The Bilateral Stress Elliptic(ellipse of plasticity) Theory is widely used in casing strength designing, as an approximate alternative to the four th strength theory.
作为第四强度理论的近似计算，目前在套管柱强度设计中广泛应用双向应力椭圆理论。
2
Based on this kind of crack element, and by introducing parametric equation of ellipse, a new method for estimating stress intensity factor is proposed.
基于这种裂纹单元，作者引入椭圆参数方程，推出一种计算裂纹前缘点应力强度因子的新方法。
3
It is reasonable takes shape the unfinished piping to the flat ellipse for reduce the remaining stress peak value and ellipticity.