Additive manufacturing (AM) has garnered increasing attention in academic and research projects, based on its unique characteristics and favorable capabilities. Although three-dimensional (3D) printing technology was initially used for rapid prototyping, currently it is being utilized in manufacturing of final products. Considering various applications of 3D-printed components, investigation of their

In this work a new universal formula suitable for accurately describing the maximum normal stress distribution along the entire ligament of orthotropic plates weakened by central holes or symmetric lateral notches is provided. To this end, a recent analytical solution proposed to describe the local stress distributions in the close neighbourhood of U- and V-shaped notches is significantly improved

In engineering practice, rock masses are often subjected to cyclic loading. Under cyclic loading, the mechanical properties of rocks are significantly different from those under conventional loading conditions. The mechanical behaviour and fatigue of intact rock has been extensively studied. However, the mechanical fatigue properties of rock masses with surface cracks and related damage evolution models

In this study, for the first time, the load-carrying capacity (LCC) of test specimens containing U-shaped and V-shaped notches made of Al6061-T6 aluminum alloy under combination of out-of-plate shear and tensile loading (mixed mode I/III) is studied. U-notched specimens are made with different notch tip radii and V-notched specimens are made with different notch tip radii and notch opening angles.

A finite element-based method for accurately determining stress intensity factors (SIF) for interacting arbitrarily-shaped 3D cracks is proposed. The method utilizes the superposition principle and does not require fine meshes or singular elements. The foundation of the new method is that disturbances in an elastic stress field due to neighbouring cracks can be captured accurately by splitting the

In this paper, a systematic study on the effect of flaws on flexural strength of ultra-high temperature ceramics (UHTCs) was carried out by using three typical materials (i.e., ZrB2, ZrB2-SiC and ZrB2-SiC-G ceramics) containing micro-sized flaws with controllable sizes, shapes as well as orientations. Depending on the flaw sizes and orientations, different fracture modes were analyzed by SEM observation

Fatigue life prediction is one of the most important problems in design of industrial components made of defect-containing materials. Not only can defects existing in these materials significantly affect the mechanical properties especially fatigue behavior, but they also lead to considerable scatter in fatigue life. Therefore, a robust design methodology for these materials should consist of statistical

En-echelon joints widely exist in rock slopes and underground rock masses, which seriously threaten the stability of rock engineerings. Majority of earlier studies have focused on conventional continuous joint, while the shear behavior of en-echelon joints has rarely been studied, especially under constant normal stiffness conditions. Therefore, in this study, the direct shear tests of en-echelon joints

Ceramic-metal laminated composites consisting of alternating ceramic and metal micro-layers can create unique “structural or composite properties” superior to the material properties of individual constituent ceramics and metals. Those unique “composite or structural properties” cannot be adequately modeled by Linear Elastic Fracture Mechanics (LEFM) or Strength of Materials (SoM) since both models

A methodology is presented in this study for estimating the crack growth of austenitic stainless steel Types 304, 304L, 316, and 316L, which are commonly used as structural materials in nuclear pressure vessels. These structural components are typically subjected to neutron irradiation and combined loadings, including repeated mechanical stresses (i.e., fatigue) resulting from startups and shutdowns

The linear elastic and viscoelastic problems with V-shaped notches under in-plane loading are investigated in this paper. We consider two different sets of boundary conditions on the radial edges: Free-Free case and Clamped-Clamped case. A novel singular finite element (SASE) with arbitrary high-order accuracy for the notched problems is proposed. Firstly, via Laplace transform, the original viscoelastic

Hydrogen diffusion kinetics, which is influenced by the hydrogen trapping and de-trapping phenomena within the steel microstructure, plays an important role on the behaviour of steel components under hydrogen environments. Hence, the complex interaction between hydrogen atoms and steel microstructure must be analyzed in order to discuss the impact of hydrogen on the structural damage. Quenched and

The understanding of failure mechanisms of rocks containing multiple cavities is important for stability assessment of rock excavations in rock engineering applications. However, published research is still limited on the failure mechanism between cavities and quantitative assessment of the crack development characteristics for different cavity configurations. In this research, specimens containing

This work deals with the use of Boundary Element Method (BEM) formulations in fracture problems in a 2D approach. BEM is a suitable method for solving this type of problem, since the absence of a domain mesh translates into a more efficient modeling of regions with high stress concentration. Besides, reducing the dimensionality of the mesh results in a convenient remeshing process. Regarding the nonlinear

In this paper, the fracture behavior and acoustic emission (AE) characteristics of reinforced concrete under mixed mode I-II load conditions are studied using three-point bending beams with a straight offset notch. Different offset ratios, different crack-depth ratios, and different sizes of reinforced concrete specimens and a set of concrete specimens as a control group were explored. The critical

We extend Inglis’s two dimensional elliptic tensile crack solution in elastic material after visiting his original work in 1913. Solving static elastic equation of motion, we find a general elliptic crack solution in elliptic coordinate. We transform the solution from elliptic to that in rectangular coordinate system and derive a general singular stress and displacement field in the slit crack model

It is widely believed that the mechanical properties of concrete structures gradually deteriorate in a corrosive environment. However, it has been observed that the fracture toughness of concrete strengthens during the initial stage of sulfate attack. With the increase in the corrosion time, the fracture toughness gradually weakens. The main reasons for this contrasting response are as follows: (1)

This study aimed to clarify the implication of the stress amplitude of the no failure state at N = 107 cycles for commercially-pure titanium and the influence of the strain age hardening of commercially-pure titanium on the fatigue characteristics. To this end, rotating bending fatigue tests on smooth and notched specimens made of commercially-pure titanium were performed. After removing the oxygen

By using a combined real-time electrical resistivity measurement and ultrasonic wave testing method, the changes in the electrical resistivity and ultrasonic wave information during the crack initiation, propagation and coalescence process of saturated greensand stone under uniaxial loading were investigated, and a method to predict the location of the potential through cracks in the sandstone was

The mixed mode I/II/III translaminar fracture of a natural fiber reinforced composites system was investigated in this paper. The specimens were made of epoxy resin and fabric cotton fibers. Compact shear tension (CTS) test configuration was utilized to determine a full range of mixed mode I/II/III translaminar critical strain energy release rate (CSERR). The CTS specimens were loaded by a novel test

Extended finite element method (XFEM) and time integration by α-method are coupled in the direct integration scheme to study the 2D dynamic fracture of concrete gravity dam-foundation-reservoir interaction. The advantages of XFEM for the strong displacement discontinuity description of a crack and α-method for the time integration in dynamic analysis to dissipate the shockwaves after crack growth are

In high cycle fatigue, damage and plasticity occur at the microscale, a scale smaller than the representative volume element (mesoscale). Therefore, the two-scale damage model is used for fatigue life assessment. In this model, a spherical inclusion is assumed to be fully embedded in the matrix. However, experimental observations show that the microplasticity and microcracks nucleate more easily in

Residual stress variations were determined through small- and large-scale specimen welds using neutron diffraction to evaluate the effect of residual stress on the brittle crack propagation path. The results revealed that significant tensile stresses accelerated brittle crack propagation, while compressive stresses obstructed the brittle crack propagation path. The evaluations were performed using

Roller compacted concrete (RCC) is a zero-slump concrete that has been extensively used in road pavements. This concrete has been considered, due to its economic and environmental potentials, including reduced construction and maintenance costs and greater environmental compatibility. A unique feature of the Roller Compacted Concrete Pavement (RCCP) is its low water-to-concrete (WC) ratio. Hence, RCCP

Previous 2D studies and tests have mainly focused on the discontinuity of fracture structures along the flaw-inclination direction, and there has been little research into the discontinuity or concealment characteristics of flaws along the flaw-strike direction. To this end, hard brittle rock-like gypsum specimens containing two parallel flaws with three types of flaw-concealment conditions (with proportions

To accurately predict the delamination behavior, bridging effect should be introduced into the numerical model so that an effective method to determine the bridging law is required. The main effort of the current study is to propose an efficient procedure for determining the mixed-mode I/II bridging law of composite laminates. The crack opening and shear displacements at the pre-crack tip are derived

The tensile load at debonding onset between stiff particles and a soft matrix is predicted with the coupled criterion which combines a stress and an energy conditions. A finite element model of a representative volume element is implemented in order to consider the influence of the size of the particles, the particle volume fraction, mixed mode conditions at the interface and the presence of residual

This paper formulated and implemented a novel local continuum damage model to be used with a continuous or a continuous-discontinuous strategy to simulate crack growth in quasi-brittle failure for mode I and mixed-mode conditions. The damage model is based on an evolution law using only physical parameters, which can be obtained through fracture and resistance tests without the need for further calibration

In this paper, the nonlocal theory is utilized to deal with a Griffith crack problem under thermal-mechanical loading for the first time to eliminate stress singularity at the crack tip. A partially, thermally insulated Griffith crack subjected to a remote heat flux and mechanical loading is investigated. Fourier transform is employed to convert the mixed, boundary-value problem to two pairs of dual

In this study, the susceptibility of API X70 weld joints to hydrogen gas was investigated using slow strain rate tensile (SSRT) tests. The microstructure of the subregion of the actual heat-affected zone (HAZ) weld joint was reproduced by weld thermal-cycle simulation techniques. The SSRT results showed that the weld and cross-weld specimens had the highest hydrogen embrittlement (HE) susceptibility

Elastic-plastic failure of multi-cracked specimens made from epoxy material is studied theoretically and experimentally for the first time under mixed mode I/II loading conditions. Different cracks arrangements are considered for preparing the specimens. For providing different mixed mode I/II loading conditions in the fracture tests on epoxy specimens, different crack inclination angles are considered

Bimrocks feature stiff blocks randomly distributed in a soft matrix. Despite their wide distribution in nature, their significant effects on the failure of rock structures such as slopes, mines and tunnels have not been fully understood. Bimrocks behave differently as compared with other rock types since they contain mix of blocks of different strength, size and volume distribution and a matrix of

This paper introduces a new extended Voronoi cell finite-element method (X-VCFEM) for modelling the propagation of multiple cracks in brittle materials. The direction of the crack propagation is adaptively determined in terms of the maximum energy release rate near the crack tip, and we apply a remeshing strategy that a node at a last incremental crack tip in the crack advance process is replaced by

For engineering projects in cold regions, the failure behaviour of jointed rocks is affected by freeze–thaw (F-T) cycle action. To reveal the fracture characteristics of rock under the influence of cyclic F-T treatments, fracture tests on semicircular specimens with different F-T cycle numbers were conducted. The fracture toughness values in different modes were investigated by SCB specimens with different

Explaining crack propagation in uniaxially compressed brittle solids is challenging because the complexity of such fracture makes it impossible to estimate the compressive capacity of a solid subjected to uniaxial compression using a well-defined, widely applicable formula. Localized tension is typically generated at the tip of a void in a solid under uniaxial compression, so we focus here on the geometrical

Mixed mode I/II fracture criterion based on strain energy density theory is presented for failure investigation of cracked composite materials. Crack is assumed to occur along the fibers in a highly orthotropic body. A new definition for fracture toughness of crack tip damage zone is proposed and employed to include the effects of dissipated energy due to formation of considerable fracture process

In recent years the phase-field method and the coupled energy and stress-based criterion have attracted much attention due to their adaptability in modeling fractures. Both approaches have been successfully used to determine crack initiation and have compared well with real-life experiments. The phase-field method diffuses the crack surface into the volume of the solid, thus making the solution viable

In this paper, a block-based Galerkin free element method is presented for the calculation of J-integral and mix-model stress intensity factors. Based on the free element collocation method, the Galerkin weak-form is constructed to achieve more accurate results. By absorbing the advantages of SFEM and FBM, the sub-domain mapping technique is used to simplify the geometry and to avoid the appearance

In the current study, a multi-scale investigation on the crack propagation of B2-NiAl alloy was performed by using coupled molecular dynamics (MD) and the cohesive finite element method (CFEM). In particular, by using python programming, a FE model with a zero-thickness cohesive element for batch insertion was established. The T-S curve obtained from MD simulation was adopted as the material input

In a fracture analysis at elevated temperature, the determination of fracture parameter C* under steady-state creep is a crucial point. This paper proposes a rate-dependent energy release rate Ġ, by analogy with the definition of creep fracture parameter C* under steady-state creep. The relationship between Ġ and C* is deduced after a brief review of the definitions of parameters in fracture mechanics

We develop a hierarchical model for the description of the stress state inside a cluster of degenerated graphite in spheroidal cast iron. The model is based on the following simplifying assumptions: at the microscale, the graphite particles are viewed as elliptical pores; at the mesoscale, clusters of graphite particles are modeled as elliptical inclusions made of an equivalent porous elastic material

Cracks and joints generally exist in various underground structures, and affect the overall mechanical behaviour (strength, elastic modulus, fracture, etc.) of wall rocks significantly. Studying the crack failure behaviour in cracked tunnel samples containing single or multiple cracks can improve our understanding of the dynamic fracture mechanism of cracked tunnels. To investigate the dynamic fracture

Assessment of residual fatigue life of railway axles commonly does not include effect of residual stress. This paper presents advanced methodology for estimation of residual fatigue life of railway axles considering not only external loading but also internal residual stresses. The studied axles made of the EA4T steel were treated by induction hardening in order to generate very high compressive residual

Residual tensile strength (hereinafter abbreviated as ‘residual strength’) is a critical fail-safe consideration but has rarely been reported in the case of shallow pre-cracked structures. When the pre-crack depth is shallower than a critical value, the residual strength of cylindrical specimens made of interstitial-free steel exhibits a plateau identical to the tensile strength of smooth specimens

Most of the existing theoretical studies to predict 3D-crack-front shape change are confined to plate-like structures. In this paper, a transient three-parameter geometric model with fewer constraints located on equivalent deflected crack planes is developed by using space oblique extension circles for a transverse surface crack in a solid round bar under fatigue tension–torsion loading. The results

Multiscale modelling of damage in cement-based materials is mostly done through a downscale approach and constitutive laws are developed based on quasi-brittleness or cracking process within these materials. However, the microscopic characteristics of each phase in these materials need to be considered in order to accurately predict the durability. This article presents an experimentally-validated

Dynamic fatigue crack growth (FCG) under chaotic excitations has not yet received due attentions. The current paper presents an analytical model for predicting the FCG in a metallic notched beam subject to external chaotic excitations. The proposed stand-alone analytical model only requires the physical properties of the cracked beam; initial crack conditions; the material constants for the Paris power

This paper is devoted to numerical investigation of holes/voids effects on crack growth in solids using a locally refined (LR) B-splines extended isogeometric analysis (XIGA). We particularly focus our attention on crack-hole interaction analysis. Special enrichment functions captured discontinuity and singularity are used, by which the computational mesh is thus independent of both cracks and holes

Concrete is the most commonly used material in civil engineering and also the most conventional and cheap material available in the market. Concrete cracking and fracturing may cause irreparable damages to concrete structures. Hence, fiber-reinforced concretes have been introduced in recent years as a strategy to eliminate these drawbacks to a large extent. In this study, crack propagation and the

This article presents analytical methods for analysis of an inclined surface crack in an orthotropic medium subjected to contact loading. Governing partial differential equations are derived in accordance with plane theory of orthotropic elasticity. Contact and crack problems are formulated separately utilizing Fourier transformation techniques. The contact problem consists of a rigid flat punch pressing

This paper addresses a damage detection method based on changes in modal curvature combined with Convolutional Neural Network (CNN). The use of modal curvature for damage detection is very well known. Some methods require modal data of healthy structures as a reference, others do not. Gapped Smoothing Method (GSM) is a vibration-based damage detection methodology, which makes use of modal curvature

Meso-structural models are presently in common use for analysis of the mechanical behaviour, damage evolution and failure of concrete. These are constructed either from XCT images, or in silico, using statistical information about concrete’s meso-scale constituents. As a minimum, such models include mortar and aggregates as separate phases, while more detailed versions consider the interfacial transition

Regularities of acoustic emission (AE) signals’ formation during cyclic loading of turbine blades of different Ni-based superalloys and steel specimens were considered and systematized. AE activity can be related to strain energy density, and for the beginning period of the cyclically loaded blade the value of summarized AE signals Nae recorded in a short time can be used for characterizing the critical

The effect of confinement pressure on fracture toughness may be significant in materials with poor tensile strength, as is the case of most rocks. In fracking wells for hydrocarbon exploitation, rock fracture is induced by a pressurized fluid. Indirect estimates of rock toughness based on injected pressure and volume records are much larger than laboratory-measured toughness values. This article discusses

Spiral Notch Torsion Test (SNTT) was developed to measure the intrinsic fracture toughness of structural materials using small specimens. The SNTT system operates by applying pure torsion to cylindrical specimens with a notch line that spirals around the specimen at a 45° pitch. 3-D finite-element analysis has been used to estimate the fracture toughness obtained from SNTT test specimen with 3-D non-coplanar

One of the criteria in the structural design is the buckling stability of the components. In cracked plates, the buckling phenomenon can be affected by the cracks. Therefore, it is important to investigate the effect of crack length and location on the buckling behavior. In this paper, the buckling stability of plates with different sizes ranging from short to long off-center cracks was studied by