Measuring the fracture parameters of rock materials under real-time high temperature is of great significance for accurately evaluating the stability and safety of high-temperature underground tunnels. At present, the related research is focused on the fracture properties of rocks after treatment with high temperature. To this end, we independently developed a set of testing apparatus with effect of

Longmaxi shale exhibits strong anisotropy due to its bedding planes induced by diagenesis. The anisotropic properties of shale have a significant effect on the stability control of geotechnical engineering. To investigate the influence of anisotropy of shale on its mixed mode fracture toughness, we performed Brazilian disc splitting tests on hollow center cracked disc shale specimens with different

The effect of single peak overload on the crack propagation of selective laser melting Inconel 625 superalloy was investigated in this study. Irwin model and Shih model were used to calculate the plastic zone size. And Irwin model was in good agreement with experimental results. A model considering two plastic zone size weight was proposed. By comparison with the calculated results of theoretical models

In order to evaluate notch effects and size effects on fatigue performances, smooth specimens without stress gradient and a group of notched specimens particularly designed are investigated in this paper. From the perspective of probability, the statistical size effect of the latter is worth studying for bodies weakened by notches. A unified model of combination of the improved theory of critical distance

This paper analyzes via the size effect method, the induced anisotropy in the fracturing behavior of 3D printed parts made using Acrylonitrile Butadiene Styrene (commonly abbreviated as ABS). The aspects of fracturing behavior considered include the strength, fracture toughness, the nonlinear fracture process zone (FPZ) size, and the degree of quasibrittleness. 3D printed ABS specimens of various sizes

In this study, finite element analyses of Mode I loading of stationary cracks in in-situ bulk metallic glass composites (BMGCs) are performed under plane strain, small scale yielding (SSY) conditions. In the first part of this work, a thermodynamically consistent finite strain constitutive theory for BMGCs is employed to represent the entire domain. In this homogenized model, the soft crystalline dendrites

The wedge driven test is a valuable tool to determine the mode I fracture energy (GIc) of adhesives or interfaces in composites. At first glance, the test is simple enough (introduction of a wedge into the specimen midplane to progagate a crack) to be a good alternative to the standard method, the DCB test. However, friction between the wedge and the specimen’s arms is not properly dealt in existing

The adoption of carbon/glass fiber hybrid composites is an economical alternative to high-cost carbon/epoxy composites and helps to address environmental issues. However, the addition of another type of fiber modifies the mechanical behavior of the composite regarding interfacial interactions, consequently affecting other properties. Research related to three interfaces, with regard to hybrid composites

This paper presents a new set of novel special crack-tip elements for analysis of interface cracks in linear elastic composite bimaterials by using the boundary element method (BEM). Such interface crack problems present some simulation difficulties based on the conventional numerical methods because the asymptotic crack-tip fields in this case exhibit an oscillatory behavior which is quite different

To introduce more fibre-reinforced polymers in cars, the automotive industry is strongly dependent on efficient modelling tools to predict the correct energy absorption in crash simulations. In this context, an adaptive modelling technique shows great potential. However, as the critical energy absorption in a crash occurs over a very short period of time, and since the deformation behaviour is very

Flexible hybrid electronics (FHEs) are finding increasing applications because they overcome many of the limitations of non-deformable traditional electronic boards while still maintaining low-cost fabrication. A critical key to the performance of FHEs depends on the adhesion energy of the interface between printed conductive silver pastes and a flexible substrate. Predicting the fracture energy and

We employed a cohesive grain-based model (GBM) to investigate the mechanical behaviour and micro-cracking response of Neuhauser granite under direct tensile loading. The microstructural properties of Neuhauser granite were incorporated into the numerical model, and hourglass-shaped specimens were generated based on the geometrical configuration of specimens. We proposed an alternative calibration procedure

Thermal stimulation for shale gas reservoirs may cause water to evaporate, accelerate desorption of adsorbed gas and induce micro-scale cracking in shale matrix, which will increase shale gas productivity. However, few researches have been focused on the thermal micro-cracking behavior of shale matrix. In this paper, a novel energy functional considering the effect of thermal contribution and initial

The recently-developed finite-volume direct averaging micromechanics (FVDAM) with progressive damage simulation capability modeled using the cohesive zone model is critically and fully assessed vis-à-vis Abaqus, a widely-adopted commercial finite-element code with cohesive element for the first time. The evolving debonding along the fiber/matrix interface of a unidirectional metal matrix composite

A micromechanical study is carried out taking the initial expected damage that is manifested in a composite laminate by the debonding between the fibres and matrix in the 90° lamina as a reference. Questions such as the influence in the appearance of damage of the inter-fibre distance and the orientation of the fibres with respect to the loading direction are studied. Additionally, the effect of the

Dynamic response mechanism of CFRP (Carbon Fiber Reinforced Polymer) panel under high-speed ice ball impact was challenging to elucidate due to inherent heterogeneity and anisotropy properties. This further leads to difficulties in theoretical prediction of the damage threshold. Simulation modelling of CFRP panel subjected to high-speed ice ball impact was conducted in this study. Through coupling

To explore the nonlinear bond behavior between ribbed bar and concrete, considering frictional resistance and the mechanical interlocking between rebar and concrete as well as the surface characteristic of crescent ribbed bar, a 3D meso-scale modelling approach is established. Comparisons between the simulation and experimental results indicate that the meso-scale method can provide good predictions

This paper presents mesoscale thermo-mechanical analyses of plain (unreinforced) concrete based on the discrete element method (DEM). The proposed discontinuum modelling strategy represents the aggregates and matrix as a system of deformable polyhedral blocks, interacting along their boundaries. The nodal velocities of each block are calculated via the explicit integration scheme of DEM, and contact

A user defined cohesive material model is implemented in the LS-DYNA finite element code. The model is based on interface properties characterised from DCB specimens loaded with unequal bending moments. Different mode mixities are obtained by applying different ratios of moments to the two beams in the cracked part of the specimen. The mixed mode cohesive law is fitted for large scale bridging delamination

The deformation behavior, the fracture mechanism, and the mechanical properties of the Cu/Ta nanoscale metallic multilayers (NMMs) with the vertical and horizontal layers under the tension process are meticulously studied using molecular dynamics (MD) simulations. The influences of the various temperatures, strain rates and modulation periods (λ) are evaluated in detail through the dynamic responses

Dynamic wellbore stimulation technologies, such as high-energy gas fracturing, electrical pulse fracturing, hydraulic pulsation fracturing, are generally designed to multi-fracture the near-wellbore region through generating high energy pulse with intermediate or high loading rate. During the stimulating process, the dynamic strength and failure mode of saturated rocks around the wellbore can be largely

New lead-free solder alloys for electronic packaging contain doping elements conferring upon them improved properties in terms of ease of processibility and strength under high temperature operation conditions. Studies on their resistance to quasi-static rupture remain however relatively limited. In this work, the SAC-based solder alloy, known as InnoLot, is considered and its rupture under monotonic

Finite element (FE) simulations are performed to investigate the effect of fiber induced anisotropy on the notch behavior in hyperelastic skin type materials. The modified anisotropic (MA) model is used to define the constitutive behavior in FE simulations through Abaqus user defined material model UMAT. A parametric study is carried out to examine the effect of fiber orientation, notch root radius

This work performs acoustic emission monitoring of damage behaviors in carbon fiber/ epoxy composite laminates during tensile loads under hygrothermal environment. First, a waveform-based clustering method is introduced by employing the wavelet packet decomposition (WPD), the Shannon’s entropy, the cosine similarity and the clustering algorithm. Second, based on the clustering results, the characteristic

CO2-based fracturing was widely introduced to stimulate shale oil reservoirs for its multiple advantages. However, fracture height containment may become noticeable as the low-viscosity CO2 used in the shale with massive mechanically weak bedding planes (BPs). To address this issue, a novel CO2-gel fracturing design is introduced in this study. The design consists of initially pumping gel to break

An EA4T steel billet was forged at the different initial forging temperatures (1050, 1150, and 1250 °C). The microstructure and fatigue fracture of forged samples were observed by laser scanning confocal microscopy and scanning electron microscopy, respectively. The fatigue performance of samples forged at an initial forging temperature of 1250 °C was better owing to the presence of fine polygonal

The relation between stress collapse and nucleation of adiabatic shear band (ASB) remains incompletely understood. To further understand this topic, the evolution of shear deformation of Ti-6Al-4V alloy under forced shear loading is systematically investigated using digital image correlation (DIC) technique. DIC results indicate that ASB nucleates after the maximum stress and drastic stress drop corresponds

Multiple cluster hydraulic fracturing is widely used in the development of shale reservoir. The morphology of multiple fractures propagating from multiple cluster is complex due to the stress shadow effect. The design and operation of multiple cluster hydraulic fracturing in horizontal wells require adequate knowledge of the effect of different factors, including rock properties, in-situ stresses and

Large displacement has a considerable effect on determination of mode I interlaminar fracture toughness of composite. It is found that the mode I interlaminar fracture toughness of composite double cantilever beam (DCB) with piano hinge under large displacement is greatly underestimated by using the data reduction methods in the ASTM D5528 and ISO 15024 standards. The nonlinear J-integral, nonlinear

An error-driven grid refinement technique is introduced for 2-D reliable crack analysis by an enriched natural element method (more exactly, Petrov-Galerkin natural element method). A quasi-exact solution for a posteriori error estimation was obtained by enhancing the bare approximation solution of NEM (natural element method) using the enrichment method and the global patch recovery. The proposed

This paper presents a failure assessment curve (FAC), which predicts a conservative failure load of austenitic stainless steel pipes with a circumferential surface crack. Changes in material deformation properties due to cold working, neutron irradiation and thermal aging were taken into account. First, stress-strain curves for stainless steels were assumed for welded, irradiated, cold worked, thermal

TiB-reinforced Ti-3Al-2.5V, in which TiB whiskers are oriented parallel to the direction of heat extrusion, was fabricated. To investigate the effects of TiB whisker orientation on fatigue properties in Ti-3Al-2.5V, four-point bending fatigue tests were conducted for plate-type specimens having three different orientations of TiB whiskers. The fatigue limit and fatigue life of Ti-3Al-2.5V having TiB

Copper (Cu)-filled through silicon (Si) via (CF-TSV) acts as an electrical conduit between different layers of circuitry in the advanced microelectronic devices. Due to wide difference in the coefficient of thermal expansion between Cu and Si, large thermal stresses get generated in both Si and Cu during the inevitable thermal excursions taking place during fabrication of microelectronic devices and

Cracked pavements can be subjected to out-of-plane sliding or mode III deformation due to movement of vehicles. In order to design suitable asphalt mixture for manufacturing high resistance pavements against mode III failure, it is necessary to determine a characteristic parameter called mode III fracture toughness (KIIIc) for these materials. In this research a comprehensive experimental study is

This paper presents the integrity analyses of a model reactor pressure vessel (RPV) subjected to pressurized thermal shocks (PTS). The analyses are performed with a one-way multi-step strategy that includes the thermo-hydraulics, thermo-mechanical and fracture mechanics analyses to simulate three hypothetical loss of coolant accidents (LOCA). The thermo-hydraulics analyses are performed with the system

This paper presents modeling of the tensile and failure behavior of different nodular cast iron microstructures under variable stress triaxialities. The model is based on a Representative Volume Element (RVE) approach, which reproduces periodic stochastic distributions of nodules within a 3-D cell. Three cast iron matrices, from fully ferritic to fully pearlitic, are considered as representing the

The current study presents a novel test method to experimentally cancel out the thermal stresses in dissimilar material joints. For the commonly used double cantilever beam test the presence of thermal stresses results in a significant mode mixity at the crack tip, which varies with applied load even if the elastic properties of the adherends are similar. This is particularly a challenge for fibre

The statistical inference of the Equivalent Initial Flaw Size Distribution (EIFSD) is developed for the first time using the Dual Boundary Element Method (DBEM) for assembled shear deformable plate structures. As part of this inference procedure, Bayesian updating is employed to enable the continuous refinement of the EIFSD via data obtained by many simulated routine inspections of a stiffened panel

The purpose of this paper is to study the interaction between multiple elliptical inclusions and straight cracks in a finite plate due to a uniform temperature change. In this solution, Eshelby’s equivalent inclusion method involving both interior Eshelby’s tensor and exterior Eshelby’s tensor is applied to calculate the thermal stress fields of an infinite plate containing multiple elliptical inclusions

The fundamental aspects of fatigue fracture mechanisms (crack onset and propagation) in riveted single lap joints of fiber-metal laminate have been disclosed through extensive failure analysis of double-riveted 2/1 Glare™ laminate layup. Three fatigue fracture mechanisms, namely, rivet fracture, Glare laminate cracking and fretting-fatigue have been determined as function of the peak stress. The roles

Cyclic hydraulic fracturing has been proved to be an effective stimulation technique to explore EGS resouces. The shear friction behaviors under cyclic normal stress are essential to understand the hydro-shearing mechanisms. This paper proposed a cyclic shear friction test to understand the friction characteristics of granite fracture during cyclic hydraulic fracturing. A cyclic normal force in sinusoidal

Phase Field Method (PFM) has remarkable performance in simulating crack patterns with complex topology and the edge-based smoothed finite element method (ES-FEM) has intrinsic advantages in modeling the fracture behavior at large deformation. A phase field fracture model for modeling hyperelastic material at large deformation is proposed based on ES-FEM. The weak forms and numerical framework of proposed

Ductile tearing resistance of a 1 mm thick interstitial free steel sheet has been characterized using single edge notched tensile (SENT) specimens with or without fatigue precracks at quasistatic strain rates. In this study, the critical Crack Tip Opening Angle (CTOA), and also crack initiation parameters, namely the initiation energy per unit ligament area (wi), critical value for the J-integral (Jc)

The widespread occurrence of heterogeneous mudstone poses several challenges for the stability of engineering structures. To understand the failure mechanism of argillaceous projects, and reveal the heterogeneity of mudstone, the mechanical properties of mineralogical compositions in mudstone were investigated, by using the nanoindentation technique at the meso-scale. Through “X-ray diffraction (XRD)

Three-dimensional (3D) braided composites have broad development prospects in various industries. This paper establishes a real parametric finite element model (FEM) to conduct progressive damage analysis and strength prediction for 3D braided composites. 3D FEM is established with consideration of the cross-section deformations and surface contact of adjacent braiding yarns. Subsequently, 3D Hashin

This paper describes a mixed extended finite element (XFEM) formulation that can handle nearly incompressible material behaviour for fracture mechanics problems as well as for heterogeneous materials under small and finite elastic and elastoplastic deformations without showing locking behaviour. Typical applications are the simulation of cracks and their propagation in rubber materials, microstructure

In this paper, an efficient stress recovery technique is presented to estimate the recovered stress field at the nodal points. The feed–forward back–propagation multilayer perceptron (MLP) neural network approach is employed to improve the accuracy of the stress recovery method. An automatic adaptive mesh refinement is performed based on a–posteriori Zienkiewicz–Zhu error estimation method. The proposed

In this study, the dynamic fracture coalescence of Fangshan granite specimens was studied using the Split Hopkinson Pressure Bar system. Two prefabricated surface cracks with varying inclination angles and inner tip distances were applied to the granite specimens. Two high-speed cameras were set up on two sides of the specimens, one for the side with speckles and the other for crack propagation. According

In view of the large difference between the traditional unit-cell model (UCM) and the actual microstructure of 2.5D woven composites, which will affect the mechanical properties and failure behavior, a representative volume element (RVE) modeling strategy considering the randomness of weft cross-section (WFCS) is developed, and the established model is called statistical volume element (SVE) in this

For the first time, performance of the Equivalent Material Concept (EMC) in investigating fracture of V-notched ductile members subjected to mixed tension/out-of-plane shear loading, so-called mixed mode I/III loading, is examined. On the basis of EMC, a ductile material can be equated with a virtual brittle material in order to avoid conducting elastic–plastic analyses. In the present research, a

A normalized equivalent initial flaw size method is proposed based on the updated Kitagawa–Takahashi diagram considering the small crack growth behavior, which is essential to accurately predict the fatigue crack initiation and propagation. Meanwhile, the updated Kitagawa–Takahashi diagram indicates that small cracks can propagate even with an applied stress below the fatigue limit, which is consistent

The ductile crack initiation of structural steels due to ultra-low cycle fatigue (ULCF) loading often governs the limit state in steel structures. This paper proposes a modified Coffin-Manson model for ULCF fracture of structural steels considering the effect of stress triaxiality. To this end, tests on coupon specimens and circular notched specimens made of Chinese Q345qC steel were conducted to form

The effect of temperature and holding time on the dwell–fatigue crack propagation behavior of a novel tempered martensitic ferritic steel G115 was studied. The crack growth duration greatly increased with the increase in dwell time at all tested temperatures (625–675 °C). The FCG data and the da/dN for the 60-s dwell tests remained nearly constant when the temperature increased from 625 to 650 °C,

Geothermal energy has been widely proposed as a potential renewable energy to replace traditional fossil fuel energy. Deep buried geothermal reservoirs are usually called Hot Dry Rock (HDR) or Enhanced Geothermal Systems (EGS). Hot dry rock (HDR) reservoirs are the main geothermal energy resources, and usually consist of low-permeability hard granite without fluid. Developing HDR requires water cyclically

Discontinuities widely exist in natural rocks. To investigate the progressive micro-cracking process and failure mechanism of fissured rocks, a series of biaxial compression tests were conducted on sandstone specimens containing two parallel filled flaws using acoustic emission (AE) analysis synchronized with digital image correlation (DIC) monitoring. Experimental results show that the peak strength