To reduce the computational burden for structural reliability analysis involving complex numerical models, many adaptive algorithms based on surrogate models have been developed. Among the various surrogate models, the support vector machine for regression (SVR) which is derived from statistical learning theory has demonstrated superior performance to handle nonlinear problems and to avoid overfitting

Many subsurface engineering applications involve tight-coupling between fluid flow, solid deformation, fracturing, and similar processes. To better understand the complex interplay of different governing equations, and therefore design efficient and safe operations, numerical simulations are widely used. Given the relatively long time-scales of interest, fully-implicit time-stepping schemes are often

Locally resonant acoustic metamaterial (LRAM) panels are excellent candidates for the low-frequency flexural wave attenuation in thin structures. To enable the efficient analysis and design of LRAM beam/shell structural elements for practical applications, a computational homogenization method for modelling wave propagation phenomena in LRAM panels is presented in this work. The approach is based on

Transient responses impose additional restrictions concerning model order reduction of acoustic finite element systems. Time-stable model order reduction methods achieve model compaction while guaranteeing frequency domain models transform in a physically meaningful way. Efficiency and stability are of course of little consequence if the model is rendered inaccurate. Krylov subspaces inherently include

Through the suitable geometry of a repeating unit, a metamaterial can exhibit a property not present in the base material. Here, we propose a class of low area-fraction, bending-dominated metamaterials that exhibit apparent piezoelectricity, even though the base material is not piezoelectric. The proposed metamaterials exploit a universal electromechanical coupling operative at sub-micron scales, flexoelectricity

The mechanical properties of hydrogels involve solvent diffusion as well as viscous dissipation in the network, with the coupling called poroviscoelasticity. To explore the poroviscoelastic behavior, we performed tests on a gelatin-based hydrogel in which poroelastic swelling/drying occured at controlled humidity levels while simultaneously developing creep deformation under a uniaxial load. These

This paper proposes a procedure based on crack tip opening displacement (CTOD) to define the boundary of the small-scale yielding (SSY) regime. Numerical modelling was applied to notched samples with different notch radii, under both plane stress and plane strain conditions, with and without crack flank contact. Results indicate that an increase in notch radius promotes the validity of SSY. The increase

This study is dealing with the effect of the grain size on the fatigue lifetime of metallic components, which is represented in the form of (S-N) Wöhler curves of two different grain sizes. The micro-models containing the microstructures of the two different grain sizes are handled by employing the Finite Element Method (FEM) and the required number of cycles for crack initiation was calculated by

The article deals with the development of advanced techniques of low cycle fatigue testing (LCF) using miniature test samples, which has the potential to be used to assess the degree of material degradation of large in-service components in the power industry. For this purpose, the results of a wide portfolio of test samples geometries have been investigated. Using the advanced techniques involving

Foreign object damage (FOD) has been identified as one of the main concerns for fan blades. In this paper, systematic experimental and numerical investigations are conducted on aerofoil specimens subjected to FOD by a falling object. The failure mechanism is attributed to the combination of stress concentration, residual stress, and initial damage. Finite element analysis is carried out to simulate

Accurate fatigue lifetime prediction is a central element in many industries. Often, a damage tolerant approach is used to ensure that some given imperfections are safe. In this context, these lifetime predictions are frequently made using simplified crack geometries leading to costly conservatism. In particular for a closed crack front, a circular or elliptical crack enclosing the real defect is generally

Fiber metal laminates (FMLs) are introduced as the kind of advanced hybrid composites consisting of the metals and composite layers, which the adhesion between those has an important role on the static and dynamic mechanical properties of these structures. To do so, the mechanical abrading, alkaline etching, forest products laboratory (FPL) and anodizing surface modification methods were performed

In this paper, a general numerical framework for the modeling of ductile fracture in 3D meshes is introduced. The strategy is inspired from the phase field model and adaptive remeshing tools. The phase field model was introduced as a continuous model for predicting the initiation and propagation of cracks in materials. However, the model has a limitation on the choice of the characteristic length scale

Fracture prediction is indispensable for polymers, like rubbers, which have a broad range of applications mainly due to their high extensibility. The phenomenon known as strain-induced crystallization further contributes to the fracture toughness of certain rubbers. In this study, a criterion based on internal bond energy, incorporating the effects of crystallization, is proposed to predict fracture

The diffusion of molecules in aqueous solutions in the domain of membrane technology is critical in the efficiency of chemical engineering and purification processes. In this study, the diffusion in high and low concentration regions is simulated with finite difference method (FDM), and then the results of numerical computations are coupled with adaptive network-based fuzzy inference system (ANFIS)

ABSTRACT Short-term hourly reliable prediction of significant wave height is an important research topic in coastal engineering. Many researchers have carried out in-depth studies in many ocean regions. Generally, most of this work is implemented through numerical models. However, as for numerical models, with the increase of hourly prediction duration, the accumulation of wave randomness leads to

This study proposes two techniques: Deep Learning (DL) and Ensemble Deep Learning (EDL) to predict groundwater level (GWL) for five wells in Malaysia. Two scenarios were proposed, scenario-1 (S1): GWL from 4 wells was used as inputs to predict the GWL in the fifth well and scenario-2 (S2): time series with lag time up to 20 days for all five wells. The results from S1 prove that the ensemble EDL generally

In this paper, a multi-disciplinary analysis method is proposed for evaluating the fatigue life of railway vehicle car body structure under random dynamic loads. Firstly, the hybrid fatigue analysis method was used with Multi-Body System simulation and finite element method for evaluating the carbody structure dynamic stress histories. The dynamics stress is calculated from the longitudinal load using

Fatigue crack growth of two carbon steels with different pearlite volume fractions were studied in pressurized gaseous hydrogen environment. Notably, pearlite was found to mitigate hydrogen-assisted fatigue crack acceleration. This positive impact of pearlite was ascribed to ferrite/cementite lamellar aligned perpendicularly to the cracking direction, which functioned as barriers to intermittently

This paper presents a new approach to estimate the fatigue life of metallic details retrofitted with bonded CFRP patch. Existing phenomenological and analytical methods to predict the fatigue life of metallic structural details retrofitted with bonded CFRP patch do not consider the cyclic degradation of the composite patch. As for all materials the composite patch (CFRP and adhesive) will experience

The fatigue crack growth behaviors of two fuel membranes are investigated at different temperatures. Fatigue crack growth rate increases with temperature, and Nafion XL membrane is more sensitive to temperature. An Arrhenius-type expression for fatigue crack growth rate is proposed and good prediction results are obtained. For Nafion XL composite membrane, fatigue crack grows by forming micropores

Hole cold expansion is an effective anti-fatigue manufacturing technology, which is widely used in hole strengthening of aviation components. In this paper, a novel small-deep hole (with the diameter less than 2 mm and the depth greater than 10 mm) cold expansion process, called the multi-spherical bump rotating cold expansion process (MBR-CEP), was proposed and verified by experiments on the Inconel

In the present paper, a criterion for fatigue assessment of high strength steels is proposed, where the influence of non-metallic inclusions on fatigue life is taken into account. To such an aim, the Carpinteri et al. criterion is used in conjunction with the area-parameter model by Murakami and Yanase. An experimental campaign available in the literature is analysed to evaluate the criterion accuracy

The phase field method (PFM) by means of regularization fractures has become a promising and popular method for complex crack propagation, especially in geotechnical applications. Attractive as it is, a challenge exists for the PFM to obtain explicit representation of cracks and jump displacement field across cracks that are essential and crucial for some applications, e.g., hydraulic fracturing, leakage

Dealing with numerical analysis of problems, especially ones with semi-infinite boundaries, scaled boundary finite element method has emerged as one of the efficient tools for the task. Combining the exactness of strong forms with the flexibility of weak formulations makes the method an improvement to its predecessors. Problem with the method arises when the analytical solution of the semi-discretized

In the present work, a computationally efficient and explicit algorithm for the rigorous enforcement of the irreversibility constraint in the phase-field modeling of brittle fracture is presented. The proposed approach is staggered and relies on the alternate minimization of the total energy functional. The phase-field evolution turns out to be governed by a complementarity boundary-value problem,

A key advantage of isogeometric discretizations is their accurate and well-behaved eigenfrequencies and eigenmodes. For degree two and higher, however, a few spurious modes appear that possess inaccurate frequencies, denoted as “outliers”. The outlier frequencies and corresponding modes are at the root of several efficiency and robustness issues in isogeometric analysis. One example is explicit dynamics

Systems composed of numerous particles, as granular materials, can be simulated by the discrete element method (DEM). There are numerous versions of DEM considering particle shapes as spheres, superellipsoids, polyhedra and others. Classically, particles are considered rigid and the only flexibility present in the model is local, embedded in the contact interface model. Such treatment seems not to

A methodology enabling the representation, sampling, and identification of spatially-dependent stochastic material parameters on complex structures produced by additive manufacturing is presented. The modeling component builds upon earlier works by the authors and relies on the combination of two ingredients. First, a fractional stochastic partial differential equation is introduced and parameterized

This paper outlines a rigorous variational-based multilevel Global–Local formulation for ductile fracture. Here, a phase-field formulation is used to resolve failure mechanisms by regularizing the sharp crack topology on the local state. The coupling of plasticity to the crack phase-field is realized by a constitutive work density function, which is characterized through a degraded stored elastic energy

The loads for bogie frame fatigue damage prediction under service environment has become a critical priority. In this study, the completeness of the measured loads was verified and bogie loads were classified into quasi-static and dynamic regions. Bogie modal vibration and rail corrugation were studied to adjust the loads. The predicted fatigue damage was closer to the actual damage and covered the

Future civil aircrafts require simple, low-noise, and highly efficient trailing-edge flaps. In this study, a detailed numerical study for flap improvements using steady and unsteady Reynolds-averaged Navier–Stokes computations was conducted. A movable trailing edge (MTE) was applied to the main element as a passive flow control method to improve the traditional Fowler flap. A new concept of a backward

A vast amount of research has been carried out towards the goal of quantifying changes related to the fatigue damaging process in materials throughout the fatigue life. However, no recommended practice has been developed for the experimental measurement of fatigue damage before a macroscopic crack has been initiated. Therefore, this paper reviews the existing fatigue damage detection and measurement

Curved features are ubiquitous on solid surfaces, but the effect of surface curvatures on growth of two-dimensional (2D) materials has not yet been established. Using a newly developed method based on the Metropolis algorithm and taking graphene as a prototype, we find that a curved feature on substrates can result in a variety of topological defects in 2D materials. As the feature's size increases

From its early days the SPH method has been criticised for its shortcomings namely tensile instability and consistency. Without thorough understanding of the method attempts were made to make the classical SPH method consistent and stable which resulted in the local and Total Lagrangian forms of SPH similar to the finite element method. In this paper we derived and analysed a consistent nonlocal SPH

This study presents new framework in which the representative volume element (RVE) method and machine learning (ML) model are used to construct continuous anisotropic effective material properties for simultaneous design of the overall topology configuration and local fiber material layout in functionally graded composite structures. It is an alternative to the asymptotic homogenization design method

In the community of topology optimization, the contradiction between the frontier research with structured meshes and the complex geometry in the real-world problems has existed for a long time. Structured mesh is attractive in convenient application of loads and boundary conditions, and easy implementation of GPU parallel calculation. Therefore, unlike existing researches solving the issue through

The dynamics of engineering structures are of great importance for topology optimization problems in both academia and industry. However, for design problems where broadband frequency responses are required, the computational burden becomes enormous, especially for large-scale applications. To remedy this numerical bottleneck, using the Reduced-Order Methods (ROMs) is an efficient approach by recasting

The paper, after analysis of a large experimental data base, shows that, depending on the material, the effect of defect on the fatigue limit should be described through 5 major parameters: Size, Type, Position, Morphology and Loading. A fatigue criterion describing the effect of the defect through the local stress gradient is discussed and the identification procedure shows that each of the 5 major

Two-dimensional (2D) materials as exemplified by graphene have received a bunch of attention for their outstanding properties and enormous application potential. Recently, a macroscopic graphene-based material was fabricated simply by stacking the few-layer graphene flakes. The resulting film, called SGA, exhibits unusual mechanical behavior, which implies the existence of tension-compression asymmetry

The optimal design, reliable manufacture and durable utilization of electromechanical systems demand objective modeling of failure under coupled electric field and mechanical actions. This is still a challenging and largely an open issue despite the large volumes of contributions from the discontinuous approach and the phase-field community for brittle fracture. In this work we propose a length scale

Two ocean models are considered for geophysical flow simulations: the multi-layer shallow water equations and the multi-layer primitive equations. For the former, we investigate the parallel performance of exponential time differencing (ETD) methods, including exponential Rosenbrock–Euler, ETD2wave, and B-ETD2wave. For the latter, we take advantage of the splitting of barotropic and baroclinic modes

Numerical modeling and simulation of complex systems is often subject to uncertainties in model parameters. Many popular uncertainty quantification (UQ) methods require repeated simulations of the underlying physical system with different samples of the uncertain model parameters. This poses great challenges to many practical engineering applications due to the high demand for computational resources

Multi-rigid-body dynamic contact systems, in other words Non Smooth Contact Dynamics (NSCD) problems, generate some inherent difficulties to multivocal laws, which results in non-linearities and non-smoothness associated to frictional contact models. Recently, Primal–Dual Active Set strategies (PDAS) have emerged as a promising method for solving contact problems. These methods are based on the following

The ship powering performance can be predicted based on model tests or simulations. However, differences exist between the full-scale ship performance and extrapolated model data. Therefore, research on full-scale ship performance simulation has important scientific significance and engineering value. This study used the REGAL general cargo vessel to perform full-scale ship resistance and self-propulsion

Accurate prediction of water level (WL) is essential for the optimal management of different water resource projects. The development of a reliable model for WL prediction remains a challenging task in water resources management. In this study, novel hybrid models, namely, Generalized Structure-Group Method of Data Handling (GS-GMDH) and Adaptive Neuro-Fuzzy Inference System with Fuzzy C-Means (ANFIS-FCM)

This study proposes a Bayesian inference-based decision framework to quantify the physical uncertainty based on fatigue life tests on maraging steel according to post-processing treatments and build orientations. Uncertainty quantification of fatigue life models is performed to determine the most suitable models for the metal additive manufacturing process by employing Bayesian inference. To select

The use of fracture mechanics based methodologies to assess the influence of defects on the high cycle fatigue resistance of mechanical components has become increasingly important for industrial applications and design. This presentation introduces the most commonly used fracture mechanics methods, emphasizing the assumptions on which they are based and analyzing their potential in predicting the

Additive manufacturing (AM) of metallic parts is a relatively new manufacturing procedure. Many industry sectors, such as the aerospace or automotive sectors, have started to apply this technology to produce some elements, thus reducing costs and weight. Several metallic alloys have been employed for AM. Due to the high strength-to-density ratio, Ti6Al4V alloy is probably the alloy most used for AM

High Frequency Mechanical Impact (HFMI) treatment offers a great opportunity to enhance the lightweight potential of welded structures using high strength steel materials. Focusing on the IIW Recommendations for the HFMI Treatment, a fatigue assessment based on the nominal, structural as well as notch stress approach is considered. Due to its sound applicability and proper assessment of the fatigue

To date the term “Fatigue Damage” has had an ambiguous usage in the fatigue community. This paper explains the reason for the poor predictive results of existing fatigue damage rules, such as Miner’s rule, through precise observation of small crack growth during multiple step loadings. For the exact evaluation of fatigue damage it is crucially important to attend to the phenomenon of the continuous

This paper proposes and assesses remedies to the significant storage requirements of unsteady adjoint methods used in gradient-based optimization, in multi-dimensional problems modeled by unsteady PDEs. Even if the application domain of the proposed technique(s) is wide, these remedies are herein demonstrated in shape optimization problems with unsteady fluid flows. In these cases, the adjoint equations

A geometrically nonlinear phase field theory accounting for dissipation, rate effects, nonlinear thermoelasticity, fracture, and other structural changes is constructed in the context of continuum thermodynamics. First, a general framework accommodating arbitrary strain energy potentials, inelastic deformation kinematics, and unlimited order parameters is formulated. Next, the framework is specialized

Fatigue crack growth in composite, single lap bonded joints is analysed by back face distributed strain sensing, using optical backscatter reflectometry. Crack growth is inferred from the back-face strain profile measured with high spatial resolution along optical fibres bonded on the joints. The indications about the position of the crack front are compared with micro computed tomography scans conducted

The probability of fracture (POF) assessment of complex cracked structures is a difficult task in the reliability assessment of engineering structures. Due to the complexity of structure, balancing efficiency and accuracy is the top concern in POF calculation. In this study, a novel probabilistic solution method called AKNN-MCS (Active learning-based K-Nearest Neighbors-Monte Carlo Simulation) is proposed

We propose a domain decomposition method for the efficient simulation of nonlocal problems. Our approach is based on a multi-domain formulation of a nonlocal diffusion problem where the subdomains share “nonlocal” interfaces of the size of the nonlocal horizon. This system of nonlocal equations is first rewritten in terms of minimization of a nonlocal energy, then discretized with a meshfree approximation