Biaxial testing of fabric materials and deriving their material properties A quantitative study Maarten Van Craenenbroeck http://www.vub.ac.be/arch/ae-lab/ Silke Puystiens Lars De Laet Danny Van Hemelrijck Marijke Mollaert
Biaxial testing of fabrics is not standardised for various reasons Young material
Biaxial testing of fabrics is not standardised for various reasons Young material Complex material
Biaxial testing of fabrics is not standardised for various reasons Young material Complex material Protection of technologies
Biaxial testing of fabric materials and deriving their material properties Testing methodologies Deriving the material parameters Inter-laboratory research
Biaxial testing of fabric materials and deriving their material properties Testing methodologies Deriving the material parameters Inter-laboratory research
Biaxial samples have been tested on the in-house biaxial rig using various protocols
The fabric used in these tests was a regular type 2 polyester-pvc fabric Sioen T2107 Polyester-PVC fabric Weight 1050g/m² Tensile strength warp 80kN/m Tensile strength weft 80kN/m Tear strength warp 600N Tear strength weft 500N
The protocol described in MSAJ M-02-1995 is still the only real standard when testing fabrics
An adaptation from the MSAJ protocol was used as default testing protocol
As a first variation the order of load ratios was changed
The second variation used a different starting ratio
Biaxial testing of fabric materials and deriving their material properties Testing methodologies Deriving the material parameters Inter-laboratory research
For the standard protocols, changing the start ratio impacted the results the most Stress (kn/30cm) 7 6 5 4 3 2 1 1:1 Warp Weft Default profile Altered sequence Altered start ratio 0-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 Stress (kn/30cm) 7 6 Stress (kn/30cm) 1:2 Weft 2:1 7 6 Warp 5 5 4 3 Warp 4 3 Weft 2 2 1 1 0-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12
For the standard protocols, changing the start ratio impacted the results the most Stress (kn/30cm) 7 6 5 4 3 2 1 1:1 Warp Weft Default profile Altered sequence Altered start ratio 0-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 Stress (kn/30cm) 7 6 Stress (kn/30cm) 1:5 Weft 5:1 7 6 Warp 5 5 4 4 3 3 2 1 Warp 2 1 Weft 0-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12
Even with the intermediate 1:1 ratio in place, slight changes of the protocol can impact the results Ex Strain minimisation Stress minimisation Default profile Altered sequence Altered start ratio Ey 0 200 400 600 800 1000 1200
Even with the intermediate 1:1 ratio in place, slight changes of the protocol can impact the results vx Strain minimisation Stress minimisation Default profile Altered sequence Altered start ratio vy 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Further research aims to quantify the practical impact and extend the testing possibilities Change the loading limits Change the prestress ratio Impact on various computational simulations Impact of the testing equipment
Biaxial testing of fabric materials and deriving their material properties Testing methodologies Deriving the material parameters Inter-laboratory research
Different institutions have different technologies and methodologies Newcastle University (NCL) Vrije Universiteit Brussel (VUB) Politecnico di Milano (PoliMi)
By investigating different parts, variations in the results can be quantified Compare biaxial test data Looking at the raw stress-strain data Compare resulting constants Investigating the influence of small variations on the processed data Compare different material models Modelling the biaxial test using various material models and compare these to reality
Next to testing fabrics, the biaxial test will be modelled using various material models Linear elastic cable net (Easy; VUB) Linear elastic with variable Poisson s coefficient (Sofistik; EMPA) Hyperelastic (Abaqus; PoliMi) Elasto-plastic (Abaqus; UGent) Neural Networks (NCL)
All data is compared to each other and simulations are compared to the reality ε xx DIC Visualisation ε yy DIC Visualisation
All data is compared to each other and simulations are compared to the reality 3 test institutions VUB, NCL, PoliMi 5 material models 3 + 10 + 15 = 28 comparisons
Biaxial testing of fabric materials and deriving their material properties Testing methodologies Deriving the material parameters Inter-laboratory research
Biaxial testing of fabric materials and deriving their material properties A quantitative study Maarten Van Craenenbroeck http://www.vub.ac.be/arch/ae-lab/ Silke Puystiens Lars De Laet Danny Van Hemelrijck Marijke Mollaert