Loading‐rate dependence of mode I crack growth in concrete

• Published in: Fatigue & fracture of engineering materials & structures Vol. 43; no. 5; pp. 978 - 990
• Main Authors: Ma, Minhua, Wu, Zhimin, Hu, Xiaozhi, Yu, Rena C., Fei, Xiaodong
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01-05-2020
• Subjects: crack growth process; Crack propagation; crack propagation criterion of concrete; Crack tips; Loading rate; loading‐rate dependence; Material properties; Peak load; Propagation modes; rate‐dependent cohesive law
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/ffe.13174

Mode I crack propagation process of concrete under relatively low loading rates which cover four orders of magnitude (0.2 μm/s to 2.0 mm/s) is investigated with three‐point bending (TPB) beams. All measured material properties exhibit rate sensitivity and follow a log‐linear relationship with the loading rate. A rate‐sensitive softening curve is established. The complete load‐crack mouth opening displacement (P‐CMOD) curve, crack propagation length, and fracture process zone (FPZ) length are simulated based on crack growth criterion with the fitted material parameters under those loading rates. Results show that the simulated P‐CMOD curves agree well with those of experimental measurements. It is clear that the peak load increases with the loading rate and so is the critical crack mouth opening displacement. Moreover, under the same load level, the length of the FPZ and the cohesive stress at the initial crack tip also increase with the increasing loading rate.