A discontinuous Galerkin (DG) isogeometric analysis (IGA) formulation with peridynamic (PD) model is proposed for the simulation of cracks in shell structure. A micro-beam PD bond which considers the planar, bending and shearing deformations of shell is applied. Then, based on the micro-beam bond, the peridynamic integral equation is implemented via DG formulation of a conventional isogeometric element

In this work, we study shape optimization problems in the Stokes flows. By phase-field approaches, the resulted total objective function consists of the dissipation energy of the fluids and the Ginzburg–Landau energy functional as a regularizing term for the generated diffusive interface, together with a Lagrangian multiplier for volume constraint. An efficient decoupled scheme is proposed to implement

The latest generation wafer scanners use extreme ultraviolet light to project a pattern of electronic connections onto a silicon wafer. A significant part of the projection light is absorbed by the mirrors in the projection system. This causes the mirrors to heat up and expand, which leads to a significant reduction in the imaging quality of the wafer scanner. The imaging quality can be improved by

This paper presents a numerical analysis for the time-implicit numerical approximation of the Boltzmann equation based on a moment system approximation in velocity dependence and a discontinuous Galerkin finite-element (DGFE) approximation in time and position dependence. The implicit nature of the DGFE moment method in position and time dependence provides a robust numerical algorithm for the approximation

The mutual interactions between intrinsic (damage) and extrinsic (shielding) mechanisms are essential for understanding fatigue crack growth in ductile materials. In the latter case, plasticity-induced crack closure is the dominating retardation mechanism in the Paris regime. The transition between plane strain and plane stress states leads to a locally different fracture surface contact, which is

The assumption of the detail categories in EN1993-1-9 is the presence of a certain weld quality level. In order to find out the sensitivity of the resulting fatigue strength for cases where a worse or better quality level compared to the selected level of EN ISO 5817 is achieved, in this paper, special fatigue experiments are presented. The experiments refer to the load-carrying cruciform joint with

The tubeless vortex reducer was used to reduce the pressure drop in a cavity with radial inflow. In previous studies, the mechanism of vortex breakdown in tubeless vortex reducers was not clear, and there was a lack of direct guidance for engineering design. In this paper, we studied the vortex and pressure in the cavity in detail by large-eddy simulation (LES) and experiments. A mathematical model

The rapid development of additive manufacturing (AM) offers new opportunities to fabricate multi-material structures, whose performance can be optimized by the integrated design of multiple materials distribution and their interface behaviors. However, the graded-interface assumption between different materials often caused some numerical difficulties during topology optimization, e.g., poor applicability

The peak stress method (PSM) is a rapid, FE-oriented method to evaluate notch stress intensity factors. In fatigue design of welded components, the PSM has been previously validated against more than 1300 experimental data to estimate the lifetime of steel welded joints under constant amplitude (CA) loadings. In the present work, the PSM has been extended to account for variable amplitude (VA) uniaxial

This work develops a dynamic linear homogenization approach in the context of periodic metamaterials. By using approximations of the dispersion relation that are amenable to inversion to real-space and real-time, it finds an approximate macroscopic homogenized equation with constant coefficients posed in space and time; however, the resulting homogenized equation is higher order in space and time.

Computational models of the human head are promising tools for estimating the impact-induced response of the brain, and thus play an important role in the prediction of traumatic brain injury. The basic constituents of these models (i.e., model geometry, material properties, and boundary conditions) are often associated with significant uncertainty and variability. As a result, uncertainty quantification

Suffusion refers to the detachment and migration of fine particles through voids among coarse particles and is one of the major causes of slope failure. This study investigates the seepage-induced suffusion and slope instability using a hierarchical multiscale finite–discrete element method (FEM–DEM). An erosion law with the critical hydraulic gradient for the onset of suffusion is proposed. Two examples

The nearly singular integral, arising in simulating thin coatings or close-boundary physical quantities, are not adequately dealt with in the isogeometric boundary element method (IGABEM), especially in 3D problems. In this paper, we propose a semi-analytical approach for the nearly singular integrals of 3D potential problems. We first expand all the kernel items by Taylor series up to second order

We consider fully discrete embedded finite element approximations for a shallow water hyperbolic problem and its reduced-order model. Our approach is based on a fixed background mesh and an embedded reduced basis. The Shifted Boundary Method for spatial discretization is combined with an explicit predictor/multi-corrector time integration to integrate in time the numerical solutions to the shallow

In this paper, the authors propose a dimension reduction level set method (DR-LSM) for shape and topology optimization of heat conduction problems on general free-form surfaces utilizing the conformal geometry theory. The original heat conduction optimization problem defined on a free-form surface embedded in the 3D space can be equivalently transferred and solved on a 2D parameter domain utilizing

Abstract not available

Tooth flank fracture (TFF) is a fatigue failure mode in gears in which the crack is initiated in a larger depth below the surface within the tooth volume. The crack propagates load-dependently and is not visually observable until final rupture of the tooth. The present publication focuses on numerical fatigue crack simulation of TFF in case-hardened spur gears. Herein, an existing phase-field model

A probabilistic model for estimating the fatigue life of composite laminates based on the mean value and standard deviation of the fatigue life is introduced here for predicting the distribution of fatigue life at any stress level for a constant stress ratio. The proposed model is validated with experimental data for several composite materials, and its accuracy is evaluated by goodness-of-fit-statistical

To investigate the hard-to-measure complex flow in a squirrel-cage fan, a slice model was established in the present study to perform a partial large eddy simulation calculations on an r-θ sectional flow field instead of the large-scale and time-consuming full three-dimensional flow calculations. The method used to build the slice model was first introduced, and then the model was verified by the results

This work undertakes the analysis of continuous media that carry simultaneously two different material or geometric structures in the same material substrate. Even when these two structures are individually perfectly uniform and homogeneous, their combination may result in a non-uniform assembly. Thus, in contradistinction to the classical interpretation of material defectivity as a manifestation of

Slip along a frictional contact between elastic bodies can be stable or unstable, leading to stick-slip motion. Frictional slip can also be associated with vibrations. The condition for these vibrations and their characteristics remains poorly understood. To address this issue, which is relevant to engineering and earth science, we carry out a linear stability analysis of a spring-and-slider system

Elastomeric membranes are flexible and stretchable, commonly found in soft devices, soft robotics, and flexible electronics. The indentation of free-standing elastomeric membranes induces large transverse deflection, leading to the puncture of elastomeric membranes. In this paper, we study the indentation and puncture of elastomeric membranes by sphere-tipped indenters. Effects of the indenter tip

Living cells are a complex soft material with fascinating mechanical properties. Confusingly, experiments have shown that cells exhibit stiffening and more solid-like behaviors under uniaxial stretches or shear, while they present softening and more fluid-like behaviors under biaxial stretches. For both of these seemingly paradoxical stiffening and softening rheological behaviors, cells often exhibit

In this manuscript, we expand the conforming to interface structured adaptive mesh refinement (CISAMR) algorithm for modeling complex two-dimensional (2D) crack growth problems involving contact/friction along the crack surface and interaction between multiple cracks. The CISAMR algorithm transforms a structured mesh into a high-quality conforming mesh non-iteratively, which is an attractive feature

A topology optimization formulation including a model of the layer-by-layer additive manufacturing (AM) process is considered. Defined as a multi-objective minimization problem, the formulation accounts for the performance and cost of both the final and partially manufactured designs and allows for considering AM-related issues such as overhang and residual stresses in the optimization. The formulation

This paper presents and validates a new local to global (L2G) FEM approach that can analyze multiple, interactive fracture processes in 2D solids with improved numerical efficiency and robustness. The method features: 1) forming local problems for individual and interactive cracks; and 2) parallel solving local problems and returning local solutions as part of the trial solution for global iteration

This work presents a Streamline-Upwind Petrov–Galerkin (SUPG) framework with finite elements discretization for the prediction of non-ionized hypersonic flows in thermal non-equilibrium. The formulation is enhanced with a residual-based discontinuity-capturing (DC) operator. The numerical framework solves the set of Navier–Stokes equations for the compressible reacting flows with an additional equation

The development of an elasto-plastic phase-field model is presented which is able to predict nonlinear behavior of high performance concrete (HPC) during low-cycle fatigue. An elasto-plastic damage model which follows the Drucker–Prager yield criterion is formulated. For the modeling of unsymmetric tension–compression behavior of HPC two different continuous stepwise linearly approximated degradation

This paper presents a kinematically consistent second-order computational homogenisation scheme for shear deformable shells. The proposed framework can accurately evaluate the membrane, bending, and transverse shear components of the shell resultants and tangent operators, whilst showing no size dependency on the fine scale model. To date, a proper extension of second-order homogenisation to a thick

The effect of single overloads on the threshold of stress intensity range of a semi-brittle material, a γ-titanium aluminide, was analysed. This material class exhibits a pronounced R-curve behaviour, which is mainly caused by the formation of shear ligaments, crack deflection and branching. Samples with short cracks on deep sharp notches were subjected to overloads of 80 % of the fracture toughness

In the present paper, a novel criterion for fatigue life assessment of engineering components under multiaxial low-cycle fatigue regime is proposed. The criterion, named Refined Equivalent Deformation (RED) criterion, allows to take into account, when the load is non-proportional, the fatigue strength decrease experimentally observed for those metals sensitive to non-proportionality. The criterion

Freeze-thaw action of rocks has caused many engineering geological disasters in cold regions. Estimation of the freeze-thaw damage degree and strengths loss of rocks are crucial for the prevention of freeze-thaw disasters. The main aim of this research is to investigate the influence of water saturation on the deterioration of rocks under freeze-thaw and find the best evaluation index. P-wave velocity

This work performs a detailed analysis of the cracks obtained in fretting fatigue tests with cylindrical contact in the presence of a small oscillatory rolling of the contact pad. To do so, fretting fatigue tests have been carried out. Preliminary observations indicate that the contact area is larger than the theoretical one according to Hertz’s theory. This could mean that, due to the contact geometry

This work applies Taylor’s Theory of Critical Distances (TCD) to assess the fatigue strength of defect-afflicted cast steel components made of G21Mn5+N. Based on radiographs of complexly shaped spatial imperfections, the established TCD-framework leads to a sound agreement of numerical and experimental fatigue strength. Moreover, a novel fatigue assessment methodology is presented, which bases on the

Cellular uptake of nanoparticle (NP) is an important biological process involving mechanically and structurally heterogeneous environments, such as biophysical heterogeneity of single extracellular vesicles and biomechanical heterogeneity of small viral capsids. Despite of these heterogeneous environments, poor understanding of membrane interacting with vesicle NP of non-uniform mechanical properties

Motivated by a simplified model for atomic structures, and based on the concept of objective structures in R3, we introduce a type of subsets of Rn that we call locally translation-isometric sets (LTI sets). These sets are defined by the property that the ɛ-neighborhoods around every point in them are isometric copies of each other. For n=3, in the case ɛ=∞ they are simply objective structures and

The aim of this paper is to analyze the integration for 3D isogeometric finite element method solvers and its effective scheduling on hierarchical computer architecture. Data necessary for concurrency over elements is independent, so computation on this level is trivially concurrent. However, constructing several layers of concurrency for the integration algorithm is challenging. In this work, we propose

Abstract not available

The effect of cold spray coating parameters on the fatigue life and cracking mechanism of AZ31B-H24 coated with AA7075 powder is investigated. Two sets of coated samples are fabricated based on the selection of different coating parameters. An in-situ control of heat transfer is performed to obtain different residual stress states and microstructure at the aluminum/magnesium interface. Subsequently

This paper presents the results of fatigue tests conducted on Ti6Al4V titanium alloy with diamond structure obtained by the Laser Power Bed Fusion method. Samples used in tests were printed with porosities: 81%, 73%, 50%, 34% and near-zero porosity. Samples were subjected to cyclic tests with a constant stress amplitude. The number of cycles until sample failure was registered. Obtained fatigue test

In this paper, a modified intermediately homogenized peridynamic (IH-PD) model for analyzing impact failure of wet concrete has been presented under the configuration of ordinary state-based peridynamic theory. The meso-structural properties of concrete are linked to the macroscopic mechanical behavior in the IH-PD model, where the heterogeneity of concrete is taken into account, and the calculation

Damage evolution in concrete after high temperature is a complicated procedure, in which the pre-peak strain hardening behaviour, the post-peak strain softening behaviour and the impact of high temperature play key roles. Uniaxial and biaxial compression damage models of concrete considering high temperature degradation effect are proposed based on damage theory and experimental phenomena. They consider

We consider the neural network approximation of systems of partial differential equations exhibiting multiscale features such as the Reissner–Mindlin plate model which poses significant challenges due to the presence of boundary layers and numerical phenomena such as locking. This work builds on the basic Galerkin Neural Network approach established in Ainsworth and Dong (2021) for symmetric, positive-definite

In this work, we establish a goal-oriented space–time finite element method for a class of dissipative heterogeneous materials. Those materials are modeled on both micro- and macroscale, with a scale transition of volume averaging type satisfying the Hill–Mandel condition. A nonuniform transformation field analysis is performed on the microscopic inelastic strain fields for a model reduction. Reduced

In this work, a method for the simulation of guided wave propagation in solids defined by implicit surfaces is presented. The method employs structured grids of spectral elements in combination with a fictitious domain approach to represent complex geometrical features through signed distance functions. A novel approach, based on moment fitting, is introduced to restore the diagonal mass matrix property

In the present work, the microstructures and mechanical properties of additively manufactured IN718 alloy were studied and the dendritic columnar microstructures elongated along the building direction are related to macroscopic mechanical properties. Detailed experiments under both proportional and non-proportional multi-axial loading conditions indicate that the influence of the building orientation

Steel catenary risers, subsea flowlines and pipelines that are used to transport oil and gas products are susceptible to corrosion fatigue in environments containing CO2 or H2S, termed sweet and sour respectively. Fatigue crack growth rates (FCGRs) in such environments are generally enhanced compared to that in air due to crack tip dissolution or the embrittling effect of ingressed hydrogen generated

The wind resistance of a model of a large container ship was investigated experimentally and numerically under various conditions to investigate the aerodynamic performance and identify approaches for reducing wind resistance. The container ship model with and without six types of forecastle fairing was tested in a wind tunnel under conditions of full load and various uneven loads in different wind

The hydraulic joint is the key driving component of a robot. To reduce the joint size of the hydraulic robot, and improve the control accuracy and dynamic response performance, this paper proposes a novel joint structure and control method of a ball double-screw hydraulic robot. Using ball and circular arc spiral groove transmission, the hydraulic joint has a small transmission friction coefficient

In fatigue life prediction of single crystal gas turbine blades, the risk of rapid crystallographic crack growth along the close-packed planes poses a large uncertainty. A criterion is proposed to predict the transition from mode I to crystallographic crack growth, which is necessary for reliable prediction of the number of cycles from crack initiation to the onset of crystallographic crack growth

The methodology previously proposed by the authors to solve particle-laden turbulent flows through a multiscale approach is extended by introducing a continuous function for the dispersed phase concentration. The proposed continuous model is especially useful for studying the motion of particle streams in which gravitational and inertial effects cause the particles to deviate from a simple trajectory

We present a comprehensive study on the approximation power of NURBS and the significance of exact geometry in stability analyses of shells. Pre-buckling analyses are carried out to estimate the critical load levels and the initial buckling patterns. Various finite element solutions obtained with the commercial code ANSYS are compared with solutions from the isogeometric version of the finite element

In this paper the Fourier series is used to evaluate mode I Stress Intensity Factors (SIF) in three-dimensional planar flaws based on a distortion transformation of a reference disc. Under the hypothesis of an isolated crack, the SIF at each point of the crack border is calculated to assess the crack shape after propagation according to the crack growth rate equation of Paris and Erdogan. The contour

The remaining useful life (RUL) prediction has an important guiding role in the preventive maintenance of wind turbine generators (WTGs). In this article, a real-time dynamic perception model of the RUL prediction is proposed for WTGs, which contains the multi-state parameters processing, the performance degradation analysis, the performance degradation prediction and the RUL prediction. First, the

Abstract not available

Mode II fatigue crack growth under reversed shear and static biaxial compression was investigated in two bearing steels. Many aborted branches, quasi-orthogonal to the main crack, were observed along the crack face. The compressive stress parallel to the main crack hindered the growth of these branches and favored coplanar mode II crack growth. The crack face sliding displacement profiles measured