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.

scholarly journals Modeling and Analysis of Web Span Tension Dynamics Considering Thermal and Viscoelastic Effects in Roll-to-Roll Manufacturing

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Kadhim A. Jabbar ◽  
Prabhakar R. Pagilla
Keyword(s):  
Temperature Change ◽  
Governing Equation ◽  
Thermal Strain ◽  
Measured Data ◽  
Material Behavior ◽  
Closed Form Expression ◽  
Roll To Roll ◽  
Viscoelastic Effects ◽  
The Web ◽  
Web Tension

A governing equation for web tension in a span considering thermal and viscoelastic effects is developed in this paper. The governing equation includes thermal strain induced by web temperature change and assumes viscoelastic material behavior. A closed-form expression for temperature distribution in the moving web is derived, which is utilized to obtain thermal strain. A model for web tension in a multispan roll-to-roll system can be developed using this governing equation. To evaluate the governing equation, measured data from an industrial web process line are compared with data from model simulations. Since the viscoelastic behavior of web materials is affected by the web temperature change, elevated temperature creep, and stress-relaxation experiments are conducted to determine the temperature-dependent viscoelastic parameters of the utilized viscoelastic model. Comparisons of the measured data with model simulation data are presented and discussed. An analysis of the web tension disturbance propagation behavior is also provided to compare transport behavior of elastic and viscoelastic materials.

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.

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.

scholarly journals Florence RockinArt

2020 ◽  
Author(s):  
Elena Pecchioni ◽  
Alba Patrizia Santo
Keyword(s):  
Close Link ◽  
Artificial Materials ◽  
Stone Materials ◽  
Geographical Position ◽  
Web App ◽  
Materials Used ◽  
Surrounding Areas ◽  
Stone Walls ◽  
The City ◽  
The Web

The city of Firenze represents, for the variety of its artistic and architectural heritage, a kind of open-air museum. Works of art and monuments are mainly made of the rocks outcropping in Firenze and in the surrounding areas; indeed, a close link exists between monuments, geographical position of the city and its history. Florence, is characterised by the color of its stone-built cultural heritage, mainly by the warm ochraceous color of the Medieval Pietraforte sandstone and the cerulean grey of the Renaissance Pietra Serena sandstone together with other natural and artificial materials used to complete or cover the stone walls. The web-app Florence RockinArt was created to deepen the knowledge of the stone materials. It is addressed to all those who are interested in discovering the monuments of Florence by carefully observing the stone materials that make up them. The web-app contains short historical notes on the main monuments and detailed geological, mineralogical and petrographic characteristics of the natural and artificial materials of which they are constituted.

scholarly journals Long-Term Behavior of Coarse-Grained Rockfill Material and Their Constitutive Modeling

2021 ◽  
Author(s):  
Erich Bauer
Keyword(s):  
Mechanical Response ◽  
Coarse Grained ◽  
Geological Condition ◽  
Dam Foundation ◽  
Solid Hardness ◽  
Rockfill Materials ◽  
Materials Used ◽  
Creep And Stress Relaxation ◽  
Long Term Behavior

For the long-term behavior and safety assessment of rockfill dams, not only the shape of the dam body, the loading history, the geological condition of the dam foundation and abutments, the assessment of possible seismic hazards and seepage events caused by defects of the sealing are important, but also the time dependent mechanical behavior of the dam materials used can be of significant influence. In this paper a novel hypoplastic constitutive model for moisture sensitive, coarse-grained rockfill materials is presented. In the constitutive equations, the so-called solid hardness is a key parameter to reflect the influence of the state of weathering on the mechanical response. With respect to the evolution equation for the solid hardness, creep and stress relaxation can be modeled for dry and wet states of the material in a unified manner. The performance of the model is demonstrated by comparing the numerical simulation with experimental data.

Modeling of Web Slip on a Roller and Its Effect on Web Tension Dynamics

2005 ◽  
Author(s):  
Ramamurthy V. Dwivedula ◽  
Prabhakar R. Pagilla
Keyword(s):  
Numerical Computation ◽  
Dynamic Models ◽  
Simple Approach ◽  
Roller Surface ◽  
Perfect Adhesion ◽  
The Web ◽  
Web Tension

This paper considers the effect of web slip over the rollers on the span tension dynamics. In classical development of the web span tension dynamics, it is assumed that there is strict adhesion between the web and the surface of the roller and thus, there is no slip-page between the web and the roller. As a result of this assumption, effect of tension disturbances in downstream spans on the upstream span tension is precluded. However, in practice, perfect adhesion between the web and roller surface is seldom achieved and tension disturbances propagate upstream also. Though web span tension dynamic models that include slippage between web and roller are proposed, these models rely to a great extent on numerical computation of slip arc angles and are prohibitively complex to be of practical use. This paper proposes an alternative, simple approach for developing web span tension dynamics to include the effect of web slip.

Modeling of Temperature Distribution in Moving Webs in Roll-to-Roll Manufacturing

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Youwei Lu ◽  
Prabhakar R. Pagilla
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Thermal Strain ◽  
Heat Transfer Model ◽  
Operating Conditions ◽  
Transfer Model ◽  
Roll To Roll ◽  
Flexible Material ◽  
Process Line ◽  
The Web

A heat transfer model that can predict the temperature distribution in moving flexible composite materials (webs) for various heating/cooling conditions is developed in this paper. Heat transfer processes are widely employed in roll-to-roll (R2R) machines that are used to perform processing operations, such as printing, coating, embossing, and lamination, on a moving flexible material. The goal is to efficiently transport the webs over heating/cooling rollers and ovens within such processes. One of the key controlled variables in R2R transport is web tension. When webs are heated or cooled during transport, the temperature distribution in the web causes changes in the mechanical and physical material properties and induces thermal strain. Tension behavior is affected by these changes and thermal strain. To determine thermal strain and material property changes, one requires the distribution of temperature in moving webs. A multilayer heat transfer model for composite webs is developed in this paper. Based on this model, temperature distribution in the moving web is obtained for the web transported on a heat transfer roller and in a web span between two adjacent rollers. Boundary conditions that reflect many types of heating/cooling of webs are considered and discussed. Thermal contact resistance between the moving web and heat transfer roller surfaces is considered in the derivation of the heat transfer model. Model simulations are conducted for a section of a production R2R coating and fusion process line, and temperature data from these simulations are compared with measured data obtained at key locations within the process line. In addition to determining thermal strain in moving webs, the model is valuable in the design of heating/cooling sources required to obtain a certain desired temperature at a specific location within the process line. Further, the model can be used in determining temperature dependent parameters and the selection of operating conditions such as web speed.

scholarly journals Identification and Frequency Dependence of Viscoelastic Parameters during Dynamic Creep Tests on Selected Pome Fruits

2019 ◽  
Vol 1 (3) ◽  
pp. 324-331 ◽  
Author(s):  
Csaba Farkas ◽  
László Fenyvesi ◽  
Károly Petróczki
Keyword(s):  
Viscoelastic Model ◽  
Model Parameters ◽  
Variable Load ◽  
Pome Fruit ◽  
Creep Tests ◽  
Viscoelastic Parameters ◽  
Wide Range ◽  
Dynamic Creep ◽  
Pome Fruits ◽  
Compressive Loads

In this paper, a novel control-loop concept is presented to investigate the viscoelastic properties of different pome fruits. Repeated mechanical effects are one of the most important risk factors during the postharvest procedures, so our work aimed to expand knowledge in the field. The actual investigations involved Golden Delicious apples and Packham pears. The developed model is based on the Poynting–Thomson body and, during the validating dynamic creep tests, different repeated compressive loads were applied. The examined frequencies were chosen from the most common components of the frequency distribution during the transportation process; the given range is responsible for the highest volume of fruit damage and the most extensive losses. The identified mathematical system determines the viscoelastic model parameters with the best fit to the measured creep data. The model properties of the tested fruit textures are compared in six different frequency setups, with the inspected pome species showing different elastic and viscous responses for the adjusted load conditions. The custom testing device with variable load functions and the proposed solution allow system identification with a wide range of setup possibilities. The resulted viscoelastic parameters can be used for further failure analysis and for the comparison of different pome fruit materials.

Advanced Optimization of Industrial Large-Scale Roll-to-Roll Systems Under Parametric Uncertainties

2012 ◽  
Author(s):  
J. Frechard ◽  
D. Knittel
Keyword(s):  
Young’S Modulus ◽  
Large Scale ◽  
Young's Modulus ◽  
Robust Design Optimization ◽  
Parametric Uncertainties ◽  
Optimization Approach ◽  
Roll To Roll ◽  
Polymer Metal ◽  
The Web ◽  
Web Tension

In industrial plants some parameters can not be evaluated properly or they are varying with time. These parametric uncertainties has to be taken into account during the design process of industrial systems. In this work, the developped optimization approach is applied on an industrial roll-to-roll sytem. Such systems are commonly used to handle materials as polymer, metal, paper and textile. The key challenge is to move the web at the expected speed while maintaining the web tension in an acceptable range around its reference. Moreover, the Young’s modulus of the web is difficult to evaluate and it is varying with time due to temperature and moisture variations. This paper deals with the web tension controller synthesis on a large-scale roll-to-roll system with uncertain Young’s modulus. To synthesize web tension controllers, an H∞ approach is applied and adapted to the system with parametric uncertainties using multi-objective robust design optimization.

Uncertainty Analysis of a Finite Deformation Viscoelastic Model

2014 ◽  
Author(s):  
Paul Miles ◽  
Michael Hays ◽  
Ralph Smith ◽  
William S. Oates
Keyword(s):  
Finite Deformation ◽  
Viscoelastic Model ◽  
Large Field ◽  
Additional Insight ◽  
Viscoelastic Models ◽  
Rate Dependent ◽  
Different Types ◽  
Viscoelastic Effects ◽  
Insight Into ◽  
Hyperelastic Models

The viscoelasticity of the dielectric elastomer, VHB 4910, is experimentally characterized, modeled, and analyzed using uncertainty quantification. These materials are known for their large field induced deformation and applications in smart structures, although the rate dependent viscoelastic effects are not well understood. To address this issue, we first quantify hyperelastic and viscoelastic model uncertainty by comparing a finite deformation viscoelastic model to uni-axial rate dependent experiments. The utilization of Bayesian statistics is shown to provide additional insight into different viscoelastic processes within elastomers. This is demonstrated by coupling two hyperelastic models, an Ogden model and a nonaffine model, to different types of viscoelastic models.

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