Failures due to high-cycle fatigue have led to a high cost in aerospace engineering over the past few decades.In this paper,the experimental results of the fatigue behavior of compressor blade specimen subjected to re...Failures due to high-cycle fatigue have led to a high cost in aerospace engineering over the past few decades.In this paper,the experimental results of the fatigue behavior of compressor blade specimen subjected to resonance and the effects of a damping hard coating on relieving the fatigue progress are presented.The crack initiation and propagation processes were observed under resonance of the first bending mode by using the resonant frequencies as the indicator.Significant nonlinear features were observed in the spectrum of the blade with a fatigue crack.The finite element model considering the breathing crack was established with nonlinear contact based on the crack localization and size,which was obtained by ultrasonic phased array technology.The simulation results of the vibration behavior of the cracked blade were obtained and consistent with the experimental results.A NiCrAlY coating was deposited on the blade,and increases in the fatigue life were observed under the same condition.The results of this paper can help to better understand the fatigue of a compressor blade subjected to resonance and provide a preference for the application of a damping hard coating on compressor blades.展开更多
北京紫竹院公园全园占地45.73 hm2,自1971年以来先后引进多种竹,现有室外观赏竹种多达12属44种,是园内主要的造景植物。近年来,竹蚜的发生蔓延不但影响竹子生长发育,而且导致叶片失绿变黄、出现锈斑、掉落的现象,严重时甚至会引起个体...北京紫竹院公园全园占地45.73 hm2,自1971年以来先后引进多种竹,现有室外观赏竹种多达12属44种,是园内主要的造景植物。近年来,竹蚜的发生蔓延不但影响竹子生长发育,而且导致叶片失绿变黄、出现锈斑、掉落的现象,严重时甚至会引起个体植株死亡,从而使竹林大片衰弱,影响景观效果。基于以上原因,通过定点、定期调查并进行分析,研究探索了北京紫竹院公园竹类2种蚜虫的为害情况及其发生规律:竹梢凸唇斑蚜在园内对竹类危害比较普遍,对刚竹属的生长发育造成较为严重的危害,主要集中于竹叶背部近叶柄或叶尖部位以及笋尖和嫩梢部位刺吸为害。1 a 12个月均有为害现象,5月和10月是该蚜为害的2个峰值。竹纵斑蚜在园内主要对斑竹的生长发育造成严重危害,主要聚集在竹叶背部中端部位,7月是该蚜为害高峰期,冬季活跃性差,有越冬阶段,以卵越冬。结论说明环境条件是影响2种蚜虫生活周期和数量变化的一个生态因子,对于2种害虫的预测预报应该实时关注北京市气温以及留意公园内的小气候,并在竹子生长周期内要做到科学管理,包括保持适当的竹林栽植密度、合理施用生物药剂、保护和利用自有天敌昆虫、人为释放天敌昆虫进行补充等,旨在蚜虫发生为害高峰期前采取有效的低公害防治措施。展开更多
基金Project(DUT20RC(3)014)supported by the Fundamental Research Funds for the Central Universities,China,Project(VCAME201801)supported by Key Laboratory of Vibration and Control of Aero-Propulsion System(Ministry of Education),ChinaProject(11472068)supported by the National Natural Science Foundation of China。
文摘Failures due to high-cycle fatigue have led to a high cost in aerospace engineering over the past few decades.In this paper,the experimental results of the fatigue behavior of compressor blade specimen subjected to resonance and the effects of a damping hard coating on relieving the fatigue progress are presented.The crack initiation and propagation processes were observed under resonance of the first bending mode by using the resonant frequencies as the indicator.Significant nonlinear features were observed in the spectrum of the blade with a fatigue crack.The finite element model considering the breathing crack was established with nonlinear contact based on the crack localization and size,which was obtained by ultrasonic phased array technology.The simulation results of the vibration behavior of the cracked blade were obtained and consistent with the experimental results.A NiCrAlY coating was deposited on the blade,and increases in the fatigue life were observed under the same condition.The results of this paper can help to better understand the fatigue of a compressor blade subjected to resonance and provide a preference for the application of a damping hard coating on compressor blades.
文摘北京紫竹院公园全园占地45.73 hm2,自1971年以来先后引进多种竹,现有室外观赏竹种多达12属44种,是园内主要的造景植物。近年来,竹蚜的发生蔓延不但影响竹子生长发育,而且导致叶片失绿变黄、出现锈斑、掉落的现象,严重时甚至会引起个体植株死亡,从而使竹林大片衰弱,影响景观效果。基于以上原因,通过定点、定期调查并进行分析,研究探索了北京紫竹院公园竹类2种蚜虫的为害情况及其发生规律:竹梢凸唇斑蚜在园内对竹类危害比较普遍,对刚竹属的生长发育造成较为严重的危害,主要集中于竹叶背部近叶柄或叶尖部位以及笋尖和嫩梢部位刺吸为害。1 a 12个月均有为害现象,5月和10月是该蚜为害的2个峰值。竹纵斑蚜在园内主要对斑竹的生长发育造成严重危害,主要聚集在竹叶背部中端部位,7月是该蚜为害高峰期,冬季活跃性差,有越冬阶段,以卵越冬。结论说明环境条件是影响2种蚜虫生活周期和数量变化的一个生态因子,对于2种害虫的预测预报应该实时关注北京市气温以及留意公园内的小气候,并在竹子生长周期内要做到科学管理,包括保持适当的竹林栽植密度、合理施用生物药剂、保护和利用自有天敌昆虫、人为释放天敌昆虫进行补充等,旨在蚜虫发生为害高峰期前采取有效的低公害防治措施。
