Investigation of the mechanical work during ultrasonic fatigue loading using pulsed time-resolved X-ray diffraction

Area of Science:

• Materials Science
• Mechanical Engineering
• Physics

Background:

• Metallic structures in energy and transportation face billions of loading cycles in the very high cycle fatigue (VHCF) domain.
• Designing for VHCF necessitates reliable methodologies to predict material behavior and prevent failure.
• Characterizing plastic activity and fatigue damage evolution is crucial for material design.

Purpose of the Study:

• To present an innovative methodology for quantifying mechanical work supplied to a material during ultrasonic fatigue tests.
• To address the challenge of estimating mechanical work in metals under VHCF conditions.
• To provide a reliable approach for designing structures operating in the VHCF domain.

Main Methods:

• Developed an experimental procedure to estimate mechanical work from stress and total strain evolution.
• Achieved high-time accuracy of approximately 50 nanoseconds for measurements.
• Utilized time-resolved X-ray diffraction coupled with strain gauge measurements.
• Conducted experiments at a synchrotron facility operating in pulsed (single-bunch) mode.

Main Results:

• Successfully estimated mechanical work with high temporal resolution during ultrasonic fatigue.
• Demonstrated the feasibility of quantifying microscopic plastic activity and fatigue damage evolution.
• Established a novel approach for analyzing material response under VHCF loading.

Conclusions:

• The presented methodology offers a reliable way to quantify mechanical work in metals during ultrasonic fatigue.
• This advancement is critical for improving the design and safety of structures subjected to very high cycle fatigue.
• The findings contribute to a better understanding of fatigue mechanisms at the microscopic level.