Key Deformation Concepts

The question asks to identify the type of deformation that is both time dependent and recoverable when a load is applied.

Defining Anelastic Deformation

Anelastic deformation refers to a type of material response where the deformation is proportional to the applied stress but exhibits a time delay in both the straining process under load and the recovery process upon unloading. Crucially, this deformation is fully recoverable, meaning the material returns to its original shape, but not instantaneously.

Comparing Deformation Types

Let's analyze the given options in the context of the question:

• Elastic Deformation: This is instantaneous and fully recoverable upon removal of the load. It is not inherently time-dependent during the loading phase.
• Anelastic Deformation: This is time-dependent and fully recoverable, fitting the description. The recovery process takes time.
• Creep Deformation: This is time-dependent deformation that occurs under a constant load, but it is irrecoverable (plastic).
• Plastic Deformation: This is permanent, irrecoverable deformation that occurs when the stress exceeds the material's yield strength.

Conclusion

Based on the definitions, the time-dependent recoverable deformation under load is specifically termed anelastic deformation.