弹性力学基础：应力：疲劳应力与寿命分析.docx

force = 1000 #

area = 0.01 #

length = 1 #

elastic_modulus = 200 * 10**9 #

stress = force / area

strain = stress / elastic_modulus

delta_length = strain * length

import numpy as np

I2 = 0.5 * (np.trace(stress_tensor)**2 - np.trace(np.dot(stress_tensor, stress_tensor)))

I3 = np.linalg.det(stress_tensor)