ELASTO-PLASTIC ANALYSIS NEAR THE NOTCH INTRODUCED TO THE ALUMINA CERAMIC GREEN SHEET.

Elasto-plastic finite element analysis is carried out to clarify the mechanism of the microcrack initiation when a notch is introduced in an alumina green sheet, in order to break down an IC plate after sintering with the dimension designed. Microcrack initiation depends on the material constant H/E, where H is work hardening coefficient, and E is Young's modulus. When H/E value is small, remarkable tension-compression multi-axial stress field is caused at the elastoplastic boundary region in front of the notch tip, and the singularity of principal shearing stress becomes not so remarkable. Therefore, the effect of principal shear stress becomes small and the probability of microcrack initiation ahead of the notch tip becomes large due to tension-compression multi-axial stress field.