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ADVANCES IN COMPUTATIONAL METHODS FOR SIMULATION
Edited by: B.H.V. Topping
The Thermomechanical Calculation of Polymer Roller with Finite Element Method
D. Severin and L. Qiao
Institute for Conveying and Gear Technology, Technical University of Berlin, Germany
D. Severin, L. Qiao, "The Thermomechanical Calculation of Polymer Roller with Finite Element Method", in B.H.V. Topping, (Editor), "Advances in Computational Methods for Simulation", Civil-Comp Press, Edinburgh, UK, pp 73-77, 1996. doi:10.4203/ccp.42.1.9
The use of rollers made of polymers is increasing in technical installations. They are, on account of their viscoelastic behaviour, very difficult to calculate mathematically. They warm up inside when they roll at higher speeds under normal load. The heat is not distributed uniformly throughout the body of the roller. Once the temperature exceeds a certain limit at the area where the stress is greatest, the temperature rises sharply at this area and the body of the roller fails. This is the principal cause of premature damage to rollers made of polymers.
In order to design rolling systems with rollers made of polymer materials which are able to withstand the load to which they are subjected, a simple method of calculation is required which takes the viscoelastic behaviour of materials during the rolling process into consideration. In view of the complicated properties of the polymer materials (coupled thermomechanical nonlinear boundary value problems), an analytical solution is not possible without making great simplifications. It is for this reason that a numerical calculation method is being developed with the aid of the finite element method for two-dimensional and three-dimensional calculation of the stress and strain. This also makes it possible to determine the distribution of temperature in the body of the roller.
The numerical calculation is based on the viscoelastic modulus. This modulus is, analogous to the Young's modulus, a quantity which, in addition to the elastic behaviour of the material, also takes the viscoelastic behaviour of the material when subjected to harmonious load into consideration and is, hence, dependent upon the material parameter, the frequency of load and the local temperature in the body of the roller. Using the viscoelastic modulus, the harmonious, viscoelastic stress and strain situation is reduced to a seemingly elastic stress and strain situation. For this reason, the method of calculation is designated as a quasi-elastic method.
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