Geometrically nonlinear simulation of textile membrane structures based on orthotropic hyperelastic energy functions

Proc Appl Math and Mech

Uhlemann

et al. 2019

Self Cite

In this contribution new orthotropic hyperelastic energy functions are proposed for the geometrically nonlinear simulation of woven textile membranes. The new models are investigated and compared with a competitive formulation with respect to mathematical characteristics, accuracy in representation of experimental data and their robustness in numerical simulations. Part of the models is polyconvex and thus, a physically meaningful and mathematically sound formulation is obtained. The models are adjusted to stress-strain paths of a glass-PTFE fabric under cyclic uniaxial and biaxial tension tests. Moreover, a new large scale experimental setup is presented which enables the study of the material behavior in real structural problems.

Section: Hyperelastic Orthotropic Materials Models and Their Mathematimentioning

confidence: 95%

“…[4]. It was observed that both models ψ NPC1 and ψ PC1 suffer from no convergence in the Newton iteration, cf.…”

Section: Numerical Robustness In Structural Analysis and A New Large-mentioning

confidence: 98%

Section: Numerical Robustness In Structural Analysis and A New Large-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Orthotropic Hyperelastic Energy Functions for the Geometrically Nonlinear Simulation of Textile Membrane Structures

Motevalli

Proc Appl Math and Mech

Uhlemann

et al. 2019

Self Cite

Unique identification of stiffness parameters for nonlinear, anisotropic textile fabrics based on full‐field measurements on a single experiment

Makhool

2021

Proc Appl Math & Mech

Self Cite

This work discusses a hybrid experimental-numerical framework by which the stiffness parameters for nonlinear anisotropic textile fabrics can be uniquely identified. In the experimental part, a non-standard setup has been designed to activate the deformation modes in a free energy function describing the mechanical material behavior. As a result, one inhomogeneous deformation field is captured by means of measuring full-field kinematics, which includes sufficient information regarding the nonlinear response for varying deformation modes and intensities. In the numerical part, the measured full-field data are inserted into a suitable discretized model of the specimen. Reformulating the free energy function to be linear in material parameters is considered in order to enable the definition of a quadratic objective function in terms of differences of discrete internal and external forces and hence to assure the uniqueness of the parameter identification. Finally, the sensitivity of the method to noisy data is studied.

Enhancement in the Numerical Simulation of Textile Fabrics by Local Calculation of Stress‐Ratio‐Dependent Material Parameters

Motevalli

Proc Appl Math and Mech

2023

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In the structural analysis of tensile membranes, the linear elastic model is still a favorable choice for design engineers due to its simplicity and straightforward interpretation of parameters. However, it is well known that such an over simplification of the complex behavior leads to inaccurate or even false response in numerical simulations. In this work, the linear elastic model together with the hyperelastic orthotropic material model proposed for geometrically nonlinear simulation of tensile surfaces is considered as the basis for a new numerical approach leading to more accurate structural simulations. The nonlinear model is able to provide a more precise description of fabric materials and becomes a competitive candidate for realistic structural analysis with only 3 material parameters. In the proposed procedure, the material parameters are estimated based on the stress ratios encountered in structural simulations. Therefore, the material properties are initially identified for each loading scenario of the load‐driven biaxial experiments. This results in a number of sets of different stress‐ratio‐dependent material parameters following the experimentally applied load ratios. In a second identification step, an iterative simulation procedure is employed in which, according to the locally obtained stress ratios in the discretized structural problem, the associated parameter values at each material point will be updated. For new stress ratios that lie between those applied experimentally, an interpolation scheme is implemented that approximates the parameter value accordingly. The iterative simulation is repeated until the total change in the updated parameters at all points becomes insignificant. By employing the proposed method, it is shown that the linear elastic model will be able to more accurately represent the complex behavior of textile membranes.