The influence of strain rate and pulp properties on the stress relaxation of wet paper — modeling of relaxation, November 2016 TAPPI JOURNAL


ABSTRACT:
The time-dependent stress (tension) relaxation behavior of wet paper plays a key role in web trans-fer from the press to the dryer section of a paper machine. In this study, three linear viscoelastic models were used to predict the short time range tension relaxation of wet paper. Over longer time periods, all three models gave relaxation moduli that were apparently linear on a logarithmic timeline. However, the results showed that the tension relaxation of wet paper had more than one characteristic time constant, meaning that the initial tension relaxation phase had a different constant than the later phase or phases. In practical applications, the most relevant time range for runnability of the wet paper web is from milliseconds to a few seconds. The obtained results suggest that the strain rate and initial tension of the relaxation dictate the shape of the tension relaxation curve of wet paper: the higher the strain rate, the greater the tension loss during the first second of relaxation. The tension relaxation behav-ior of wet paper did not generally depend on pulp type, refining level of pulp, or solids content. However, there can be significant differences between furnishes and solids content in the amount of draw that leads to a sufficient web tension. The results indicated that the tension relaxation behavior of wet paper may be based on a general visco-elastic mechanism that is independent of fiber network properties but depends on the fiber wall material. The find-ings suggest that the redistribution mechanism of stresses in the wet fiber network has a high level of regularity. The Prony series was capable of predicting tension relaxation behavior of wet paper over a wide time range. Therefore, it can be a very useful simulation tool not only for wet webs, but for any viscoelastic material that shows stress (ten-sion) relaxation.

Application: The process efficiency of paper and board making can be improved, especially in unstable or in problematic running conditions, by taking full advantage of the proposed relatively simple modelling method for the relaxation behavior of wet paper webs.

TAPPI conference proceedings and presentations, technical papers, and publication articles provide technical and management data and solutions on topics covering the Pulp, Paper, Tissue, Corrugated Packaging, Flexible Packaging, Nanotechnology and Converting Industries.

Simply select the quantity, add to your cart and your conference paper, presentation or article will be available for immediate download.

Author: Jarmo Kouko, Joonas Sorivari, and Elias Retulainen
The influence of strain rate and pulp properties on the stre
The influence of strain rate and pulp properties on the stress relaxation of wet paper — modeling of relaxation, November 2016 TAPPI JOURNAL
0.00

New Releases

 

TAPPI PRESS Catalog eBook 2022


Experience the Power of Publications in the 2022 TAPPI Press Catalog


Open


 

Kraft Recovery Boilers, Third Edition  


Sponsored by the Recovery Boiler Program R&D Subcommittee of the American Forest & Paper Association (AF&PA) and published by TAPPI Press.


Purchase


 

Handbook For Pulp and Paper Technologists (The SMOOK Book), Fourth Edition

The best-selling text to introduce the entire technology of pulp and paper manufacture.

Purchase

 

Guidelines for Safe Assessment and Operation of Yankee Dryers  


A project of the Yankee Dryer Safety & Reliability Committee.

Purchase

 

Check our newest additions.


TAPPI Press offers some of the most in-depth resources and references for the forest products and related industries. 

See More

   
 

Available for Purchase – Conference Proceedings


TAPPI maintains a record of key conference papers, presentations, and other conference publications, available for purchase in a variety of formats.

See More