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The influence of test conditions and mathematical assumptions on biaxial material parameters of fabrics.
Tijdschriftbijdrage - Tijdschriftartikel
Due to the complex nature of woven fabrics, biaxial testing forms an integral part of designing lightweight fabric structures. By mimicking the multi-axial stress states the material experiences during its lifetime as a structure, the observed stress-strain relations and derived material parameters are much more representative than uniaxial results.
Until recently however, no real standard regarding biaxial testing of fabric materials existed, leading to a significant variation in test and interpretation methods. The publication of EN 17117-1 in 2018 aimed to provide a modern reference which could serve as a framework for the biaxial testing of coated textiles. However, given the historical development within the field of testing fabrics, the code refrains from providing clear rules and rather opts to formulate guidelines and possibilities for various steps of the testing process. As a result, different test contexts and parameter derivation methods can still exist next to one another making inter-laboratory comparison of derived parameters still somewhat of a challenge.
During this research a type II polyester-PVC fabric (Sioen T2103) was tested using a number of different test methods. Afterwards linear elastic orthotropic material constants were derived using a number of established mathematical methodologies and assumptions. By comparing the resulting material constants, the influence of the imposed alterations was assessed.
This paper describes the testing and derivation procedures, compares the resulting material parameters and proceeds to formulate conclusions based on the observed differences, or lack thereof. These findings not only allow for a more founded comparison of test results between different facilities, but also aids to better understand the impact certain choices in test or derivation methodology can have on the test outcomes.
The conducted tests did not only reveal that the variability of the derived material parameters in function of the verified parameters varied in function of the applied load profile, but also allowed for the identification of some relations between alterations in the test/derivation methodology and the resulting material parameters. Observing the effective variability that exists on the derived material parameters shows that the characterisation of coated textiles is still a valuable subject for further research and development.
Through this study, and the identified relations between the boundary conditions and the resulting material parameters, we can now assess to a reasonable degree what variation to expect from biaxial tests conducted using various approaches and methodologies. The results presented in this paper not only further highlight the importance of a harmonised methodology for testing fabric materials and derive non-project-oriented material parameters, but also illustrate the need for a broader approach when interpreting these generalised material parameters and applying them in (preliminary) numerical models.
Until recently however, no real standard regarding biaxial testing of fabric materials existed, leading to a significant variation in test and interpretation methods. The publication of EN 17117-1 in 2018 aimed to provide a modern reference which could serve as a framework for the biaxial testing of coated textiles. However, given the historical development within the field of testing fabrics, the code refrains from providing clear rules and rather opts to formulate guidelines and possibilities for various steps of the testing process. As a result, different test contexts and parameter derivation methods can still exist next to one another making inter-laboratory comparison of derived parameters still somewhat of a challenge.
During this research a type II polyester-PVC fabric (Sioen T2103) was tested using a number of different test methods. Afterwards linear elastic orthotropic material constants were derived using a number of established mathematical methodologies and assumptions. By comparing the resulting material constants, the influence of the imposed alterations was assessed.
This paper describes the testing and derivation procedures, compares the resulting material parameters and proceeds to formulate conclusions based on the observed differences, or lack thereof. These findings not only allow for a more founded comparison of test results between different facilities, but also aids to better understand the impact certain choices in test or derivation methodology can have on the test outcomes.
The conducted tests did not only reveal that the variability of the derived material parameters in function of the verified parameters varied in function of the applied load profile, but also allowed for the identification of some relations between alterations in the test/derivation methodology and the resulting material parameters. Observing the effective variability that exists on the derived material parameters shows that the characterisation of coated textiles is still a valuable subject for further research and development.
Through this study, and the identified relations between the boundary conditions and the resulting material parameters, we can now assess to a reasonable degree what variation to expect from biaxial tests conducted using various approaches and methodologies. The results presented in this paper not only further highlight the importance of a harmonised methodology for testing fabric materials and derive non-project-oriented material parameters, but also illustrate the need for a broader approach when interpreting these generalised material parameters and applying them in (preliminary) numerical models.
Tijdschrift: Engineering Structures
ISSN: 0141-0296
Issue: 109691
Volume: 200
Jaar van publicatie:2019
Trefwoorden:Biaxial testing, Coated fabric, Material constants, Architectural fabric
CSS-citation score:1
Toegankelijkheid:Open