Xiaowei Deng

University of California, San Diego | UCSD · Jacobs School of Engineering

This study developed Geometry Physics neural Operator (GPO), a novel solver framework to approximate the partial differential equation (PDE) solutions for solid mechanics problems with irregular geometry and achieved a significant speedup in simulation time compared to numerical solvers. GPO leverages a weak form of PDEs based on the principle of l...

Wind tunnel tests and numerical simulations are the mainstream methods to study the wind-induced vibration of structures. However, few articles use statistical parameters to point out the differences and errors of these two research methods in exploring the wind-induced response of membrane structures. The displacement vibration of a saddle membran...

This contribution is comprised of two parts. In the first part we provide an overview of the Dynamically Data-Driven Applications Systems (DDDAS) concept, with particular emphasis on the analytics of systems coming from the field of Applied Mechanics and focusing on the applications to aerospace structures. Aerospace composite materials and structu...

The accurate assessment of the dynamic response of the offshore wind turbine is fundamental to its economical and safe design, where the precise characterization of the incident wind and waves is essential. While reliable aerodynamic models can accurately reproduce wind characteristics, the widely-used empirical JONSWAP spectrum in wave field simul...

The paper presents the random vibration and structural reliability of composite hyperbolic–parabolic membrane structures under wind load. First, the non-linear random vibration equation of the hyperbolic–parabolic membrane structures is established by the moment-free theory of thin shells, von Karman’s large deflection theory, and the potential flo...

This wind tunnel study was conducted to investigate the similarity laws involved in the reasonable simulation of the wake characteristics of a full-scale wind turbine. A 5 MW scaled wind turbine model was designed using an optimization method based on the blade element momentum (BEM) theory. Subsequently, wind tunnel tests were carried out on the g...

In this paper, the impact of the hail with the single and combined particle sizes on the saddle membrane structure is studied by experiments and numerical simulations. In the experiment, the hail particles fall at a certain height and hit the membrane, while the dynamic response of feature points on the membrane and the cable tension is monitored....

Tunable waterbomb origami has attracted significant attention for its superior capability in structural reconfiguration, which is utilized to tailor the mechanical properties of metamaterials. Recent researches mainly focus on the kinematic analysis of waterbomb origami folding process to convert the planar crease pattern to a three-dimensional fol...

An appropriate cooperative yaw control strategy, in which the accurate power prediction and efficient optimization method play an essential role, can mitigate the significant power loss owing to the wake interference. The present study develops a novel double-layer machine learning framework, which combines an artificial neural network (ANN) yawed...

Based on von Karman’s large deflection theory, the nonlinear dynamic response governing equation of composite umbrella pretensioned membrane structure under hail load is established. The vibration mode function is obtained by the Bessel function and Euler equation. The governing equation is solved by the KBM perturbation method and Galerkin method,...

The vortex shedding phenomenon caused by flow separation at windward corners of a high-rise building would lead to significant vortex-induced vibrations (VIVs). This paper proposes a novel and efficient two-way coupled fluid-structure interaction (FSI) method named as equivalent lumped mass system (ELMS) method to study the wind-induced responses o...

The verification and validation (V&V) of multi-fidelity turbulence models is crucial for the efficient and reliable industrial application of computational fluid dynamics (CFD). This study aims to evaluate the performance of detached eddy simulation (DES) modeling approaches embedded with various unsteady Reynolds Averaged Navier-Stokes (URANS) mod...

Monopile-supported wind turbines are usually placed in a harsh ocean environment and wave load becomes a major consideration in the nearshore wind farm design. Affected by the coastal geography and seabed terrain, the wave field inside a wind farm is usually spatially inhomogeneous and the wave load on each turbine can be greatly different. However...

Nowadays, tubular joints with superior structural properties have been extensively applied in constructing the complicated multi-planar steel joints that are often adopted in the grid shell structure system. However, sometimes it is challenging to maintain high-quality on-site welding joints or even difficult to assess the quality of on-site weldin...

The accurate prediction of the dynamic behavior of the offshore wind turbine plays a significant role in its safe and efficient operation, where special importance should be attached to the foundation modeling of soil-pile-structure interaction. The present study aims to compare the three foundation modeling approaches with special attention to the...

In isogeometric analysis (IGA), the boundary representation of computer-aided design (CAD) and the tensor-product non-uniform rational B-spline structure make the analysis of three-dimensional (3D) problems with irregular geometries difficult. In this paper, an IGA method for complex models is presented by reconstructing analysis-suitable models. T...

Geopolymer cementitious materials and recycled aggregate are typical representatives of material innovation research in the engineering field. In this study, we experimentally investigated a method to improve the performance of geopolymer-recycled aggregate concrete (GRAC). The recycled concrete aggregates and steel fiber (SF), fly ash (FA), metaka...

The raw materials of geopolymer come from industrial wastes, which have the advantages of lower carbon emissions and less energy consumption compared with traditional cement products. However, it still has the disadvantages of low strength, easy cracking, and low production efficiency, which limit its engineering application and development. At pre...

Graphene oxide (GO) is one of the nanomaterials that have attracted the most attention of researchers in recent years. Because of its excellent mechanical, thermal and electrical properties, it is widely used in the fields of energy, photoelectric, catalysis and materials, and it has shown broad development prospects. For the high demand of cement-...

In the global construction industry, with the growth of population, two important construction problems have to be faced, namely, the excessive consumption of non-renewable resources and the massive accumulation of construction waste. In order to solve these problems, geopolymer recycled aggregate concrete (GRAC) arises at the historic moment. On t...

Large-span composite membrane structure is light in weight and small in stiffness, which may produce violent random vibration under the random impact, such as wind, rain, hail and windborne debris. In order to accurately understand the random vibration response of membrane structure, the dynamics of composite saddle membrane structure under the sto...

In the wind industry, power prediction of wind farm is commonly implemented by analytical wake models, which is low-cost but insufficient in accuracy for high-turbulent wake modelling. In this study, a novel machine-learning-based wake model is developed to improve the power prediction of wind farms. The presented model can reproduce the velocity a...

For the high demand for cement-based materials in buildings, improving the performance of cement-based materials has become the focus of relevant researchers. In recent years, nanomaterials have broad prospects in many fields such as architecture by virtue of their “lightweight, high strength, and strong solidity” characteristics. As a modifier of...

The inclusion of micro bubbles often exists in polyimide films (PI) during the liquid molding process, which can largely affect the mechanical performance. However, there lacks an effective method to quantify the bubble content. Herein, an obvious tension variation of a pre-stressed polyimide film is observed firstly in a vacuum test. This phenomen...

In the recent decades, traditional concrete poses a great challenge to the modernization of the construction industry because of low tensile strength, poor toughness, and weak resistance to cracking. To overcome these problems, ultra-high performance concrete (UHPC) with superior mechanical properties and durability is developed for broad applicati...

The membrane structure is a flexible structure, which is easy to vibrate or even relax under dynamic load. Engineering accident analysis shows that the relaxation of membrane structure is more likely to lead to structural failure. In this article, the impact load problem is combined with the flexible structure to analyze the impact of hailstone imp...

In this paper, the dynamic response of a typical four-point pretensioned saddle membrane structure under hail impact load is investigated by numerical simulations and experimental studies. Firstly, the initial shape of saddle membrane is obtained by form-finding analysis using the finite element analysis software ANSYS. The complex mechanical proce...

In this study, dynamic response of a typical umbrella membrane structure under heavy rainfall load is studied by experimental and numerical methods. In the experiment, heavy rainfalls of three rainfall intensities are applied to a typical umbrella membrane structure under five different tensile force levels. The dynamic responses of feature points...

In recent years, with the higher requirements for the performance of cement-based materials and the call for energy conservation and environmental protection, a wave of research on new materials has set off, and various high-performance concrete and more environmentally friendly geopolymers have appeared in the public. With a view to solving the de...

In this paper, dynamic analysis of functionally graded porous (FGP) plate with reinforcement of graphene platelets (GPLs) resting on elastic foundation and restrained by elastic boundary condition is investigated. Four types of porous materials reinforced with four types of graphene platelets varying along the thickness direction are considered. Th...

We simulate two back-to-back full-scale tidal turbines using an in-house computational freesurface flow code. We briefly present the mathematical formulation of the computational framework. We first validate the proposed method on a single turbine configuration. A mesh refinement study is conducted to ensure the result is converged. We then quantif...

In the paper, a novel framework that employs the machine learning and CFD (computational fluid dynamics) simulation to develop new wake velocity and turbulence models with high accuracy and good efficiency is proposed to improve the turbine wake predictions. An ANN (artificial neural network) model based on the back-propagation (BP) algorithm is de...

A robust discontinuous Galerkin (DG) finite element method is proposed for elasticity problems with interfaces, where the continuity across the interfaces is weakly enforced by using Nitsche’s method. We employ a weighting for the interfacial consistency terms arising in the Nitsche variational form and present a detailed finite element formulation...

The geopolymer recycled concrete specimens were produced by using hypergolic or calcined coal gangue, slag, fly ash and recycled aggregate as the raw materials. Five different ratios of recycled coarse aggregate to total coarse aggregate and two types of geopolymer recycled concrete schemes (hypergolic coal gangue and calcined coal gangue respectiv...

Estimation of sound transmission loss (TL) due to the piezoelectric effects, as an attenuation of acoustic waves, is studied for a thick-walled piezo-composite cylindrical shell excited by an oblique incident plane wave. The cylinder is filled with and submerged in an acoustic media. The three-dimensional (3D) exact theory of elasticity and piezoel...

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Isogeometric analysis (IGA), due to its high efficiency and accuracy, can be replaced the conventional finite element method in the topology optimizations (TOs). In this paper, we present an efficient isogeometric TO method based on the scheme of bi-directional evolutionary structural optimization (BESO). The structural response analysis is impleme...

Experimental study is reported on the seismic behavior of a type of exterior beam–column connections, which feature service holes in the connecting ends of the beams. Specimens with three typical lengths of the holes (450, 500, and 400 mm) are tested under quasi‐static reversed cyclic loading with constant axial compression on columns. Failure mode...

This manuscript presents the experimental investigations on the seismic behavior of precast grouted sleeve column-to-foundation connections. Six full-scale specimens were constructed with varying longitudinal reinforcement ratios and stirrup ratios. Four specimens were precast with grouted sleeve connections. Two cast-in-place reference specimens w...

In this paper, the free vibrations of functionally graded porous (FGP) rectangular plate with uniform elastic boundary conditions is investigated by means of an improved Fourier series method (IFSM). It is assumed that the distributions of porosity are uniform or non-uniformly along a certain direction and three types of the porosity distribution a...

In the process of bone regeneration, new bone formation is largely affected by physico-chemical cues in the surrounding microenvironment. Tissue cells reside in a complex scaffold physiological microenvironment. The scaffold should provide certain circumstance full of structural cues to enhance multipotent mesenchymal stem cell (MSC) differentiatio...

Mechanical energy harvesters are designed to capture the ambient energy and transform it into usable electrical energy. Power harvesting from mechanical vibrations is the fundamental step toward providing self-powered smart systems in the developing wireless and portable electronic devices marketplace. This paper presents a new design and an analyt...

As a novel class of weight-efficient engineering materials, the functionally graded porous (FGP) beam structures have great potential value. However, the current research on it is relatively small. Based on this research status, the aim of this paper is establishing a unified analytical model to study the vibration behavior of moderately thick func...

Fabric membrane, a typical composite material, is widely applied in building structures, agricultural facilities, packaging engineering, and aeronautical engineering, etc. However, it may fail subject to large-amplitude vibration induced by impact due to its lightweight and small stiffness properties. Herein, the nonlinear damped vibration of a pre...

As traditional composite materials, concrete and reinforced concrete (RC) have been widely used for civil and military purposes. The multi-scale response analysis of concrete structures can be implemented by coupling the finite element and discrete element methods (FEM-DEM). To study the response sensitivities, this paper presents a novel approach...

This article reviews state-of-the-art numerical techniques for fluid–structure interaction (FSI) of full-scale wind-turbine systems. Simulation of floating wind turbines subjected to combined wind-flow and ocean-wave forcing, and modeling of high-cycle fatigue failure of blades due to long-term cyclic aerodynamic loading, are the focal points of th...

Large, thin, prestressed membranes known as ‘gossamer’ structures have many applications in space, including light reflection and electromagnetic signal collection. The prestress forces applied to these structures usually causes some wrinkling of the membrane to occur, and the degree of wrinkling affects the reflective performance of the structure....

This article reviews state-of-the-art numerical techniques for fluid–structure interaction (FSI) of full-scale wind-turbine systems. Simulation of floating wind turbines subjected to combined wind-flow and ocean-wave forcing, and modeling of high-cycle fatigue failure of blades due to long-term cyclic aerodynamic loading are the focal points of thi...

Multistable tensegrity structures are an intriguing form of compliant prestressed structures. Due to their attractive properties, these structures are attractive for a wide range applications. This papers aims the form-finding problem of tensegrity structures with multiple equilibrium modes. An optimization method for form-finding of multi-mode ten...

The buckling capacity of a radially retractable hybrid grid shell in the closed position was investigated in this paper.The geometrically non-linear elastic buckling and elasto-plastic buckling analyses of the hybrid structure were carried out. A parametric study was done to investigate the effects rise-to-span ratio, beam section, area and pre-str...

The thermal stress due to temperature rise may increase the element strain and internal forces, which may lead to the failure of the deployment of deployable structure. However, few works are carried out to study the dynamic performance of the flexible multibody under different temperatures, especially for retractable roof structures. Based on this...

The galloping of a tensioned orthotropic saddle closed membrane structure is theoretically investigated in this paper. The aerodynamic force acting on the membrane surface is determined by the potential flow theory of fluid mechanics and the thin airfoil theory of aerodynamics. Based on the von Kármán's large amplitude theory and the D'Alembert's p...

In recent years, with the development of the space structures, thin film reflector structures have the feature of lightweight, high compact ratio, easy to fold and unfold and so on. Its form has received wide attention from researchers and a broad application prospect. In this paper, the nonlinear finite element software ABAQUS was used to carry ou...

In this chapter the numerical challenges of simulating aerodynamics and fluid–structure interaction (FSI) of wind turbines are summarized, and the recently developed computational methods that address these challenges are presented. Several wind-turbine computations at full scale and with full complexity of the geometry and material composition are...

The behavior of a bistable strut for variable geometry structures was investigated in this paper. A three-hinged arch subjected to a central concentrated load was used to study the effect of symmetric imperfections on the behavior of the bistable strut. Based on a nonlinear strain–displacement relationship, the virtual work principle was adopted to...

In recent years, with the development of the space industry, thin film reflector structures have the feature of lightweight, high compact ratio, easy to fold and unfold and so on. Its form has received wide attention from researchers and a broad application prospect. In this paper, the nonlinear finite element software ABAQUS was used to carry out...

On the basis of the introduction of the stiffness matrix of tensegrity structures, the eigenvalue analysis is carried out to study the influence of the prestress level on the stiffness of tensegrity structures. The triangular prismatic tensegrity structure, the star-shaped tensegrity structure and the star-shaped tensegrity structure with a central...

A computational free-surface flow framework that enables 3D, time-dependent simulation of horizontal-axis tidal-stream turbines (HATTs) is presented and deployed using a complex-geometry HATT. Free-surface flow simulations using the proposed framework, without any empiricism, are able to accurately capture the effect of the free surface on the hydr...

This work presents a collection of advanced computational methods, and their coupling, that enable prediction of fatigue-damage evolution in full-scale composite blades of wind turbines operating at realistic wind and rotor speeds. The numerical methodology involves: (1) a recently developed and validated fatigue-damage model for multilayer fiber-r...

Deployable cable-strut structures are spatial structures that are composed of struts, active and passive cables. A deployable structure based on di-pyramid (DP) cable-strut unit was studied in this paper. Firstly, the concept of the deployable cable-strut system is proposed. Then a prototype is built to validate the concept. Then the mechanical beh...

In this paper, we propose a computational fluid–structure interaction (FSI) framework for the simulations of the interaction between free-surface flow and floating structures, such as offshore wind turbines. The framework is based on a suitable combination of the finite element method (FEM) and isogeometric analysis (IGA), and has good efficiency,...

This paper focuses on rigid foldability of the cylindrical origami with Kresling pattern. The theory of quaternion representing spatial fixed-point rotation and the rotating vector model were proposed by some researchers to obtain the quaternion rotation sequence method (QRS method) to study the foldability of origami, but the method is limited def...

The folding and deployment of a cylinder with Miura origami patterns are studied in this paper. First, the geometric formulation of the design problem is discussed. Then the loading case of the axial strains and corresponding external nodal loads applied on the vertices of the top polygon during the motion is investigated analytically. The influenc...

The dynamic behavior of the folding process of a prismatic mast based on Kresling origami pattern is studied in this paper. The mast consists of identical triangles with cyclic symmetry. Firstly, bar strains and necessary external nodal loads of the mast during the motion are studied analytically. The results show that the mechanical behaviors are...

Optimization of the femur prosthesis is a key issue in femur replacement surgeries that provide a viable option for limb salvage rather than amputation. To overcome the drawback of the conventional techniques that do not support topology optimization of the prosthesis design, a parameterized level set method (LSM) topology optimization with arbitra...

This paper investigates the geometry of a foldable barrel vault with Yoshimura Origami patterns during the motion. On the base of the geometry analysis of the origami unit, the radius, span, rise, and longitudinal length of the foldable barrel vault with regular Yoshimura Origami pattern in all configurations throughout the motion are determined. T...

In this paper, we combine recent developments in modeling of fatigue-damage, isogeometric analysis (IGA) of thin-shell structures, and structural health monitoring (SHIM) to develop a computational steering framework for fatigue-damage prediction in foil-scale laminated composite structures. The main constituents of' the proposed framework are desc...

The basic concept of a deployable pyramidal shelter structure based on origami is introduced. Various radially foldable systems are composed by leaf units in leaf-in and leaf-out patterns. Then the geometry and motion of the system are studied. The geometry in the fully deployed configuration for the leaf-out pattern is identical to that for the le...

A radially retractable roof structure based on the concept of the hybrid grid shell is proposed in this paper. The single-layer steel trusses of the radially foldable bar structure are diagonally stiffened by cables, which leads to a single-layer lattice shell with triangular mesh. Then comparison between the static behavior between the retractable...