Finite element analysis is performed for transient thermal deformations of a shadow mask inside the Braun tube of a T.V. set. The shadow mask numerous slits through which the electronic beams are guided to land on the designed phosphor of red, green of blue. Its thermal deformations therefore cause the mislanding of the electronic beam and result in decolorization of a T.V. screen.
For the realistic finite element analysis, firstly the apparent thermal conductivity and the apparent elastic modulus are calculated, and the shadow mask is modeled as shell without slits. Next the finite element formulation is developed for transient heat transfer on the shadow mask, wherein thermal radiation is a major heat transfer mechanism. The resulting temperature distribution is employed for finite element analysis of thermal deformation where the degenerate, shell elements are used for modelling the shadow mask.
The simulation results are in good agreement with the test results, and the present finite element code may be efficiently used for thermal deformation design of a shadow mask.
