An Enhanced Method to Evaluate Tensile Yield Stress by Small Punch Tests Using Deflection Curves

Area of Science:

• Materials Science
• Mechanical Engineering
• Experimental Mechanics

Background:

• Small Punch (SP) testing is a valuable technique for material characterization.
• Force-displacement curves in SP tests are susceptible to significant uncertainties due to frame compliance.
• Existing methods may not fully capture the complexities of the force-deflection behavior.

Purpose of the Study:

• To develop and validate a novel methodology for predicting yield stresses from force-deflection curves in SP tests.
• To mitigate uncertainties associated with frame compliance in SP testing.
• To improve the accuracy of yield stress determination for various materials.

Main Methods:

• A new methodology is presented to predict yield stresses from force-deflection data.
• The method analyzes multiple force levels from the initial curve segment, considering both slope and curvature.
• This approach moves beyond relying on a single force level for prediction.

Main Results:

• The developed methodology accurately predicts yield stresses for diverse materials, including low- and high-strength alloys.
• Predicted yield stresses show good agreement with experimentally determined proof stresses.
• The maximum error observed in the predictions was 16%.

Conclusions:

• The proposed method effectively predicts yield stresses from force-deflection data in SP tests.
• This approach offers a more reliable alternative to traditional methods by accounting for curve characteristics.
• The findings contribute to more accurate material property assessment in mechanical testing.