Residual stress anisotropy in High Pressure Sodium Lamp Seals

摘要

One of the major failure modes of the High Pressure Sodium (HPS) Lamp is leakage of the seal connecting the metallic electrical feedthrough and the ceramic arc tube. Different thermal expansion coefficients of the various phases in the seal causes residual stress in the seal. Vickers indentation based experiments showed that in a plane perpendicular to the axis of the lamp there is a tangential tensile stress and approximately 3 times larger radial compressive stress in the seal [1]. Current work aims to describe the stress state by Finite Element calculation and to explore the effect of cyclic indentation loading on crack formation and cracking statistics.