In this paper, we present a semi-numerical method for determining the dynamics of micro-resonators with finite width immersed in incompressible viscous fluids. The micro-resonator is modeled using Kirchhoff plate theory, and the hydrodynamic force acting on the plate is determined from a boundary integral formulation of the Stokes equations. The resulting equation of motion is solved with a continuous/discontinuous

In order to model prominent failure modes experienced by multi-layered composites, a fine through-thickness discretisation is needed. If the structure also has large in-plane dimensions, the computational cost of the model becomes large. In light of this, we propose an adaptive isogeometric continuum shell element for the analysis of multi-layered structures. The key is a flexible and efficient method

This study presents a new modeling technique to estimate the stiffness matrix of a thin-walled beam-joint structure using deep learning. When thin-walled beams meet at joints, significant sectional deformations occur, such as warping and distortion. These deformations should be considered in the one-dimensional beam analysis, but it is difficult to explicitly express the coupling relationships between

The analysis of rolling tires using numerical methods sheds light on the understanding of complex phenomena, while reducing the amount of experimental tests, which are used to calibrate and validate the models. Among different approaches, the finite element method is often used in tire industry, due to its capabilities of describing structural behavior, where material properties and an accurate geometry

Quasi-Newton methods have proven to be an efficient way to couple partitioned solvers in fluid-structure interaction problems, as they are able to stabilize cases with high added-mass, as well as accelerate the convergence. However, these methods assume that the coupled system is a complete black-box, whereas often, its behavior is well approximated by a surrogate model. Such a model may be obtained

A coupled damage-plastic based constitutive model using a traction-separation law is developed in this study to simulate the behaviour of mortar joints in masonry structural panels subjected to in-plane (2D) and out-of-plane (3D) loading. A smooth hyperbolic failure surface is used to develop the interface material model, which is implemented numerically using a fully implicit backward Euler integration

We present a novel further development of overlapping finite elements. The formulation of the enhanced elements is based on the earlier published elements but has an important new ingredient which renders the enhanced formulation more effective with respect to the evaluation of the element matrices and the solution of the governing finite element equations. The novel ingredient is that the elements

A method is presented for reconstructing the geometry, the pith, the knots and the local fibre orientations in timber boards, based on X-ray computed tomography scans. The local fibre deviations around knots were found by a new algorithm, based on image analysis. The experimental data comprised tomography scans, eigenfrequency measurements and four-point bending tests of 20 Norway spruce boards. 3D

The recent innovations of computational material models by machine learning (ML) methods face formidable challenges. Incorporating internal heterogeneity and diverse boundary conditions (BC’s) into existing ML methods remains difficult, and the weak interpretability of ML remains unresolved. To tackle these challenges, this paper generalizes a recently developed self-evolving computational material

We propose to combine the ideas of mass redistribution and component mode synthesis. More specifically, we employ the MacNeal method, which readily leads to a singular mass matrix, and an accordingly modified version of the Craig-Bampton method. Besides obtaining a massless boundary, we achieve a drastic reduction of the mathematical model order in this way compared to the parent finite element model

This study presents a multimode coupled nonlinear flutter analysis method for long-span bridges with consideration of vibration-amplitude-dependent flutter derivatives. By converting the equation of motion into a complex eigenvalue problem, a double layer iterative method (DLIM) is proposed to determine the real iterative frequency as well as the participation of each structural mode shape to the flutter

The Finite Element Method (FEM) is the gold standard for spatial discretization in numerical simulations for a wide spectrum of real-world engineering problems. Prototypical areas of interest include linear heat transfer and linear structural dynamics problems modeled with partial differential equations (PDEs). While different algorithms for direct integration of the equations of motion exist, exploring

This study explored the use of artificial neural networks to predict UHPC compressive strengths given thermal history and key mix components. The model developed herein employs Bayesian variational inference using Monte Carlo dropout to convey prediction uncertainty using 735 datapoints on seven UHPC mixtures collected using a variety of techniques. Datapoints contained a measured compressive strength

In this paper, a frame structural topology optimization methodology for the generation of moment resisting braced frames for tall buildings, considering dynamic seismic loading, is presented. Real-world loading conditions along with standardized steel profiles of Euronorm are employed. In the literature, the studies that employ the ground structure topology optimization method are limited mostly to

This paper presents new variable-order shell elements that require only the shell mid-surface to be discretized, contain no rotational degree of freedom and adopt the full three-dimensional constitutive relationship. In the formulation, a shell element is treated as a three-dimensional continuum undergoing small deformations and its middle surface is represented by a quadrilateral spectral element

Structural optimization is increasingly used across academia and industry because of the great design freedom it offers and due to the increasing availability of computational power. In this context, binary methods - which generate clear (0/1) designs - are an effective approach to solve optimization problems, especially multiphysics, wherein precise definition of the structural boundary is essential

In this paper, a novel level set-based topology optimization method for shell structures is presented to minimize both compliance and stress under a volume constraint. During the optimization process, trimmed quadrilateral shell meshes are generated by cutting a background quadrilateral shell mesh with the zero-isolines of a level set function. Polygonal shell elements with assumed strains are used

We present a worst-case approach to topology optimization (TO) for maximum stiffness under boundary displacement parametrized by a matrix-valued scaling function times an uncertain vector giving its direction. The objective function in the TO problem is the minimum of the potential energy maximized over the set of boundary displacements, which in the absence of prescribed loads means maximizing the

This paper presents a numerically efficient tool for linear buckling predictions of perforated thin-walled bars within the framework of generalized beam theory (GBT). GBT-based beam finite element methods (GBT-FEM) have been well developed for eigenvalue buckling analyses of non-perforated thin-walled bars. The novelty of this paper consists in an extension of the standard GBT to the scope of thin-walled

In conventional fail-safe optimization of frame structures the damage is usually modelled as complete removal of one or more members. We propose and incorporate two additional types of damage models into the fail-safe design problem. The first describes thickness degradation caused e.g. by corrosion. The second describes severe local damage by removal of a part of a member that causes a gap and free

Several damping models were proposed to incorporate un-modeled damping when simulating seismic response of large-scale structures, but most did not provide parameter calibration against energy dissipation. This study addresses this problem by developing a new bell-shaped proportional damping model, allowing energy dissipation to be directly related to modal damping ratio. It also addresses the concerns

The assumptions made in design codes can result in unconservative predictions of shear strength for reinforced concrete members. The limitations of empirical methods have prompted the development and use of numerical techniques. A three-dimensional bond-based peridynamic framework is developed for predicting shear failure in reinforced concrete members. The predictive accuracy and generality of the

In this paper, optimal designs for precast beams were determined using a genetic algorithm. Two new features for enhancing genetic algorithms were developed in the present study, considerable improvements obtained by applying the proposed methods were shown in a parametric study. Firstly, probabilistic-based natural selection was introduced, selecting parental chromosomes for reproduction using inherited

In this paper, a non-standard finite element (FE) method, coupled with a mathematical programming procedure, is presented to simulate initiation and propagation of in-plane tensile cracks in quasi-brittle material. Potential crack lines are defined and limited by the FE edges. The cracks are considered as localized plastic deformations imposed at the nodes along the potential crack paths. Crack opening

A numerical analysis of the limit state for solids, with an adequately described structural geometry, is often a computationally demanding task, and there is a need for an effective method. The existing solid elements for Finite Element Limit Analysis (FELA) are either computationally expensive or require a stress cutoff of the yield surface for triaxial stress states. This paper presents an effective

A recurrent neural network (RNN) based model is developed as a surrogate to predict nonlinear plastic response under multiaxial loading. The RNN-based model is trained and tested on stress versus strain curves generated using a numerical solution based on the classical radial return method. Besides simply learning the basic constitutive relationship, a novel approach is taken to enforce certain physical

The dynamics of elastic cantilevered smart pipes conveying fluid with non-uniform flow velocity profiles is presented for optimal power generation. The Navier-Stokes equations are used to model the incompressible flow in the circular smart pipe, and flow profile modification factors are formulated based on the Reynolds number and Darcy friction factor. The coupled constitutive dynamic equations, including

The paper presents a finite element method to investigate the critical buckling loads and the natural frequencies of laminated Kirchhoff plates including the nonlocal strain gradient effect, which could have considerably consequences at the nanoscale. With respect to the existing literature, the proposed numerical methodology is developed to deal with general stacking sequences of orthotropic layers

This paper proposes a computational approach for studying the overall behaviour and local stress state of strand-type structures. This method is based on the homogenization theory of periodic beamlike structures, with the local problem posed on the strand axial period being solved using the finite element method. This approach fully utilises the strand’s helical symmetry, thus minimising the size of

A stress-update algorithm for the recently proposed distortional anisotropic hardening law is developed based on the Newton–Raphson (N–R) algorithm and line search method. The investigated yield function enables the modeling of complex path-dependent flow stress evolutions, particularly the Bauschinger effect, latent hardening/softening, and differential permanent softening. Computationally, the continuous

In this work, we extend goal-oriented mesh adaptivity to parameter identification for a class of linear micromorphic elasticity problems. Starting from a compact formulation in our previous work (Ju and Mahnkhen, 2017), we propose a two-level optimization framework based on goal-oriented error estimation. By means of a sensitivity analysis of the generalized constitutive relations, we establish a gradient-based

A novel method for characterising and propagating system uncertainty in structures subjected to dynamic actions is proposed, whereby modal shapes, frequencies and damping ratios constitute the random quantities. The latter, defined in the modal subspace rather than the full geometrical space, reduce the number of the random variables and the size of the dynamic problem. A numerical procedure is presented

A model for the non-linear dynamic behaviour of pre-stressed cable trusses is presented. The model provides the basis for a simplified description of the (in-plane) non-linear dynamical behaviour of biconcave and bi-convex cable structures (as well as of single cables) subject to different loading (and mass distribution) conditions. The simplicity of the proposed approach is coupled with its ability

This paper presents a novel probabilistic approach for fail-safe robust topology optimization with the following novelties: (1) the probability for failure to occur at a specified location is considered; (2) the possibility for random failure size is incorporated; (3) a multi-objective problem is pursued encompassing both the expected value of the structural performance and its variance as a robustness

In the present paper, we propose the Continuous Displacement for Fracture (CDF) method, a continuous energy-based numerical approach to find mechanisms and crack patterns exhibited by 2D masonry structures subjected to given loads and settlements. The structure is modelled through the normal, rigid, no-tension material, and the equilibrium problem is solved as the minimum of the total potential energy

The objective of this paper is to present a load balancing algorithm for the parallel automated multilevel substructuring (PAMLS) method. In the PAMLS method, load balancing is highly dependent on the computation time for the transformation and back transformation procedures corresponding to substructures. To balance the workload among threads, the proposed algorithm consists of two types of granularity:

A micro-mechanical model for fibre bundle failure is formulated following a phase-field approach and is embedded in a semi-analytical homogenisation scheme. In particular mesh-independence and consistency of energy release rate for fibre bundles embedded in a matrix phase are ensured for fibre dominated failure. Besides, the matrix cracking and fibre-matrix interface debonding are modelled through

This paper presents a methodology to assess the stability of vaulted masonry structures using Thrust Network Analysis (TNA). It offers a new numerical strategy to compute the Geometric Safety Factor (GSF) of a given structure by directly evaluating its minimum thickness. Moreover, it provides an approach for tracing the vault’s stability domain based on its extreme thrust values, which indicates the

This paper proposes a sub-step based iterative constitutive model for line interface elements used to analyse masonry structures loaded in-plane. Based on a total deformation theory, the model adopts characteristics of multi-surface plasticity, including a Coulomb friction failure surface for shear, with tension and compression cut-off and softening for all three domains. The model is driven by two

A multi-fidelity probabilistic optimisation method for the design of composite structures subjected to thermomechanical loading is introduced in this work for the first time. The proposed multi-fidelity approach offers considerable computation efficiency as well as sufficient accuracy, enabling probabilistic optimisation to include more design variables in the early design phase. This approach incorporates

This paper proposes a continuous approach to formulation of a general three-dimensional nonlinear cable model. The model’s assumptions include selected acceptable restrictions regarding its application to various types of civil engineering structures. The model is dedicated to static and dynamic analyses of complex tension structures, particularly the ones subjected to moving loads. In order to demonstrate

Design for six sigma has become increasingly important in complex optimization work considering uncertainty. In this paper, we present a six sigma robust optimization method based on a pseudo single-loop optimization strategy and an ensemble of random forest regression and deep belief networks (RFR-DBN). To verify its validity, we take a lightweight passenger car seat with insufficient samples as an

A new joint modeling method for a beam-based analysis of a car body applied during the concept design phase is presented. The body-in-white (BIW) of a car mainly consists of thin-walled beams with closed cross-sections, the joints of which show a significant flexibility owing to higher-order deformation modes. The joint flexibility effect cannot be evaluated using conventional beam theories. Although

Point collocation methods are strong form approaches that can be applied to continuum mechanics problems and possess attractive features over weak form-based methods due to the absence of a mesh. While various adaptive strategies have been proposed to improve the accuracy of weak form-based methods, such techniques have received little attention for strong form-based methods. In this paper, combined

Simulation-based inverse analysis plays a vital role in studying the actual working conditions of hydraulic structures, and has been largely implemented by network models in recent years. However, network-based models generally demand expensive sampling of numerical simulations and often rely on different search algorithms. Accordingly, a camp chain (CC) model is proposed to reduce numerical calculations

In this paper, the isogeometric formulations of the finite element and boundary element methods are applied to the dynamic analysis of thin-walled structures submerged in an infinite, inviscid, and incompressible fluid medium. This fluid–structure interaction problem is decoupled using the modal analysis technique, and the fluid effect on the structure is taken into account through the generalized

This study presents a multi-director continuum beam finite element developed for efficient analysis of multi-layer strand cables. The beam element is derived from the continuum mechanics based beam formulation incorporating multi-directors and cross-sectional elements to describe the helical geometries of wires that constitute the strand cables. The main advantage of the present continuum beam formulation

Fatigue resistance is a key performance for the life-cycle sustainability of materials and structures. Structural members subjected to flexural forces such as spring hinges in origami structures are one of the most commonly existing in nature and engineering practice but predicting their fatigue resistance is a challenge because of complex mechanisms of crack localization, nonstationary amplitudes

Gradient additive manufacturing techniques are capable of implementing multiple materials with graded compositions into the fabrication of a single component. This provides a unique opportunity to control the properties of materials, such as thermal expansion, Young’s modulus, and yield stress, and create a structure that otherwise would be infeasible. To utilize this capability, a density-based topology

In this paper, an Enhanced Forensic-Based Investigation (EFBI) is proposed for optimal design of frequency-constrained dome-like trusses. The Forensic-Based Investigation (FBI) algorithm is a newly developed population-based metaheuristic inspired by the criminal investigation process. Throughout the FBI algorithm, the investigation and pursuit teams (i.e., the diversification and the intensification

This paper proposes a modified Lemke algorithm to determine the non-holonomic response of rigid plastic skeletal structures subjected to extreme dynamic loading. The basic formulation for the dynamic rigid-plastic response has a mathematical form of linear complementarity problem (LCP), and, equivalently, a pair of dual quadratic programs (QP). Previous attempts using the Wolfe type LCP solver exhibited

The present research contributes in the structural topology optimization with the manufacturing limitation called the overhang constraint and the optimization of the anisotropic material properties. For the optimization with self-supporting structure, the overhang-free shadow filter method is developed. To consider the anisotropic material property, the raster angles of each layer (the printing direction

Optimum design of post-tensioned flat slabs with its columns is complicated by the presence of many nonlinear constraints and the non-homogeneous nature of the material used. This study presents three design optimization algorithms where the design provisions are implemented in accordance with ACI 318-11. Design variables are divided into two groups. The first group of variables refers to post-tension

Stiffness matrices of beams embedded in an elastic medium and subjected to axial forces are considered. Both the bending and the axial deformations have been incorporated. Two approaches for deriving the element stiffness matrix analytically have been proposed. The first approach is based on the direct force–displacement relationship, whereas the second approach exploits shape functions within the

In this paper, a novel design strategy to minimize the dynamic compliance of a vibrating infill structure with a solid outer coating and a periodic uniform infill lattice is presented. The vibration of the linearly elastic infill structure is excited by time-harmonic external mechanical loading. The design optimization of the infill lattice is performed simultaneously with the topology optimization

In many applications, such as textiles, fibreglass, paper and several kinds of biological fibrous tissues, the main load-bearing constituents at the micro-scale are arranged as a fibre network. In these materials, rupture is usually driven by micro-mechanical failure mechanisms, and strain localisation due to progressive damage evolution in the fibres is the main cause of macro-scale instability. We

We introduce a finite-element-model-updating-based open-source framework to identify mechanical parameters of heterogeneous hyperelastic materials from in silico generated full-field data which can be downloaded here https://github.com/aflahelouneg/inverse_identification_soft_tissue. The numerical process consists in simulating an extensometer performing in vivo uniaxial tensile experiment on a soft

A new substitution approach is proposed for decoupled two-scale analysis of a materially nonlinear composite plate with in-plane periodic meso-structures within the framework of computational homogenization. The macroscopic nonlinear mechanical behavior of the plate is characterized by numerical plate tests on an in-plane unit structure (IPUS), which enables us to obtain the relationship between macroscopic