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过去,船用螺旋桨主要是以获得较高的推进效率为目的而进行设计的。近年来,螺旋桨叶片的疲劳断裂增加了。其原因在于近来发动机的大功率化和船舶的高速化,增加了桨叶的负荷。螺旋桨叶的疲劳强度已成为设计中的关键问题。要确定船用螺旋桨叶的疲劳设计标准,就必须确定螺旋桨材料的疲劳强度。但是,至今螺旋桨材料可用的疲劳强度数据不多,而且大部分数据是通过旋转弯曲疲劳试验获得的,其应力条件和实体螺旋桨叶的应力条件全完不同。一般情况下,疲劳强度受应力条件的影响很大,所以这些数据作为船用螺旋桨叶疲劳没计标准的依据是不充分的。因此,进行了Ni—Al青铜和锰黄铜两种螺旋桨材料的疲劳试验和裂纹扩展试验。精心地选择试验应力和环境条件,使其接近于实体螺旋桨的使用应力和环境条件。同时还研究了应力比、应力频率等参数时螺旋桨材料的疲劳强度和疲劳裂纹扩展特性的影响。
In the past, marine propellers were mainly designed for the purpose of obtaining higher propulsion efficiency. In recent years, the fatigue fracture of propeller blades has increased. The reason for this is that the recent increase in the engine and the speed of the ship have increased the load on the blades. The fatigue strength of propeller blades has become a key issue in design. To determine the fatigue design criteria for marine propeller blades, it is necessary to determine the fatigue strength of the propeller material. However, the available fatigue strength data of propeller materials so far are few, and most of the data is obtained by rotational bending fatigue test, the stress conditions of which are different from the stress conditions of the solid propeller blades. Under normal circumstances, the fatigue strength is greatly affected by the stress conditions, so these data as a marine propeller blade fatigue is not based on the standard is not sufficient. Therefore, the fatigue tests and crack propagation tests of two kinds of propeller materials, Ni-Al bronze and manganese brass, were carried out. Carefully select the test stress and environmental conditions, make it close to the physical propeller stress and environmental conditions. At the same time, the effects of stress ratio, stress frequency and other parameters on the fatigue strength and fatigue crack propagation of propeller materials were also studied.