| Flexible cable and beam components are widely used in practical engineering.The design and analysis of mechanical systems containing flexible cable and beam components involve the dynamics and statics of flexible multi-body systems with large deformation and large movement.Although the dynamics of flexible multibody systems have undergone decades of development,resulting in a large number of theoretical and practical engineering achievements,due to its inherent complexity,there are still no mature and universal solutions for many flexible multibody systems.The cable installation system in high-voltage transmission engineering,cable-driven mechanism,and lifting sling system of cranes are typical mechanical systems containing flexible cables and beam components.The dynamic and statics analysis of these systems is actually a dynamic and statics problem of the flexible cable system with variable-length due to the expansion and contraction of the flexible cable itself as well as the mutual sliding,winding and other movements between the flexible cable and the supporting structure.The characteristics of variable-length,contact,sliding and other characteristics make the analysis of these systems extremely complex.At present,it is still a difficult point in the engineering,and there is no good solution.This paper focuses on these systems based on the absolute node coordinate method and arbitrary Lagrangian Euler description.Firstly,the modeling method of a multibody system containing variable-length cables is studied.Then,based on this,the research focuses on the dynamic modeling and efficient analysis methods of wire running and breaking conditions during high-voltage cable installation,ice layer cleaning conditions of covered cables,cable-driven mechanism,and tower crane lifting and luffing motions.The research on modeling and dynamic solution of flexible cable and beam components with variable-length has been conducted as follows:Modeling and dynamic analysis of high-voltage cables have been conducted.A piecewise cable element based on absolute node coordinate formulation is used to model the potential cable slip during the installation of high-voltage cables.to study the working conditions of conductor running and breaking during the installation of high-voltage cables.An elastic force model suitable for describing large deformation of piecewise cable element based on absolute node coordinate formulation has been proposed.The working conditions of cable running and breaking during the installation of high-voltage cables is studied.In order to describe the initial tension in high-voltage cables,a static solution strategy was established.The configuration of the cable when it reaches equilibrium under the action of elastic force,gravity,and tensile force of the tension machine is solved.Using this equilibrium configuration as the initial value for solving the dynamics of high-voltage cables,the dynamic behavior of cables breaking under tension is solved.At the same time,the working conditions of cables crossing multiple towers in the event of breakage is also solved.An analysis was conducted on the dynamic behavior of cables during the ice layer cleaning process of iced cables.In order to describe variable topology cables,a multi-layer circular cross-section element called Arbitrary Lagrange Euler Absolute Nodal Coordinate Formulation(ALE-ANCF)multi-layer circular cross-section beam element is proposed based on the arbitrary Lagrangian Euler and absolute node coordinate formulation,which can flexibly describe the thickness of the ice layer and the length of the covered wire.A dynamic analysis model for iced cables was established using the proposed ALE-ANCF multi-layer circular cross-section element.The effects of the cleaning speed of the ice layer and the initial vertical span ratio of the cable installation on the tension in the cable and the displacement of the node in the cable span were studied.The research results provide a theoretical basis for safely and efficiently clearing the ice layer.Modeling of variable-length cables of cable-driven mechanism and dynamic analysis of cable-driven mechanism have been conducted.The length of the cable in the cable-driven mechanism changes.When describing cables with variable-length structures,the traditional absolute node coordinate formulation needs to continuously establish new grids to model cables with new topology structures.This makes it inefficient to use the the traditional absolute node coordinate formulation for dynamic analysis of variable-length cables in cable-driven mechanism.Based on the combination of the absolute node coordinate formulation and the arbitrary Lagrangian Euler method,a circular section beam element,called ALE-ANCF circular section beam element,is proposed,which can efficiently describe flexible cables with variable-length.The end-effector of the cable-driven mechanism is modeled using absolute node coordinate formulation reference node.A dynamic analysis model of cable-driven mechanism in absolute coordinate system is constructed.The effects of initial cable pretension on the trajectory and cable tension of the end effector of the cable-driven mechanism during motion were studied.This provides theoretical support for improving the control accuracy of the cable-driven mechanism and reducing the vibration of the cable-driven mechanism.A study was conducted on the payload swing suppression method considering tower crane vibration.The existing research on swing suppression of tower cranes has neglected the coupling between structural vibration and load swing.A control method for load swing considering tower crane vibration has been proposed.Existing research on swing suppression considers changes in the length of the lifting sling as disturbances.It causes the existing methods of swing suppression method ineffectual in the actual working situation.In contrast,the structural vibration of the tower crane is taken into account in this study.At the same time,the sling length is regarded as a control variable to reduce the payload swing.A new swing suppression algorithm is proposed in conjunction with phase plane analysis method.In addition,a systematical tower crane multibody system dynamic analysis platform with changing of sling length is established to verify the effectiveness of the algorithm.The traditional finite element method is used to model the tower body and boom of tower crane while the ALE-ANCF cable element is applied for modeling the sling.This two parts are connected with sliding joint obtaining the tower crane multibody system model.Numerical examples show that the proposed method can reduce the swing amplitude the payload effectively when considering the coupling between the structural vibration and the payload swing. |
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