Viscoelastic Effects in Modeling Web Handling Systems: Steady-State Analysis

1995 ◽  
Vol 62 (4) ◽  
pp. 908-914 ◽  
Author(s):  
X. Guan ◽  
M. S. High ◽  
D. A. Tree
Keyword(s):  
Steady State ◽  
Equation Of State ◽  
Viscoelastic Model ◽  
Tension Control ◽  
Control Case ◽  
Web Handling ◽  
Steady State Analysis ◽  
Viscoelastic Effects ◽  
Viscoelastic Equation ◽  
The Web

The effect of viscoelasticity in web handling systems is examined by introducing a viscoelastic equation of state into a model for tension control. Case studies and generalized results for a single open-span system and a double open-span system are presented to compare the results of the viscoelastic model to a model based on a purely elastic equation of state. The results show only small differences in the tension behavior for the single-span system. However, large differences in the magnitude and reversal of the sign of the tension in the second span of a two-span system are seen for even small degrees of viscoelasticity in the web material. The results clearly demonstrate that viscoelasticity must be considered in modeling multispan web handling systems.

Viscoelastic Effects in Modeling Web Handling Systems: Unsteady-State Analysis

1998 ◽  
Vol 65 (1) ◽  
pp. 234-241 ◽  
Author(s):  
Xiaofeng Guan ◽  
M. S. High ◽  
D. A. Tree
Keyword(s):  
Steady State ◽  
Deborah Number ◽  
System Response ◽  
Governing Equations ◽  
Web Handling ◽  
Periodic Disturbance ◽  
Start Up ◽  
Viscoelastic Effects ◽  
Unsteady State Analysis ◽  
Predictor Corrector

A model to predict the tension in open spans of web handling systems during transient operations has been developed. Governing equations were developed by using the White-Metzner equation to describe the material response in conjunction with mass and force balances. The governing equations were nondimensionalized and solved via the MacCormack predictor/corrector technique. Two dimensionless parameters emerged from the analysis, the Deborah number, De, and the ratio of the viscous stress to the steady state stress, N. The resulting model is the companion to a previously reported model for steady-state operations (Guan et al, 1995). The model was used to predict the behavior of a web handling system during start-up, transition between steady states, and a periodic disturbance. During start-up and transition, systems responded more rapidly at low De. The system response during a periodic disturbance was correlated to De, the frequency, and the magnitude of the disturbance.

Modeling Web Tension Dynamics Considering Thermal and Viscoelastic Effects: Simulations and Experiments

2014 ◽  
Author(s):  
Kadhim A. Jabbar ◽  
Prabhakar R. Pagilla
Keyword(s):  
Thermal Strain ◽  
Viscoelastic Model ◽  
Model Simulations ◽  
Viscoelastic Parameters ◽  
Viscoelastic Effects ◽  
Processing Line ◽  
Materials Used ◽  
Creep And Stress Relaxation ◽  
The Web ◽  
Web Tension

In this paper, a governing equation for web tension considering thermal and viscoelastic effects in a multi-span system is developed. The thermal effect is included in the web tension dynamics by considering the thermal strain induced by temperature distribution in the web span. The viscoelastic effect is introduced by using a standard linear solid (SLS) model from which a relationship between the applied stress and the resulting strain is obtained. Elevated temperature creep and stress relaxation experiments are conducted on several web materials used in an industrial web processing line to determine the viscoelastic parameters of the utilized viscoelastic model. Model simulations are conducted with the same control systems as those used in an industrial web processing line. Data from model simulations are compared with measured data obtained from the industrial web processing line.

Advanced Motion Control Design for Longitudinal Web Dynamics in Roll-to-Roll Systems: Velocity or Position Control?

2013 ◽  
Author(s):  
Y. Martz ◽  
J. Frechard ◽  
D. Knittel
Keyword(s):  
Control Strategy ◽  
Position Control ◽  
Tension Control ◽  
Web Handling ◽  
Reference Tracking ◽  
External Loop ◽  
Roll To Roll ◽  
Processing Line ◽  
The Web ◽  
Web Tension

Roll-to-Roll systems handling web material such as papers, polymers, textiles or metals are very common in the industry. One of the main objectives in web handling plant is to reach an expected web speed while maintaining the web tension within an acceptable range around the tension reference in the entire processing line. In the recent years, several works have focused on the topic of web tension control using H∞ approaches. In the traditional way, each motor driven roller is controlled in speed and the web tension control is ensured by an external loop. This paper proposes to compare, for the first time, the traditional control strategy with a control strategy including position control rather than speed control. In fact, position control is commonly used in printing industry. The comparison will be ensured in frequency and time domain and take into account the reference tracking performances and the robustness to web elasticity variations.

Analysis of Single Buffer Random Polling System With State-Dependent Input Process and Server/Station Breakdowns

2018 ◽  
Vol 9 (1) ◽  
pp. 22-50 ◽  
Author(s):  
Thomas Y.S. Lee
Keyword(s):  
Steady State ◽  
Linear Model ◽  
Repair Process ◽  
Polling System ◽  
Steady State Analysis ◽  
Relaxation System ◽  
Polling Model ◽  
State Dependent ◽  
Non Linear ◽  
State Analysis

Models and analytical techniques are developed to evaluate the performance of two variations of single buffers (conventional and buffer relaxation system) multiple queues system. In the conventional system, each queue can have at most one customer at any time and newly arriving customers find the buffer full are lost. In the buffer relaxation system, the queue being served may have two customers, while each of the other queues may have at most one customer. Thomas Y.S. Lee developed a state-dependent non-linear model of uncertainty for analyzing a random polling system with server breakdown/repair, multi-phase service, correlated input processes, and single buffers. The state-dependent non-linear model of uncertainty introduced in this paper allows us to incorporate correlated arrival processes where the customer arrival rate depends on the location of the server and/or the server's mode of operation into the polling model. The author allows the possibility that the server is unreliable. Specifically, when the server visits a queue, Lee assumes that the system is subject to two types of failures: queue-dependent, and general. General failures are observed upon server arrival at a queue. But there are two possibilities that a queue-dependent breakdown (if occurs) can be observed; (i) is observed immediately when it occurs and (ii) is observed only at the end of the current service. In both cases, a repair process is initiated immediately after the queue-dependent breakdown is observed. The author's model allows the possibility of the server breakdowns/repair process to be non-stationary in the number of breakdowns/repairs to reflect that breakdowns/repairs or customer processing may be progressively easier or harder, or that they follow a more general learning curve. Thomas Y.S. Lee will show that his model encompasses a variety of examples. He was able to perform both transient and steady state analysis. The steady state analysis allows us to compute several performance measures including the average customer waiting time, loss probability, throughput and mean cycle time.

Sign in / Sign up

Export Citation Format

Share Document