Zhou, J.; Wang, H., and Jiang, Z., 2020. Motion and whiplash effect of a floating crane model under wave load: Experiment. In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea ...Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 346–357. Coconut Creek (Florida), ISSN 0749-0208. The top parts of tall terrestrial buildings are sometimes damaged or even destroyed during strong earthquakes because of the whiplash effect. Similarly, the marine floating high-rise multibody structure with a floating base may experience the whiplash effect even more easily, which means that marked motion of the upper part of the structure will occur accompanying minor motion of the floating base under the action of an external load induced by a wave or seismic load. The whiplash effect would threaten the operation and the survival of these offshore high-rise platform structures. In this paper, a physical experiment involving a floating crane without a mooring system under wave loads was set up. The data and results were analyzed and discussed mainly in terms of the motion and the whiplash effect of the floating crane. The whiplash coefficient is defined to estimate the magnitude of the whiplash effect. Some factors, including wave amplitude, wave length, boom angle and boom length, are investigated to determine how they affect the motion and the whiplash effect of the floating crane. Some suggestions are given to control the whiplash effect, and those are useful for the operation of offshore floating platform structures, such as the oil-drill platform, the floating wind farm, the floating crane and some other high-rise marine floating structures.
•The classical Newton-Euler method and Lagrangian formulation are revisited in this work.•The Lagrangian formulation can be quite complex when applied to closed loop systems.•Three approaches are ...presented to transform the closed loop topologies into open-loop systems.•The cut joint, the clearance joint constraint, and the elastic joint formulations are utilized.•The different approaches described are applied and the results are compared for a closed loop system.
This work aims at presenting, in a comprehensive manner, several approaches to model and simulate closed loop topologies using the classical Lagrangian formulation. One of the great advantages of the Lagrangian approach is its simplicity and easiness of obtaining the equations of motion. However, a critical aspect arises when the mechanical systems include closed loop topologies, since the process of deriving the equations of motion becomes a complex task. The key point of the present study is to convert the closed loop nature into open systems, which ultimately simplifies the modeling process when the Lagrangian formulation is utilized. For this purpose, three different methods are considered, namely those based on the cut joint approach, the clearance joint constraint model, and the elastic joint formulation are used. In the sequel of this process, a slider-crank mechanism is utilized as a demonstrative application example, and the main results are compared with those obtained with the well-established Newton-Euler method for constrained multibody systems. Moreover, this example allows the comparison of the main characteristics and peculiarities of the described approaches.
•A field-to-field control strategy is presented for motion control of continuum systems.•Multilayer dielectric elastomer actuators (DEAs) are modeled via the nonlinear thin plate elements of ...ANCF.•Inverse static design is proposed for the analytical input voltages of DEAs with active bending deformation.•Inverse dynamic design is proposed for the numerical input voltages of DEAs with active bending deformation during overall motion.•The reliability of the proposed approach is validated by an experiment of dynamic actuation.
Dielectric elastomers (DEs) are a sort of electroactive polymers with large and fast responses, light masses and high energy densities. Hence, they are regarded as one of the most potential materials for artificial muscles and soft robots. Previous researches on DEs focused mainly on experimental prototypes and property optimization in a component level, while the system-level design and control of dynamic motions of DE actuators are still open problems. In this study, the computational method of inverse dynamic design (IDD) for input voltages of DE actuators is proposed by taking the electromechanical coupling mechanics and the effects of rigid-body motions into account. The proposed inverse dynamic design with nonlinear finite elements enables one to realize the high-precision modeling of soft actuators and to derive the dynamic voltages for desired trajectories in a system level. To describe the overall motions and deformations of DE actuators, the gradient constraints of the dynamic configurations of the actuators are introduced upon the assumption of time-varying uniform curvatures for the desired deformation. And then, based on the principle of energy equivalence, the dynamic voltages for the target deformations in motions are computed inversely from the Lagrange multipliers of the desired trajectories. In addition, the forward simulations by removing the constraints and applying the voltages are further conducted to validate and predict the final configurations. Finally, five numerical case studies and demonstrative experiments are presented to validate the effectiveness of the proposed method. This study endeavors to establish a universal inverse dynamic design method for the motion control of soft DE actuators, allowing for the application of theoretical methodology to engineering problems.
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In the present work, an introduction to the contact phenomena in multibody systems is made. The different existing approaches are described, together with their most distinctive features. Then, the ...term of coefficient of restitution is emphasized as a tool to characterize impact events and the algorithm for calculating the relative indentation between two convex-shaped bodies is developed. Subsequently, the main penalty contact models developed in the last decades are presented and developed, analysing their advantages and drawbacks, as well as their respective applications. Furthermore, some models with specific peculiarities that could be useful to the reader are included. The aim of this work is to provide a resource to the novice researcher in the field to facilitate the choice of the appropriate contact model for their work.
This paper proposes a novel modelling approach for a heavy-duty manipulator with parallel–serial structures connected in series. Each considered parallel–serial structure contains a revolute segment ...with rigid links connected by a passive revolute joint and actuated by a linear hydraulic actuator, thus forming a closed kinematic loop. In addition, prismatic segments, consisting of prismatic joints driven by hydraulic linear actuators, also are considered. Expressions for actuator forces are derived using the Newton–Euler (N–E) dynamics formulation. The derivation process does not assume massless actuators decoupled from manipulator links, which is common in the Lagrange dynamics formulation. Actuator pressure dynamics are included in the analysis, leading in total to a third-order system of ordinary differential equations (ODEs). With fewer parameters than its predecessors, the proposed model in the N–E framework inspires revision of the virtual decomposition control (VDC) systematic process to formulate a control law based on the new model. The virtual stability of each generic manipulator revolute and prismatic segment is obtained, leading to the Lyapunov stability of the entire robot.
•General Newton–Euler dynamics equations for a hydraulic manipulator configuration.•Closed kinematic loops are considered using no approximations.•A straightforward analytic solution for a linear hydraulic actuator force is derived.•The results are compared to the ones obtained using the SimScape Multibody™.•A systematic subsystem-based process to formulate control is presented.
The growing popularity of electric vehicles brings opportunities and challenges to the battery industry. Designers need to develop reliable battery packs to ensure the safety of consumers’ property ...and passengers’ lives. Due to the complex structure of the battery pack, the traditional finite element analysis design consumes a lot of computational resources. The utilization of multibody system dynamics (MSD) and machine learning (ML) methods can assist developers in the efficient design of reliable battery packs. In this work, an MSD model of a battery pack was constructed based on the recursive idea, which can characterize the state information of each cell, such as velocity, acceleration, deformation, etc., during extrusion. By utilizing ML techniques, it is possible to achieve both the forward and reverse design of the adhesive for the battery pack. This enables accurate prediction of battery deformation under various adhesive stiffness and damping coefficients, as well as different battery SOCs. Consequently, the design of the battery adhesive can be guided, resulting in minimal distortion of the battery pack during extrusion and reducing the risk of internal short circuits. This method enables efficient battery pack design and provides ideas for future reliable battery pack designs.
•An MSD model of the battery pack was proposed.•Six ML models were utilized to predict the extrusion deformation.•The DNN model which performs best was used to optimize the adhesive.•This method provides ideas for reliable battery pack design.
The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics, capable of addressing the challenges of complex modeling, ...diminished computational efficiency, and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems, such as self-propelled artillery. This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery. Recognizing the shortfall of overlooking the band engraving process in existing theories, this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system. This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery. Additionally, it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process. Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery, thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.
E-sail technology enables a continuous propulsion system based on the repulsive force exerted by solar wind protons on a set of positively charged tethers. Diverse methods have been explored within ...the last two decades to investigate the dynamics of E-sail. This work introduces a dynamic multibody model combining Absolute Nodal Coordinate Formulation (ANCF) and Natural Coordinates (NC) to describe flexible and rigid bodies, respectively. A complete formulation for cable elements considering nonlinear bending and internal damping is provided. Coulomb propulsive forces are included and the expressions for the integration of the resulting Differential Algebraic Equation (DAE) system are given. Based on the simulation results obtained from the proposed model, the convenience of considering bending stiffness to accurately capture the dynamics is proven. The in-plane and out-of-plane oscillations of the tethers are reported and explained. By means of the Power Spectral Density (PSD) representation, the relevant role on the E-sail dynamics of the spin, bending and axial modes, associated to the well-known problem of a rotating cable with a tip mass, is described. The force and perturbation moments transmitted to the central body are compared to the generated thrust, and its complexity and instability under non-null sailing angle operation is established.
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•A high-fidelity rigid–flexible multibody model for E-sail dynamics is presented.•E-sail transit dynamics is studied by numerical simulation for different scenarios.•Bending impacts the dynamics of rotating tethers summitted to Coulomb force.•The coupling of Coulomb force and tether dynamics derives in perturbation torques.
•Moving forward by lateral actuation is explained for the Snakeboard and Waveboard.•A non-holonomic 3D multibody model of a Waveboard is proposed.•Wheels are modeled both as rings and as toruses with ...non-slipping ground contact.•An inverse dynamic analysis of winding trajectories is made.•A comparative analysis of the main design parameters is included.
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This paper studies the forward motion of the Waveboard, a variant of the Skateboard that consists of two platforms and two caster wheels. This system exhibits a very interesting propelling mechanism, since the rider can achieve a forward motion by means of an oscillatory lateral motion of the platforms, without touching the ground.
Because of the complex nature of the Waveboard dynamics, a three-dimensional multibody model is proposed, modeling the wheels as two rings first and as tori later on. Some holonomic constraints arise at the contact of the wheels with the ground, while some non-holonomic constraints appear from the assumption of rolling without slipping. The equations of motion of the system are derived and a kinematic and inverse dynamics simulation of a realistic meandering trajectory is carried out, in order to understand the necessary forces and torques to obtain the desired motion. Moreover, an analysis of the influence of the design parameters on the external actions exerted by the rider is made.
Finally, the multibody model is enhanced by modeling the wheels as two tori, performing a comparison between the ring and toroidal models.
•Thermal-integrated ANCF solid-beam element is developed.•The heat generation caused by frictional creep is included in the model.•The transmission ratio loss caused by the temperature rising is ...captured.
Due to the apparent heat generation and the observed multiple thermal effects in the long-term operation of belt drive system, the thermo-mechanical coupled analysis for the flexible multi-body system is necessitated. A previously proposed absolute nodal coordinate formulation solid-beam element is adopted to create its thermal integrated counterpart since its deformation modes are appropriate for capturing the deformation of V-belt geometry. By means of the unified description of the temperature field and displacement field, the analysis for heat transfer and the continuum mechanics could be integrated in the V-belt drive system. The heat generation caused by frictional creep and the hysteresis loss due to the material viscosity, as well as the thermal deformation, are all included in the model. By describing the flange of pulley groove using a parameterized revolving segment centered by the pulley axis, the contact between V-belt and the flange of pulley groove could be implemented efficiently without complex 3D geometric description of the pulley. The contact force is calculated using penalty method, and the frictional force is determined by the Coulomb friction law in integral form. Numerical results demonstrate the feasibility of the proposed analysis method.
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