Deformation Coupling Research Articles

Thermal shock induced dynamics of a spacecraft with a flexible deploying boom

The dynamics in the process of deployment of a flexible extendible boom as a deployable structure on the spacecraft is studied. For determining the thermally induced vibrations of the boom subjected to an incident solar heat flux, an axially moving thermal-dynamic beam element based on the absolute nodal coordinate formulation which is able to precisely describe the large displacement, rotation and deformation of flexible body is presented. For the elastic forces formulation of variable-length beam element, the enhanced continuum mechanics approach is adopted, which can eliminate the Poisson locking effect, and take into account the tension-bending-torsion coupling deformations. The main body of the spacecraft, modeled as a rigid body, is described using the natural coordinates method. In the derived nonlinear thermal-dynamic equations of rigid-flexible multibody system, the mass matrix is time-variant, and a pseudo damping matrix which is without actual energy dissipation, and a heat conduction matrix which is relative to the moving speed and the number of beam element are arisen. Numerical results give the dynamic and thermal responses of the nonrotating and spinning spacecraft, respectively, and show that thermal shock has a significant influence on the dynamics of spacecraft.

Modeling of composite coupling technology for oil-gas pipeline section resource-saving repair

The article presents a variant of modeling and calculation of a main pipeline repair section with a composite coupling installation. This section is presented in a shape of a composite cylindrical shell. The aim of this work is mathematical modeling and study of main pipeline reconstruction section stress-strain state (SSS). There has been given a description of a structure deformation mathematical model. Based on physical relations of elasticity, integral characteristics of rigidity for each layer of a two-layer pipe section have been obtained. With the help of the systems of forces and moments which affect the layers differential equations for the first and second layer (pipeline and coupling) have been obtained. The study of the SSS has been conducted using the statements and hypotheses of the composite structures deformation theory with consideration of interlayer joint stresses. The relations to describe the work of the joint have been stated. Boundary conditions for each layer have been formulated. To describe the deformation of the composite coupling with consideration of the composite cylindrical shells theory a mathematical model in the form of a system of differential equations in displacements and boundary conditions has been obtained. Calculation of a two-layer cylindrical shell under the action of an axisymmetric load has been accomplished.

Material Selection and Process Configuration for Free-Form, Voluminous and Textile-Based Multi-Material-Design by the Example of a Bucket Seat

Hybrid textile-based composites possess an enormous potential for energy and resource efficient large-scale production, with freedom in and high specific mechanical properties. This paper covers the connection of available and established production processes for textiles in a differential process chain for the manufacturing of complex shaped and elastic sandwich components. The technology enables both stiffness and comfort through elasticity.OLU-Preg®-organic sheets, polyurethane foam cores and 3D-spacer fabrics form the targeted properties of demonstrator models. This article refers to the demonstrator part “bucket seat”. To show the benefit of complex composite material, the lightweight and mechanical properties of the sandwich structures are tested in several variations of core and comfort shapes. Absolute and specific improvements of performance are shown in static and dynamic examinations. An Analysis of coupling effects, deformation and failure behavior of the multi-material design (MMD) complete the scientific approach of the structure-property relationships of hybrid composites.

FEM-DEM coupling analysis for solid granule medium forming new technology

Solid Granule Medium Forming (SGMF) is a new flexible die forming technology which uses solid granules as the soft die to form the sheet metal. The process numerical analysis of this technology involves the discrete element (granules) and the continuum solid element (sheet metal), as they belong to different solving system—the discrete element method (DEM) solving system and finite element method (FEM) solving system, now there is no effective simulation ways for this kind of problems. Based on this, this paper established a new FEM-DEM coupling method according to the force conservation principle. And the simulation platform based on this method is developed through Visual Basic, which can realize the interaction, inheritance and transmission of the calculating data between FEM and DEM, with it the problems of elastic-plastic mechanics in the contact between continuum and discontinuum are solved for the first time. Such as the influence laws of the shape and mechanical parameters of discrete object on the plastic deformation of the continuum could be obtained. The limitations and errors brought by using FEM alone to analyze the fission problems are also eliminated by this. Solid granule medium tube outer pressure compression forming is used as a carrier to build the FEM-DEM coupling model, with the simulation platform both the force transmission characteristics and the mesostructure variation rule of solid granule medium in the tube forming process were obtained, and the impacts of technical parameters on the plastic forming property of the tube were analyzed. The accuracy of FEM-DEM coupling method is proved by the forming tests. This article provides an efficient way to solve the coupling deformation problems between the continuum and discontinuum in the field of engineering and a good experience for the solution of complicated engineering problems which need to be worked out with the secondary development of software.

EFFECTS OF BEND-TWIST COUPLING DEFORMATION ON THE AERODYNAMIC PERFORMANCE OF A WIND TURBINE BLADE

Comprehensive research exists on passive pitch control of wind turbines using bend-twist coupling property of composite materials. Blades with bend-twist coupling deformation can increase energy capture, improve dynamic stability, or reduce aerodynamic loads. The objectives of this work are to apply bend-twist coupling into an existing blade design and to investigate the resulting aerodynamic performance. The 41.25-meter blade was based on GE 1.5 GLX wind turbine. Aerodynamic loads were calculated using Blade Element Momentum (BEM) theory and Computational Fluid Dynamics (CFD) simulation. The resultant thrust and torque from both methods agree well. However, only the CFD can provide details of pressure distribution over the complex blade surface. Three levels of bend-twist coupling were designed for the Glass/Epoxy blade skins i.e. no coupling, low coupling, and high coupling. From Finite Element Analysis (FEA), the deflections of the three blades were slightly different while the twist angles were considerably different. The deformed geometries of the blades were then used to produce new three dimensional (3D) models for the prediction of the power coefficient (CP) by CFD. The results show that the proper bend-twist coupling laminate can improve the performance of the blade. At low wind speed, the CP is higher than the baseline blade. At wind speed greater than rated speed, however, the blades twist two much and the CP decreases below the baseline blade. Simulation of 3D blade models can help in the design of a bend-twist coupling level suitable to the blade shape and wind speed.

Three-dimensional vibration of rotating functionally graded beams

The three-dimensional free vibration and time response of rotating functionally graded (FG) cantilevered beams are studied. Material properties of functionally graded beams are assumed to change gradually through both the width and the thickness in power-law form. The second-kind Lagrange’s equations are used in conjunction with the Ritz method to derive the comprehensive coupling dynamic equations for the axial, chordwise, and flapwise motions. The trial functions of deformations are taken as the products of the Chebyshev polynomials and the corresponding boundary functions. Nonlinear coupling deformations are considered to capture the dynamic stiffening effect due to the rotating motion. The influences of the material gradient index and rotational speed on modal characteristics are investigated by the state space method. The eigenvalue loci veering phenomena with modal conversions are exhibited. The time responses indicate that the deformations of rotating functionally graded beams are greatly affected by the material gradient index. It is shown that for large deformation problems, using Chebyshev polynomials is more efficient in computing precision and robustness than using other polynomials.

Vibration and aeroelastic control of wind turbine blade based on B-L aerodynamic model and LQR controller

Vibration and aeroelastic control of anisotropic composite wind turbine blade modeled as symmetric layup beam analysis have been investigated based on Beddoes-Leishman (B-L) dynamic stall aerodynamic model and linear quadratic controller. The blade is modeled as single-cell thin-walled beam structure, exhibiting flap bending-lag bending-twist coupling deformation, with constant pitch angle set. The stall flutter and aeroelastic control of composite blade are investigated based on some structural and dynamic parameters, with structural damping computed. The aeroelastic partial differential equations are reduced by Galerkin method, with the nonlinear aerodynamic forces computed by the method of fitting static elastic coefficients. Linear quadratic controller is applied to enhance the vibrational behavior in stall situation under divergent conditions and stabilize displacements that might be unstable in the absence of control.

Coupled flow and deformations in granular systems beyond the pendular regime

A pore-scale numerical model is proposed for simulating the quasi-static primary drainage and the hydro-mechanical couplings in multiphase granular systems. The solid skeleton is idealized to a dense random packing of polydisperse spheres by DEM. The fluids (nonwetting and wetting phases) space is decomposed to a network of tetrahedral pores based on the Regular Triangulation method. The local drainage rules and invasion logic are defined. The fluid forces acting on solid grains are formulated. The model can simulate the hydraulic evolution from a fully saturated state to a low level of saturation but beyond the pendular regime. The features of wetting phase entrapments and capillary fingering can also be reproduced. Finally, a primary drainage test is performed on a 40,000 spheres of sample. The water retention curve is obtained. The solid skeleton first shrinks then swells.

On the Cohomological Derivation of Yang-Mills Theory in the Antifield Formalism

We present a brief review of the cohomological solutions of self-coupling interactions of the fields in the free Yang-Mills theory. All consistent interactions among the fields have been obtained using the antifield formalism through several order BRST deformations of the master equation. It is found that the coupling deformations halt exclusively at the second order, whereas higher order deformations are obstructed due to non-local interactions. The results demonstrate the BRST cohomological derivation of the interacting Yang-Mills theory.

Multi-objective optimization of flexure hinge mechanism considering thermal–mechanical coupling deformation and natural frequency

Flexure hinge mechanism plays a key part in realization of terminal nano-positioning. The performance of flexure hinge mechanism is determined by its positioning design. Based on the actual working conditions, its finite element model is built and calculated in ANSYS. Moreover, change trends of deformation and natural frequency with positioning design parameters are revealed. And sensitivity analysis is performed for exploration response to these parameters. These parameters are used to build four objective functions. To solve it conveniently, the multi-objective optimization problem is transferred to the form of single-objective function with constraints. An optimal mechanism is obtained by an optimization method combining ANSYS with MATLAB. Finite element numerical simulation has been carried out to demonstrate the superiority of the optimal flexure hinge mechanism, and the superiority can be further verified by experiment. Measurements and tests have been conducted at varying accelerations, velocities, and displacements, to quantify and characterize the amount of acceleration responses obtained from flexure hinge mechanism before and after optimization. Both time- and frequency-domain analyses of experimental data show that the optimal flexure hinge mechanism has superior effectiveness. It will provide a basic for realizing high acceleration and high precision positioning of macro–micro motion platform.

Numerical and experimental investigations on large-diameter gear rolling with local induction heating process

Gear rolling with local induction heating process is a novel method to produce large-diameter gears with great advantages. To investigate the gear forming process, a simplified finite element (FE) model coupling electromagnetic-thermal and deformation fields is developed in the DEFORM-3D software and is validated by corresponding experiments. According to the numerical and experimental results, producing large-diameter gears using gear rolling process with local induction heating is feasible. Moreover, the blank heated by local induction heating has a temperature gradient distribution in the radial direction, which results in the defect reduction of inner hole enlarging. Thanks to the heat compensation function of induction heater, the defect of metal folding in the tooth top of the blank is reduced. In addition, the formability is improved by using local induction heating and the rolling force drops drastically compared with cold rolling process.

A deformation mechanism based material model for topology optimization of laminated composite plates and shells

This paper presents a novel deformation mechanism based material model for topology optimization of laminated plates and shells considering large displacements. Discussed firstly are the one-node hinges in optimum designs of plate and shell structures and the numerical issues caused by void elements in geometrical nonlinear analysis. To circumvent these two problems, we propose a new material model in which different penalties are applied to different strain energy terms related to extensional, shear, bending and extensional-bending coupling deformation mechanisms and void elements are removed in nonlinear finite element analysis. An efficient algorithm is developed by using the present material model and the moving iso-surface threshold method. Numerical results are presented for isotropic and composite plates and shells and compared with those available in the literature to validate the present material model.

Energy shaping control of an inverted flexible pendulum fixed to a cart

Control of compliant mechanical systems is increasingly being researched for several applications including flexible link robots and ultra-precision positioning systems. The control problem in these systems is challenging, especially with gravity coupling and large deformations, because of inherent underactuation and the combination of lumped and distributed parameters of a nonlinear system. In this paper we consider an ultra-flexible inverted pendulum on a cart and propose a new nonlinear energy shaping controller to keep the pendulum at the upward position with the cart stopped at a desired location. The design is based on a model, obtained via the constrained Lagrange formulation, which previously has been validated experimentally. The controller design consists of a partial feedback linearization step followed by a standard PID controller acting on two passive outputs. Boundedness of all signals and (local) asymptotic stability of the desired equilibrium is theoretically established. Simulations and experimental evidence assess the performance of the proposed controller.

Particle-rotor versus particle-vibration features ingfactors ofCd111andCd113

The emergence and evolution of collective excitations in complex nuclei remains a central problem in the quest to understand the nuclear many-body problem. Nuclear quadrupole collectivity is usually investigated via electric quadrupole observables. Here, however, we measure the $g$ factors of low-excitation states in $^{111}\mathrm{Cd}$ and $^{113}\mathrm{Cd}$ and show that they are sensitive to the nature of the collectivity in these nuclei in ways that the electric quadrupole observables are not. The particle-vibration model, which assumes spherical core excitations, cannot explain the $g$ factors, whereas a particle-rotor model with a small, nonzero core deformation does. The contrast of the two models is made stark by the fact that they begin from the same limiting $g$-factor values: It is shown that when an odd nucleon occupies a spherical orbit with angular momentum $j=1/2$, or a deformed orbit with $j=1/2$ parentage, the particle-vibration model and the particle-rotor model both reduce to the same $g$-factor value in their respective limits of zero particle-vibration coupling or zero deformation.

Investigation of the influence of the chemical composition of HSLA steel grades on the microstructure homogeneity during hot rolling in continuous rolling mills using a fast layer model

The newly developed LaySiMS simulation tool provides new insight for inhomogeneous material flow and microstructure evolution in an endless strip production (ESP) plant. A deepened understanding of the influence of inhomogeneities in initial material state, temperature profile and material flow and their impact on the finished product can be reached e.g. by allowing for variable layer thickness distributions in the roll gap. Coupling temperature, deformation work and work hardening/recrystallization phenomena accounts for covering important effects in the roll gap. The underlying concept of the LaySiMS approach will be outlined and new insight gained regarding microstructural evolution, shear and inhomogeneous stress and strain states in the roll gap as well as local residual stresses will be presented. For the case of thin slab casting and direct rolling (TSDR) the interrelation of inhomogeneous initial state, micro structure evolution and dissolution state of micro alloying elements within the roughing section of an ESP line will be discussed. Special emphasis is put on the influence of the local chemical composition arising from direct charging on throughthickness homogeneity of the final product. It is concluded that, due to the specific combination of large reductions in the high reduction mills (HRM) and the highly inhomogeneous inverse temperature profile, the ESP-concept provides great opportunities for homogenizing the microstructure across the strip thickness.

Landslide Deformation Analysis by Coupling Deformation Time Series from SAR Data with Hydrological Factors through Data Assimilation

Time-series SAR/InSAR techniques have proven to be effective tools for measuring landslide movements over large regions. Prior studies of these techniques, however, have focused primarily on technical innovation and applications, leaving coupling analysis of slope displacements and trigging factors as an unexplored area of research. Linking potential landslide inducing factors such as hydrology to SAR/InSAR derived displacements is of crucial importance for understanding landslide deformation mechanisms and could support the development of early-warning systems for disaster mitigation and management. In this study, a sequential data assimilation method named the Ensemble Kalman filter (EnKF), is adopted to explore the response mechanisms of the Shuping landslide movement in relation to hydrological factors. Previous research on the Shuping landslide area shows that the reservoir water level and rainfall are the two main triggering factors in slope failures. To extract the time-series deformations for the Shuping landslide area, Pixel Offset Tracking (POT) technique with corner reflectors was adopted to process the TerraSAR-X StripMap (SM) and High-resolution Spotlight (HS) images. Considering that these triggering factors are the primary causes of displacement fluctuations in periodic displacement, time-series decomposition was carried out to extract the periodic displacement from the POT measurements. The correlations between the periodic displacement and the inducing factors were qualitatively estimated through a grey relational analysis. Based on this analysis, the EnKF method was adopted to explore the response relationships between the displacements and triggering factors. Preliminary results demonstrate the effectiveness of EnKF in studying deformation response mechanisms and understanding landslide development processes.

Coupled deformation–seepage analysis of dynamic capacity tests on open-ended piles in saturated sand

Open-ended piles such as tubular piles or I-beams are used as foundations for offshore and nearshore construction. After the pile installation a load test to estimate the bearing capacity of these open-ended piles is necessary. Due to the offshore conditions and the high bearing capacity of the installed piles a static load test is not normally feasible. Therefore, dynamic load tests are carried out where the wave propagation due to an dynamic impact at the pile head is measured. The methods to estimate the bearing capacity from the measured signal of the dynamic tests were derived for solid pile profiles. It is questionable whether these evaluation techniques are applicable for open-ended piles. Hence, the influence of various important system parameters as well as the differences between static and dynamic load tests on open-ended piles is investigated in this paper.

Novel continuum models for coupled shear wall analysis

Summary Replacement beam formulations represent a family of 1D continuum models suitable for approximate analyses of the structural arrangements of buildings. In this paper, an energy equivalence approach is applied to coupled shear walls to develop suitable replacement beam models. Assuming properly compatible coupling fields between walls, a novel three-field coupled two-beam approach, therein providing shear and axial deformations, is proposed. The corresponding mathematical formulation provides closed-form solutions for simple loading cases with homogenous properties. Considering slender coupled shear walls, as typically found in tall buildings, the coupled two beams can be reduced to a two-field formulation, i.e., a parallel assembly of an extensible Euler–Bernoulli beam and a rotation-constraining beam. The latter model is solved analytically, and expressions for the tip displacement and base bending moment are presented. A finite element model is then presented and demonstrated to be an efficient tool for static and dynamic analyses. The effects of the axial deformation and degree of coupling on slender coupled shear wall responses are described as being dependent upon two suitable parameters. Various approximate relations are also proposed for design purposes. Finally, the validity of both analytical solutions and the finite element model is confirmed via numerical examples. Copyright © 2015 John Wiley & Sons, Ltd.

FLEXIBLE DYNAMIC MODEL OF ATTITUDE MANEUVERING OF RAZAKSAT® SATELLITE

In this paper, a dynamic model equation of the RazakSAT® class satellite three flexible solar panels for three-dimensional dynamic studies is developed based on the coupling deformation field. In the model, each solar panel is flexible and attached to the satellite body via a fixed joint where the assumption of Euler-Bernoulli beam is applied for the solar panels. Lagrange and assumed mode method are used to develop the dynamic model of the RazakSAT® multi-body system. A comprehensive model of flexible satellite has been provided in ANSYS environment as a reference when simulating the theoretical response generated by MATLAB to show that the coupling effect on the characteristics of the flexible sub system while undergoing rigid-body rotational motion.

Coupled Solving Thermal Deformation of Hydrostatic Bearing Rotary Worktable Based on Temperature Fields of Oil Film

Coupled Solving Thermal Deformation of Hydrostatic Bearing Rotary Worktable Based on Temperature Fields of Oil Film