Ultrasonic fatigue testing of concrete

Area of Science:

• Materials Science
• Civil Engineering
• Structural Engineering

Background:

• Concrete is a crucial construction material.
• Understanding its fatigue properties under cyclic loading is essential for structural integrity.
• Existing testing methods can be time-consuming for generating very high cycle fatigue (VHCF) data.

Purpose of the Study:

• To investigate the cyclic compression fatigue properties of concrete using ultrasonic fatigue testing.
• To compare the effectiveness of ultrasonic testing with traditional servo-hydraulic methods.
• To explore methods for analyzing fatigue damage in concrete under ultrasonic loading.

Main Methods:

• Ultrasonic fatigue testing at a 19 kHz cycling frequency.
• Servo-hydraulic fatigue testing at a 60 Hz cycling frequency.
• Analysis of fatigue damage using resonance frequency observation, higher-order harmonic analysis, and computed tomography.
• Calorimetric evaluations to determine cyclic irreversible strain.

Main Results:

• Ultrasonic testing is applicable for rapid generation of VHCF data in concrete.
• Fatigue cracks initiate, but specimens do not rupture in displacement-controlled ultrasonic tests due to decreasing cyclic stresses.
• Methods like resonance frequency analysis, harmonic analysis, and CT scanning successfully detect fatigue damage.
• Calorimetric evaluations show cyclic irreversible strain is approximately 1% of elastic strain in ultrasonic VHCF tests.

Conclusions:

• Ultrasonic fatigue testing offers a rapid approach for obtaining VHCF data for concrete.
• While rupture is not achieved, ultrasonic testing provides valuable insights into fatigue damage mechanisms.
• Advanced analysis techniques are effective in characterizing fatigue-induced damage in concrete specimens.