Additional Dynamic Effects Research Articles

Computational Fluid‐Structure Interaction towards Simulating Large Wind Turbines with openFOAM and deal.II Coupled via preCICE

AbstractWind energy is an essential part of the Green Deal. The trend to increase the size of wind turbines, especially offshore, introduces additional dynamic effects at the long and flexible blades. Embedded in the CRC 1463, DFG, we are working on the fluid‐structure interaction to avoid dynamic stall and investigate flutter effects and blade breathing of ultra‐slim blades [1,2]. This requires an accurate numerical setup that reliably captures the fluid‐structure interactions due to the highly turbulent flow and large deformations of the blades. In preliminary work, the Unsteady Reynolds‐averaged Navier‐Stokes method (URANS) in openFOAM [3] was used to simulate the flow around rotating helicopter blades with a changing angle of attack. [4] successfully predicted the distinct dynamic stall hysteresis with moderate computational effort and captured extreme values (load peaks) within the experimental uncertainties. This aerodynamic solver is to be coupled with a structural solution, for which deal.II [5] provides the linear elastic blade model. The fluid and the structure solvers are coupled via the software preCICE [6] and solved with a staggered approach. Numerical results are presented for a simplified 2D cross‐section of a rectangular solid of carbon‐fiber‐reinforced polymers and a steady inflow velocity. Key challenges for the coupling of the solvers are discussed and the future work is outlined.

Vibration control of beams under moving loads using tuned mass inerter systems

Traditional tuned mass dampers (TMDs) have been proven efficient for the moving-load-induced vibration control of beams. However, a large tuned mass is required in TMDs to adjust the structural dynamic characteristics and achieve the demanded performance targets, which leads to additional dynamic effects and inconvenience of installation. The tuned mass inerter system (TMIS) is an ungrounded lightweight passive control device, which contains a suspended mass, a parallel-connected tuned spring and an inerter-based subsystem. In this study, the application and optimization of TMISs on vibration suppression of multi-span beam models under moving load series are investigated. Using the Bubnov-Galerkin integration method, the modal-superposition generalized system for specified modes of a beam with TMIS under successive moving load series is established. Then, a design strategy for TMISs is proposed to achieve the structural target performance demand by decreasing the moving load-induced resonant responses and attached tuned mass. In the optimization algorithm, the tuned mass ratio is taken as the optimal objective, and the limited dynamic response amplitude under different speed parameters is the constraint condition. A single-span simply supported beam with the TMIS under a moving load series is analyzed. The designed TMISs are tuned to the dominating mode with the maximum mass participate factor of the main structures. TMISs show good vibration mitigation compared to TMDs with equal tuned mass. Meanwhile, under the premise of identical structural performance demands, TMISs require less tuned mass than TMDs and achieve a lightweight control effect. The corresponding dynamic amplitude vs speed curves and time history response curves of beams with TMISs and TMDs are also depicted through comparative analyses. The vertical deflection and acceleration responses apparently decrease, and the resonance is mitigated due to the designed TMISs. The sensitivity analysis results indicate that TMISs attached to beams are insensitive to the perturbance of their parameters and the input moving load excitations; thus, TMIS proves to be a robust tuning system.

Analytical and Numerical Estimation of Fracture Initiation and Propagation Regions around Large-Diameter, Deep Boreholes for Disposal of Long-Lived Intermediate-Level Waste

The safety of high-level radioactive waste disposal has been studied across the world considering mined geologic repositories. Here, we introduce large-diameter, deep borehole disposal as one of the potential solutions for small volumes of long-lived intermediate-level waste (ILW). The short- and long-term stability of deep disposal boreholes is critical for environmental safety and public health. In this paper, we first use a recently revisited extensional strain criterion for fracture initiation and apply analytical solutions of a two-dimensional stress model to predict the fracturing region around a 2 km deep and 0.7 m diameter disposal borehole. Analytical solutions of fracture initiation are compared with results from the numerical simulator FRACOD, while the latter model also predicts dynamic effects such as fracture propagation. Both analytical and numerical methods predicted similar fracture initiation characteristics around the minor horizontal compressive stress springline, consistent with literature data. Numerical results showed deeper fracturing zones than those predicted by analytical solutions, mainly because the analytical predictions provide static snapshots under specific given conditions, while the numerical model calculates additional dynamic effects of fracture propagation. Including stress dynamics is shown to further weaken the rock around the borehole. At the bottom plane of the borehole, three-dimensional numerical simulations showed the development of fracturing zones around the major horizontal compressive stress springline. Borehole stability analyses are essential to plan the safe operation of drilling operations while also giving insights as to what borehole depths are more prone to fracturing and hence potentially less suitable as a waste disposal zone.

The formation of input–output architecture: Evidence from the European Union

Abstract Employing sector-level data on production input interlinkages within and across all countries of the European Union, I use a stochastic actor-oriented model to estimate the evolution of input–output architecture over the period 2001–2014. My behavioral model of network formation approaches these dynamics from the perspective of individual nodes and thus provides a framework to test alternative microfoundations of an endogenous production network. The proposed methodology resolves at least two fundamental problems of empirical investigations into the dynamics of production networks. First, it bypasses the endogeneity problem that arises when topological features of the network determine the formation or dissolution of network ties. Second, it accounts for the mutual dependence between the network and producers’ individual behaviors. Building on this model, I find that supplier heterogeneity in productivity, growth, and labor costs, the introduction of a common currency, and several structural network characteristics such as degree centrality (preferential attachment) as well as the tendencies to connect to indirect suppliers in the nearest network neighborhood (transitivity) and to form bilateral relationships (reciprocity) determine the evolution of the production network. At the same time, changes of the network structure feed back on productivity, growth, and labor costs as producers converge in behavior to their supply chain partners. My results, therefore, testify to additional dynamic network effects on aggregate outcomes that arise from the adjustment of the production network in response to idiosyncratic shocks.

Online terrain estimation for autonomous vehicles on deformable terrains

In this work, a terrain estimation framework is developed for autonomous vehicles operating on deformable terrains. Previous work in this area usually relies on steady state tire operation, linearized classical terramechanics models, or on computationally expensive algorithms that are not suitable for real-time estimation. To address these shortcomings, this work develops a reduced-order nonlinear terramechanics model as a surrogate of the Soil Contact Model (SCM) through extending a state-of-the-art Bekker model to account for additional dynamic effects. It is shown that this reduced-order surrogate model is able to accurately replicate the forces predicted by the SCM while reducing the computation cost by an order of magnitude. This surrogate model is then utilized in an unscented Kalman filter to estimate the sinkage exponent. Simulations suggest this parameter can be estimated within 4% of its true value for clay and sandy loam terrains. It is also shown in simulation and experiment that utilizing this estimated parameter can reduce the prediction errors of the future vehicle states by orders of magnitude, which could assist with achieving more robust model-predictive autonomous navigation strategies.

Dynamics Analysis of Spatial Mechanisms with Dry Spherical Joints with Clearance Using Finite Particle Method

The presence of clearance in a spherical joint makes the ball of the joint easy to collide with the socket, which causes additional dynamic effects on the motion of spatial mechanisms. The complexity of interaction between different clearance joints and that between a clearance joint and connected component requires an effective analysis method. In this paper, a practical method is proposed for evaluating the dynamic effects of spatial flexible mechanisms with multiple spherical clearance joints using finite particle method (FPM) combined with a clearance contact model. First, the equations of motion of the particles and internal force formulas of spatial beam elements in the discretized FPM model are derived, and the explicit generalized-[Formula: see text] method is adopted for time integration. Then, the contact state is detected based on the penetration depth, using the Lankanani–Nikravesh model to calculate the contact force and the Threlfall model to calculate the friction force during collision in the clearance joint. Specifically, a method considering the particle rotations is utilized to better evaluate the direction of the friction force. A spatial four-bar mechanism with spherical clearance joints is used to demonstrate the feasibilities of the proposed method. The effects of four parameters (i.e. clearance size, friction coefficient, multiple clearance joints, and bending stiffness) on the dynamic responses of the mechanism are fully investigated.

Nonlinear dynamic response analysis of vehicle–bridge interactive system under strong earthquakes

Seismic design codes for highway bridges and viaducts in most countries do not specify the simultaneous presence of live vehicle loads and earthquake loads. However, urban highway bridges and viaducts are loaded constantly by heavy traffic, therefore it is important to elucidate the effects of moving vehicles on the seismic response of bridges. This paper proposed a seismic response analysis framework incorporating vehicle–bridge interactions (VBI) with nonlinear dynamic analysis. The proposed method integrates a commercial FEA package, ABAQUS, into the authors’ in-house VBI-solving programs developed using MATLAB. With the proposed method, the effects of vehicle dynamics on seismic responses of a highway bridge could be clarified and the seismic performance of the bridge could be checked. For the bridge and ground motions studied herein, it was observed that continuously moving vehicles might yield larger longitudinal displacement responses at pier tops and plastic deformations at pier bottoms than those of the bridge alone, implying that ignoring vehicles’ additional mass effect and dynamic effects during earthquakes might be on the non-conservative side. Acceleration responses of pier tops and relative displacements of bearings were generally reduced by the moving vehicles. Besides the reason that the vehicles act like dampers on the bridge, it was most probably that the vehicle-bridge in-phase modes were excited by specific ground motions to a level lower than the original bridge-alone mode was, which could be indicated from their corresponding pseudo acceleration response spectra. Although the out-of-phase modes were excited to a similar level to the original bridge-alone mode was, these modes might dissipate some seismic energy that would have been dissipated by the bridge components and reduced displacement of the bearing.

RESEARCH OF THE DYNAMIC OPERATION OF ROAD METAL CONTINUOUS BRIDGE UNDER TEMPORARY LOAD

Purpose. Research of the real dynamic of metal road under continuous over the span of modern time load, the influence of defects and structural features on the bridge of additional dynamic effects as well as a character research of dynamic parameters change after long term operation of the bridge structure. Methodology. Dynamic testing using modern bridge strain gauge instrumentation, structural analysis in accordance with applicable rules, modeling of the superstructure with a modern software system, as well as processing and experimental results are compared with the calculated values. Findings. On the basis of the complex scientific and technical work on a metal test continuous over the span of the bridge was able to determine the dynamic factors caused nearby, appeared with time operation, defects, and design features of the bridge, which adversely affect the dynamic performance of the span,causing increased wear of the metal elements of its construction. Originality. Based on the analysis of dynamic features of metal road bridges after a long period of their operation, was able to study a number of influences that allow more accurately account for the dynamic singularity of such bridges in the design, compared with the classical engineering-stock method using the dynamic factor, which is regulated serving the normative documents of Ukraine. Practical value. This research allows us to improve and expand the opportunities for existing building codes, namely, the dynamical calculations of road metal bridges for modern live loads, as well as – to take into account a number of features that affect the appearance of additional dynamic effects that increase the rate of wear their designs.

Crystallization of Supramolecular Pseudoblock Copolymers

Because of the presence of supramolecular bonds, the crystallization process of supramolecular pseudoblock copolymers (SPBCP) is more complex in comparison to conventional covalently bonded block copolymers (BCP). Thus, supramolecular binding motives included on the polymer chain-ends display additional dynamic effects as well as possible nuclei for the crystallization. In this article we systematically study nonisothermal crystallization processes in SPBCP’s consisting of a crystallizable poly(e-caprolactone) (PCL) connected via triple hydrogen bonds to either a short alkyl-modified 2,4-diaminotriazine, or bound to a large block of amorphous poly(isobutylene) (PIB). The crystallization of the PCL is studied with both groups acting as supramolecular barriers for the crystallization process, either during nucleation or during crystal growth. A strong influence of the short alkyl-modified 2,4-diaminotriazine barrier on the crystallization temperature of the PCL compared to the control sample devoid of this ...

Classical Oscillator Model on Canonical, Lie-Algebraic Deformation and Heisenberg-Weyl Algebra Deformation Nonrelativistic Space

The oscillator model on nonrelativistic Canonical (soft), Lie-Algebraic deformation noncommutative space and deformed Heisenberg-Weyl Algebra noncomutative phase space are analyzed. For canonical deformation the additional dynamical effects are absent. For two kinds of Lie-Algebraic deformation space the additional effects are generated. Remarkably angular frequency ω ρ is stepfunction, non-periodic function, and contains imaginary frequency. The corresponding particle trajectory varies greatly along with the deformation and time parameter $\hat{k}$ , t. For deformed Heisenberg-Weyl Algebra noncommutative phase space the additional corrections are generated. K ρ ,ω ρ and particle trajectory have constant second-order correction with deformation parameters Θ and Π, but the particle still keep trajectory of classical oscillator.

Numerical–experimental identification of the most effective dynamic operation mode of a vibration drilling tool for improved cutting performance

This study is concerned with application of numerical–experimental approach for characterizing dynamic behavior of the developed piezoelectrically excited vibration drilling tool with the aim to identify the most effective conditions of tool vibration mode control for improved cutting efficiency. 3D finite element model of the tool was created on the basis of an elastically fixed pre-twisted cantilever (standard twist drill). The model was experimentally verified and used together with tool vibration measurements in order to reveal rich dynamic behavior of the pre-twisted structure, representing a case of parametric vibrations with axial, torsional and transverse natural vibrations accompanied by the additional dynamic effects arising due to the coupling of axial and torsional deflections ((un)twisting). Numerical results combined with extensive data from interferometric, accelerometric, dynamometric and surface roughness measurements allowed to determine critical excitation frequencies and the corresponding vibration modes, which have the largest influence on the performance metrics of the vibration drilling process. The most favorable tool excitation conditions were established: inducing the axial mode of the vibration tool itself through tailoring of driving frequency enables to minimize magnitudes of surface roughness, cutting force and torque. Research results confirm the importance of the tool mode control in enhancing the effectiveness of vibration cutting tools from the viewpoint of structural dynamics.

A Study on Additional Dynamic Effects after Members' Failure: Mechanism and Design Applications

A Study on Additional Dynamic Effects after Members' Failure: Mechanism and Design Applications

A Study on Additional Dynamic Effects after Members' Failure: Mechanism and Design Applications

Regular anti-collapse analyses with dynamic factors to adjust static results are often not accurate enough. To solve this problem, theory of additional dynamic effects after members' failure (known as F-ADE) is discussed in this presented work with a study of two important parameters to reveal its mechanism. Theory of F-ADE explains why and how the results of regular anti-collapse analyses go inaccurate. Several safety measures for structure design are proposed based on the mechanism of F-ADE. Further researches are expected.

차량 윤하중에 대한 LOOP이음 프리캐스트 바닥판의 가속도 특성분석

교량 위를 지나는 차량하중에 의한 동적영향을 파악하기 위하여 바닥판을 프리캐스트로 제작하여 루프이음으로 연결한 단순교의 영향을 실험적으로 분석하였다. 그 중 시간이력해석 및 동적해석의 기초자료가 되는 가속도를 파악하여 분석하므로 실동차량에 대한 구조물의 동적응답을 통하여 국부적 영향과 특히 이동질량의 동적영향을 파악하는데 매우 중요한 실험이 됨을 알 수 있었다. This Paper presented in the behavior of Loop connected Precast panels under the Tracking machine with real truck tire. For this purpose a wheel tracking machine and adequate precast concrete deck single span bridge are designed. For the purpose of dynamic behavior in the precast panels, at first we take moving vehicle's longitudinal displacement data. and make estimated acceleration factor for test specimen. Results presented in this paper show that interaction between vehicle and structure produce additional dynamic effects of structure and various motion of traffic loading cases on the deck.

Improvement of Feeding Mechanism of Printing Machine

It is found that additional dynamic tension triggered by eccentric shaft affects printing paper is obvious by analyzing the relation between tension and eccentric shaft of feeding mechanism in the paper. Using the dual-tensition control system has the advantages of high examination precision, compensating strip's length, reducing additional dynamic effects to the feeding mechanism, ensuring color printing position precision and improving printing quality.

Dynamic effects in thin liquid films containing ionic surfactants

This paper is dedicated to studying dynamic effects in thin liquid films (TLF) containing ionic surfactants. The standard theory of TLF drainage has been developed without considering the electrical double layer (EDL) in the hydrodynamic equations, although EDL always exists. In addition, it has been found that this theory very well describes the drainage of TLF containing non-ionic surfactants in the presence of electrolytes. The inclusion of EDL into the hydrodynam ics of TLF complicates the theory , producing additional dynamic effects during film drainage. For example, a gradient of electrostatic disjoining pressure across the film arises, thus causing non-uniform electrostatic repulsion between the film surfaces. This paper analyzes the hydrodynamics of TLF with EDL. A new equation of drainage was derived. This equation accounts for the non-uniform distribution of surface charges during the films drainage, which is coupled with non-uniform electrostatic repulsion between the film surfaces and results in faster film drainage. The theory was tested with drainage experiments on TLF with ionic surfactants. Foam films containing sodium dodecyl sulfate (SDS) in the presence and in the absence of added electrolyte were studied and the experimental data compared to the theoretical predictions. The experimental results, however, disagree with the theory. For example, the kinetic equation predicted faster film drainage for foam films at low ionic strength; at high ionic strength the theory tends to “Reynolds drainage”. Inversely, the experiment exhibited slower drainage than predicted by the Reynolds equation in both cases of low and high ionic strengths. Numerical simulations yielded V / V Re < 1 . In addition, cases of “positive” and “negative” velocity of film surfaces were shown. Despite the sign of the velocity the dependence V / V Re < 1 remained. The analysis showed similarity between the experimental data and the prediction of the Manev–Tsekov–Radoev (MTR) drainage model at R < R c r . The analysis showed rather complex dynamics of the film drainage. The paper calls upon further development on this topic.

A Pneumatically Actuated Ball and Beam System

A ball and beam balancing mechanism actuated by a pneumatic rotary drive is presented in this paper. A laboratory model of the pneumatically actuated ball and beam system has been developed within student projects during courses related to mechatronics and automatic control. A mathematical model of the nonlinear system is developed using Lagrange's equations. The model is linearized at the equilibrium point, and the linear model has been implemented for the design of control algorithms. The cascade proportional derivative (PD) controller and the optimal linear quadratic regulator have been applied and experimentally verified. The utilization of a pneumatic actuator introduces additional dynamic terms and nonlinear effects, and that makes the balancing mechanism even more difficult to control. The methods discussed in this paper have good potential application to other control techniques and offer great possibilities for giving students a better understanding of the theoretical and practical aspects of nonlinear system control.

The restricted active space followed by second-order perturbation theory method: Theory and application to the study of CuO2 and Cu2O2 systems

A multireference second-order perturbation theory using a restricted active space self-consistent field wave function as reference (RASPT2/RASSCF) is described. This model is particularly effective for cases where a chemical system requires a balanced orbital active space that is too large to be addressed by the complete active space self-consistent field model with or without second-order perturbation theory (CASPT2 or CASSCF, respectively). Rather than permitting all possible electronic configurations of the electrons in the active space to appear in the reference wave function, certain orbitals are sequestered into two subspaces that permit a maximum number of occupations or holes, respectively, in any given configuration, thereby reducing the total number of possible configurations. Subsequent second-order perturbation theory captures additional dynamical correlation effects. Applications of the theory to the electronic structure of complexes involved in the activation of molecular oxygen by mono- and binuclear copper complexes are presented. In the mononuclear case, RASPT2 and CASPT2 provide very similar results. In the binuclear cases, however, only RASPT2 proves quantitatively useful, owing to the very large size of the necessary active space.

Stability limits of unsteady open capillary channel flow

This paper is concerned with steady and unsteady flow rate limitations in open capillary channels under low-gravity conditions. Capillary channels are widely used in Space technology for liquid transportation and positioning, e.g. in fuel tanks and life support systems. The channel observed in this work consists of two parallel plates bounded by free liquid surfaces along the open sides. The capillary forces of the free surfaces prevent leaking of the liquid and gas ingestion into the flow.In the case of steady stable flow the capillary pressure balances the differential pressure between the liquid and the surrounding constant-pressure gas phase. Increasing the flow rate in small steps causes a decrease of the liquid pressure. A maximum steady flow rate is achieved when the flow rate exceeds a certain limit leading to a collapse of the free surfaces due to the choking effect. In the case of unsteady flow additional dynamic effects take place due to flow rate transition and liquid acceleration. The maximum flow rate is smaller than in the case of steady flow. On the other hand, the choking effect does not necessarily cause surface collapse and stable temporarily choked flow is possible under certain circumstances.To determine the limiting volumetric flow rate and stable flow dynamic properties, a new stability theory for both steady and unsteady flow is introduced. Subcritical and supercritical (choked) flow regimes are defined. Stability criteria are formulated for each flow type. The steady (subcritical) criterion corresponds to the speed index defined by the limiting longitudinal small-amplitude wave speed, similar to the Mach number. The unsteady (supercritical) criterion for choked flow is defined by a new characteristic number, the dynamic index. It is based on pressure balances and reaches unity at the stability limit.The unsteady model based on the Bernoulli equation and the mass balance equation is solved numerically for perfectly wetting incompressible liquids. The unsteady model and the stability theory are verified by comparison to results of a sounding rocket experiment (TEXUS 41) on capillary channel flows launched in December 2005 from ESRANGE in north Sweden. For a clear overview of subcritical, supercritical, and unstable flow, parametric studies and stability diagrams are shown and compared to experimental observations.

Dynamical simulations of magnetically channelled line-driven stellar winds - II. The effects of field-aligned rotation

Building upon our previous magnetohydrodynamics (MHD) simulation study of magnetic channelling in radiatively driven stellar winds, we examine here the additional dynamical effects of stellar rotation in the (still) 2D axisymmetric case of an aligned dipole surface field. In addition to the magnetic confinement parameter η* introduced in Paper I, we characterize the stellar rotation in terms of a parameter W≡Vrot/Vorb (the ratio of the equatorial surface rotation speed to orbital speed), examining specifically models with moderately strong rotation W= 0.25 and 0.5, and comparing these to analogous non-rotating cases. Defining the associated Alfvén radius RA≈η1/4*R* and Kepler corotation radius RK≈W−2/3R*, we find rotation effects are weak for models with RA < RK, but can be substantial and even dominant for models with RA≳RK. In particular, by extending our simulations to magnetic confinement parameters (up to η*= 1000) that are well above those (η*= 10) considered in Paper I, we are able to study cases with RA≫RK; we find that these do indeed show clear formation of the rigid body disc predicted in previous analytic models, with however a rather complex, dynamic behaviour characterized by both episodes of downward infall and outward breakout that limit the build-up of disc mass. Overall, the results provide an intriguing glimpse into the complex interplay between rotation and magnetic confinement, and form the basis for a full MHD description of the rigid body discs expected in strongly magnetic Bp stars like σ Ori E.