As the core component of locomotive power system, the fatigue life and reliability of locomotive crankshaft forging are very important to the safety and performance of locomotive. Fatigue life refers to the time during which the forgings can maintain a certain level of performance under the action of alternating stress or strain. Reliability refers to the ability of forgings to complete predetermined functions under certain conditions. This paper will investigate the fatigue life and reliability of locomotive crankshaft forgings.
Influencing factors of fatigue life
Material properties: Tensile strength, yield point, elongation and other mechanical properties of materials have significant effects on fatigue life. High strength, high toughness, corrosion resistant materials can improve the fatigue life of crankshaft forgings.
Manufacturing process: Reasonable forging process, heat treatment process and fine processing process can improve the structure and performance of the material, thereby improving the fatigue life.
Stress level: The alternating stress level of crankshaft forgings directly affects its fatigue life. Lower stress levels help extend fatigue life, while higher stress levels shorten it.
Working environment: working environment temperature, humidity, corrosive media, etc., have a certain impact on the fatigue life of crankshaft forgings. A good working environment can extend the fatigue life, otherwise it will shorten the fatigue life.
Reliability analysis method
Probabilistic method: Using probabilistic statistical method, the reliability of crankshaft forgings is evaluated and predicted. By collecting large amounts of data, failure modes and mechanisms are analyzed to assess the impact of different factors on reliability.
Failure Mode and Effect Analysis (FMEA) : FMEA is a preventive reliability analysis method, through the analysis of various failure modes of crankshaft forgings, to find out the potential failure causes, and put forward the corresponding improvement measures.
Reliability block diagram: A reliability block diagram is a graphical tool used to represent the interrelationships and dependencies between the various components of a system. By constructing the reliability block diagram of crankshaft forgings, the contribution and influence of each part to the overall reliability can be clarified.
Measures to improve fatigue life and reliability
Material selection and optimization: Select materials with excellent mechanical properties and anti-fatigue properties, such as high-strength alloy steel. At the same time, the chemical composition and organizational structure of the material are optimized to further improve its fatigue life and reliability.
Process optimization: The manufacturing process is optimized to ensure that the crankshaft forgings can obtain uniform organizational structure and excellent mechanical properties during the manufacturing process. For example, advanced heat treatment technology and precision machining technology are used to improve the reliability and fatigue life of products.
Surface strengthening and treatment: Through surface strengthening technology, such as shot peening, carburizing hardening, etc., improve the hardness and fatigue resistance of the crankshaft forging surface. At the same time, the use of anti-corrosion coating and other surface treatment technology to enhance the corrosion resistance of crankshaft forgings in harsh environments, so as to improve its reliability.
Monitoring and maintenance: Establish a sound monitoring and maintenance system, regular inspection and performance testing of crankshaft forgings, timely detection of potential defects and failure modes. Through reasonable maintenance and repair measures, the service life of crankshaft forgings can be extended and its reliability can be improved.
Design optimization: From the design point of view, rationally arrange the stress structure to reduce the influence of stress concentration and alternating stress. The strength and fatigue of crankshaft forgings are analyzed by finite element analysis and other numerical simulation methods to optimize the design scheme and improve its reliability.
The fatigue life and reliability of locomotive crankshaft forging is a complicated problem, which involves many factors. In order to improve its performance indicators, it is necessary to consider many aspects such as material selection, manufacturing process, working environment and monitoring and maintenance. By deeply studying the influencing factors and analysis methods of fatigue life and reliability, and taking effective optimization measures, the performance level and service life of locomotive crankshaft forgings can be improved, and powerful support can be provided for ensuring the safe operation of locomotive.
