Thermoforming Modelling and Simulation of Multilayer Composites with Continuous Fibre and Thermoplastic Matrix

2015 ◽  
Vol 651-653 ◽  
pp. 387-392 ◽  
Author(s):  
Eduardo Guzmán Maldonado ◽  
Nahiène Hamila ◽  
Philippe Boisse ◽  
Peng Wang ◽  
Philippe Chaudet
Keyword(s):  
Viscoelastic Model ◽  
Shear Mode ◽  
Thermoplastic Resin ◽  
Plane Shear ◽  
Continuous Fibre ◽  
Thermoplastic Matrix ◽  
Nonlinear Viscoelastic ◽  
Element Simulation ◽  
Thermoforming Process ◽  
Nonlinear Viscoelastic Model

CFRTP prepreg laminates thermoforming (Continuous Fibre Reinforcements and Thermoplastic Resin) is a fast composite manufacturing process. Furthermore the thermoplastic matrix is favourable to recycling. The development of a thermoforming process is complex and expensive to achieve by trial/error. A simulation approach for thermoforming prepregs thermoplastic is presented. This model is based on a continuous approach. A hyperelastic behaviour is associated with dry reinforcements. The hyperelastic potential is built from the contribution of three principal deformation modes that are supposed to be independent. A nonlinear viscoelastic model based on the generalization of simple rheological models is associated with the in-plane shear mode. The finite element simulation of a thermoforming example using this model is presented.

Thermoforming Simulation of Multilayer Composites with Continuous Fibre and Thermoplastic Matrix

2014 ◽  
Vol 611-612 ◽  
pp. 368-374
Author(s):  
Eduardo Guzman Maldonado ◽  
Nahiene Hamila ◽  
Philippe Boisse ◽  
Philippe Chaudet
Keyword(s):  
Friction Model ◽  
Contact Friction ◽  
Thermoplastic Resin ◽  
Forming Process ◽  
Plane Shear ◽  
Shell Elements ◽  
Continuous Fibre ◽  
Thermoplastic Matrix ◽  
Different Temperatures ◽  
Thermoforming Process

CFRTP prepreg laminates thermoforming (Continuous Fibre Reinforcements and Thermoplastic Resin) is a fast composite manufacturing process. Furthermore the thermoplastic matrix is favourable to recycling. The development of a thermoforming process is complex and expensive to achieve by trial/error. A simulation approach for thermoforming of multilayer thermoplastic is presented. Each prepreg layer is modelled by semi-discrete shell elements. These elements consider the tension, in-plane shear and bending behaviour of the ply at different temperatures around the fusion point. The contact/friction during the forming process is taken into account using forward increment Lagrange multipliers. A lubricated friction model is implemented between the layers and for ply/tool friction. Thermal and forming simulations are presented and compared to experimental results. The computed shear angles after forming and wrinkles are in good agreement with the thermoforming experiment.

Free volume based nonlinear viscoelastic model for polyurea over a wide range of strain rates and temperatures

2021 ◽  
Vol 152 ◽  
pp. 103650
Author(s):  
Chencheng Gong ◽  
Yan Chen ◽  
Ting Li ◽  
Zhanli Liu ◽  
Zhuo Zhuang ◽  
...  
Keyword(s):  
Free Volume ◽  
Viscoelastic Model ◽  
Strain Rates ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Nonlinear Viscoelastic Model

Identification of Nonlinear Viscoelastic Models of Flexible Polyurethane Foam From Uniaxial Compression Data

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yousof Azizi ◽  
Patricia Davies ◽  
Anil K. Bajaj
Keyword(s):  
Uniaxial Compression ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Model Parameters ◽  
Viscoelastic Models ◽  
Nonlinear Viscoelastic ◽  
Compression Data ◽  
Computationally Intensive ◽  
Nonlinear Viscoelastic Model ◽  
Flexible Polyurethane

Flexible polyethylene foam is used in many engineering applications. It exhibits nonlinear and viscoelastic behavior which makes it difficult to model. To date, several models have been developed to characterize the complex behavior of foams. These attempts include the computationally intensive microstructural models to continuum models that capture the macroscale behavior of the foam materials. In this research, a nonlinear viscoelastic model, which is an extension to previously developed models, is proposed and its ability to capture foam response in uniaxial compression is investigated. It is hypothesized that total stress can be decomposed into the sum of a nonlinear elastic component, modeled by a higher-order polynomial, and a nonlinear hereditary type viscoelastic component. System identification procedures were developed to estimate the model parameters using uniaxial cyclic compression data from experiments conducted at six different rates. The estimated model parameters for individual tests were used to develop a model with parameters that are a function of strain rates. The parameter estimation technique was modified to also develop a comprehensive model which captures the uniaxial behavior of all six tests. The performance of this model was compared to that of other nonlinear viscoelastic models.

On the Nonlinear Viscoelastic Behaviour of the PVC-Coated Fabric

2010 ◽  
Vol 160-162 ◽  
pp. 1476-1481 ◽  
Author(s):  
Wu Lian Zhang ◽  
Xin Ding ◽  
Xu Dong Yang
Keyword(s):  
Viscoelastic Model ◽  
Constitutive Relationship ◽  
Viscoelastic Behaviour ◽  
Viscoelastic Response ◽  
Nonlinear Parameters ◽  
Creep And Recovery ◽  
Nonlinear Viscoelastic ◽  
Coated Fabric ◽  
Nonlinear Viscoelastic Model

The nonlinear viscoelastic response of a PVC-Coated Fabric has been studied. For the needs of the present study, creep and recovery tests in tension of both the warp and the weft directions at the different stress levels were executed while measurements were made of the creep and recovery strain response of the system. For the description of the viscoelastic behaviour of the material, Schapery’s nonlinear viscoelastic model was used. For the description of the nonlinear viscoelastic response and the determination of the nonlinear parameters, a method by using a combination of analytical formulations and numerical procedures based on a modified version of Schapery’s constitutive relationship where an instantaneous plastic and a transient plastic terms were added, has been developed. The method has been successfully applied to the current tests.

scholarly journals Delayed electromechanical instability of a viscoelastic dielectric elastomer balloon

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190316 ◽  
Author(s):  
Xiongfei Lv ◽  
Liwu Liu ◽  
Jinsong Leng ◽  
Yanju Liu ◽  
Shengqiang Cai
Keyword(s):  
Hoop Stress ◽  
Mechanical Load ◽  
Viscoelastic Model ◽  
Dielectric Elastomer ◽  
Time Dependent ◽  
Convex Shape ◽  
Nonlinear Viscoelastic ◽  
Electromechanical Instability ◽  
Electromechanical Loading ◽  
Nonlinear Viscoelastic Model

When a dielectric elastomer (DE) balloon is subjected to electromechanical loading, instability may happen. In recent experiments, it has been shown that the instability configuration of a DE balloon under electromechanical loading can be very different from that only subjected to mechanical load. It has also been observed in the experiments that the electromechanical instability phenomena of a DE balloon can be highly time-dependent. In this article, we adopt a nonlinear viscoelastic model for the DE membrane to investigate the time-dependent electromechanical instability of a DE balloon. Using the model, we show that under a constant electromechanical loading, a DE balloon may gradually evolve from a convex shape to a non-convex shape with bulging out in the centre, and compressive hoop stress can also gradually develop the balloon, resulting in wrinkles as observed in the experiments. We have further shown that the snap-through instability phenomenon of the DE balloon also greatly depends on the ramping rate of the applied voltage.

A nonlinear viscoelastic model for polymer solutions and melts—II

1968 ◽  
Vol 23 (8) ◽  
pp. 901-911 ◽  
Author(s):  
Pierre J. Carreau ◽  
Ian F. MacDonald ◽  
R.Byron Bird
Keyword(s):  
Polymer Solutions ◽  
Viscoelastic Model ◽  
Nonlinear Viscoelastic ◽  
Nonlinear Viscoelastic Model

Linearization of a Viscoelastic Model for Light-Weight Embankment

2011 ◽  
Vol 324 ◽  
pp. 368-371
Author(s):  
Hayssam El Ghoche
Keyword(s):  
Viscoelastic Model ◽  
Light Weight ◽  
Specific Density ◽  
Linear Forms ◽  
Plastic Films ◽  
Nonlinear Viscoelastic ◽  
New Process ◽  
Real Behavior ◽  
Nonlinear Viscoelastic Model ◽  
Experimental And Theoretical Studies

A new process of light-weight embankment by using parallelepipedal blocks which made up of plastic films in order to obtain a density of 0.4, 0.5 or 0.6. The experimental and theoretical studies of this material enabled us to elaborate a nonlinear viscoelastic model. It shows clearly the real behavior, but it needs the identification of a great number of parameters. The purpose of this paper is to simplify the model by linearzing it. This linearization was carried out for a specific density (0.6) in two ways: - Adoption of linear forms of the elastic and delayed deformations according to the stress. - Adoption of a linear form of the elastic deformation and a constant delayed one (linear viscoelasticity). The comparison between experience and theory shows that the linear model describes the reality in a field of stresses which can reach 200 kPa.

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