Fatigue Crack Growth in Complex Residual Stress Fields due to Surface Treatment and Foreign Object Damage under Simulated Flight Cycles

模拟飞行周期下表面处理和异物损坏导致复杂残余应力场中的疲劳裂纹扩展

• 批准号: EP/E05658X/1
• 负责人: Jie Tong
• 金额: $ 35.42万
• 依托单位: University of Portsmouth
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE05658X%2F1
• 关键词: Fatigue; Crack; Growth; Complex; Residual

Damage tolerance approach has been employed in the assessment of structural integrity of critical aeroengine components, where a conjoint action of high cycle fatigue (HCF) and low cycle fatigue (LCF) often occurs. The low cycles are identified with the period between takeoff and landing, while high cycles are a result of inflight aerodynamically induced vibrations. It is imperative that fatigue integrity assessment of aero engine components is carried out under the combined HCF and LCF loading conditions to simulate in service loading conditions. The Portsmouth team is one of the leading exponents in the study of fatigue crack growth under combined HCF and LCF loading conditions, in close collaboration with Rolls-Royce, QinetiQ and US Air Force. In recent years, foreign object damage (FOD) has been identified as one of the main life limiting factors for turbine blades. Impacts due to small hard particle ingestion during takeoff and landing can reach velocities up to 500 m/s and cause severe damage to aerofoils in aero engines. Damage due to FOD is estimated at 4 billion US dollars annually for the aeroengine industry. Reduction in fatigue strength due to projectile impacts has been studied exclusively for HCF loading conditions, mainly in the US. The first study on the effects of combined HCF and LCF under FOD on crack growth was carried out at Portsmouth (GR/R79258). Significant progress has been made in the assessment of residual stresses and their effects on crack driving force. Specifically, tensile residual stresses were found in the vicinity of the crater root made by FOD; and the depth of these tensile stresses can reach to more than 0.2 mm. Upon application of a combined HCF and LCF loading block, the local stress ratios were elevated which prompted early crack growth preferentially from these sites, resulting in significantly increased crack growth rates, as compared with either HCF or LCF loading alone. For aerofoils, the accelerated crack growth was only revealed when the residual stresses due to FOD were considered in the calculation of crack driving force. The leading edge of aerofoils is particularly susceptible to FOD. In recent years, the introduction of advanced surface treatments, such as laser shock peening (LSP) or low plasticity burnishing (LPB), have significantly improved the fatigue strength and crack growth resistance. Such treatments aim at producing significant compressive residual stresses along the leading edge of fan blades, such that the critical region of the blades becomes considerably more damage tolerant to avoid catastrophic failures. Typically, the depths of the compressive residual stresses can be achieved using LSP or LPB are 1-2 mm, as opposed to ~0.2 mm by conventional shot peening. A fundamental understanding of fatigue damage process due to FOD in the presence of LSP/LSB is vital, if they are to be utilized to the full potential in enhancing fatigue resistance of fracture critical components, particularly in the event of FOD.The proposed research aims at developing a predictive model for fatigue crack onset and early growth under simulated flight cycles. The model will take into account of the effect of residual stresses due to surface treatment as well as FOD. Dynamic impact will be modelled and the stabilised and the relaxation of residual stresses will be studied using the finite element analysis and validated by the X-ray diffraction method. The effectiveness of the surface treatment will be evaluated and the model will be validated using simulated inflight test data. Such studies are critical if onset and early crack growth due to FOD is to be modelled accurately, so that predictive tools may be made available to aeroengine industry for FOD-affected fatigue integrity. The work contributes to the safe design and life management of critical aeroengine components such as turbine blades.

损伤耐受方法已用于评估关键航空发动机组件的结构完整性，其中经常发生高循环疲劳（HCF）和低周期疲劳（LCF）的联合作用。低循环是在起飞和着陆之间的周期中确定的，而高循环是信沟空气动力学诱导的振动的结果。必须在HCF和LCF加载条件下对Aero发动机组件的疲劳完整性评估进行模拟，以模拟服务加载条件。朴茨茅斯团队是研究在HCF和LCF加载条件下研究疲劳裂纹增长的主要指数之一，与Rolls-Royce，Qinetiq和美国空军密切合作。近年来，异物损害（FOD）被确定为涡轮叶片的主要生命限制因素之一。起飞和着陆期间的小颗粒摄入造成的影响可能达到高达500 m/s的速度，并对航空发动机的气管造成严重损坏。 AeroEngine行业每年估计由于FOD造成的损失估计为40亿美元。仅针对HCF加载条件（主要在美国）研究了由于弹丸撞击引起的疲劳强度的降低。在朴次茅斯（GR/R79258）进行了关于FOD在FOD下联合HCF和LCF对裂纹生长的影响的第一项研究。在评估残余应力及其对裂纹驱动力的影响方面取得了重大进展。具体而言，在FOD制成的火山口根附近发现了拉伸残留应力。这些拉伸应力的深度可能达到0.2 mm以上。在应用HCF和LCF加载块合并后，将局部应力比升高，从而使这些位点的早期裂纹优先生长，从而导致裂纹的生长速率显着提高，而与HCF或LCF载荷相比。对于气管，只有在裂纹驱动力计算中考虑了由于FOD引起的残留应力时，才揭示了加速的裂纹生长。航空翼的前缘特别容易受到FOD的影响。近年来，引入晚期表面处理，例如激光减震（LSP）或低可塑性耐磨（LPB），已显着提高了疲劳强度和裂纹耐药性。这种处理旨在沿风扇叶片的前缘产生明显的压缩残留应力，以使叶片的临界区域变得更加耐受损伤，以避免灾难性的失败。通常，使用LSP或LPB可以实现压缩残留应力的深度为1-2毫米，而不是传统的射击态度约为0.2 mm。如果要在LSP/LSB的存在下对FOD引起的疲劳损伤过程的基本理解至关重要，如果将它们充分利用来增强裂缝关键组件的疲劳抗性，尤其是在FOD的情况下，尤其是在FOD的情况下。该模型将考虑由于表面处理和FOD而导致的残留应力的影响。将建模动态影响，并使用有限元分析研究稳定和残留应力的松弛，并通过X射线衍射方法验证。将评估表面处理的有效性，并将使用模拟的运输测试数据验证该模型。如果要准确地对FOD引起的发作和早期裂纹生长，则此类研究至关重要，因此可以向Aeroengine行业提供预测工具，以实现受FOD影响的疲劳完整性。这项工作为关键航空发动机组件（例如涡轮刀片）的安全设计和生活管理做出了贡献。

项目成果

Residual stress fields after FOD impact on flat and aerofoil-shaped leading edges

• DOI: 10.1016/j.mechmat.2012.08.007
• 发表时间: 2012-12
• 期刊: Mechanics of Materials
• 影响因子: 3.9
• 作者: P. Frankel;P. Withers;M. Preuss;H.T. Wang;J. Tong;D. Rugg

Residual stresses due to foreign object damage in laser-shock peened aerofoils: Simulation and measurement

• DOI: 10.1016/j.mechmat.2014.12.001
• 发表时间: 2015-03-01
• 期刊: MECHANICS OF MATERIALS
• 影响因子: 3.9
• 作者: Lin, B.;Zabeen, S.;Withers, P. J.
• 通讯作者: Withers, P. J.

Fatigue crack growth in laser-shock-peened Ti-6Al-4V aerofoil specimens due to foreign object damage

• DOI: 10.1016/j.ijfatigue.2013.10.001
• 发表时间: 2014-02-01
• 期刊: INTERNATIONAL JOURNAL OF FATIGUE
• 影响因子: 6
• 作者: Lin, B.;Lupton, C.;Tong, J.
• 通讯作者: Tong, J.

Evolution of a laser shock peened residual stress field locally with foreign object damage and subsequent fatigue crack growth

• DOI: 10.1016/j.actamat.2014.09.032
• 发表时间: 2015-01-15
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: Zabeen, S.;Preuss, M.;Withers, P. J.
• 通讯作者: Withers, P. J.

Ratchetting strain as a driving force for fatigue crack growth

• DOI: 10.1016/j.ijfatigue.2012.01.003
• 发表时间: 2013
• 期刊: International Journal of Fatigue
• 影响因子: 6
• 作者: J. Tong;Liguo Zhao;B. Lin