基于概率密度演化的风机基础疲劳可靠度计算

风机底部基础在风荷载作用下会产生疲劳破坏.为了研究风荷载作用下风机的疲劳可靠性，将随机脉动风荷载进行正交展开，用数论选点法和概率密度演化方法将展开的风荷载模型用于风机塔身的疲劳可靠度计算.采用推力系数法计算风荷载作用下风机基础较危险部位的应力时程，然后用雨流计数法统计该点的疲劳损伤，将其代入概率密度演化方程并通过差分计算可求得疲劳损伤的概率密度函数.通过累计疲劳损伤小于1的概率可求得危险部位的疲劳可靠度，也就是整个基础的疲劳可靠度.以一3 MW风机作为算例验证了本文方法的有效性，应用概率密度演化方法，可以精确地给出基础在风荷载作用下的疲劳可靠度，本文成果对于近似工况的风机基础疲劳可靠度的计算具有借鉴意义.

Fatigue Reliability Calculation of Wind Turbine Foundation Based on Probability Density Evolution

The bottom of wind turbine foundation will cause fatigue damage under wind loads. In order to study the fatigue reliability of wind turbines under wind loads, the random fluctuating wind loads were expanded orthogonally, and the expanded wind load model was used to calculate the fatigue reliability of the wind turbine tower using the number theory selection method and the probability density evolution method. The thrust coefficient method was used to calculate the stress time history of the dangerous part of the wind turbine foundation under the wind load, and then the fatigue damage of the point was calculated by the rain flow counting method, which is substituted into the probability density evolution equation. The probability density function of fatigue damage can be obtained by solving differential equation. By accumulating the probability of fatigue damage less than 1, the fatigue reliability of the dangerous parts can be obtained, that is, the fatigue reliability of the entire foundation. The effectiveness of the proposed method is verified by a 3 MW wind turbine. Using the probability density evolution method, the fatigue reliability of the foundation under wind load can be accurately given. The findings of this paper have reference significance for the calculation of fatigue reliability of wind turbine foundation under similar working conditions.