Transcript Simulation of micro structure mechanics in dynamic fibre networks
PTS research activities related to COST FP 1005
Simulation of micro structure mechanics in dynamic fibre networks
Timo Kuntzsch, Jan Matheas, Sven Altmann
Competencies of PTS – all under one roof
Scientific methods
•
Design & Simulation
• Sensorics • Analytics
… – wood – Value chain paper – converting – … Scientific methods Environmental relevance and sustainability aspects Material testing and expert opinions Education and training
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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
H D d
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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L d
70 60 50 40 30 20 10 Kosten in €/t Papier
Investitionen Entsorgung Chemikalien Energie Rohstoffe
0 -10 -20 0,0 -7,2 -1,4 8,3 5,8 0,7 1,4 18,0 18,3 54,6 55,6 1,1 1,5 1,5 2,3 3,2 24,9
IST nur 1.02
nur 1.04
nur 4.01
Altpapier 40% 4.02
50% 100% DAF 10% 50KW 10% 100KW 30% 50KW 30% 100KW 30% 25KW 30% 25KW VS
Szenarien
30% 50KW 55% 25KW Fraktionierung 55% 50KW 100% 100% Flotation Wäsche Kombi
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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 elements
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fibre network e.g. 2 x 2 x 0,1 mm³
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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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Example: numerical simulation of tensile testing
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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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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 7
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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Expertise to bring in to COST FP 1005
• 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 8
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