Selecting a Suitable Specimen Shape with Low Constraint Value for Determination of Fracture Parameters of Cementitious Composites

Abstract

The stress intensity factor and the T-stress describing the near-crack-tip fields for selected specimen shapes of a test geometry based on wedge splitting and three point bending tests with several variants of boundary conditions are computed using finite element software ANSYS. The test configuration in question is expected to be a convenient alternative to classical fracture tests (especially the tensile ones) for investigation of the quasi-brittle fracture of building materials, when low constraint is requested. These specimens are investigated within the framework of two-parameter fracture mechanics; near-crack-tip stress field parameters are determined and compared with those of the wedge splitting test due to their shape similarity. The sensitivity of the values of these parameters to the boundary conditions is also shown. Suitable choice of the shape of the specimens is discussed.

Evaluation of mixed mode I/II fracture toughness of C 50/60 from Brazilian disc test

“…Fracture mechanical parameters of cementitious materials are usually obtained from recommended tests such as: three-point (3PBT) and four-point (4PBT) bending test with notch in tested specimen [4], for mixed mode load [5], wedge splitting test (WST) [6][7][8][9], or a combination of WST/3PBT [10] and modified compact tension test (MCT) [11,12]. All tests have a predefined prismatic geometry and using them on specimens made from the core-drill is expensive and not very efficient, therefore it is very appropriate to use a Brazilian disc test specimen with central notch (circle cut from the core-drill cylinder) [13][14][15][16] to determinate fracture parameters of building materials see Fig.…”

Two Parameter Description of Crack Tip Stress Fields for Wedge Splitting Test Specimen: Influence of Wedge Angle

“…Note that the paper follows the previous work of authors [19], where the suitable specimen shape with low constraint was studied as combination of WST and 3PB specimens.…”

Numerical study and pilot evaluation of experimental data measured on specimen loaded by bending and wedge splitting forces

“…1. Note that geometries are symmetric for all considered specimen shapes (including boundary conditions); therefore, only one half of the problem was modelled like in [21,22,26]. The size of the smallest element in the crack tip is 5 × 10 -5 mm.…”

“…In the paper, the numerical support (calibration and compliance curves) for evaluation of the experimentally obtain data is shown/introduced. The pilot numerical study of the selected shape of specimens by using Williams expansion was introduced in [22,25,28,30]. The values of stress intensity factor (SIF), T-stress and crack opening displacement (COD, see Fig.…”