圆弧形榫连结构高/低循环疲劳试验研究

针对大涵道比涡扇发动机风扇叶/盘榫连结构,提出了缩比为1:2.5的圆弧形榫连结构疲劳试验方案,分别设计了高、低循环疲劳试验件及其夹具,并进行了疲劳试验验证.为了简化试验,低循环疲劳试验采用拉-拉循环加载试验方案,高循环疲劳试验则通过测定试验件1阶弯曲振型下的疲劳极限来实现.在低循环疲劳试验中,试验件结构的裂纹萌生寿命远大于60000次循环,具备足够的抗低循环疲劳能力;在高循环疲劳试验中,试验件结构在设计目标为207 MPa下通过了3×107循环的疲劳寿命考核.结果表明:圆弧形榫连结构的高、低循环疲劳试验装置设计合理,实现了预期的试验目标;所设计的圆弧形榫连结构具有良好的抗疲劳性能,满足大涵道比发动机的寿命设计目标;失效形式为由微动磨损引起的疲劳裂纹萌生和扩展.

Investigation of High and Low Cycle Fatigue Experiment for a Curved Dovetail Assembly

Focused on curved dovetail assemblies used in high bypass-ratio turbofan engines, a design concept with scale-reduced ratio of 1:2.5 for curved dovetail assemblies was proposed, in which both HCF and LCF specimens and its corresponding experimental fixtures were designed and machined to carry out the verification tests. In order to simplify the tests, tensile-tensile cyclic loading tests were conducted to evaluate the LCF properties and by measuring 1 stage curve vibration of the specimen, the fatigue limit was achieved in HCF tests. During LCF tests, the specimen had adequate capability of LCF resistance that the crack initiation life was far more than 60000 cycles, while the specimen passed the test of 3×107 cycles under stress level of 207MPa in HCF tests. The results indicate that the presented experimental concept is so feasible that achievies the design goals, and the curved dovetail assemblies, in which the failure mode of fatigue crack initiation and growth induced by fretting wear, are capable of meeting the requirement of high anti-fatigue properties for high bypass-ratio turbofan engines.