Fracture behavior and acoustic emission characteristics of reinforced concrete under mixed mode I-II load conditions

This paper evaluated mixed mode I/II fracture toughness of fiber-reinforced concrete using cracked semi-circular bend (SCB) specimens subjected to three-point bending test. Additionally, a comparison was made between the experimental results and the estimations made by different theoretical criteria. Natural and synthetic fibers at various concentrations were used in this study. After producing cracks in SCB specimens at different inclination angles to induce different mixed mode loading conditions (from pure mode I to II), the fracture toughness of SCB specimens was determined. Furthermore, the compressive, splitting tensile, and flexural strength of natural and synthetic fiber-reinforced concrete were measured after 7 and 28 days of curing. While there is an increase in the aforementioned strengths with fiber content increase, 0.3% was found to be the optimum percentage regarding fracture toughness for both fibers. Also, the comparison between the experimental and theoretical results showed that generalized maximum tangential stress criterion estimated the experimental data satisfactorily.

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Effect of polypropylene fibers on the mode I, mode II, and mixed-mode fracture toughness and crack propagation in fiber-reinforced concrete

Theoretical and Applied Fracture Mechanics ◽

10.1016/j.tafmec.2020.102723 ◽

2020 ◽

Vol 109 ◽

pp. 102723

Author(s):

Mitra Hatami Jorbat ◽

Mehdi Hosseini ◽

Mahdi Mahdikhani

Keyword(s):

Fracture Toughness ◽

Reinforced Concrete ◽

Crack Propagation ◽

Mixed Mode ◽

Fiber Reinforced Concrete ◽

Mode I ◽

Mode Ii ◽

Mixed Mode Fracture ◽

Polypropylene Fibers ◽

Mode Fracture

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Investigation by Digital Image Correlation of Mixed Mode I and II Fracture Behavior of Metallic IASCB Specimens with Additive Manufactured Crack-Like Notch

Metals ◽

10.3390/met10030400 ◽

2020 ◽

Vol 10 (3) ◽

pp. 400 ◽

Cited By ~ 2

Author(s):

Ivo Campione ◽

Tommaso Maria Brugo ◽

Giangiacomo Minak ◽

Jelena Janković Tomić ◽

Nebojša Bogojević ◽

...

Keyword(s):

Digital Image Correlation ◽

Digital Image ◽

Mixed Mode ◽

Fracture Behavior ◽

Selective Laser Sintering ◽

Local Stress ◽

Fatigue Loading ◽

Image Correlation ◽

Mode I ◽

Displacement Fields

This work investigates the fracture behavior of maraging steel specimens manufactured by the selective laser sintering (SLS) technology, in which a crack-like notch (sharp notch) was directly produced during the additive manufacturing (AM) process. For the evaluation of the fracture toughness, the inclined asymmetrical semi-circular specimen subjected to three points loading (IASCB) was used, allowing to cover a wide variety of Mode I and II combinations. The effectiveness of manufacturing crack-like notches via the SLS technique in metals was evaluated by comparing the obtained experimental results with the ones obtained with pre-cracks induced by fatigue loading. The investigation was carried out by using the digital image correlation (DIC) technique, that allowed the evaluation of the full displacement fields around the crack tip. The displacement field was then used to compute the stress intensity factors (SIFs) for various combinations of Mode I and II, via a fitting technique which relies on the Williams’ model for the displacement. The SIFs obtained in this way were compared to the results obtained with the conventional critical load method. The results showed that the discrepancy between the two methods reduces by ranging from Mode I to Mode II loading condition. Finally, the experimental SIFs obtained by the two methods were described by the mixed mode local stress criterium.

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