Ferroelectric polymers have attracted increasing attention due to their distinguished dielectric and piezoelectric properties. Dielectric breakdown is one of the main failure behaviors for ferroelectric polymers. Understanding dielectric breakdown of ferroelectric polymers under mechanical and electrical loadings is crucial to their applications in energy storage and conversion devices with high-energy-density. In the present work, a multi-field coupling phase field model is developed to investigate the dielectric breakdown of ferroelectric polymers under mechanical and electrical loadings. To describe the effect of mechanical stresses on the evolution path and critical electric field of dielectric breakdown, a strain-dependent breakdown energy is proposed in the phase field model. The phase field simulations show that a compressive stress restrains the branching of the breakdown path and increases the critical electric field of breakdown. On the contrary, a tensile stress accelerates the branching of the breakdown path and decreases the critical electric field of breakdown. The results in the present work may stimulate further experimental investigations on the effect of mechanical stresses on the dielectric breakdown of ferroelectric polymers and provide a guidance for improving the breakdown strength of ferroelectric polymers through a mechanical way.

铁电聚合物由于其杰出的介电和压电性能而受到越来越多的关注。介电击穿是铁电聚合物的主要失效行为之一。了解铁电聚合物在机械和电负载下的介电击穿对于其在高能量密度的储能和转换设备中的应用至关重要。在当前的工作中，建立了一个多场耦合相场模型来研究铁电聚合物在机械和电负载下的介电击穿。为了描述机械应力对介质击穿的演化路径和临界电场的影响，在相场模型中提出了应变相关的击穿能量。相场仿真表明，压应力抑制了击穿路径的分支，并增加了击穿的临界电场。相反，张应力加速了击穿路径的分支并减小了击穿的临界电场。本工作的结果可能会刺激对机械应力对铁电聚合物介电击穿的影响进行进一步的实验研究，并为通过机械方式提高铁电聚合物的击穿强度提供指导。