高温接触超高周微动疲劳试验系统研制

In aviation and aerospace, energy, traffic applications, many failures of some key metallic components in the contact condition at room temperature and high temperature are caused by fretting fatigue loads which occurs in Very High Cycle Fatigue regime. The failures often happen in the high frequency and small displacement contact cases, and the fatigue cycle life can be in the VHCF regime. For the project, the piezoelectric ceramic device is applied to obtain the high mechanical frequency test load for the fretting fatigue tests in order to develope the very high cycle fatigue fretting test system in room temperature and high temperature. The system will be used to test some aeronautical metals like titanium and high temperature alloys after developed to obtain the fatigue behaviors. The test results are compared with the traditional fretting fatigue test results, in order to verify the new experimental method. The fretting fatigue strength and fracture behaviors are also investigated for titanium and high temperature alloys in room temperature and high temperature. The failure section of the specimen are observed by SEM method in order to analysis the crack initiation and propagation in very high cycle fretting fatigue. The test system gives out a rapid way to study the fatigue behaviors and damage in very high cycle fretting fatigue. The test system is useful to choose the material for designing the metallic components in the fretting fatigue at room temperature and high temperature.

在航空、航天、交通、能源等行业的实际应用中，某些关键零部件在室温或高温下受到摩擦和疲劳载荷的作用引发微动疲劳断裂。这种失效通常发生在高频，小位移的接触条件下，在服役期内循环周数能达到超高周疲劳领域。本课题利用压电陶瓷的高频振动特性，采用加速的疲劳试验方法，研发室温和高温环境下超高周微动疲劳试验设备。利用本系统对钛合金和高温合金等金属材料进行超高周微动疲劳试验，并与传统试验方法的结果对比，检验加速的高温超高周微动疲劳试验方法。通过研发的试验设备，研究在室温和高温下的钛合金和高温合金的微动疲劳行为。采用电子扫描电镜对微动疲劳损伤部位和断口进行观察，分析室温和高温下金属材料超高周微动疲劳的损伤和裂纹的萌生机理和扩展路径。本课题研发的试验设备可用于快速获得高温下超高周微动疲劳载荷作用下材料的疲劳行为。

本课题利用压电陶瓷的高频振动特性，应用振动加速的疲劳试验技术（20kHz，），高温加热控制技术（20℃-1000℃），高频平均应力加载技术（-1-0.8），高频微动摩擦加载技术（0-2kN）研发高温环境下超高周微动疲劳试验设备（0-1e9）。在分别研制压电高频振动模块，高温加热模块，平均应力加载模块，微动摩擦加载模块并检测后，设计控制系统整合上述模块并研制出高温微动超高周疲劳试验系统。本课题研发的试验设备可用于快速获得高温下超高周微动疲劳载荷作用下材料的疲劳行为。利用研发系统对GCr15轴承钢，S31008不锈钢，TC17钛合金和GH80A高温合金等材料，进行平均应力、高温、微动摩擦下的超高周疲劳试验，检验加速的高温超高周微动疲劳试验方法，研究在室温或高温下的轴承钢、不锈钢，钛合金和高温合金的超高周疲劳和微动疲劳行为。采用白光干涉仪和电子扫描电镜分析微动摩擦损伤和疲劳损伤及断裂，分析室温和高温下金属材料超高周微动疲劳裂纹萌生机理和扩展路径。发现横向接触摩擦降低材料疲劳强度，磨损面面积与深度与疲劳寿命呈正比关系；对于TC17材料而言在不同应力比下频率效应不显著，超高周裂纹萌生区解理面比例随应力比升高而增加；高温超高周微动疲劳裂纹在磨损区边缘产生，局部复杂应力和微动疲劳损伤的共同作用降低超高周疲劳强度。