Abstract Controllable pitch propeller ( C P P ) is a versatile solution to fulfill high hydrodynamic efficiency and low environmental emissions for different operative scenario of a seagoing vessel because it allows the most suitable matching between the prime mover and the propulsor. In contrast, this configuration is a complex mechanical system and, therefore, it may be subjected to a wide range of failures related to the automation system of blade pitch variation, strength and fatigue life of the various mechanical components. This paper focuses on blade fretting, that is a small amplitude vibratory motion of the blade with respect to its lodging in the hub; this motion causes the wear between the contact surfaces, reducing the fatigue life of the material as well. The prediction of this phenomenon in realistic sailing conditions during the design stage is of utmost importance to prevent damages and failures during ship operations, by developing suitable control laws. The analysis is based on single blade loads measurements, obtained with a novel set–up installed on a free running maneuvering, self–propelled model of a twin screw ship. The experimental campaign was aimed to characterize single blade loads during different ship operations, with particular effort on maneuvering (standard and safety maneuvers) and motion in waves. This paper is focused on the straight ahead motions as well as steady and transient phases of the turning circle maneuver, performed at different rudder angles and speeds. The results show that the onset of fretting is sensitive to the wake evolution, and, hence, to the rudder angles; moreover, consistently to the asymmetric behavior of the propellers, fretting is differently triggered on the port and starboard propeller.

中文翻译：

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实际工况下单桨叶载荷测量分析船用螺旋桨微动开始。直行和转圈机动

摘要 可调螺距螺旋桨 (CPP) 是一种通用的解决方案，可以在不同的海船作业场景中实现高水动力效率和低环境排放，因为它可以实现原动机和推进器之间最合适的匹配。相比之下，这种配置是一个复杂的机械系统，因此，它可能会遭受与叶片桨距变化、强度和各种机械部件的疲劳寿命的自动化系统相关的各种故障。本文重点研究叶片微动，即叶片相对于其在轮毂中的位置的小幅度振动运动；这种运动会导致接触面之间的磨损，从而降低材料的疲劳寿命。在设计阶段预测现实航行条件下的这种现象对于通过制定合适的控制法则来防止船舶运营期间的损坏和故障至关重要。该分析基于单叶片载荷测量，该测量是通过安装在双螺杆船的自由机动自航模型上的新型装置获得的。实验活动旨在表征不同船舶操作期间的单个叶片载荷，特别是操纵（标准和安全操纵）和波浪运动。本文重点介绍在不同舵角和速度下进行的直线前进运动以及转弯圆机动的稳定和瞬态阶段。结果表明，微动的开始对尾流演化很敏感，因此对舵角也很敏感；