中文摘要：

为了给半潜式钻井平台的安全性和寿命评价提供可靠试验依据,在室温下对半潜式钻井平台用钢DH36钢进行了考虑加载波形、加载速率和应力比影响的多工况单轴棘轮安定试验。结果表明：循环硬化速率随循环周次的增加快速下降,在低于某一值的循环应力作用下,应变将最终趋于棘轮饱和状态;正弦应力波比三角波更快地趋于安定,采用较低的加载速率可以加速材料趋向饱和棘轮状态;峰值应力固定不变时,棘轮应变对应力比历史无明显的记忆性;波形和加载速率对饱和棘轮应变的影响有限,饱和棘轮应变随着应力峰值的增加而增大。

英文摘要：

In order to provide experimental basis for evaluation of safety and life of semisubmersible, the shakedown behavior of DH36 steel used for semisubmersible was experimentally investigated under uniaxial cyclic loading at room temperature. The effects of loading rates, loading wave forms and stress ratio on the ratcheting of DH36 steel were analyzed. The experimental results show that the rate of cyclic hardening rapidly decreases with the increase of loading cycles, and the stress amplitude will becomes gradually saturated when the cyclic strain is below a certain value. A quick shakedown of ratchetting was observed from sine loading waves instead of triangular loading waves and lower loading rates could accelerate cyclic saturation. With the same peak stress, ratcheting strain presents no memorization on previous stress ratio in loading history. Loading wave forms and loading rates hardly influence the saturated ratcheting strain of the material and saturated ratcheting strain increases with the peak stress.