Prairie Dog Optimization is a population-based optimization method that uses the behavior of prairie dogs to find the optimal solution. This paper proposes a novel optimization method, called the Opposition-based Laplacian Distribution with Prairie Dog Optimization (OPLD-PDO), for solving industrial engineering design problems. The OPLD-PDO method combines the concepts of opposition-based Laplacian

An efficient and inherently consistent integration method, named projection integration(PI), is proposed for Galerkin meshfree methods with arbitrary order. In contrast to traditional numerical integration methods, PI defines a projection operator based on a weighted norm to systematically approximate meshfree shape functions in an appropriate and consistent function space. Then a substitute function

We present a structure-preserving scheme based on a recently-proposed mixed formulation for incompressible hyperelasticity formulated in principal stretches. Although there exist several different Hamiltonians introduced for quasi-incompressible elastodynamics based on different multifield variational formulations, there is not much study on the fully incompressible materials in the literature. The

This study aims to propose critical fatigue indicators for evaluating the restoration effectiveness of various rejuvenators on the fatigue performance of aged bitumen. The influence factors of rejuvenator type/dosage and aging degree of bitumen are involved, and different fatigue parameters from linear viscoelastic (LVE), linear amplitude sweep (LAS), and time sweep (TS) tests are analysed. The results

The paper discusses from first principles all aspects relevant to the plasticity of porous materials. Emphasis is laid on unhomogeneous yielding, defined as the process of yielding and plastic flow under gradient-free macroscopically nonuniform deformation. The nonuniformity is represented by strain localization in one or more bands of finite thickness. A universal feature of all intrinsic yield criteria

A modified robust design optimization approach is presented, which uses the first-order second-moment method to compute the mean value and the standard deviation for arbitrary objective functions. Existing approaches compute the gradient of the variance using the adjoint method, direct differentiation or finite differences, respectively. These approaches either access to the FE-code and/or have high

We introduce a new family of high order accurate semi-implicit schemes for the solution of nonlinear time-dependent systems of partial differential equations (PDE) on unstructured polygonal meshes. The time discretization is based on a splitting between explicit and implicit terms that may arise either from the multi-scale nature of the governing equations, which involve both slow and fast scales,

Dry-wet cycle and fatigue loading both severely affect the stability of hydraulic engineering. In this paper, the deterioration process of red sandstone under coupled dry-wet cycle-fatigue loading was investigated from three aspects of deformation, energy, and damage. And the variation law of crack propagation mode of the samples was revealed. The results showed that the elastic modulus and the deformation

The influence of the size effect is investigated experimentally on unnotched 42CrMo4+QT fatigue specimens of four configurations with different critical volumes. An investigation of external factors present during experiments is also carried out. The paper shows how complicated it is to analyze a single effect in fatigue experiments. The effects of uneven surface roughness, semi-product hardness across

Green hydrogen is emerging as one of the most promising alternatives to replace fossil fuels. While hydrogen gas has a good energy density by weight, its poor energy density by volume requires it to be stored under high pressure for commercial use. The hydrogen infrastructure developed to handle this high pressure hydrogen contains multiple components made of polymers such as O-rings, pipes, hoses

Indentation tests are largely exploited in experiments to characterize the mechanical and fracture properties of the materials from the resulting crack patterns. This work proposes an efficient theoretical and computational framework, whose implementation is detailed for 2D axisymmetric and 3D geometries, to simulate indentation-induced cracking phenomena caused by non-conforming contacts with indenter

Photopolymerized materials are widely used for a broad range of industrial applications including coatings, three-dimensional (3D) printing, micro/nano-scale fabrications, restorative dentistry, etc. However, the service quality and life of these materials are dramatically impaired by polymerization shrinkage stress evolved during the photopolymerization process in practices. A theoretical model for

The mechanism by which cells measure the dimension of the organ in which they are embedded, and slow down their growth when the final size is reached, is a long-standing problem of developmental biology. The role of mechanics in this feedback is considered important. Morphoelasticity is a standard continuum framework for modeling growing elastic tissues. However, in this theory, in the absence of additional

An alternative modelling framework is proposed for capturing the rate-dependency in the loading and unloading (i.e., with softening) deformation behaviour of a wide range of isotropic incompressible elastomers. The proposed framework departs from the existing approaches in the literature which assume an additive contribution of the ‘non-equilibrium’, or ‘viscous’, part to the elastic response. Instead

The Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) method was introduced in 1990 as a moving-mesh method for computational analysis of flows with moving boundaries and interfaces (MBI), which is a wide class of problems that includes fluid–particle and fluid–structure interactions and free-surface and multi-fluid flows. The method was inspired by Thomas Hughes’s 1987 work on space–time finite

This paper proposes a new Fluid–Structure Interaction computational framework. The coupling between the solid and an incompressible fluid is formulated by means of the method of localized Lagrange multipliers (LLM). Instead of applying a direct coupling between the fluid and the structure, which is the traditional approach, LLM introduces an intermediate surface with its own degrees of freedom that

The total Lagrangian material point method (TLMPM) is a recent modification to the conventional material point method (MPM). It poses the weak form in the undeformed configuration, and has shown great potential in solid mechanics applications because it seamlessly eliminates the so-called cell-crossing instability and overcomes numerical fracture. Despite its promise, it has not been widely adopted

Electro-mechanical response exists in growing materials such as biological tissues and hydrogels, influencing the growth process, pattern formation and geometry remodelling. To gain a better understanding of the mechanism of the coupled effects of growth and electric fields on the deformation behaviour, a finite element framework for coupled electro-elastic growth is established. Based on the extended

The fatigue behaviour of adhesive joints under the influence of environmental conditions has been the subject of several studies. However, a significant knowledge gap still exists, particularly regarding the understanding of failure mechanisms associated with these phenomena. This research presents a novel investigation into failure modes under varying environmental conditions of adhesively bonded

Vibration is closely related to structural dynamics, and the study of random vibration fatigue loads is typically conducted in the frequency domain. In this study, various frequency domain methods were employed to predict the random vibration fatigue life of DZ125L directionally solidified superalloy under different vibration signal intensities. Experimental analysis was used to examine the fatigue

The morphogenesis of plant organs and tissues has fascinated scientists for centuries. However, it remains a challenge to quantitatively decipher the biomechanical mechanisms underlying the morphological evolutions of growing plants. In this study, we investigate the formation, optimization, and evolution mechanisms of plant roots through biomechanical morphogenesis. A transdisciplinary computational

This paper presents a model-free data-driven framework for breakage mechanics. In contrast with continuum breakage mechanics, the de facto approach for the macroscopic analysis of crushable granular media, the present framework does not require the definition of constitutive models and phenomenological assumptions, relying on material behavior that is known only through empirical data. For this purpose

Polymer gels are promising surrogates for human tissues, whereas simulating the behavior of these materials in 3D scenarios, particularly when they are subjected to dynamic loads, can be a complex and computationally demanding task. This work presents a solution to this challenge through developing a three-dimensional meshfree framework based on bond-based peridynamics. The novelties of this method

Advanced fibre composite materials are often used for weight-efficient thin-walled designs, making a plate-based modelling approach suitable for their structural assessment. However, as the sub-structural geometrical features of these materials govern much of their behaviour, a multi-scale approach is necessary. A related challenge, however, is that the in-plane variation of these sub-structural features

Fatigue fracture of aluminum wires due to Aeolian vibrations (high-cycle fatigue) is one of the severe problems in the high-capacity conductors of the power transmission lines. On the other hand, previous studies have shown that graphene can significantly increase aliminum’s mechanical and electrical properties. In this regard, this research has studied the high-cycle fatigue (HCF) of Al-0.5 wt. %

Several new algorithmic aspects of the conforming to interface structured adaptive mesh refinement (CISMAR) mesh generation technique are presented for creating high-fidelity finite element models of 3D problems with non-smooth (C0–continuous) geometries. The Stereolithography (STL) file characterizing the domain geometry is first pre-processed to identify its sharp edges and corners, followed by overlaying

We introduce a denoising diffusion algorithm to discover microstructures with nonlinear fine-tuned properties. Denoising diffusion probabilistic models are generative models that use diffusion-based dynamics to gradually denoise images and generate realistic synthetic samples. By learning the reverse of a Markov diffusion process, we design an artificial intelligence to efficiently manipulate the topology

The rib-to-deck welded joints in orthotropic steel decks (OSDs) are prone to fatigue damage with different fatigue failure modes. The damage accumulation of the corresponding failure modes should be estimated in repair design. This study proposed a unified fatigue life evaluation method for different failure modes of rib-to-deck welded joints based on the structural stress method and linear damage

Recent advances in the field of data-driven dynamics allow for the discovery of ODE systems using state measurements. One approach, known as Sparse Identification of Nonlinear Dynamics (SINDy), assumes the dynamics are sparse within a predetermined basis in the states and finds the expansion coefficients through linear regression with sparsity constraints. This approach requires an accurate estimation

Electron beam welding is an autogenous welding process that leads to microstructural heterogeneities; crystallographic texture, elongated and larger grain size relative to the surrounding parent material. The goal of this study is to predict the changes in mechanical response of the weld fusion zone as a function of grain morphology and texture by using the parent material properties to avoid extensive

We present a general form of the gradient-enhanced damage theory and its numerical implementation using finite element method (FEM) in modeling quasi-static brittle crack growth in one- (1D), two- (2D) and three-dimensional (3D) bodies. Coupled equations of the equilibrium and a new implicit gradient damage formulation are introduced to govern the deformation of the solid and evolution of the damage

The present work investigates the generation process of crack face closure under laser shock and its effect on the crack opening behavior to reveal the underlying reason for the high-level crack closure induced by laser peening (LP) on the initial fatigue crack. It is found that crack face closure generates a firm compression to the crack face, causing the significant elongation in the crack wake during

Fatigue cracking is a primary asphalt pavement distress and various models have been developed to predict the fatigue life of asphalt mixtures using laboratory tests. One such model is the simplified viscoelastic continuum damage (S-VECD) model, which has been implemented in the pavement performance prediction program, FlexPAVETM. The S-VECD model test protocols (AASHTO TP 133 and AASHTO T 400) and

This paper concerns the study of history dependent phenomena in heterogeneous materials in a two-scale setting where the material is specified at a fine microscopic scale of heterogeneities that is much smaller than the coarse macroscopic scale of application. We specifically study a polycrystalline medium where each grain is governed by crystal plasticity while the solid is subjected to macroscopic

Curved weak interfaces present promising advantages to be implemented as crack arrestors in structures designed under the damage tolerant-design principles. Among other advantages, they neither add extra weight nor significantly affect the global stiffness of the structural element, in contrast with alternative crack arrestors concepts. To be employed as a crack arrestor, it is key that the interface

In this study, Fa–N curves and σn_s–N curves of bolted connections under different geometric and load parameters were obtained through tensile-shear fatigue tests. The correlation of these curves was poor and did not satisfy engineering requirements. To this end, first, an equivalent structural stress calculation model capable of accurately characterizing the stress state of a bolted connection was

Wide applications of powder metallurgy superalloys in mechanical engineering imply the great significance of studying their mechanical properties. Fatigue property of superalloys is complicated because of many influencing factors with variability. This means the difficulty to correctly predict a real-valued fatigue life due to the propagation of error. Specially, extreme dispersion of multiaxial fatigue

In this study, the effect of microstructure on dwell-fatigue response for Ti-6Al-4V alloy was studied. Tensile tests and fatigue tests with varying dwell periods and maximum stresses were performed on samples having varying fractions of primary alpha (αp). Yield and ultimate tensile strength increased with a reduction in the αp, whereas elongation is highest for the samples with smallest effective

Many experiments showed that cell groups can exhibit various impressive motion modes (e.g., global rotation and local swirling) in different-sized geometrical spaces, with the underlying mechanisms still unclear. However, recent experiments showed that different types of cells perform distinct motion modes (i.e., global rotation and coherent oscillation) in the same constraint conditions, which brings

By using the threshold on the phase-field variable as an error indicator, an adaptive fourth-order phase-field method in the framework of isogeometric analysis is proposed for fracture simulation. The spatial and geometric discretization is based on locally refined non-uniform rational B-splines (LR NURBS), which have the ability for local refinement. The C1 continuous LR NURBS basis function is employed

The low-cycle fatigue performance of high-manganese twinning-induced plasticity (TWIP) steels with the specimen axial direction of 0°, 22.5°, 45°, 67.5°, and 90° to the rolling direction is investigated in the range of the total strain amplitudes (Δε/2) of 0.6% ∼ 4.4% and two types of pre-deformed conditions (i.e., tension and tension-unloading). Experimental results show that the dependence of the

The rolling contact fatigue (RCF) of both a high carbon through-hardening bearing steel (SAE52100) and a low carbon case-hardening bearing steel (SAE4320) have been investigated using RCF. The RCF-life for the SAE4320 steel was found to be ≈ 7.0 x 107 cycles, about 7 times higher than the RCF-life found for the SAE52100 steel of ≈ 1.0 x 107 cycles. Measurements from fracture surfaces of specimens tested

Damage tolerant structures require accurate fatigue crack growth rate models for life prediction. Central to these models are fracture mechanics similitude and empirically gathered growth rates. In this work, standard test methods failed to achieve similitude for 17-4PH stainless steel round-rod but succeeded for plate. Material product form differences are interrogated through constant ΔK tests, crack

A parameter identification approach is proposed to calibrate the Ottosen high cycle fatigue model using numerical optimization with regularization. The damage evolution was predicted by a continuum approach based on a moving endurance surface in the stress space, so the stress states outside the endurance surface may lead to damage evolution. The calibration of the model relied on uniaxial and multiaxial

Very high cycle fatigue properties of 17-4 PH stainless steel aged for 1 h and 4 h after hydrogen charging were studied. Results show that hydrogen reduces fatigue strength and changes crack initiation mode to mainly inducing by inclusions. The existence of intergranular facets on fracture surface indicates that hydrogen accelerates crack initiation and early crack growth. Hydrogen-granular bright

The derivation and implementation of an asynchronous direct time integration scheme for domain-decomposed finite element models is presented. To maximize clarity in the description of the proposed asynchronous integration, the scheme is restricted to the linear-elastic stress wave propagation case. The proposed method allows the integration of individual subdomains with independent time steps. There

In this work, the eXtended finite element method (XFEM) is implemented for the multiphysics analysis of edge dislocations near a heterostructure (bi-material) interface with nonuniform misfit strain. A novel enrichment is defined to incorporate the singular behavior of the electric potential due to dislocation. Nonlinear material properties due to temperature are taken for a thermo-electro-elastic

The compressive residual stress on the gear tooth’s surface, a vital parameter to control mechanical properties, such as strength, has a beneficial effect on the component’s fatigue life. A novel procedure, double induction quenching (DIQ), effective for improving the fatigue strength of gear products, has been used for producing gears with steep gradients of compressive residual stress generated in

In many industrialized regions of the world, large-scale photovoltaic systems now contribute a significant part to the energy portfolio during daylight operation. However, as energy demands peak shortly before sunset and persist for several hours afterwards, the integration of solar-thermal systems is extremely advantageous as a green “bridge” energy source. Accordingly, this work develops a digital-twin

This paper proposes a computational framework for the design optimization of stable structures under large deformations by incorporating nonlinear buckling constraints. A novel strategy for suppressing spurious buckling modes related to low-density elements is proposed. The strategy depends on constructing a pseudo-mass matrix that assigns small pseudo masses for DOFs surrounded by only low-density

Dwell sensitivity of titanium alloys at ambient temperature (∼25° C) is a well-reported phenomenon, although the question about the phenomena of crack initiation remains open. In this work, the normal and dwell fatigue response of a near alpha titanium alloy is studied. A dwell fatigue debit (number of continuous cycles to failure to number of cycles to failure with a dwell period) of up to 2 and 10

Accurate monitoring of mechanical device conditions requires a large number of sensors working together. There are potential connections between sensors throughout the degradation monitoring process of mechanical devices. Conventional deep learning (DL) models suffer from the following shortcomings when dealing with this type of multi-sensor degraded data. To begin with, most existing methods based

In this paper, the plastic component of the crack-tip opening displacement (CTODp) is experimentally evaluated to characterize the fatigue crack growth behavior in a Grade 2 titanium sample under single overload with constant amplitude loading conditions. The CTOD measurements were performed with the 2D-Digital Image Correlation (DIC) technique. The experimental results show a linear correlation between

Selective laser melting (SLM) is one of the most promising additive manufacturing technologies for obtaining end-use components with excellent mechanical properties. However, the presence of manufacturing defects harms mechanical properties and fatigue performance. This work investigated the crack behaviour within an SLM Ti-6Al-4V alloy sample stressed with in-phase axial and torsional loading by X-ray