Apparent stress intensity factor KI with different radius are calculated by the stress method and KI is obtained by interpolation to the crack tip circular arc.
采用应力法计算不同半径处的表观应力强度因子，插值到裂尖圆弧而得。
2
In arc ignition process, it has apparent effect and improves the stability of arc, so that power factor is advanced and current drain is reduced.