crack. Given the information of the crack size, further analysis demonstrates that the location of the crack can be traced through the calculation based on flexoelectric outputs of the distributed sensors. A specimen with Mode-I crack was then prepared with two strain gradient sensors (4.7 mm × 0.9 mm × 0.3 mm) attached close to the crack tip to verify the analytical model for detection of cracks. The experimental results yield accurate location of the crack, confirming that flexoelectric strain gradient sensing can be a good avenue for monitoring cracks.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2014}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014} }
 @article{huang_yang_zhang_yuan_jiang_2015, title={Direct Measurement of Opening Mode Stress Intensity Factors Using Flexoelectric Strain Gradient Sensors}, volume={55}, ISSN={["1741-2765"]}, DOI={10.1007/s11340-014-9914-y}, number={2}, journal={EXPERIMENTAL MECHANICS}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2015}, month={Feb}, pages={313–320} }