NANOENGINEERED COMPOSITES: Strength and fatigue resistance. Computational modelling Leon Mishnaevsky Jr.

DSF (DANISH FOUNDATION OF BASIC SCIENCE) PROJECT High reliability of large wind turbines via computational micromechanics based enhancement of materials performances

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

FUTURE OF WIND ENERGY ARE OFF-SHORE WIND PARKS

Such wind turbines are very difficult and expensive to

repair if they are broken. Reliability must be increased!

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

GOAL OF THIS PROJECT: to create a scientific basis for the development of advanced, strong materials (with optimized at microlevel microstructures) for wind blades.

3D MULTIFIBER UNIT CELL SIMULATIONS

L. Mishnaevsky Jr and P. Brøndsted, Composites Sci & Technol, Vol. 69, No.7-8, 2009, pp. 1036-1044; Materials Science &Engineering: A, Vol.498, No. 1-2, 2008, pp. 81-86

Matrix crack growth from a fiber crack

Fiber bridging:

3 Competing Damage Modes:

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

ENHANCED EFFECTIVE INTERFACE MODEL Effective interface model (EIM) was proposed by Odegard and his colleagues to take into account the interface/interphase effects in nanocomposites. EIM represents molecular structure of the perturbed polyimide , interphases and interfacial molecules with gradual transition to the bulk molecular structure.

Generalized effective interface model: consists of two layers with different properties; outer layer is allowed to overlap. Allows to model nanoparticle clustering

Effect of aspect ratio of particles

0 2 4 6 8 1042204240426042804300432043404360438044004420

Ove

rall Y

oung

's M

odul

us (M

Pa)

Aspectratio

Interphases thickness 1.2 nm 0 30 45 60 90

Exfoliated nanoparticles with EIM

Clustered particles with EIM

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

HYBRID CARBON/GLASS COMPOSITES: Static & fatigue behaviour

L. Mishnaevsky Jr., G.M. Dai, Hybrid carbon/glass fiber composites: Micromechanical analysis of structure-damage resistance relationship,

Computational Materials Science, Vol. 81, 2014, pp. 630-640

Critical stress(plotted versus the fraction of carbon fibers under static

compression

Unit cell models and stress-strain curves of hybrids

Crack formation in aligned (a) and misaligned (b) structures

S-N curves of different hybrid composites under compression-compression cyclic loading

Some observations: Tensile cyclic loadings: composites with highest fraction of carbon fibers show best performances and longest lifetime. Compression loading: composites with largest fraction of carbon show the lowest maximum stress and fatigue lifetime. Fiber misalignment has some potential for increasing the fracture toughness of the composites

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

GRAPHENE REINFORCED POLYMERS: Modelling

Multielement unit cell model

Crack morphology in an aligned and misaligned model

Aspect ratio and clustering effecrs

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

MULTISCALE HYBRID COMPOSITE WITH CARBON NANOTUBE REINFORCEMENT: Modelling

Risø DTU, Technical University of Denmark Risø DTU, Technical University of Denmark

HIERARCHICAL COMPOSITES with secondary nanoclay reinforcement

G.M. Dai, L. Mishnaevsky Jr., Fatigue of multiscale composites with secondary nanoplatelet reinforcement: 3D canalysis, Composites Science and Technology (accepted); Damage evolution in nanoclay-reinforced polymers: 3D computational study, Composites Science & Technology, 74 (2013) 67–

77

Effect of nanoclay in matrix and fiber sizing on the crack path deviation ↑ … and on the S-N curves

(below) (compression cyclic loading on glass/epoxy/nanoclay composite)

Crack path at different orientations and clustering of nanoplatelets

SOME REFERENCES

G.M. Dai, LM, Fatigue of multiscale composites with secondary nanoplatelet reinforcement: 3D computational analysis, Composites Science and Technology, Vol. 91, 2014, pp. 71-81

LM., G.M. Dai, Hybrid carbon/glass fiber composites: Micromechanical analysis of structure-damage resistance relationship, Computational Materials Science, Vol. 81, 2014, pp. 630-640

G.M. Dai, LM., Fatigue of hybrid carbon/glass composites: 3D Computational modelling Composites Science & Technology, Vol. 94, 2014, pp. 71–79

LM, Micromechanical analysis of nanocomposites using 3D voxel based material model, Composites Science & Technology, 72 (2012)

LM., G.M. Dai, Hybrid carbon/glass fiber composites: Micromechanical analysis, Comput Materials Sci, Vol. 81, 2014

G.M. Dai, LM., Damage evolution in nanoclay-reinforced polymers: 3D computational study, Composites Science & Technology, 74 (2013)

L. Mishnaevsky Jr., Micromechanics of hierarchical materials: a brief overview, Reviews on Advanced Materials Science, 30 (2012)

L. Mishnaevsky Jr. et al Materials of large wind turbine blades: Recent results in testing and modelling, Wind Energy, Vol. 15, No.1, 2012

LM., Hierarchical composites: Analysis of damage evolution based on fiber bundle model, Composites Sci & Technol, 71 (2011)

H. Qing, LM, Fatigue modelling of materials with complex microstructures, Comput Materials Sci, Vol.50, N.5, 2011

H.W. Wang, et al.., Nanoreinforced polymer composites: 3D FEM modeling with effective interface concept, Composites Scie & Technol, 71/7, 2011