The analysis of three-dimensional (3D) stress states can be complex and computationally expensive, especially when large deflections cause a nonlinear structural response. Slender structures are conventionally modelled as one-dimensional beams but even these rather simpler analyses can become complicated, e.g. for variable cross-sections and planforms (i.e. non-prismatic curved beams). In this paper

This paper presents a novel mesoscale finite element model for predicting the effective mechanical properties of concrete-like particle-reinforced composites with concave aggregates. In the mesoscale model, unit cells (UC) with randomly distributed non-convex particles and period boundaries are generated through computationally efficient algorithms to represent the periodic microstructures of concrete

Continuum models based on the combination of the theories of plasticity and damage mechanics pose a powerful framework for representing the highly nonlinear material behavior of cohesive-frictional materials. However, non-associated plastic flow rules for representing the inelastic volumetric expansion of such materials may result in unstable material behavior and, accordingly, strongly mesh-dependent

Adaptive growth method is a structural topology optimization approach based on the growth mechanism of natural biological branching systems, and it has been successfully applied for the static reinforcement of three-dimensional box structures. However, due to the effect of structural characteristics towards natural frequencies, it is difficult for adaptive growth method to effectively grow stiffeners

Fiber reinforced materials (FRMs) can be modeled as bi-phasic materials, where different constitutive behaviors are associated with different phases. The numerical study of FRMs through a full geometrical resolution of the two phases is often computationally infeasible, and therefore most works on the subject resort to homogenization theory, and exploit strong regularity assumptions on the fibers distribution

Suppressing enclosed voids in topology optimization is an important problem in design for manufacturing. The method of Poisson equation-based scalar field constraint (i.e., Poisson method) can effectively address this problem. Nevertheless, the numerical performance of this method is not well understood. This paper investigates the numerical functionality and characteristics of the Poisson method.

This paper presents a highly efficient and accurate approach to determine the bounds on the first excursion probability of a linear structure that is subjected to an imprecise stochastic load. Traditionally, determining these bounds involves solving a double loop problem, where the aleatory uncertainty has to be fully propagated for each realization of the epistemic uncertainty or vice versa. When

Several simplified models have been developed to simulate unbound soil for dynamic soil-structure interaction analysis in time domain. However, the existing models may have critical limitations for general applications. This study presents an approach to systematically generate lumped-parameter models with frequency-independent coefficients to represent the dynamic stiffness of rigid foundations in

In this study, a novel scheme for modelling and analysis of spot-welded shell structures is presented by placing local spider-web shell meshes representing the weld nugget region in a global shell mesh. Interface shell elements are employed for trimmed shell elements with arbitrary number of nodes created by cutting a global shell mesh with the boundaries of local spider-web shell meshes. Transverse

The use of multiscale schemes for computational failure evaluations of quasi-brittle composites, particularly concrete, has become a promising challenge for evaluating the complex degradation mechanisms at different scales of observations. In the framework of standard finite element procedures, both concurrent and semi-concurrent multiscale procedures have so far been considered for analysing failure

This paper, for the first time in literature, formulated and validated a three-dimensional, nonlinear augmented finite element method (3D A-FEM) that can account for multiple crack evolution in laminated composites under large deformation. The 3D A-FEM accounts for all major cracking events (intra-ply matrix cracking, fiber rupture/kinking, and inter-ply delamination) with explicit cohesive cracks

The optimization of damping composite material in a certain frequency range has become one of the critical issues in structural engineering applications due to the fact that the structures usually work in a wide vibration frequency range. This paper proposes a topology optimization method for designing the damping composite materials with high stiffness and high broadband damping. The broadband damping

In this paper, we develop a CAD-oriented topology optimization method incorporating directly the CAD model into the feature-driven optimization (FDO) framework. Practically, any free-form design domain model (FDDM), defined by the CAD model in stereolithography (STL) file format, is first represented by a level set function employing a radial basis function (RBF) interpolation technique. Feature-based

This paper presents a comprehensive numerical finite element implementation of the nonlocal strain gradient theory applied to thin laminated composite nanoplates using Kirchhoff theory (known as Classical Laminated Plate Theory or CLPT). Hermite interpolation functions are used to approximate membrane and bending degrees of freedom according to the conforming and nonconforming approaches. To the best

Assuming Timoshenko’s beam hypothesis, this paper proposes a unified strategy to derive exact finite-element (FE) matrices for framed structures having elements with variable rigidity. Its basic idea is to apply the principle of virtual forces (PVF), at the element level, to obtain a flexibility-based set of equations from which structural-property and nodal-load coefficients can be directly evaluated

We present in this paper a novel and efficient computational approach in terms of triangular extended stochastic finite element method (T-XSFEM) for simulation of random void problems. The present T-XSFEM is further enhanced by local mesh refinement with the aid of variable-node elements to couple/link different mesh-scales, increasing the efficiency of the developed approach and saving the computational

Traditional origami design is generally based on designers’ artistic intuition and skills, mathematical calculations, and experimentations, which can involve challenges for crease patterns with a large number of vertices. To develop novel origami structures for engineering applications, systematic and easy-to-implement approaches capable of generating diverse origami patterns are desired, without requiring

This paper shows experimental and numerical analyses on rammed earth arches asymmetrically loaded and successively strengthened with a natural composite. The aim is to evaluate the capability of finite element codes to faithfully describe the mechanical response, including the post peak branch and post elastic deformations. The mechanical properties of rammed earth were determined through specific

This paper concerns a computational implementation for solving a Moving Load (ML) problem on an infinite Euler–Bernoulli elastic beam on a Pasternak visco-elastic support. A steady-state dynamic response in convected coordinate is sought, by a numerical approach with discretization over a finite domain, implying spurious boundary reflections of non-evanescent waves. This is effectively solved by: (a)

This paper proposes a sampling-based system reliability-based design optimization (SRBDO) method with local approximation of constraints. To enhance the optimization efficiency of SRBDO problems with time-consuming constraints, Kriging metamodels are employed to replace the true constraint functions. A new composite active learning strategy based on the possibility of correctly predicting the state

Efficient modeling and optimization techniques are required to overcome the high design complexity and computational costs concerning the engineering of composite structures. In this paper, a modeling framework for the dynamic analysis of doubly curved composite panels is developed. Lamination parameters are used to characterize the stiffness properties of the laminate, and the responses are calculated

The application of structural topology optimization with complex engineering materials is largely hindered due to the complexity in phenomenological or physical constitutive modeling from experimental or computational material data sets. In this paper, we propose a new data-driven topology optimization (DDTO) framework to break through the limitation with the direct usage of discrete material data

An isogeometric membrane element based on the non-uniform rational basis spline (NURBS) model is presented that accounts for membrane wrinkling based on tension-field theory. First, the element is validated by means of a benchmark problem involving a partly wrinkled membrane. It is then applied to the large deformation of a thin membrane structure using a two-stage procedure that combines dynamic relaxation

The Shanghai Tower is presently the tallest structure in China and one of the super tall buildings in the world. To get a quick and direct insight into the overall dynamic behavior of this complex structure, a lumped-mass finite element model based on macro beam theory was developed. Next, an in-depth sensitivity analysis was performed on this baseline model and model updating was conducted by using

A fast reanalysis solver using linear tetrahedral elements is developed for 3D transient thermo-mechanical problems with temperature-dependent materials. The core idea is to formulate the reanalysis framework of a stable node-based smoothed finite element reanalysis method. In the developed solver, the stable node-based smoothed finite element method (SNS-FEM) is used as the main solver due its accuracy

Real fire incidents have shown that the structural systems of high-rise buildings perform much better during a fire attack than what classical structural fire analysis predicts. The reason behind this phenomenon is the empirically established fact that beneficial interaction mechanisms evolve between the fire-exposed and the fire-unexposed parts of structural systems. However, there is no computational

Particle damping is a passive damping technique at which granular material is either filled in a box attached to a vibrating structure or it is filled in holes embedded in the vibrating structure. Due to the structural vibrations, momentum is transferred to the granular material which interacts with each other. As a result, energy is dissipated by impacts and frictional phenomena between the particles

Prediction of vibrations generated by railway traffic experiences an increasing interest, as new lines are being constructed and planned in many countries. The paper proposes a numerical model to analyse a coupled vehicle–bridge–soil system, taking into account the most important phenomena affecting the structure, while at the same time being comparatively computationally efficient. Such model is useful

We study and use overlapping triangular finite elements enriched by trigonometric functions and implicit time integration to solve transient wave propagations in inhomogeneous media. We show explicitly that the total dispersion error of the calculated solutions can be split into two parts, the spatial error and temporal error. The study of the spatial dispersion error shows the effectiveness of the

The determination of effective material properties of composites based on a three-dimensional representative volume element (RVE) is considered in this paper. The material variation in the RVE is defined based on the colour intensity in each voxel of an image which can be obtained from imaging techniques such as X-ray computed tomography (XCT) scans. The RVE is converted into a numerical model using

We present a modeling framework for propagating the uncertainty, stemming from random heterogeneity of concrete microstructure, to its mesoscale elastic properties at the level of statistical volume element. The microstructure of concrete is modeled as a three-phase composite, consisting of aggregates (inclusions) in mortar (matrix), and interfacial transition zone (ITZ), a thin high porosity zone

The field of optimal design of linear elastic structures has seen many exciting successes that resulted in new architected materials and structural designs. With the availability of cloud computing, including high-performance computing, machine learning, and simulation, searching for optimal nonlinear structures is now within reach. In this study, we develop convolutional neural network models to predict

We propose a new adaptive NURBS upper-bound limit analysis approach for the assessment of general three-dimensional curved masonry structures, based on different meta-heuristic mesh adaptation schemes. The method, which can easily be integrated within CAD modeling environments, allows to establish the actual failure mechanism and load bearing capacity of a masonry structure by iteratively adjusting

In this paper, we introduce a level set topology optimization formulation considering coupled mechanical and thermal loads. Examples considering stress and compliance minimization under temperature and volume constraints, and mass minimization under stress and temperature constraints, are presented. The p-norm of the stress field and temperature field is used to approximate the maximum stress and temperature

This paper describes a cell-based smoothed finite element method (CS-FEM) for computing unsteady viscoelastic fluid–structure interaction (VFSI) within the arbitrary Lagrangian–Eulerian framework. The incompressible Navier–Stokes equations incorporating the Oldroyd-B constitutive relation are decoupled via the smoothed characteristic-based split scheme that allows equal low-order interpolations for

In this paper an efficient optimized seismic design of steel moment resisting frames is presented. Non-linear time history analysis is utilized to evaluate structural responses under seismic excitations. The goal is to optimize the cross-section properties of all elements comprising the frame, in order to achieve the minimal structural steel volume as a representation of the cost. Performance based

A new efficient and robust metaheuristic algorithm called “Interactive Autodidactic School (IAS)” is proposed in this paper to solve numerical optimization and structural design optimization problems. IAS is a population-based algorithm on the basis of the interactions between students in an autodidactic school with the goal of increasing their knowledge through a combination of self-teaching/self-learning

In this paper a new and efficient metaheuristic algorithm is proposed for discrete performance-based seismic design optimization of steel moment frames. The proposed metaheuristic uses the Newton gradient-based method as its updating scheme in a population-based framework and therefore it is termed as Newton Metaheuristic Algorithm (NMA). In order to enable the NMA to effectively explore the discrete

This paper presents a 3D model aiming at investigating the out-of-plane collapse behavior of multi-leaf non-periodic masonry walls. These structural elements are widely employed in several constructions that are part of the European architectural heritage, but have been seldom addressed in the available literature due to their natural complexity and uniqueness. Specifically, the model here proposed

In this research effort, the generalized warping and distortional problem of straight or horizontally curved composite beams of arbitrary cross section, loading and boundary conditions is presented. An inclined plane of curvature is also considered (with respect to the horizontal plane) in order to account for a slope in the cross-section plane. Additionally, a finite stiffness of diaphragmatic plates

Based on the thought of Green’s kernel function method (GKFM), an improved time-domain load identification method using moving weighted least square technique (MWLST) which can accurately fit dynamic load is proposed. Better than the traditional shape function method using moving least square fitting (SFM_MLSF), the proposed method considers continuity and correlation of dynamic load between two adjacent

The paper concerns the importance of dynamic structure–soil–structure interaction (SSSI) for structures with two or more foundations. Firstly, analysis of such polypod foundations is performed in frequency domain, considering the range 0–50 Hz and employing Green’s function for wave propagation in layered soil. Normalised dynamic stiffnesses related to individual foundations and cross-coupling between

Rheumatic heart disease (RHD) is identified as a serious health concern in developing countries, specifically amongst young individuals, accounting for between 250 000 and 1.4 million deaths annually. As such, attention is initially placed on the importance of the development of a cardiac analysis toolbox with functionality for pathophysiological analysis of the disease. Subsequently, in order to develop

WYPiWYG hyperelasticity is a data-driven, model-free computational procedure for finite element analysis of soft materials. The procedure does not assume the shape of the stored energy function and does not employ material parameters, predicting accurately any smooth prescribed behavior from a complete set of experimental tests. However, fuzzy experimental data may yield useless highly oscillatory

In this research, a reduced order method (ROM) called the Proper Orthogonal Decomposition with Interpolation (PODI) is used to drastically reduce computation time of highly complex and nonlinear problems as encountered in simulating the heart. The idea behind the method is to first construct a database of pre-computed full-scale solutions using the Element Free Galerkin method (EFG) or the Finite Element

Materials exhibiting a heterogeneous and non-uniform composition in terms of elastic and anisotropic properties such as biological tissues require special efforts to accurately describe their constitutive behavior. In contrast to classical models, micromorphic formulations can predict the macroscopically observable material response as originated from distinct scale-dependent micro-structural deformation

The Isogeometric Analysis (IGA) uses the Non-Uniform Rational B-Spline (NURBS) basis functions for the representation of both the geometry and the field variables. In IGA, the enforcement of the essential boundary conditions is complex because the NURBS basis functions do not satisfy the Kronecker-Delta property owing to their non-interpolating nature. Thus in the present formulation the strength of

We consider acoustic waves in fluid-saturated periodic media with large contrasts in the permeability and other poroelastic coefficients, whereby some of the mesoscopic material parameters depend on the scale parameter. The effective behaviour is described by a model obtained using the homogenization of the heterogeneous Biot continuum relevant to the mesoscopic level at which the dual porosity is

A hierarchic optimisation approach is presented for relieving inaccuracies in conforming shell elements arising from locking phenomena. This approach introduces two sets of strain modes: (i) objective strain modes, defined in the physical coordinate system, and (ii) corrective strain modes, representing conforming strains enhanced with hierarchic strain modes. This leads to two alternative families

In this paper, a reduced order coupled finite element/boundary element method (FEM/BEM) for control of noise radiation and sound transmission of vibrating structure by viscoelastic and passive piezoelectric treatments is presented. The system consists of a sandwich structure composed of elastic faces and a viscoelastic core (with surface mounted piezoelectric patches) and coupled to external/internal

This paper describes a macro model for a shallow foundation. The macro model represents the non-linear soil structure interaction (SSI) exemplified by a suspension bridge anchor-block. The model can be adjusted and used for other structures. The formulation uses an elasto-plastic framework to calculate the foundation response. A yield surface in the V – M - H (Vertical, Moment and Horizontal loading)

Depending on the required solution, this paper presents results for the state of stress and buckling of a uniformly pressurized elastic toroidal vessel of four segments. In the first part of the paper, a closed-formed stress solution is formulated for the novel shell form, by adopting the membrane solution as the particular solution of the Reissner-Meissner general bending-theory equations, and an

This paper presents a multiobjective optimization approach to minimize weight and maximize modal damping in laminated composite panels with Constrained Layer Damping (CLD) treatments. The design variables are the number and position of the CLD patch treatments on the surface of the laminated plate. The Direct MultiSearch (DMS) solver for multiobjective optimization problems is used in this work. DMS

This paper investigates a new passive damper coupling the energy dissipative mechanisms of dry friction and piezoelectric shunting circuit for Integrally Bladed Disks (blisks). The idea is to distribute piezoelectric material to the dry friction ring so that the elastic deformation of the dry friction ring is utilized to generate additional damping. Mounting piezoelectric material on the additional

The purpose of this work is to propose a computational framework for impact fracture of laminated glass. The novel computational framework is based on a newly proposed extrinsic cohesive shell model that is theoretically more accurate than the element deletion method and the intrinsic cohesive model to describe fracture in thin-shell glass layers. A laminated glass model is established, where the glass

This paper discusses the implementation of an artificial neural network (ANN) for predicting the critical flutter velocity of suspension bridges with closed box deck sections. Deck chord length, bridge weight and structural damping were varied. The ANN model was derived and trained using a dataset of critical flutter velocities, calculated using flutter derivatives (FDs) from experiments and by varying

Surrogate models enable efficient propagation of uncertainties in computationally demanding models of physical systems. We employ surrogate models that draw upon polynomial bases to model the stochastic response of structural dynamics systems. In linear structural dynamics problems, the system response can be described by the frequency response function. It is well known that standard polynomial chaos

The long-term behavior of cracked fiber reinforced concrete is still poorly understood, and the interaction between fibers and matrix is of high importance. This paper presents the results of a numerical investigation into the creep of two types of polypropylene fiber reinforced concrete under sustained uniaxial tensile loading with discrete fiber modeling. The material models are calibrated on an

In this paper, a novel numerical procedure is proposed for the force-displacement description of out-of-plane collapse in masonry structures. The numerical procedure herein proposed represents one first attempt to couple limit analysis-based solutions to displacement-based evolutive analysis strategies. Limit-analysis based solutions are considered trustworthy to investigate collapse mechanisms in