In modern industry, fasteners are a key basic component, and their performance and quality play a crucial role in the safety and reliability of the entire equipment and system. With the continuous progress of science and technology, the research of fastener fatigue life and reliability becomes more and more important. In this paper, the fatigue life and reliability of fasteners will be studied in order to improve the service life and safety of fasteners.
First, fatigue life theory
Fatigue life refers to the total number of cycles experienced by fasteners from the beginning of loading to fracture under the action of alternating loads. Fatigue life is affected by many factors, such as material, size, surface treatment, stress level, etc. The fatigue life theory is the basis of studying the fatigue behavior of fasteners, which includes three basic stages: fatigue crack initiation, crack propagation and fracture.
The fatigue crack initiation stage is the process of microdefects gradually gathering and expanding under the action of alternating load. These microscopic defects include voids, scratches and inclusions inside the material. When these defects aggregate to a certain extent, they form macroscopic cracks.
The crack propagation stage is the process of crack propagation under the action of stress. When the crack is formed, with the cyclic action of the load, the crack will gradually expand. The crack propagation rate is affected by many factors, such as stress intensity factor, material damping, environmental medium, etc.
The fracture stage is the process in which the whole fastener breaks. When the crack extends to a certain extent, the fastener will break as a whole in an instant. The fracture mode may be ductile fracture or brittle fracture, the former is obvious plastic deformation of the material before the fracture, the latter is no obvious plastic deformation of the material before the fracture.
- Reliability assessment
The reliability evaluation of fasteners is to evaluate their reliability in actual use through comprehensive analysis of its failure rate, failure rate and maintenance costs. The failure rate is the ratio of the number of parts that fail per unit time to the total number. The failure rate is the probability of a component failing within a specified period of time. Maintenance costs refer to the costs required to repair and replace parts.
When assessing the reliability of fasteners, the following factors should be considered:
Material properties: Different materials have different mechanical properties and fatigue characteristics, which directly affect the reliability of fasteners.
Manufacturing process: The manufacturing process has an important impact on the accuracy, surface quality and internal defects of fasteners, which are directly related to the reliability of fasteners.
Stress level: Stress level is one of the important factors affecting the reliability of fasteners. Too high stress is easy to cause fatigue fracture of components, while too low stress may cause creep failure of components under low cycle times.
Environmental factors: Environmental factors such as temperature, humidity, corrosive media, etc., have a great impact on the reliability of fasteners. For example, fasteners may suffer corrosion fatigue failure in humid environments.
Maintenance: Regular maintenance and maintenance can effectively extend the service life of fasteners. Proper maintenance can reduce the failure rate of fasteners and improve their reliability.
By studying the fatigue life and reliability of fasteners, we can draw the following conclusions:
The fatigue life theory is the basis of studying the fatigue behavior of fasteners, including three basic stages: fatigue crack initiation, crack propagation and fracture. The factors affecting fatigue life include material, size, surface treatment, stress level and so on.
When evaluating the reliability of fasteners, indicators such as failure rate, failure rate and maintenance cost should be considered comprehensively to evaluate their reliability in actual use.
Factors such as material properties, manufacturing processes, stress levels, environmental factors and maintenance have an important impact on the reliability of fasteners. In the design and use process, we should pay attention to these factors and take corresponding measures to improve the reliability of fasteners.
Looking to the future, with the continuous progress of science and technology and the continuous improvement of safety and reliability requirements in the industrial field, the research on the fatigue life and reliability of fasteners will be more in-depth and detailed. Future research will pay more attention to the application of cutting-edge technologies such as material genomics, digital twin technology, and artificial intelligence in fastener design and manufacturing to achieve more accurate prediction and optimization design, and improve the performance and reliability of fasteners. At the same time, with the rapid development of industry 4.0 and intelligent manufacturing, higher requirements will be put forward for quality control and supply chain management in the manufacturing process of fasteners to achieve reliability and performance management throughout the life cycle.
