Multiaxial Critical Plane Strain Life Analysis for Conformal Cooled Tooling
Multiaxial critical plane strain-life analysis models out-of-phase thermal and pressure fatigue on internal conformal cooling walls to prevent die failure.
Strain Life
Meaning
A fatigue analysis methodology relates the number of cycles to failure to both the elastic and plastic strain amplitudes experienced by a material. The strain life approach proves useful for assessing components that undergo plastic deformation during thermal cycling or mechanical movement. It combines the Basquin equation for elastic behavior with the Coffin-Manson equation for plastic behavior.
This method provides the mathematical foundation for evaluating cell fatigue under deep cycling conditions.
Fatigue Evaluation
Low-cycle fatigue in structural batteries occurs where stress levels exceed the yield strength of the metallic current collectors. The strain life formulation models these conditions by separating total strain into reversible elastic and permanent plastic components. It calculates the cumulative damage generated during each charge and discharge cycle.
Deformation Resistance
High capacity electrodes undergo large cyclic volume changes that put the current collector foils under plastic deformation. Applying strain life equations to these foils helps estimate how long they can resist crack initiation under these harsh conditions. This calculation guides the selection of hard-rolled versus annealed copper foils.
Material Selection
Pack designers use fatigue data to select materials that can withstand the swelling forces of large format pouch cells. The strain life parameters of different metals guide the optimization of structural enclosures and restraining plates. This ensures the battery pack maintains its mechanical integrity over its service life.