Showing papers in "Engineering Fracture Mechanics in 2019"

TL;DR: In this paper, a review of the synergistic interplay of hydrogen embrittlement mechanisms in STEEL and IR is presented, with a particular emphasis on the proposal of the novel and unified HELP+HEDE model based on the specific microstructural mapping of the dominant HE mechanisms with implications on the fracture process and resulting hydrogen-assisted fracture modes.

TL;DR: The proposed inverse algorithm based on Proper Orthogonal Decomposition (POD) and Radial Basis Functions (RBF) for single and multiple cracks identification in plate structures is found to accurately estimate the cracks' locations with high accuracy and much faster than other techniques used in the literature.

TL;DR: In this article, a 3D crack growth inside the transparent 3D resin samples in real-time for the first time was studied with the aid of high-speed cameras, and the results indicated that flaw geometry has remarkable influence on the mechanical and fracture behaviors of the flawed samples.

TL;DR: Three popular PFMs for brittle and cohesive fracture in the literature are selected, implemented within a single code and used to study the sensitivity to the length scale parameter and the mesh alignment of the solutions to various brittle and quasi-brittle fracture problems with/without singularities and notches.

TL;DR: In this article, a damage model for fractured rock is established from the viewpoint of energy dissipation, which takes into account the initial damage of fractured rocks and introduces the concept of equivalent modulus, which make the model more practical and easier to apply.

TL;DR: In this article, a series of point-bending tests were conducted on granite disc samples with the same diameter but different heights, and the micro-crack evolution during the test was measured and recorded by acoustic emission experiments.

TL;DR: A mesoscopic numerical model for the simulation of the splitting-tensile failure and size effect at different strain rates (10−5/s∼ 200/s) was established in this article.

TL;DR: In this article, the authors applied acoustic emission (AE) monitoring for the qualitative and quantitative assessment of the fracturing process in two types of rocks subjected to diametral compression tests.

TL;DR: In this paper, the authors investigated the influence of pore-structure and mortar properties on the fracture behavior of geopolymer foamed concrete and found that a decrease in pore size results in higher compressive strength and this influence is more significant for materials with lower porosity.

TL;DR: In this article, acoustic emission (AE) experiments were carried out to study short-time creep behavior under uniaxial compression for cuboid-shaped fine sandstone specimens with two pre-existing cracks.

TL;DR: In this paper, four representative analyses methods, including the b-value method, acoustic emission signal intensity, average frequency (AF) versus RA (RA means rise time divided by the amplitude) value, and cluster analyses, are utilized to characterise and analyse the damage mechanisms and failure modes of three-point and four-point crumb rubber concrete bending beams with different rubber contents, including, 0, 5, 10, and 15%.

TL;DR: In this paper, the impact of cyclic heating and cooling treatments on mode I fracture characteristics of granite was examined, and fracture tests of semi-circular bend specimens were conducted, acoustic emission (AE) events were monitored, and morphology characteristics of fracture surfaces were analyzed.

TL;DR: In this article, a cyclic loading and unloading test under stress gradients with a constant lower limit of stress on sandstone samples with cracks at different angles was performed to obtain influence laws of crack angles on energy characteristics of sandstones in complex stress environment.

TL;DR: In this paper, an attempt has been made to understand the evolution of fracture process zone in plain concrete member utilizing Digital Image Correlation (DIC) technique and series of experiments have been performed in centre point bending under the action of monotonic and repetitive loadings and DIC technique is used during the entire test process.

TL;DR: In this paper, a phase-field regularized cohesive zone model (PF-CZM) is combined with the X-ray computed tomography (XCT) imaging technique and applied to the modeling of mesoscopic cracking in concrete.

TL;DR: In this article, the effect of the cohesive element (CE) parameters on delamination modeling is systematically examined, and the sensitivity of the overall progressive damage process and failure load to the assumed CE strengths and stiffness is studied based on selected examples of fracture and coupon-level tests.

TL;DR: In this paper, acoustic emissions data from a series of laboratory hydraulic fracturing experiments on granite were used to understand the effect of external stress conditions on the hydraulic fracturing process and to predict crack initiation.

TL;DR: In this paper, a comparative study of the gradient-enhanced damage models (GED) and phase field damage/fracture models (PFM) is presented for modeling the fracture process on a fixed finite element mesh.

TL;DR: In this paper, coal samples within original cracks were selected to conduct uniaxial compressive loading experiments to achieve the qualitative and quantitative damage expression, and they collected acoustic emission signals by AEwin Test for Express-8.0 and cracks evolution were captured by video camera.

TL;DR: In this article, the authors show how atomistic simulations can be used to reveal important features of the behavior of hydrogen embrittlement (HE) in metals, including previously-unpublished studies on the effects of H on the bowout of the edge dislocations in α -Iron and predictions of solute-drag by H in nickel.

TL;DR: In this article, the authors introduced a more accurate representation of the deformation gradient and the bond associated (BA) force density vector by using the peridynamic differential operator (PDDO) and presented the weak form of BA-NOSB PD governing equations in order to impose natural and essential boundary conditions.

TL;DR: In this article, a closed-form solution of a non-Linear Elastic Fracture Mechanics (non-LEFM) model emphasizing the influence of average grain size on quasi-brittle fracture of granite was presented.

TL;DR: In this paper, the authors investigated the strength and deformation behavior of transversely isotropic composite rock-like material, which consists of a hard rocklike material and a weak rock-based material, under different confining pressures by using a rock triaxial testing system.

TL;DR: The stopping criterion of the iterative scheme based on the control of the residual norm is introduced and implemented in the finite element software Abaqus, alleviating the problem of the common single iteration staggered algorithm, which requires fine loading incrementation to produce an accurate solution.

TL;DR: In this article, the effect of the end-notched disk bend (ENDB) geometry on the fracture toughness and fracture energy of two widely used asphalt mixture types namely, HMA and Stone Mastic Asphalt (SMA) at low temperatures was investigated.

TL;DR: In this paper, in-situ tensile fatigue experiments under SEM environment at room temperature and elevated temperature are performed for studying the fatigue performance and crack propagation process of selective laser melting (SLM) additive manufactured Al-Si10-Mg materials.

TL;DR: In this article, a continuum damage mechanics (CDM) based methodology for high cycle fatigue crack growth simulations is proposed and implemented in the framework of extended finite element method (XFEM), a new criterion is proposed based on damage evolution to identify the appropriate definition of stress triaxiality for acquiring the constraint effect on the stress state correctly.

TL;DR: A novel and effective computational approach based on polygonal XFEM (named as PolyXFEM) for the analysis of two-dimensional (2D) linear elastic fracture mechanics problems, equipped with a new numerical integration technique that uses the concept of Cartesian transformation method (CTM) overpolygonal domains.

TL;DR: In this paper, a damaging block-based model is proposed for the numerical analysis of the cyclic behavior of full-scale masonry structures, where solid 3D finite elements governed by a plastic damage constitutive law in tension and compression are used to model the blocks, while a cohesive-frictional contact-based formulation is developed to simulate their cyclic interaction.

TL;DR: In this paper, a combined finite element approach, namely ELFEN, has been used for better reflection of entire failure process and intrinsic properties of hard rock mass, thus rock heterogeneity, around circular tunnels during excavation unloading process.