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本研究是针对大型可调螺距螺旋桨桨叶固定螺栓的疲劳寿命而进行的,着重对作用在螺栓上的应力及螺栓材料的疲劳强度进行了分析。为估算螺栓的工作应力,试验采用全尺度调距桨模型。相当于所估算的水动力和离心力的作用力分别固定地作用在模型桨叶及其叶边上(毂径437.5毫米)。由于螺栓强度似乎是按材料的疲劳强度及刚度而变化的,试验中就选用了不锈钢SUS44B、铜合金AMB102F及ABB-2等高度防蚀材料。对由这三种材料制成的全尺度螺栓头模型也作了试验,以估算其在直接应力状态下的疲劳强度。由上述试验可得到下列结论: (1)桨叶固定螺钉的工作载荷分布,与常规计算方法中的数值区别很大。 (2)压力面前边的螺栓载荷大于其它螺栓的载荷。 (3)当增加预紧力时,各个螺栓的分配载荷减少,趋近于一定值。 (4)为获得各个螺栓的最小工作载荷,有一个毂径、螺栓节径和叶根法兰厚度的最佳组合。 (5)三种材料的疲劳强度由高到低的次序为SUS44B、AMB102F、ABB-2。 (6)借助于工作载荷——预紧力图及螺栓耐久极限图,可找到最佳预紧力值。
This study was conducted on the fatigue life of large-scale adjustable pitch propeller blade fixing bolts, focusing on the stress on the bolt and the fatigue strength of the bolt material. To estimate the working stress of the bolt, a full-scale pitch propeller model was used. The forces corresponding to the hydrodynamic and centrifugal forces estimated, respectively, act fixedly on the model blade and its blade edge (hub diameter 437.5 mm). As the bolt strength seems to vary according to the fatigue strength and stiffness of the material, the test is made of stainless steel SUS44B, copper alloy AMB102F and ABB-2 and other highly corrosion-resistant materials. Full-scale bolt head models made of these three materials were also tested to assess their fatigue strength under direct stress conditions. From the above test, the following conclusions can be drawn: (1) The working load distribution of the blade fixing screw is very different from that in the conventional calculation method. (2) Bolt load in front of pressure surface is larger than load of other bolts. (3) When increasing the preload, the distribution of each bolt load decreases, approaching a certain value. (4) In order to obtain the minimum working load of each bolt, there is an optimum combination of hub diameter, bolt pitch diameter and root flange thickness. (5) The fatigue strength of the three materials from high to low order SUS44B, AMB102F, ABB-2. (6) With the help of the working load - preload diagram and bolt durability limit map, you can find the best preload value.