随机变幅荷载作用下焊接节点海水腐蚀疲劳裂纹扩展试验

SEAWATER CORROSION FATIGUE CRACK GROWTH TESTS ON WELDED JOINTS UNDER RANDOM VARIABLE AMPLITUDE LOAD

本工作采用国产海上平台用钢的T型和十字形板状焊接节点试件,模拟导管架臂节点的弯曲受力状态,在随机变幅荷载下进行了海水腐蚀疲劳裂纹扩展试验,分别测得在海水自由腐蚀和阴极保护条件下的(~—da/dN)-AK^(NM)关系曲线。对于十字型焊接节点试件,根据试验测得的裂纹扩展速率曲线,用断裂力学方法对其海水腐蚀疲劳裂纹扩展寿命(有阴极保护)进行了估算,估算得到的裂纹扩展寿命曲线与试验数据,以及用线性累积损伤理论估算的寿命曲线,进行了分析比较和讨论。

Scawatercorrosion fatigue crack growth tests were carried out on T-shaped and cruciform welded joints of China-made plateform steel under random variable amplitute loading to simulate the actual situation of the tubular joints of jacked-type offshore plateform during its term of service.The da /dN-ΔK curves of seawater corrosion fatigue with and without cathodic protection were obtained.Based on the crack growth rate curves obtained,fracture mechanics method has been used to predict the corrosion fatigue crack propagation life of the cruciform welded joints with cathodic protection under random variable amplitute loading.The predicted crack propagation life curve has been compared with the test data and the life curve obtained by using the linear cumulative damage summation rule.