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Dynamic and Time-Dependent Fracture
Published in T.L. Anderson, Fracture Mechanics, 2017
where P is the applied load and Δ is the load-line displacement. Similarly, C* can be defined in terms of a power release rate C*=−1B(∂∂a∫0Δ˙PdΔ˙)Δ˙
lc measurement method for tubular structures
Published in József Farkas, Károly Jármai, Tubular Structures VII, 1996
A. Ben Dhia, J. B. Bai, D. François, V. Grigoriev, B. Josefsson
Fig. 6 shows the J-integral as a function of the load-line displacement. We notice firstly the qualitative similarity between the global reaction force and the J-integral curves. Secondly, gradient value of the curve, (dJ/dΔ) increases drastically for displacement values larger than 0.6 mm. This remark is of critical importance in determining JIC. The load-line displacement value for which crack propagation initiation (denoted by Δc) was determined visually by video monitoring and was found to be around 0.8 mm (Fig. 4a). Therefore, the accuracy of JIC value depends closely on the experimental measurement precision. For example, if a ± 5% dispersion of experimental results on Ac determination is assumed (almost ideal case), JIC will be included in the interval 60 - 84 N/mm with an average numerical value of 72 N/mm.
J-Integral
Published in Ashok Saxena, Advanced Fracture Mechanics and Structural Integrity, 2019
In this section, we will discuss a method for estimating J for elastic, elastic–plastic, and fully plastic conditions for several crack configurations that are important in applications. The estimation of J in these situations is not dependent on the measurement of the load-line displacement. Instead, the displacement is computed from the deformation properties of the material, α, σ0, ε0, and m. However, prior to presenting these results, it is important to develop a framework which specifies these equations in approximately the same form.
Definition of mode-I fracture behaviour of plain and fiber reinforced various grades of concretes by digital image analysis
Published in Mechanics of Advanced Materials and Structures, 2023
Muhammed Gümüş, Abdussamet Arslan, Hüseyin Kalkan
The use of steel fibers provides an additional stress transfer mechanism between the newly formed crack surfaces. This improves the load-bearing capacities of the concrete specimens [7]. Enhancement in the load-bearing capacity of the crack body is directly related to the bond strength between the fiber and the surrounding matrix. Moreover, the quality of bonding, too, is affected by the concrete grade [8]. While high-strength concrete leads to the rupture of fibers due to improved bonding, slippage at relatively low loads is observed in the case of ordinary concrete [9]. Besides the improvement in the load-bearing capacities of the concrete specimens due to fiber inclusion, steel fibers also amend the residual flexural strength remarkably, which leads to a higher amount of fracture energy [10] to complete the separation of the crack surfaces at the failure. Accordingly, many researchers have investigated the size effect [11–15], fracture energy [16–19], and fracture toughness [20–23] of steel fiber reinforced concrete (SFRC) through the notched specimen under three-point loading. In those studies, crack mouth opening displacement (CMOD) or the load line displacement was considered. Based on the test results, it was noted that (i) steel fibers mitigate the effect of the notched specimen’s size [11, 12], (ii) steel fiber remarkably increased the fracture energy of concrete [16, 18], and (iii) fracture toughness of concrete could be enhanced by adding steel fibers [20, 21].
Evaluation of effects of short and long-term thermo-oxidative aging on chemo-rheological and mechanical properties of asphalt concretes
Published in Road Materials and Pavement Design, 2023
S. C. Somé, A. B. Kouevidjin, V. Mouillet, A. Feeser, J.-F. Barthélémy, H. Ben Dhia
Three-point bending tests on SCB specimens have been performed. The specimens have been placed in a chamber with the designated temperature for 24 hours before the test to reach temperature equilibrium. They have been taken out of the chamber and placed in the loading cell rapidly to perform the test in less than a minute. The loading cell consists of two rigid roller supports and lateral thick metallic plates which allows placing the specimen onto the bending fixture in order to avoid eccentric loading. Another roller support allows applying the load vertically (see Figure 8(b)). The specimen's mean diameter is , resulting in a span length of 120 mm between two cylindrical supports. Monotonic displacement rate has been applied on the specimen until failure. The force and the vertical load-line displacement have been continuously recorded during the test. The tests have been performed at 0C and at a loading rate of .
Investigations of electrical conductivity and damage healing of graphite nano-platelet (GNP)-taconite modified asphalt materials
Published in Road Materials and Pavement Design, 2022
Jia-Liang Le, Mihai Marasteanu, Jhenyffer Matias De Oliveira, Thomas Calhoon, Mugurel Turos, Lawrence Zanko
All tests were performed using a MTS servo-hydraulic testing system in an environmental chamber. The load was applied along the vertical diameter of the specimen. The load magnitude and load line displacement were measured during the entire duration of the test. The SCB specimens have a 15 mm notch at the mid-span and are symmetrically supported by two fixed rollers with a span of 120 mm. . The load line displacement (LLD) was measured using a vertically mounted Epsilon extensometer with 38 mm gauge length and ±1 mm range; one end was mounted on a button that was permanently fixed on a specially made frame, and the other end was attached to a metal button glued to the sample. The crack mouth opening displacement (CMOD) was recorded by an Epsilon clip gage with a 10 mm gauge length and a +2.5 and -1 mm range. The clip gauge was attached at the bottom of the specimen. The load was applied such that a constant CMOD of 0.0005 mm/s was obtained and maintained for the duration of the test to ensure stable crack growth conditions. The test set-up is shown in Figure 5.