The strength criterion of graphene grain boundaries (GBs) under complex stress states plays an important role in guiding the design of high-performance graphene-related materials and devices under severe mechanical environments like ultrastrong structural materials or flexible electronics. However, finding a unified strength criterion that can adapt to different GB angles and loading states is still

Fatigue life knockdown due to surface roughness induces local stress concentrations. Physical fatigue experiments are crucial to qualify materials for use but are limited in their capability to examine the mechanisms underlying the fatigue crack formation driving force due to these stress concentrations. Microstructure-sensitive computational models can aid in this regard and are employed in this work

We present an efficient algorithmic framework for constructing multi-level hp-bases that uses a data-oriented approach that easily extends to any number of dimensions and provides a natural framework for performance-optimized implementations. We only operate on the bounding faces of finite elements without considering their lower-dimensional topological features and demonstrate the potential of the

This paper investigated the damage healing, local life compensation and intrinsic healing characteristics of asphalt binder. The damage healing (ΔS) is independent of damage level and the percent local life compensation (%ΔN) increases with a higher strain amplitude in TSH test. The integrated ΔS-ΔN analysis is recommended for the healing compensation characterization. The totally stored pseudo strain

In this study, a nickel-based powder metallurgy alloy was processed via turning, ceramic bead peening, and shot peening by high-intensity cast-iron shots and low-intensity ceramic beads (denoted as compound shot peening). We investigated the surface morphology (surface stress concentration factor, Kst), the surface residual stress profile, microstructure, and the hardness gradient of three surface

In this paper, third-harmonic phase velocity matching nonlinear Lamb waves are used for the early fatigue damage detection of aluminum alloys. An analysis is conducted regarding the relationship of third harmonic and third-order nonlinear parameters with fatigue accumulation. According to the analytical results, the amplitude of the third harmonic increases when the fatigue life falls below about 80%

This study examined the effects of ultrasonic shot peening (USSP) and stress relieving treatment at 400°C (USSP-SR) on low cycle fatigue behaviour of Ti-13Nb-13Zr alloy. The Un-USSP, USSP and USSP-SR samples were characterized for microstructure, surface roughness, hardness and low cycle fatigue. The surface microstructure of the USSP and USSP-SR specimens was refined to ∼35 nm. At strain amplitudes

A dislocation movement-based physical failure indicator parameter (FIP) was proposed and incorporated into crystal plasticity finite element to assess the damage for components subjected to low cycle fatigue (LCF) and creep-fatigue interaction (CFI) loadings. The concept of net slip was introduced through the distance of dislocation movement whose evolution was analyzed and compared with other FIPs

Reducing the intensity of wind excitation via aerodynamic shape modification is a major strategy to mitigate the reaction forces on supertall buildings, reduce construction and maintenance costs, and improve the comfort of future occupants. To this end, computational fluid dynamics (CFD) combined with state-of-the-art stochastic optimization algorithms is more promising than the trial and error approach

Understanding fluid–structure interaction (FSI) is important because it dominates diverse natural phenomena and engineering problems. This paper presents an integrated particle model for FSI problems involving irregular channel flows and crack propagation in structures. The proposed model is implemented as follows: (1) we couple weakly compressible smoothed particle hydrodynamics (WCSPH) with bond-based

We present a novel particle-based computational framework for the numerical simulation of dynamic crack propagation in functionally graded materials under highly dynamic loading conditions and large deformations. The approach is based on an innovative computational method that solves phase field of brittle fracture with smoothed particle hydrodynamics. The meshfree nature of the discretization technique

Wire arc additive manufacturing (WAAM), also known as directed energy deposition (DED) process, is an efficient additive manufacturing technology, offers high potential to rapidly fabricate large-scale parts with complex geometries layer-by-layer. However, the fundamental understanding of the fatigue behaviour of such parts and the material requirements need to be significantly improved at all levels

Immersed boundary methods (IBMs) are versatile and efficient computational techniques to solve flow problems in complex geometric configurations that retain the simplicity and efficiency of Cartesian structured meshes. Although these methods became known in the 1970s and gained credibility only in the new millennium, they had already been conceived and implemented at the beginning of the 1960s, even

Oceanic motions with spatial scales of 200 m–20 km, called submesoscales, are ubiquitous in the upper ocean and serve as a key intermediary between larger-scale balanced dynamics and unbalanced turbulence. Here, we introduce the fluid dynamics of submesoscales and contrast them with motions at larger and smaller scales. We summarize the various ways in which submesoscales develop due to instabilities

ABSTRACT Due to frequent drought events, increased water demand for agricultural production and limited, accurate estimation of reference evapotranspiration (ETo) is necessary for developing crop irrigation schemes and rational allocation of regional water resources. The extreme learning machine (ELM) was optimized using four biological heuristic algorithms, namely, Grey Wolf Optimizer (GWO-ELM), Moth-Flame

Blockages are commonly formed in fluid pipelines such as water supply systems, which may greatly affect the internal flow states and conveyance capacities. This paper investigates the transient behavior of a pressured water pipeline with blockage under different transient wave perturbations based on the Computational Fluid Dynamics (CFD) model. To this end, a water pipeline is modeled in a 2D axisymmetric

Viscoelasticity and roughness are among the possible causes of the adhesive hysteresis displayed by soft contacts. Viscoelasticity causes an increased effective work of adhesion due to stiffening of the contact, while roughness is responsible for elastic instabilities. Herein, we explore the interplay between viscoelasticity and roughness by simulating in two dimensions the retraction of a rigid cylinder

In this paper, a new response spectrum method is proposed for high-cycle fatigue damage assessment of a linear multi-degree-of-freedom system subjected to random base acceleration. Mode damage response can be accessed by separating the modal participation factor and stress mode from the contribution of a mode to the total damage, assessed by the Single Moment method. The fatigue damage response spectrum

In recent thermal gradient mechanical fatigue (TGMF) investigations, it is verified that the material fatigue lives are significantly affected by the temperature gradients. Determination of temperature gradients of thin-walled structures is always a difficult task. In the present work, tubular specimens were experimentally and computationally investigated under different conditions. The inverse heat

Engineering components often operate under complex loadings, in which the variable amplitude multiaxial stresses are raised by geometric discontinuities including holes, grooves, fillets and shoulders, etc. Besides, the non-proportional loading will lead to the rotation of maximum principal stress/strain and additional fatigue damage of structural elements in service. Consequently, the multiaxial and

It is essential for car manufacturers to ensure their vehicle robustness under a daily usage. As no detailed method nor standard prevails, each manufacturer is expected to setup its own methodology for safety parts life-assessment. The early stages of a renewed methodology are proposed in this study. This is based on proving-grounds measurements analysis to quantify the impact of various loads. The

In this study, based on the nominal stress method and the influence of stress gradient on fatigue life, a fatigue life prediction method combined with the Weibull distribution is proposed. Firstly, the strain energy density is defined as the damage parameter to determine the location of the critical plane. Then, the equivalent stress function is established by extracting the equivalent stress of the

Progressive degradation of material mechanical properties in the low cycle fatigue (LCF) and creep-fatigue (CF) interaction at high temperature affects the safe operation of in-service materials. By considering material degradation, the present work aims to establish a method for evaluating LCF and CF damage levels with wide applicability. Material-level data accumulations as well as theoretical foundations

We propose a new approach for unsupervised learning of hyperelastic constitutive laws with physics-consistent deep neural networks. In contrast to supervised learning, which assumes the availability of stress–strain pairs, the approach only uses realistically measurable full-field displacement and global reaction force data, thus it lies within the scope of our recent framework for Efficient Unsupervised

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Abstract not available

The work presents the numerical implementation of the multiplicative hyperelastic-based Extended Subloading Surface model. The theoretical development of the constitutive equations of the unconventional plasticity theory has already been formulated in the literature. However, its application to finite element simulations has been not proposed yet. In particular, this paper discusses in detail the adaptation

The phase-field microelasticity theory of Khachaturyan has been widely applied in materials science that is based on the small strain assumption. Here we develop an incremental realization of inelastic deformation (IRID) algorithm to deal with finite/large deformation with yet small elastic strain. A large deformation process is decomposed into a sequence of small deformation processes with intervals

This article presents a hybrid IBM/CGM scheme for the study of two-dimensional orbital regimes of flexible and inextensible filaments in low-Reynolds number shear flows. The study includes a parametric analysis of the mechanical response for a range of the filament length, bending rigidity and shear-strain rate. The results are compared to theoretical estimates and previous numerical and experimental

This work develops a numerical solver based on the combination of isogeometric analysis (IGA) and the tensor train (TT) decomposition for the approximation of partial differential equations (PDEs) on parameter-dependent geometries. First, the discrete Galerkin operator as well as the solution for a fixed geometry configuration are represented as tensors and the TT format is employed to reduce their

Physics informed neural networks (PINNs) are capable of finding the solution for a given boundary value problem. Here, the training of the network is equivalent to the minimization of a loss function that includes the governing (partial differential) equations (PDE) as well as initial and boundary conditions. We employ several ideas from the finite element method (FEM) to enhance the performance of

This article presents error bounds for a velocity–pressure segregated POD reduced order model discretization of the Navier–Stokes equations. The stability is proven in L∞(L2) and energy norms for velocity, with bounds that do not depend on the viscosity, while for pressure it is proven in a semi-norm of the same asymptotic order as the L2 norm with respect to the mesh size. The proposed estimates are

The work deals with the fatigue lifetime estimation of Short Fiber Reinforced Thermoplastics (SFRP), with a focus on conjugated effects of thermal aging. Two materials containing 35% (V35) and 50% (V50) weight ratio of short glass fibers were aged for 500h at 200°C in air and compared to the same materials in a Dry-As-Molded (DAM) state. Monotonic and fatigue tests were performed in samples machined

In strain-controlled fatigue testing, a conventional extensometer is usually used to measure the average strain between its two blades. However, the actual strain distribution in the gauge section cannot be revealed by the extensometer. To measure this distribution during strain-controlled fatigue testing of 304 stainless steel, stereo Digital Image Correlation (stereo-DIC) was used in this study.

This work characterises crack growth in AA2024-T315 by combining different methods to further increase the reliability of the results. The Christopher-James-Patterson (CJP) model was fitted to experimental data obtained by digital image correlation (DIC). The effective value of the CJP stress intensity factors were successfully correlated with the ΔK-da/dN curve as obtained with Scanning Electron Microscopy

The study was devoted to developing a reliable multiaxial fatigue life prediction method with the effect of additional cyclic hardening considered. Based on the original assumptions of traditional critical plane methods, a new characteristic plane (subcritical plane) was defined to describe the particularity of additional cyclic hardening under non-proportional loading condition. On the new defined

ABSTRACT This study focuses on the correlative mechanism of the ambient pressure and inflow uniformity on the vortex and cavitation dynamics of an axial flow pump. The shear stress transport k – ω turbulence model and Schnerr–Sauer cavitation model are applied in the unsteady detached eddy simulation. The results show that the vortex merging between the primary and secondary tip leakage vortices (TLV)

Transitional–turbulent spots bridge the deterministic laminar state with the stochastic turbulent state and affect the transition zone length in engineering flows. Turbulent spot research over the past four decades has expanded from incompressible flat-plate boundary layer and pipe flow to hypersonic boundary layer flow, turbomachinery flow, channel flow, plane Couette flow, and a range of more complex

A general framework is developed for finding the equations describing the equilibrium of an inextensional material surface with arbitrary flat reference shape that is deformed by applying tractions or moments to its edge. This is facilitated by using a representation of all isometric deformations of the material surface to convert the bending energy of the material surface to a line integral over the

Epithelial monolayers are the simplest tissues in multicellular organisms, yet they play a vital role in many physiological processes, including development, growth, and wound healing. During these processes, the epithelia are usually subjected to mechanical cues, and involve multiple scales acting at molecular, cellular, and tissue levels. Computational techniques provide a useful and convenient means

Suspended sediment load (SSL) is essential to river and dam engineering. Due to the complexity and stochastic nature of sedimentation, SSL prediction is a challenging task and conventional methods often fail to generate accurate results. Aiming to provide an improved estimation, this paper contributes to a new forecasting framework by integrating the seasonal adjustment (SA) and Bayesian optimization

The prediction of the crack growth propagation direction due to Non-Proportional Mixed-Mode missions is still an open debate in industrial applications. This study proposes two algorithms, both based on the dominant step criterion, to evaluate the cyclic crack propagation due to missions with varying mixed-mode loading conditions. They are implemented in the commercial software FRANC3D (coupled with

Hot-section components made by single crystal (SC) Ni-based superalloys with geometrical discontinuities such as film holes suffer from spatially inhomogeneous rafting of the γ'/γ microstructure due to harsh circumstances. Therefore, low cycle fatigue (LCF) life prediction is critical for ensuring the safety of engineering structures. Within this regard, an energy-based LCF life model is proposed based

The work reports an extensive experimental campaign for the aluminium lithium alloy Al-Li 2198-T851. Static, fatigue and fatigue crack-growth behaviour was investigated through tests on laboratory specimens manufactured along the longitudinal and transversal orientation with respect to the rolling direction. Microstructure was observed through macro-graphic evaluations and a Scanning Electron Microscope

ABSTRACT In this research, a coupled numerical–experimental approach is employed to investigate the spray–wall interaction on step geometries with slope angles from 0° to 90° as well as impinging on and off the step geometry. Spray contours are used to compare the numerical and experimental results and, in general, good agreement between them is found. The results from the model are used to provide

ABSTRACT Two hybrid back-propagation neural network (BPNN) models optimized by two heuristic search algorithms, namely genetic algorithm (GA-BP) and particle swarm optimization (PSO-BP), are proposed in this paper to predict radial maximum wall shear stress instead of traditional computational fluid dynamics (CFD) methods. The two proposed models are trained and validated using a database of 150 radial

In this study, a computational method for the coupled four-field problem of thermo-fluid–structure interaction (TFSI) using finite elements for all fields is proposed. Residual-based variational multiscale formulations are used for ensuring stable and accurate solutions of the flow as well as the temperature-transport problems. Adequate formulations for considering both the flow of gases and liquids

In this paper we study the efficacy of combining machine-learning methods with projection-based model reduction techniques for creating data-driven surrogate models of computationally expensive, high-fidelity physics models. Such surrogate models are essential for many-query applications e.g., engineering design optimization and parameter estimation, where it is necessary to invoke the high-fidelity

This paper employs a new tangential derivative of boundary integral equation for the optimization problems in the acoustic field with a objective function involving tangential derivatives of the sound pressure on the boundary. The level set method is adopted to generate the topological structure by updating the level set function which defines the boundary of the material domain with its zero contour

We present a rate-independent model for isotropic elastic–orthotropic plastic material behaviour in a hyper-elasto-plastic setting at finite strains, which is based on a covariant formulation that includes plastic-deformation-induced evolution of orthotropy. The model relies on a treatment by Lu and Papadopoulos, who made use of the postulate of covariance for an anisotropic elasto-plastic solid and

We investigate both theoretically and numerically the consistency between the nonlinear discretization in full order models (FOMs) and reduced order models (ROMs) for incompressible flows. To this end, we consider two cases: (i) FOM–ROM consistency, i.e., when we use the same nonlinearity discretization in the FOM and ROM; and (ii) FOM–ROM inconsistency, i.e., when we use different nonlinearity discretizations

Martensitic steel presents high fatigue crack resistance due to its complex and hierarchical microstructure, but its mechanisms are unclear. This work experimentally investigated effect of the lath and the prior austenitic grain (PAGs) on crack initiation and the early propagation behavior in high cycle fatigue. It is found that micro cracks initiated from the slip bands in the interior of thin monocrystalline

This work investigated the crack growth behaviors of EH36 joints, 316H steels, 6063-T6 and TC4 alloys at room temperature, proposing a unified approach. This model was achieved via the product of monotonic tensile crack tip displacement (φmt) and cyclic crack tip displacement (φc), in which φmt also considered the metallic capability to affect crack propagation behavior to eliminate the effect of material

The development of numerical methodologies to investigate material damages is a crucial aspect of aerospace components design. The advent of composite materials has made this aspect more critical due to their anisotropic properties, which result in damage mechanisms difficult to control and predict. Despite the progress made in the development of computational approaches for composites failure assessment

A physics-informed neural network (PINN) is proposed for fatigue life prediction with small amount of experimental data enhanced by physical models describing the fatigue behavior of materials. A multi-fidelity network architecture is constructed to accommodate the mixed data with different fidelities by embedding the physical models into the hidden neuron as the activation functions. Experimental

In the present study, strain-controlled low cycle fatigue (LCF) behaviour of SS 316L at room temperature (RT) and −80 ℃ were investigated. RT LCF specimens show cyclic softening, whereas −80 ℃ specimens show initial cyclic softening followed by hardening due to strain-induced martensitic transformation (SIMT). Fatigue damage evolution mechanism is proposed for specimens tested at −80 °C, where compressive

In this study, a new framework for the fatigue life prediction of nickel-base single crystal (SX) superalloys with different drilling film cooling holes (FCHs) at high temperatures (900 ℃ and 980 ℃) is investigated based on surface integrity quantification and fracture mechanics. For all the tested SX superalloys with anisotropy (smooth and FCHs specimens), the initial damage state is regarded as the

The study of the mixed mode Ⅰ-Ⅱ fracture damage characteristics of the rock-concrete interface under cyclic loading is essential to grasp the operation of gravity dams under seismic loading. To reveal the mixed mode fracture damage characteristics of the rock-concrete interface under cyclic loading, a four-point shear (FPS) test for rock-concrete specimens was carried out at first. The entire fracture