16.6L: Late-News Paper: Thermal Stress and Crack Behavior in Perfectly Flat CRTs

摘要

For the perfectly flat CRT, corner cracking of the panel going through the exhaust lehr has been a long standing problem. These cracks frequently occur during the heat up cycle and originate on the corner of the inner surface of the panel. In this paper, the transient stresses for the perfectly flat CRT during the heat up cycle of the evacuation in the exhaust lehr in which both thermal and vacuum loads are applied are analyzed by the finite element method. The results show that at 4000 second from the operation of the lehr when the thermal gradient is highest, the stresses of the panel are highest in the corner, which means that the thermal loads are dominant. The panel stresses however, are highest in the center at 6000 second, which indicates that at that time the vacuum loads are more dominant than the thermal loads. And the stress distributions and stress directions calculated explain the crack propagation direction and agree with the failures occurred well.