Efficient bolted joint design is an essential part of designing the minimum weight aerospace structures, since structural failures usually occur at connections and interface. A comprehensive numerical study of three-d...Efficient bolted joint design is an essential part of designing the minimum weight aerospace structures, since structural failures usually occur at connections and interface. A comprehensive numerical study of three-dimensional(3D) stress variations is prohibitively expensive for a large-scale structure where hundreds of bolts can be present. In this work, the hybrid composite-to-metal bolted connections used in the upper stage of European Ariane 5ME rocket are analyzed using the global-local finite element(FE) approach which involves an approximate analysis of the whole structure followed by a detailed analysis of a significantly smaller region of interest. We calculate the Tsai-Wu failure index and the margin of safety using the stresses obtained from ABAQUS. We find that the composite part of a hybrid bolted connection is prone to failure compared to the metal part. We determine the bolt preload based on the clamp-up load calculated using a maximum preload to make the composite part safe. We conclude that the unsuitable bolt preload may cause the failure of the composite part due to the high stress concentration in the vicinity of the bolt. The global-local analysis provides an efficient computational tool for enhancing 3D stress analysis in the highly loaded region.展开更多
目的:以定量方式分析全球网络新闻语料库(NOW)中与中医药相关的英语新闻文本,探讨中医药文化媒介形象。方法:检索NOW中与中医药相关的英语新闻文本,以字符串查询方式进行检索,分别设定“traditional Chinese medicine(中医)”“acupunct...目的:以定量方式分析全球网络新闻语料库(NOW)中与中医药相关的英语新闻文本,探讨中医药文化媒介形象。方法:检索NOW中与中医药相关的英语新闻文本,以字符串查询方式进行检索,分别设定“traditional Chinese medicine(中医)”“acupuncture(针灸)”“Chinese herbal(中药)”为检索词,设定时间范围为2020年1月1日至2024年4月18日,分别获得含有上述3组检索词的文本,分别为2 535、6 157、327条。通过特征词提取分析文本关键词及其分布特征;对语料的情感向度和主客观度进行分析,初步了解近年来中医药英语新闻传播现状;用潜在狄利克雷分布(LDA)模型抽取新闻主题。结果:词频分析中health(健康)、pain(疼痛)等高频词反映了海内外民众对中医药基本诉求;文本分析的整体情感倾向值为0.099、主客观性倾向值为0.413,考虑医疗类新闻的特殊性,整体呈现积极且客观的传播态势;LDA主题建模获得“卫生服务相关”“体验描述相关”“病症与具体诊疗相关”3个主题,其中卫生服务相关话题在国际新闻中占有相当大的比例,个人体验和具体诊疗相关话题作为中医文化的核心传播点,通过真实故事和医疗实践,具有一定的发展潜力。结论:中医药文化在国际媒体上展现出较为积极客观的媒介形象,中医药卫生服务相关话题在国际新闻传播中占据重要地位,其影响力随时间推移逐渐增强;体验描述和病症治疗作为中医药文化传播的2个关键方面,分别通过个人体验和具体诊疗实践,展现出持续的发展潜力和传播热点。展开更多
基金Project(282522)supported by the European Union's Research and Innovation Funding Programme
文摘Efficient bolted joint design is an essential part of designing the minimum weight aerospace structures, since structural failures usually occur at connections and interface. A comprehensive numerical study of three-dimensional(3D) stress variations is prohibitively expensive for a large-scale structure where hundreds of bolts can be present. In this work, the hybrid composite-to-metal bolted connections used in the upper stage of European Ariane 5ME rocket are analyzed using the global-local finite element(FE) approach which involves an approximate analysis of the whole structure followed by a detailed analysis of a significantly smaller region of interest. We calculate the Tsai-Wu failure index and the margin of safety using the stresses obtained from ABAQUS. We find that the composite part of a hybrid bolted connection is prone to failure compared to the metal part. We determine the bolt preload based on the clamp-up load calculated using a maximum preload to make the composite part safe. We conclude that the unsuitable bolt preload may cause the failure of the composite part due to the high stress concentration in the vicinity of the bolt. The global-local analysis provides an efficient computational tool for enhancing 3D stress analysis in the highly loaded region.
