Finite-Element Simulations of the Static Behavior and Explosive-Rupture Dynamics of 500 kV SF6 Porcelain Hollow Bushings

We investigate the explosive-rupture behavior of porcelain hollow bushings using a representative 500 kV SF6 incident as the reference case. Finite-element simulations are performed for both the static response and the rupture process. Results show that internal SF6 pressure drives the maximum equivalent (von Mises) stress to the flange, while strain localizes near the bushing mid-span. These findings highlight the cement–grout potting between the porcelain shell and flange, the waterproofing treatment, and the mid-span bonded joint as key manufacturing control points. Dynamic simulations further indicate that comparing the explosive-equivalent energy of the SF6 pressure impulse with the gas expansion (burst) energy enables diagnosis of the failure mode. From the viewpoint of fragment kinetic energy, the analysis indirectly verifies that rupture is initiated by intrinsic porcelain defects and subsequent crack propagation. The simulated fragment morphology and ground dispersion agree with field observations from the actual event, underscoring the critical role of microcracks in brittle fracture. Accordingly, optimizing firing processes to reduce internal cracks and voids—via raw-material control and firing-temperature optimization—is essential for reliability improvement and life extension. The results provide a practical reference for the design and long-term operation of porcelain bushings.