剪切载荷下航空发动机螺栓松动行为及其临界值的数值模拟研究

为研究剪切载荷下螺栓连接结构松动行为,首先建立了多种螺栓连接结构精细有限元模型,进行了全六面体网格划分,并运用Yamamoto方法和Spowith方法验证了模型的有效性,然后通过多种模型仿真对比,分阶段首次研究了不同影响因素下塑性松动期、旋转松动期内以及整个松动期内的螺栓松动行为及其重要临界值.结果表明:剪切载荷下螺栓...

Numerical Simulation of Bolt Loosening Behavior and Critical Value of Aeroengine under Shear Load

In order to study the loosening behavior of bolted connections under shear loa-d, a variety of fine finite element models of bolted connections were established, and t-he full hexahedral mesh was generated. The effectiveness of the models was verified by Yamamoto method and spowth method. Then, through the simulation comparison of va-rious models, the plastic loosening period, deformation time and deformation time under different influence factors were studied by stages for the first time The behavior of bolt loosening in the rotation loosening period and the whole loosening period was analyzed, and some important critical values in the loosening period were analyzed for the first time. The results show that when the ratio of initial pre tightening stress to yield stress is between 1.32 and 1.44, loosening is the least likely to occur; When the ratio of the residual preload to the initial preload is 0.84, the critical value of the plastic loosening stage and the rotational loosening stage is from the plastic loosening stage to the rotat- ional loosening stage; There is a critical value of the initial preload. When the initial p-reload is less than this critical value, the loosening begins in the rotational loosening p-eriod, and vice versa; When the initial pre tightening stress of bolt is less than the yiel-d stress of material, there are two critical values of shear load amplitude. When the ini-tial pre- tightening stress is greater than the first critical value, bolt loosening will occur, on the contrary, it will not occur. When the initial pre tightening stress is greater than the se-cond critical value, the loosening process goes through the plastic loosening peri-od and the rotation loosening period, on the contrary, it only goes through the rotation looseni-ng period; When the initial pre tightening stress of bolt is greater than the yiel-d stress of material, the larger the shear load amplitude is, the easier the bolt loosens. The chan-ge rate of bolt looseness is not monotonous, and there is a sudden change at a certain amplitude; There is a range of friction coefficient between the thread engagement surfac-es and the loading frequency range of shear load, which makes bolt looseness the least likely to occur. The larger the eccentric distance is, the easier the bolt looseness is; The results show that the alternate change of slip adhesive contact state is the main factor of bolt loosening, and the thread contact surface enters relative slip state before the bolt head contact surface. It has a certain guiding significance for understanding the bolt lo-osening mechanism under shear load and optimizing the anti loosening desig-n.