Meaning
Mathematical model used to predict the life of materials subjected to repeated plastic deformation. Thermal cycling in battery cells creates strain that developers evaluate using the coffin manson criteria to ensure long term durability. The model focuses on low cycle fatigue where stresses are high enough to cause permanent shape changes.
Reliability decreases when applied to high cycle fatigue where elastic strain is the primary driver.
Plastic Strain
Total strain amplitude is divided into elastic and plastic components to determine the fatigue resistance of a joint. When temperature swings occur, coffin manson criteria calculate the damage accumulated in electrical interconnects and busbars. Plastic strain dominates the failure mechanism in these soft metal components.
Calculating the ratio between these two types of strain allows for a more accurate life prediction in diverse environments. Developers use the data to choose alloys that can withstand the specific expansion rates of the battery module.
Cycling Durability
Number of cycles to failure depends on the ductility of the material and the magnitude of the applied displacement. Higher temperatures generally accelerate the degradation process. Engineers use the calculated life to define warranty periods for energy storage systems.
Low Cycle Fatigue
Empirical constants derived from laboratory testing calibrate the equation for specific metal alloys or solder types. While other models handle high cycle vibration, the coffin manson criteria remain the standard for thermomechanical fatigue. Reliable data prevents unexpected failures in the field.
