The fracture features of the 3D-printed samples are assessed employing Semi-Circular Bending (SCB) specimens. The critical failure loads are experimentally measured and have been predicted using both Maximum Tangential Stress (MTS) and Generalized Maximum Tangential Stress (GMTS) criteria. The 3D-printing process is improved with several approaches to decline the voids volume and escalate the weld

The mechanical performance of the interface between fiber reinforced polymer (FRP) laminates and concrete is essential for the analysis of FRP-strengthened concrete structures through external bonding. This paper presents an analytical solution for the pull-off behavior of FRP-to-concrete bonded joints considering local unloading and reloading. With the interfacial slip at the free end as the control

The research presented in this paper aims to provide an insight of tungsten (W) nano-particles reinforced polychloroprene rubber (CR) material (W-CR material) developed for nuclear decommissioning applications and fabricated in sheets by means of rolling process. Static and cyclic anisotropic mechanical properties have been investigated by means of laboratory experiments and finite element simulations

The design of reliable structures and the estimation of the residual fatigue life of industrial parts containing flaws or cracks rely on our ability to predict the propagation of fatigue cracks. Whereas in industrial component cracks might have a complex path due to geometry and loading, lab experiments used for identifying crack propagation law are often in pure mode I. The paper presents a synthesis

In the present study, the hydraulic fracturing volumetric opening is referred to the volumetric opening in per unit bulk volume of rocks, in fact, the increment of porosity due to hydraulic fracturing, including the pore volumetric opening and fracture volumetric opening. The former is an idealized representation of elastic volumetric opening of widely distributed microcracks, fissures, and pores due

Ferroelastic domain switching is considered as that a twin undergoes a lattice orientation described by a deviatoric eigenstrain in this work. A continuum analysis, based on Eshelby equivalent inclusion theory, is derived to study the nucleation and evolution of twin near a pre-existing crack tip (Mode-I) in a mono-phase tetragonal crystal, in an attempt to achieve a better understanding of the contribution

In this study, based on an experimental digital laser dynamic caustic system, a dynamic fracture experiment on a polymethyl methacrylate (PMMA) semi-disc specimen with a weak precast double-layer surface under an impact load was carried out, the cracking, expansion, and wearing patterns of the cracks under different tilt angles (60°, 45°, and 30°) were studied, and the changing characteristics of the

In this paper, the two-dimensional problem of a circular hole with two unequal cracks in infinite thermoelectric materials subjected to a uniform electric current and thermal flux is studied. Meanwhile, the boundary conditions at hole and cracks are assumed to be electrically impermeable and thermally impermeable. By using the complex function method and the conformal mapping theory, the exact solutions

A novel multiscale simulation framework was proposed to investigate the mechanical properties of single layer graphene platelets reinforced crosslinked epoxy. Crosslinking reactions in composites were simulated with the molecular dynamics (MD) method in the nanoscale, and the mechanical properties of bulk epoxy and interfaces between unfunctionalized graphene and epoxy were obtained. These mechanical

Fracture of hyperelastic materials such as synthetic rubber, hydrogels, textile fabrics is an essential problem in many engineering fields. The computational simulation of such a fracture is complicated, but the use of phase field models (PFMs) is promising. Indeed, in PFMs, sharp cracks are not treated as discontinuities; instead, they are approximated as thin damage bands. Thus, PFMs can seamlessly

This work presents the development of an improved data reduction method for the shear-torsion-bending (STB) test designed for monolithic laminates. The analytical derivation extends the applicability of the STB rig to composite sandwich specimens subjected to an out-of-plane shear loading. The data reduction method consists of an analytical model that expresses the global energy release rate in terms

Shear induced asperity degradation and gouge formation significantly affect the mechanical and fluid flow behaviors of single rough rock fractures, but the asperity damage process during shear has not been entirely understood and requires further investigation. In this study, direct shear tests were performed on the artificial and natural fractured granite specimens, respectively. The evolution of

Mode I fracture mechanics tests of mostly calcareous Vaca Muerta shale rocks were performed in a new experimental device. A hydraulic system allows the injection of pressurized fluids inside of cracks to generate applied KI and measure fracture toughness in room pressure and temperature conditions. Multi-notched 1.5″ plugs were tested with different polar and non-polar fluids (water-based fluids and

According to meso-damage mechanics, the evolution of the volume of micro-voids is an important factor that contributes to damage and fracture. Improving the prediction accuracy of plastic deformation of aluminum alloy sheet is an important endeavor for studying the influence of various factors on plastic meso-damage evolution. Based on the GTN (Gurson-Tvergaard-Needleman) model, the meso-mechanics

Adhesive joints are widely developed in aeronautic and automotive design applications. When subjected to impact loading, the rate sensitivity of adhesively bonded joints becomes a subject of interest. In this study, the Mode I fracture behavior of an aeronautic adhesive is characterized. Double Cantilever Beam tests are performed under various displacement rates. A new protocol is developed to accurately

Cohesive zone modelling is increasingly applied to predict the strength of structural adhesive joints. A method is here proposed to determine the bondline shear traction-separation law needed for cohesive zone models. The method combines an effective crack length approach derived from a beam model and an existing J-integral analysis of the end-notched flexure specimen. The resulting work done by the

Prestressed structures are frequently encountered in civil engineering. This paper gives a theoretical analysis of a cracked orthotropic elastic plane with initial stress. The problem of an orthotropic composite with a crack parallel to a material principal axis under initial stress along the crack line reduces to a mixed boundary value problem. It is solved using the Fourier transform. Application

Six constraint parameters (namely T-stress, Q, h, Tz, Ad and Ap) have been numerically calculated for semi-elliptical surface cracks in pipes so as to comparatively investigate their capability, applicability and ease of use for characterizing in-plane and out-of-plane constraints. The results show that the parameters T-stress and Tz can separately characterize in-plane and out-of-plane constraints

Due to the wide existence of tensile stresses in cemented paste backfill (CPB) mode-I fracture toughness (KIC) plays a crucial role in the mechanical stability of CPB under complex field loading conditions. However, the studies on KIC of CPB materials and associated influential factors are very limited. Hence, the main objective of this study is to experimentally investigate the effects of curing time

Limit analysis, without the complicated elasto-plastic computation, is an efficient method for estimating safety load of engineering structures. This paper develops a novel computational approach by integrating second-order cone programming (SOCP) into adaptive extended isogemetric elements (XIGA) for upper-bound limit analysis of cracked structures. The advantage of XIGA is to model cracks without

Research on rock fracture behavior is usually limited to static mixed mode I/II fracture and static or dynamic mode I fracture. In this study, the notched semi-circular bend (NSCB) specimens with different notch inclination angles were introduced into the split Hopkinson pressure bar (SHPB) system to numerically investigate dynamic mixed mode I/II fracture behavior of cracked rocks. First, the feasibility

A method to determine crack tip position and fracture process zone (FPZ) in concrete was proposed based on Bažant Crack Band Model (CBM) and digital image correlation (DIC) technique, which was described as: firstly, the critical crack opening displacement of concrete (wcr) was determined based on CBM and the basic mechanical properties; secondly, DIC method was used to obtain the displacement field

Many experiments have apparently shown that hard nanoparticle-reinforced elastomer matrix composites have not only an improved loading bearing capacity but also a good flexibility. The microscopic damage mechanism and its effect on the mechanical properties of such composites are systematically investigated in this paper by both tensile and tear experiments on nano-silica-particle reinforced silicone

This paper presents for the first time an improved meshfree particle method without the need for background cells in terms of numerical integration for thermal-mechanical crack growth analysis. In this work, both adiabatic and isothermal crack surfaces are considered. Asymptotic solutions-based enriched functions are incorporated into the approximation scheme to mathematically capture jump across crack

Pressure response and structural integrity assessment of cast iron and HDPE pipes were investigated in this study. The failure analysis of pipes in a branched network was considered taking into consideration the maximum stress generated by hydraulic transient events and the presence of an initial external semi-elliptical defect. The numerical study was conducted based on a developed non-conventional

A new area of application of Fracture Mechanics methods is proposed: the determination of surface deformation induced by internal volume change (e.g. due to underground hydrocarbon extraction). The finite layer-like zone of volume alteration is modelled as a crack, that is as a continuous distribution of dislocation loops. This approach allows the determination of surface deformation and can serve

Crack prediction is an important step of car design: its accuracy is crucial to avoid additional development costs and delays. The prediction of steel or aluminium sheets tearing is particularly challenging, and its simulation is not always reliable yet. This could be explained by the use of too simple fracture criteria based on a critical plastic strain that are uncoupled with the constitutive behavior

Defects present in the structure of nanostructures strongly affect and determine their performance, especially at high loadings and temperatures. Herein, molecular dynamics simulation (MD) was employed to theoretically pattern the fracture toughness, mechanical properties and crack propagation behavior of the defective monolayers of beryllium oxide graphene-like nanostructures subjected to some shape

We propose a new digital image correlation (DIC)-based method to calculate the location of a fracture process zone (FPZ) tip. Accordingly, we measure the FPZ length and crack opening displacement of heat-treated granite specimens. When the heat treatment temperature is below 300 ℃, the FPZ is fully developed between the peak and 90% post-peak load. When the heat treatment temperature exceeds 300 ℃

A hydro-mechanical coupled lattice-based model for the simulation of crack propagation induced by fluid injection in porous saturated rocks containing cohesive joints is presented. Rock follows an isotropic damage model for tensile fracture and cohesive joints follow a coupled plasticity-damage model. The discretisation uses a dual lattice approach: a Delaunay triangulation for the solid and the boundaries

Cracking is a critical issue in the preparation and application of thermoelectric materials. Traditional models for thermoelectric fracture predict infinite electric current and heat flux at the crack tip. However, it is impossible since infinite electric current and heat cannot be sustained at the atomic level. To give a physically reasonable fracture prediction of thermoelectric materials, this paper

Simulation of hydraulic fracturing process based on numerical manifold method (NMM) is a valuable research direction considering its advantages in dealing with continuous-discontinuous deformation problems. In this paper, an NMM-based fluid-solid coupling model is proposed, including numerical solution of unsteady fracture flow, hydraulic pressure-load conversion algorithm, rectification of hydraulic

Unloading compliance method (UC) and normalization method (NM) are two of the most commonly used methods for determining the fracture toughness of steels. Since the NM has been recognized as the most practical method there is a need to evaluate its accuracy against the classic UC method. This paper intends to investigate the factors that affect the agreement between UC and NM, including material mechanical

A unified viscoplastic constitutive model is proposed coupling fluid pressure rate control and damage evolution for warm medium forming (WMF), which also includes flow stress function, hardening law and dislocation density evolution. The pressure rate and damage behavior are investigated based on the experimental data of Ref. (Lang et al., 2013) [10] and the fracture morphology observations of specimens

Fracture mechanical testing of micro-sized cantilevers was conducted in order to quantify the fracture toughness and behaviour of the (1 0 0)[0 1¯ 1] crack system in α-iron at 37.5 K, 133 K and room temperature. The cantilevers are outside the range of validity for linear-elastic fracture mechanics due to the small sample size, rendering the cantilevers out of bounds in relation to linear-elastic fracture

This paper presents the coupled model of a hydraulic fracturing and proppant transport. The former is described in terms of enhanced pseudo-3D model that considers height growth across two symmetric stress barriers, while the latter is given by two-dimensional transport model, stemming from the solution of an elliptical equation for fluid pressure and advection equation for the proppant transport.

An analytical model has been developed to study the fracture behavior of bi-layer electrodes in the lithium-ion battery under galvanostatic intercalation and deintercalation. The bi-layer electrode is composed of an active strip and a current collector. Crack initiation and propagation may occur when the peak tensile stress caused by diffusion exceeds the theoretical strength of the active strip. For

The present paper presents the results from extensive studies of the fatigue damage evolution in fillet welded steel joints subjected to Constant Amplitude (CA) stress under membrane and bending loading modes. The welded joints in question are F class details (category 71) with plate thicknesses ranging from 25 to 32 mm. The steel quality is a medium strength carbon manganese steel. Crack growth histories

During the last decades various phase-field model have been developed in the variational approach to model dynamic fracture of brittle solids. Complex fracture phenomena such as crack branching, dynamic crack instability and fragmentation, etc., can be captured with a minimal list of physical parameters. However, an objective evaluation of existing results is missing and in particular, the issues of

The qualitative and quantitative effects of proppant on the near-front region of a hydraulic fracture are investigated by solving the problem of a semi-infinite fracture driven by a slurry of Newtonian fluid with proppant. The results demonstrate that proppant bridging and slurry dehydration cause proppant accumulation near the crack front and, in turn, a pressure difference over the proppant pack

In this paper, the mode I notch fracture toughness of graphite specimens weakened by notches of different shapes is investigated experimentally and theoretically. For this purpose, first, by conducting experiments, the apparent fracture toughness values of cracked semi-circular bending (SCB) graphite specimens with four various radii are determined. Next, numerous fracture experiments are performed

It is widely acknowledged that a finite width correction factor is required for the stress intensity factor in the fatigue prediction of built-up structures. This paper examines how a correction factor can be incorporated in the established model for the fatigue crack analysis of fibre metal laminates. It is revealed that the bonded fibres ahead of the crack tip mitigate the finite width effects, resulting

A fully coupled enriched-FEM (XFEM) model is proposed to investigate the interaction between hydraulic fractures and natural fractures in finite 2D porous media. The weak forms of both equilibrium and continuity equations are discretized in an enriched form in the space and by the Newmark scheme in the time domain. The Newton-Raphson method is adopted to solve these discretized equations. To account

The fracture mechanism and microstructure evolution around film-cooling holes in a nickel-based single crystal superalloy specimen under tensile creep at high temperatures were investigated using thin-walled plate specimens with close-packed film-cooling holes. The results demonstrated that the film-cooling hole structure has a weakening effect on the specimen for the creep life and creep ductility

In this article, 3-D simulations of hydraulic fracture propagation with the Generalized Finite Element Method (GFEM) are compared with several experiments. The GFEM in this work uses mesh adaptivity and a quadratic basis to control discretization error while avoiding the mapping of 3-D solutions between propagation steps. Linear Elastic Fracture Mechanics is adopted and geometrical singular enrichments

Numerical simulations of concrete fracture performed with a probabilistic mesoscale discrete model are presented. The model represents a substantial part of material randomness by assigning random locations to the largest aggregates. The remaining part of randomness is introduced by causing material parameters to fluctuate randomly via a homogeneous random field. An extensive numerical study performed

Brittle crack arrest behavior in steel plates and its evaluation test technique were investigated exhaustively from the1950s to the 1980s. Nevertheless, similar discussions have been revived recently by issues related to brittle crack arrest design applicable to mega-container ships. For example, the issue of whether the brittle crack arrest properties of steel plates evaluated under isothermal conditions

The leak-before-break (LBB) concept has been widely used to design the piping system in nuclear power plant, which is based on the fracture resistance (J-R) curves of cracked nuclear pipes. However, accurate fracture resistance evaluation of nuclear pipe is always a tough task. Full-scale nuclear pipe tests are costly and difficulty, and the specimens listed in test standards (e.g. ASTM E1820) are

A semi-analytical method is presented to investigate fracture behavior of a mode-I crack in a thin ductile plate. In the part of theoretical analysis, a total deformation theory of plasticity, in conjunction with a power law hardening stress-strain relation, is employed. Three-dimensional Maxwell stress functions, the minimum complementary potential energy principle and three dimensional J-integrals

The fracture characteristics of fine-grained granite were examined for a potential geothermal-energy reservoir. The granite was thermally cycled in a furnace between 100℃ and 300℃ and its mechanical behavior and meso-crack characteristics were analyzed. The results indicate that thermal cycling leads to decreased fracture toughness (Keff), absorbed energy (U), longitudinal wave velocity (Pv), and increased

This paper presents an analytical treatment to the fracture problem of a penny-shaped crack in a graded interfacial zone or FGMs interlayer with varied shear modulus and Poisson’s ratio. An efficient multilayered model is proposed to address the general form of material inhomogeneity. Formulation of the crack problem is reduced to a Fredhom integral equation of the second kind. The solution procedure

Notch features often raise critical influences on fatigue lives of engineering components, which deserve particular attentions for ensuring their structural integrity and reliability. The theory of critical distance provides a simple way to evaluate fatigue lives of notched components without extracting complicated stress fields within the notch vicinities. In this study, a probabilistic model for

A reinforcement of the interface between the fiber and polymer matrix using reactive polymer colloids were investigated by the acoustic emission (AE) method. The correspondence between the fracture mechanisms, fracture types and AE signals parameters during tensile loading of composites using the discrete wavelet transform (DWT) and the energy criterion for identification of fracture type based on

Symplectic analytical singular element (SASE) is a special crack-tip element in the framework of finite element method (FEM) for modelling cracks. A group of SASEs, which have been developed by the authors, for various crack problems almost in two-dimensional (2D), but not touched yet more complex ones, i.e., in three-dimensional (3D) domain. The underlying reason lies in the fact that analytical symplectic

Thin barrier coatings on polymer films are used increasingly in various applications. In coatings development, it is of interest to characterise the fracture toughness. The tensile fragmentation test potentially provides data to determine the critical energy-release rate for channelling cracks in the coatings during crack accumulation with increasing strain. Also, the crack-opening of displacement

Directional rock rupture is an important and common problem in the engineering of rock breaking. Directional rock rupture can be effectively achieved by linear collaborative directional hydraulic fracturing controlled via pre-slotted guide and fracturing boreholes. In this paper, the RFPA2D-Flow software is utilized to verify the experimental results of linear collaborative directional hydraulic fracturing

Quasi-brittle fracture properties of a medium-grain sandstone with an average grain size G around 0.3–0.4 mm were investigated under three-point-bending (3-p-b) conditions. In total, 95 specimens were tested with the beam width W varying from 10 to 300 mm, or the specimen-size/grain-size ratio from 30 to 900. 45 medium-sized specimens (W = 30, 60, 100 mm) were tested first to determine the tensile

Mode I fracture mechanics has been relatively mature but mixed mode fracture mechanics continues to present challenges, in particular for ductile materials under multiaxial stresses. Since most engineering materials, e.g., metals, exhibit elasto-plastic or ductile behaviour and are subjected to inclined cracks and/or multiaxial loading, there is a well justified need to establish a solid understanding