Reply To: Johnson-Cook material strength model and the Johnson-Cook fracture model.

[Nanda Veralla]

 

Hello Kikuji,

The Johnson-Cook strength model is a model that defines the flow stress of a material as a function of plastic strain, strain rate, and temperature. This model captures how materials harden with deformation (strain hardening), how they respond to changes in strain rate (strain-rate hardening), and how temperature affects their strength (thermal softening). The Johnson-Cook fracture model, on the other hand, specifically addresses when a material will fail based on accumulated damage. It typically uses a criterion where failure occurs when the accumulated plastic strain exceeds a certain threshold. 

Differences in failure/fracture definition: The strength model describes how materials deform under load without specifying when they will fail. The fracture model defines failure based on accumulated strain, indicating that once this accumulated strain exceeds a critical value, fracture occurs.

What’s best for what: The strength model applies to various materials under various loading conditions. The fracture model is particularly suited for dynamic loading scenarios and may be more appropriate for ductile materials where failure occurs after significant deformation.

For more information, you might want to look at the links below.

11.7.5. Johnson-Cook Strength

11.11.7. Johnson-Cook Failure

 

Regards,

Nanda.

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