Publication: Stress analysis on stretchable conductive polymer under cyclic loading condition
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Date
2023-07-01
Authors
Muhamad Aiman Bin Amir
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Abstract
Stretchable electronics have become a topic of focus for many academic and industrial research groups due to their ability to enable myriad emerging applications such as stretchable strain gauge, flexible piezoelectric sensors, and flexible display. In this study, we aim to investigate the performance of a stretchable conductive polymer, specifically a polydimethylsiloxane (PDMS) substrate with silver-polydimethylsiloxane (Ag-PDMS) conductive ink, under uniaxial and cyclic loading conditions using the digital image correlation (DIC) technique. The DIC technique was employed to extract the deformation fields. In addition, a finite element analysis (FEA) was used to compare the results with the experimental results to determine its accuracy and reliability. The results of the experiments and simulations are discussed, highlighting the effects of the presence of stretchable conductive ink and different ink shapes on the mechanical behaviour of the sample. It was found that the presence of the ink did not significantly alter the mechanical response of the sample initially, but deviations from the pure PDMS behaviour became evident as the test progressed. Moreover, it was observed using DIC technique that the conductor experienced higher strains compared to the substrate during the test. Furthermore, the investigation shows the cyclic nature of the material's softening phenomenon when subjected to cyclic loading conditions. Notably, beyond the initial plastic strain that emerges during the first cycle, no significant subsequent plastic deformation is detected across the subsequent loading cycles. Intriguingly, the FEA outcomes diverge from the observed cyclic softening, portraying cyclic hardening instead. Noteworthy data from the FEA includes the maximum equivalent stress encountered within the Ag-PDMS body during the 20th cycle (2360 s). This stress is at its lowest in the straight ink configuration (0.2390 MPa), slightly higher in the rectangular configuration (0.2425 MPa), and highest in the zigzag configuration (0.2609 MPa).