PTS research activities related to COST FP 1005 Simulation of micro structure mechanics in dynamic fibre networks Timo Kuntzsch, Jan Matheas, Sven Altmann.

PTS research activities related to COST FP 1005Simulation of micro structure mechanics in dynamic fibre networks

Timo Kuntzsch, Jan Matheas, Sven Altmann

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PTS 201104/18/23

Environmental relevance andsustainability aspects

Material testing and expert opinions

Education and training

Scientific methods

Competencies of PTS – all under one roof

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… – wood – paper – converting – …

Scientific methods• Design & Simulation• Sensorics• Analytics

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PTS 201104/18/23

Design & Simulation – Focal Points

Development of methods and tools for numerical simulation of paper properties

Transition from micro- to final product properties

• micro structure generation

• micro structure mechanics simulation

• homogenisation methods

Simulation based optimisation of the paper production process considering material and economical criteria

Linkage of pulp characteristic, process parameters, paper properties and calculation of costs

Maintenance of comprehensive pulp property data base

• PTS-ProductOptimizer

• PTS-SoftMcNett

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PTS 201104/18/23

Micro structure simulation – fibre network generation

Making available digital models of single fibres, fibre bonds and fibre networks

Fibre arrangement and accumulation

• Size of modelled section (x-y-plane)

• Fibre number (~g/m²), morphology, size distribution

• Fibre orientation distribution und x-y-arrangement

• Fibre shape profiles in Z-direction after sheet forming

• Adjustment of sheet thickness and apparent density by pressing process simulation

Subsequent modelling of:

• Behaviour under mechanical load

• Capillary force driven liquid penetration

• Optical properties

Comparison of different model approaches

e.g. shell vs. beam elementsfibre network e.g. 2 x 2 x 0,1 mm³

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PTS 201104/18/23

Micro structure mechanics simulation

Finite element model of fibre bond mechanics

• Size and shape of bonding areas

• Mechanical characteristics of fibre bond and fibre wall materials (deformation, failure)

Model of fibre network mechanics

• Search algorithm for contact sites

• Implementation of fibre bond model

• Modelling the behaviour under mechanical load (e.g. tensile testing)

• Deduction of a homogenised material model

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PTS 201104/18/23

Example: numerical simulation of tensile testing

a) Numerically created paper fibre network (area 1mm², height 0.09, sheet density 0.6g/cm³)

b) Mechanical model of the fibre network; centre fibre line, idealised fibre bonds)

c) longitudinal fibre forces (network is stretched by 2% in x-direction; tension; pressure)

d) bonding forces of idealised fibre bonds in the stretched network

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PTS 201104/18/23

Expected benefit from COST FP 1005

Micro structure simulation in fibre networks requires insight in dynamic processes during sheet forming largely determined by pulp suspension fluid dynamics

• more realistic and verified micro structure models for improved fibre network mechanics simulation

• Improved characterisation of physical processes during sheet forming, pressing, and drying, thus more realistic paper and fibre network properties

Elucidation of interactions between fibre properties (surface structure, flexibility, morphology …) and suspension flow characteristics

• Effect of fibre modification on pulp suspension flow characteristics

• Impact of fluid dynamics on fibre properties during stock preparation treatment

• Influence of pulp suspension flow parameters on resulting fibre network properties

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PTS 201104/18/23

• modelling and simulation of paper properties and processes, micro structure simulation, mechanics of fibre networks

• optimal use and modification of fibres for different processes and products, fibre and fibre network characterization (e.g. fibre morphology distribution …)

• experimental investigations under conditions very similar to processes in paper mills using the pilot scale paper machine (stock preparation, sheet forming)

• linking fundamental research to applied research activities

Expertise to bring in to COST FP 1005