Three trends in mechanical modelling of materials · Institute for Mechanics of Materials and...
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Josef Füssl, Markus Lukacevic, Josef Eberhardsteiner Institute for Mechanics of Materials and Structures WKO – The Future of Building 2018, 08.05.2018 Three trends in mechanical modelling of materials
Transcript of Three trends in mechanical modelling of materials · Institute for Mechanics of Materials and...
Josef Füssl, Markus Lukacevic, Josef Eberhardsteiner
Institute for Mechanics of Materials and Structures
WKO– TheFutureof Building2018,08.05.2018
Three trends in mechanical modelling of materials
Motivation
Demands:
à Stabilityà Structural safetyà Serviceability
Design methods:
à Static methods16. Jhd da Vinci, Galilei 17. Jhd Bernoulli, Newton18. Jhd Euler19. Jhd Ritter
à Numerical methods20. Jhd Zienkiewicz
Building Structure Material
Material behaviour:
à Material model17. Jhd Hooke 18. Jhd Coloumb19. Jhd Mohr
à Material propertiesstiffness, strengthviscosity, ...
à ExperimentsTensile-,compression-,Bending tests
Design methods:
à Analytical methods20. Jhd. Eshelby20. Jhd. Mori, Tanaka21. Jhd. ???
à Numerical methods20. Jhd Zienkiewicz
à Timeà Moneyà Less informationVariability of “nature”
Complexity of model
First: Looking into the microstructure of materialsWood
MicroCT Scanning Electron Microscope
Atomic Force Microscope
Different scales of observation, with different material phases and different morphologies
First: Looking into the microstructure of materialsFired clay
MicroCT SEM-EDX / NI Atomic Force Microscope - SThM
Material behaviour of certain material phases
Second: Mechanical linking of these scales up to the product scale
lpolynet=20 nm
Zellulose
lcwm=0.5-1 µm lHW=2-4 mm
CMM, Mori-Tanaka Unit Cell Method CMM,
Mori-Tanaka
lT≈lR=20-40 µm
Composite Cylinder Assemblage
lcellulose=10 nm
amorpheZellulose
kristallineZellulose
Wasser
LHC-Komplex
CMM, Mori-Tanaka
Multiscale model for wood
Second: Mechanical linking of these scales up to the product scale
Mechanical behaviour of material as function of its microstructure (morphology, behaviour of material phases)
Input: wood species (microstructural characteristics), density, moisture content
Output: macroscopic stiffness and strength behaviour for specific wood sample
Multiscale model for wood
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F [N
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s [mm]latewood
earlywood
TR configuration
§ Finite Element modellate-/earlywood modeledhomogeneouslywith new multisurface crack criteria
§ Micro-wedge-splitting testsfor RT and TR configurations[Frühmann2003, Keunecke2007]
Third: Implementation of non-linear material behaviour into design concepts
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s [mm]
TR configuration
Third: Implementation of non-linear material behaviour into design concepts
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TR configuration
Third: Implementation of non-linear material behaviour into design concepts
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TR configuration
Third: Implementation of non-linear material behaviour into design concepts
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TR configuration
First crack
Maximum load
Third: Implementation of non-linear material behaviour into design concepts
Plastic zones
GLT with hole underbending
Realistic simulation considering plasticity and cracking
Third: Implementation of non-linear material behaviour into design concepts
Bending load:Unit cell representation:
Example: Cross-laminated timber (CLT)
Third: Implementation of non-linear material behaviour into design concepts
Realistic mechanical behaviour of products
Summary
Necessary information to …
First: Looking into the microstructure of materials
Second: Mechanically linking the microstructural scales up to the product scale
Third: Implementation of non-linear material behaviour into design concepts
Realistic predictions of mechanical behaviour
Efficient optimisation and improvement of materials
Potential for targeted development of new products
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