Inverse Method to Determine Fatigue Properties of Materials by Combining Cyclic Indentation and Numerical Simulation

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Mechanics

Background:

• Instrumented indentation is a standard technique for measuring material properties like Young's modulus and microhardness.
• Advanced methods combine indentation experiments with simulations for inverse analysis to determine parameters such as yield strength and tensile strength.

Purpose of the Study:

• To introduce and validate an inverse method for determining kinematic hardening parameters, crucial for understanding cyclic plasticity.
• To establish a quasi-nondestructive technique that complements or potentially replaces conventional fatigue testing.

Main Methods:

• Cyclic Vickers indentation experiments were performed on materials with unknown properties.
• Finite element simulations of the indentation process were conducted.
• An inverse analysis approach was employed to determine the material's cyclic plasticity parameters from experimental and simulation data.

Main Results:

• The developed inverse method successfully determined kinematic hardening parameters.
• The determined parameters accurately predicted the uniaxial stress-strain response of the tested materials.
• Excellent agreement was observed between measured and predicted cyclic stress-strain curves for martensitic steel and copper.

Conclusions:

• The proposed inverse method, utilizing cyclic nanoindentation and finite element analysis, is effective for characterizing cyclic plasticity.
• This technique offers a promising, quasi-nondestructive alternative to resource-intensive conventional fatigue testing for certain applications.