Material model of pulp fibres

Seidlhofer, T. (Speaker)

Activity: Talk or presentationTalk at conference or symposiumScience to science

Description

Paper is a natural product formed by a three dimensional network of fibres and shows a highly nonlinear and load-rate dependent behaviour. Neither the structure nor the fibre bonds can fully describe the time or rate dependent behaviour of paper [1]. Consequently, much experimental and numerical work was done to study the mechanics of a single fibre. As the fibre renders a viscoelastic, viscoplastic behaviour more advanced material models are necessary to evaluate material parameters. Based on uniaxial tension tests [2] an appropriate one-dimensional plasticity framework is derived. The final model comprises a Perzyna type viscoplastic model with nonlinear hardening extended with a generalised Maxwell model to describe viscoelastic effects. The material properties are subjected to changes during plastic deformation. Hence, the model includes a damage/healing concept. The one-dimensional model shows a good performance and is ported to a finite strain three-dimensional formulation. We employ the framework of Hencky strains and a dual stress measure to ensure objectivity [3]. Finally, the model parameters are recalibrated with the one dimensional model. The investigation shows that pulp fibres have a distinct plastic behaviour, which could be the cause of the nonlinear behaviour on the macroscopic level of the network. [1] Niskanen, K. (1998). Papermaking Science and Technology: Paper Physics (16th ed.). Fapet Oy. [2] Dumbleton, D. F. (1972). Longitudinal Compression of Individual Pulp Fibres. Tappi, 55(1), 127-135. [3] Miehe, C., Apel, N., & Lambrecht, M. (2002). Anisotropic additive plasticity in the logar- ithmic strain space: Modular kinematic formulation and implementation based on incremental minimization principles for standard materials. Computer Methods in Applied Mechanics and Engineering, 191(47-48), 5383-5425. https://doi.org/10.1016/S0045-7825(02)00438-3
Period18 Feb 2019 - 22 Feb 2019
Held atGAMM 2019
Event typeConference
LocationVienna, Austria
Degree of RecognitionInternational