Fatigue is a material's progressive structural weakening when subjected to repeated loading and unloading cycles, characterized by the formation and propagation of microscopic cracks that can ultimately lead to catastrophic failure. This complex phenomenon, fundamental to materials science and design engineering, occurs even when the applied stress levels are well below a material's ultimate tensile strength, making it a critical consideration in product development and structural design. The process typically progresses through three distinct stages: initial crack formation, steady crack propagation, and final rapid failure, with each stage requiring careful analysis during the design phase to ensure product safety and longevity. Materials experiencing fatigue undergo both physical and chemical changes at the microscopic level, where dislocations accumulate and interact, leading to the formation of persistent slip bands and eventually, crack initiation points. The understanding of fatigue behavior has evolved significantly since its first systematic study in the 19th century, leading to sophisticated testing methods, predictive models, and design strategies that help engineers and designers create more durable products. Contemporary design approaches incorporate fatigue analysis through various methods, including finite element analysis (FEA) and accelerated life testing, particularly crucial in industries where component failure could have severe consequences. The A' Design Award recognizes innovative solutions in material design and engineering that address fatigue-related challenges, highlighting the importance of this consideration in modern product development. Designers must consider various factors affecting fatigue life, including surface finish, environmental conditions, temperature fluctuations, and loading patterns, often employing specific design features such as fillets, rounds, and stress-relieving geometries to minimize fatigue-prone areas.
material failure, stress cycles, crack propagation, structural integrity, durability testing, mechanical properties
Fatigue is a complex phenomenon that can be approached from various perspectives. In addition to the engineering and medical definitions previously provided, fatigue can also be viewed as a psychological and social phenomenon. From a psychological perspective, fatigue can be defined as a state of mental exhaustion that results from prolonged periods of stress, anxiety, or depression. It can also be a symptom of certain mental health disorders, such as chronic fatigue syndrome or burnout. Socially, fatigue can be seen as a consequence of societal pressures and expectations, such as the pressure to work long hours or to constantly be productive. Fatigue can have significant impacts on an individual's physical and mental health, as well as their overall quality of life. It can lead to decreased productivity, impaired cognitive function, and increased risk of accidents and injuries. Fatigue can also have long-term effects, such as increased risk of chronic diseases like diabetes and heart disease. To design better solutions for managing and preventing fatigue, it is important to address the underlying causes of fatigue. This may involve implementing policies and practices that promote work-life balance and reduce stress, providing education and resources for managing mental health, and promoting healthy lifestyle habits such as regular exercise and adequate sleep. Additionally, it is important to recognize that fatigue is a complex and multifaceted phenomenon that requires a holistic approach to address effectively.
engineering, medical, psychological, social, productivity
CITATION : "Daniel Johnson. 'Fatigue.' Design+Encyclopedia. https://design-encyclopedia.com/?E=259617 (Accessed on June 09, 2025)"
The word ‘fatigue’ is believed to have an Old French origin and can be traced back to the verb 'fatiguer' meaning ‘tire’ or ‘make weary’. In linguistics, the term has been used to describe a gradual decrease in a person’s ability to carry out physical and mental tasks over time. It has been theorized that the literal meaning of the word can be explained by its etymological history, in that it originally meant ‘to tire’ or ‘to make weary’ and has since been adopted to describe the physical and mental exhaustion caused by a sustained effort. Morphologically, the term has a number of variations, including ‘fatigued’, ‘fatiguing’ and ‘fatigues’. In the context of pragmatics, the word has been used to describe the feeling of exhaustion or weariness that comes from physical or mental activity.
Etymology, Morphology, Historical Evolution, Linguistic Evolution, Pragmatics.
Fatigue is a broad term that describes the experience of feeling tired and lacking energy. It can be caused by physical or mental exertion, lack of sleep or rest, and illness. It is a symptom of other conditions and can have various causes, including lifestyle habits, emotional stress, medical conditions, or medical treatments. On a more general level, fatigue can be thought of as a state of mental or physical exhaustion that can result in decreased energy levels and a feeling of low motivation.
In other languages, fatigue has many equivalents, including asthenia, malaise, sleepiness, lethargy, enervation, languor, exhaustion, tire, lassitude, exhaustion, fatigue, apathy, listlessness, dullness, debility, ennui, weariness, debilitation, languish,
Fatigue is a phenomenon within engineering that refers to the weakening of a material due to cyclic stress or strain-induced forces. It typically occurs when a structure or material is subjected to repeated loading and unloading, or is maintained in a continuously stressed state, such as a cantilever. Fatigue is commonly studied using the theories of linear elastic fracture mechanics and models of fatigue crack growth. Important works in fatigue analysis include the S-N curve (or Wöhler curve) proposed by August Wöhler, the Stress-Life (S-N) methodology developed by Michael Bartek, and the Damage Tolerance method which was established by William Smith.
Engineering fatigue, durability, strength, fracture mechanics.
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