| Roll-to-Roll(R2R)manufacturing has been found extensive applications in not only traditional industries,but also flexible printed electronics,thin-film solar cells,radio frequency identification(RFID)tags,flexible display and so on,which shows higher productivity and better performance compared with batch manufacturing.Higher precision and efficiency of the product manufacturing put forward stricter requirements for the stable travelling of the web.For the travelling web under complex working conditions in the actual engineering applications,considering the non-homogeneous tension distribution and intermediate elastic supports,the transverse vibration characteristics and active vibration control of the axially travelling web in R2 R manufacturing are investigated in this paper.The main research effort and contributions of the presented dissertation are introduced as follows:Firstly,a mechanical model is established to address the transverse vibration of the axially travelling web at high speed.Both the transverse vibration and the in-plane motion are considered in the dynamical equations.The Galerkin method is used to discretize the governing equations of motion and then,the natural frequency and mode shape of the web can be computed from the characteristic equation.The generalized-α time integration method is also adopted to compute the dynamic response of the travelling web.Secondly,on account of the non-homogeneous tension distribution of the web in the actual engineering applications,the transverse vibration and instability of the travelling web subjected to parabolically distributed tension are investigated.The influence of the tension inhomogeneity,travelling velocity and aspect ratio on the dynamic behavior and stability of the travelling web by employing the numerical calculation and finite element simulation.The in-plane stresses of the web are strongly influenced by the tension inhomogeneity.The critical velocity when the web lose stability will be decreased as the tension inhomogeneity increases.A small tension inhomogeneity is enough to change the mode shapes completely compared with the mode shapes under homogeneous tension.In order to predict the dynamic characteristics and instability of travelling web more accurately,it is necessary to consider the tension inhomogeneity in the modeling.Thirdly,considering the selection problem of the elastic support position and stiffness for the web with long span,the dynamic behaviors of the travelling web with intermediate elastic supports are investigated.Both of the axial movement and intermediate elastic supports are considered in this modeling.A single intermediate elastic support case as well as multiple supports case are discussed.The effects of the support position and stiffness on the natural frequency,stability and dynamic response of the travelling web are studied based on the numerical results,which provides a theoretical basis and guidance for the layout design of the web-handling machine.Fourthly,considering the stability of web seriously affected by the transverse vibration for the web travelling at high speed,the optimal vibration control strategies are proposed.The linear quadratic regulator(LQR)and linear quadratic gaussian(LQG)control method are used to design the optimal controller of active force control.The concentrated force is applied at the surface of the web by changing the magnitude and direction of the force in real time to control the transverse vibration.Lastly,an experimental R2 R platform is designed and constructed with an open architecture.For the requirement of fast and non-contact measurement of web tension in engineering applications,a vibration-based estimation of web tension is proposed.There is no need to change or modify the existing layout of the web-handling machine using this method.A major advantage of this method is its contactless with web,which has no additional influence on the dynamic behavior of the travelling web,especially for some situations where load cells are not available. |
