Core Viewpoint - The NTSB has found evidence of metal fatigue cracks in key components of the McDonnell Douglas MD-11 cargo plane that crashed, leading to a temporary grounding of all MD-11 aircraft by the FAA [1][1][1] Group 1: Incident Details - A UPS McDonnell Douglas MD-11 cargo plane crashed shortly after takeoff from Louisville International Airport in Kentucky on November 4, resulting in 14 fatalities [1] - The NTSB reported that most of the structure of the left engine pylon remained connected to the engine but had separated from the wing during the accident [1] Group 2: Investigation and Regulatory Response - Investigators discovered signs of metal fatigue cracks on the components connecting the engine to the wing [1] - The FAA issued a grounding order for all MD-11 aircraft on November 8 to establish new engine inspection procedures, with the investigation still ongoing [1]

Core Insights - The article discusses a viewpoint published in the journal "Nature Materials" by researchers from the Institute of Metal Research, Chinese Academy of Sciences, focusing on the challenges and strategies related to metal fatigue in extreme environments [1][2] - Metal fatigue is identified as a significant threat to the safety and reliability of critical sectors such as aerospace and energy equipment, despite nearly two centuries of research [1] Summary by Sections Research Background and Progress - The article systematically reviews the foundational research and advancements in the field of metal fatigue, emphasizing its status as a major challenge in materials science [1] - The unpredictable nature of fatigue behavior in metals under complex cyclic loads in extreme environments like deep space, deep sea, and nuclear energy is highlighted [1] Proposed Strategies - A dual-path strategy is proposed to overcome the bottlenecks in fatigue research: - Basic research should focus on exploring the fundamental fatigue characteristics of new materials and understanding their evolutionary laws and physical essence [2] - Engineering applications should concentrate on the fatigue damage behavior of traditional metals and related components in complex service environments, particularly under asymmetric or multi-axial complex fatigue loads and extreme conditions [2] Innovative Approaches - The integration of materials design, advanced manufacturing technologies, and artificial intelligence-assisted analysis is suggested to accelerate the development of high-performance anti-fatigue materials and promote paradigm shifts in extreme environment material design [2] - The research received funding from significant projects including the National Natural Science Foundation of China and the Chinese Academy of Sciences [2]

Core Insights - Metal fatigue is referred to as the "invisible killer" of engineering materials, posing potential threats to the safety and reliability of major engineering projects in fields such as aerospace, energy equipment, and transportation [1][5] - Chinese scientists have published a viewpoint article in the journal Nature Materials, emphasizing the need to break through current research bottlenecks in metal fatigue by advancing both fundamental research and engineering applications [1][4] Summary by Categories Fundamental Research - The article highlights the importance of exploring the fundamental fatigue characteristics of new materials, such as cross-scale multi-level structured metals, to reveal their evolution laws and physical essence [4] - A deeper understanding of the microscopic mechanisms of metal fatigue damage is essential for advancing the field [4] Engineering Applications - The focus is on studying the fatigue damage behavior of traditional metals and related components under complex service environments, particularly under asymmetric or multi-axial complex fatigue loads and extreme conditions (e.g., high temperature, low temperature, irradiation, corrosion, and their interactions) [4][5] - The article stresses the need for innovative integration of material design, advanced manufacturing technologies (such as additive manufacturing), high-precision characterization methods, and AI-assisted analysis to address these challenges [4] Challenges and Future Directions - Despite nearly two centuries of research on metal fatigue, it remains one of the most challenging topics in materials science, especially in extreme environments like deep space exploration and nuclear energy systems [5] - The rapid development of new material systems and the expansion of engineering application scenarios present new challenges to traditional fatigue design methods [5]