Experimental and Numerical Study for Determining the Mechanical Properties of Automobile Weatherstrip Seals

2006 ◽  
Author(s):  
Emre Dikmen ◽  
Ipek Basdogan
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Test Data ◽  
Compression Test ◽  
Strain Energy ◽  
Energy Functions ◽  
Material Models ◽  
Compression Load ◽  
Hyperelastic Materials ◽  
Strain Energy Functions

Structural parts made of hyperelastic materials such as rubber mounts in automotive powertrains and weatherstrip seals are widely used in automotive and other engineering applications. In this study, compression load deflection (CLD) behavior of a highly non-linear type of joint, automotive weatherstrip seal made of Ethylene Propylene Diene Monomer (EPDM) sponge rubber is examined using finite element modeling techniques. The finite element modeling (FEM) results are then compared with the compression load deflection data obtained experimentally. The compression load deflection data for various punch velocities can be used to model the weatherstrip seal as a nonlinear spring-dashpot system with varying stiffness and damping coefficient proportional to the amount of compression. The weatherstrip seals should be modeled accurately in order to predict the dynamic performance of the automobiles under various load conditions. First part of the study includes modeling of the seal using various hyperelastic material models which are available in ANSYS. The strain energy functions’ coefficients required for the various material models are calculated using both linear and nonlinear least square fit procedures implemented in ANSYS for fitting the tension, shear and compression test data. After the coefficients are calculated, the compression test is performed in ANSYS using various hyperelastic material models. Second part of the study includes the compression experiment of weatherstrip seal with a robotic indenter specifically designed for measuring hyperelastic materials. The measured CLD data is then compared with the FEM results. The accuracy of using only simple tension test data to acquire the coefficients for strain energy functions is investigated and suitable strain energy functions to model compression of weatherstrip seal are determined. Additionally, Mullins Effect (stress softening) for this application is investigated using the compression experiments data.

Finite Bending and Straightening of Hyperelastic Materials: Analytical Solution and FEM

2019 ◽  
Vol 11 (09) ◽  
pp. 1950084 ◽  
Author(s):  
Sara Sheikhi ◽  
Mohammad Shojaeifard ◽  
Mostafa Baghani
Keyword(s):  
Finite Element ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Optimization Procedure ◽  
Element Analysis ◽  
Energy Functions ◽  
Hyperelastic Materials ◽  
Finite Bending ◽  
Strain Energy Functions ◽  
Analytical Approaches

In this research, an incompressible, isotropic, nonlinear elastic rectangular block and a circular cylindrical sector are studied under bending and straightening moments, respectively. Analytical approaches are presented on implementing of the left Cauchy–Green tensor and Cauchy stresses. In addition, finite element analysis of both problems is carried out using UHYPER user-defined subroutine in ABAQUS to verify the analytical methods. Four different invariant-based strain energy functions, including neo-Hookean, Mooney–Rivlin, Arruda–Boyce, and recently proposed polynomial Exp-Exp models, are examined, and the results are compared. Material parameters of silicon rubber for the strain energy functions are identified by applying an optimization procedure. Finite element method results confirmed the analytical approach with great compatibility. Results showed that the length of the unbent beam does not affect the stress. Likewise, the initial angle of curved structure does not affect the unbending moment and stresses. Moreover, the Exp-Exp model had a slightly different result rather than other strain energies, which means that this model is more conservative than its counterparts. Furthermore, the Exp-Exp strain energy function is calibrated for tissue-like phantom and is compared with experimental data.

scholarly journals Numerical and Experimental Investigation of Oil Palm Shell Reinforced Rubber Composites

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 314
Author(s):  
Subhashini Anandan ◽  
Cuin Yang Lim ◽  
Boon Thong Tan ◽  
Vivi Anggraini ◽  
Mavinakere Eshwaraiah Raghunandan
Keyword(s):  
Experimental Investigation ◽  
Finite Element ◽  
Oil Palm ◽  
Strain Energy ◽  
Shape Effect ◽  
Strain Response ◽  
Energy Functions ◽  
Palm Shell ◽  
Oil Palm Shell ◽  
Strain Energy Functions

This paper presents a pioneering effort to ascertain the suitability of hyperelastic modelling in simulating the stress–strain response of oil palm shell reinforced rubber (ROPS) composites. ROPS composites with different oil palm shell contents (0%, 5%, 10% and 20% by volume) were cast in the laboratory for the experimental investigation. ROPS specimens with circular, square, hexagon, and octagon shapes (loading surface) were considered to evaluate the accuracy of finite element simulation considering the shape effect of composites. Strain-controlled (compressive) tests with ε ≈ 50% at 0.8 Hz frequency were conducted in the laboratory and the test data obtained was used as input to simulate material coefficients corresponding to the strain energy functions chosen. Five different strain energy functions were selected and utilized for the hyperelastic modelling in this study using finite element approach. The shape effect was then used to ascertain any variation in the simulation outcomes and to discuss the effect of shape on the behaviour of ROPS composites in comparison to existing literature. The numerical predictions using the Yeoh model (error ≤ 2.7% for circular shaped ROPS) were found to perform best in comparison with the experimental results, thus a more stable and suitable hyperelastic model to this end. The Marlow (error ≤ 4.6% for circular shaped ROPS) and Arruda Boyce (error ≤ 4.7% for circular shaped ROPS) models were amongst the next alternatives to perform better. Even with the other shapes considered in this study, Yeoh, followed by the Marlow function, were more appropriate models. The shape effect was then studied with particular emphasis on comparing and assessing them with that observed in the literature. To this end, adopting the Yeoh function in the finite element model is the ideal approach to estimate the stress–strain response of ROPS composites.

Extending Marlow’s general first-invariant constitutive model to compressible, isotropic hyperelastic materials

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Florian Hüter ◽  
Frank Rieg
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Test Data ◽  
Curve Fitting ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Content Type ◽  
Hyperelastic Materials ◽  
Fitting Procedures

Purpose A general first-invariant constitutive model has been derived in literature for incompressible, isotropic hyperelastic materials, known as Marlow model, which reproduces test data exactly without the need of curve-fitting procedures. This paper aims to describe how to extend Marlow’s constitutive model to the more general case of compressible hyperelastic materials. Design/methodology/approach The isotropic constitutive model is based on a strain energy function, whose isochoric part is solely dependent on the first modified strain invariant. Based on Marlow’s idea, a principle of energetically equivalent deformation states is derived for the compressible case, which is used to determine the underlying strain energy function directly from measured test data. No particular functional of the strain energy function is assumed. It is shown how to calibrate the volumetric and isochoric strain energy functions uniquely with uniaxial or biaxial test data only. The constitutive model is implemented into a finite element program to demonstrate its applicability. Findings The model is well suited for use in finite element analysis. Only one set of test data is required for calibration without any need for curve-fitting procedures. These test data are reproduced exactly, and the model prediction is reasonable for other deformation modes. Originality/value Marlow’s basic concept is extended to the compressible case and applied to both the volumetric and isochoric part of the compressible strain energy function. Moreover, a novel approach is described on how both compressive and tensile test data can be used simultaneously to calibrate the model.

Failure Prediction of Unidirectional Composites Undergoing Large Deformations1

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
Jacob Aboudi ◽  
Konstantin Y. Volokh
Keyword(s):  
Strain Energy ◽  
Large Deformations ◽  
Static Stability ◽  
Energy Functions ◽  
Micromechanical Analysis ◽  
Hyperelastic Materials ◽  
Failure Envelopes ◽  
Special Cases ◽  
Enhanced Strain ◽  
Strain Energy Functions

In previous publications, strain-energy functions with limiters have been introduced for the prediction of onset of failure in monolithic isotropic hyperelastic materials. In the present investigation, such enhanced strain-energy functions whose ability to accumulate energy is limited have been incorporated with a finite strain micromechanical analysis. As a result, macroscopic constitutive equations have been established which are capable to predict the onset of loss of static stability in a hyperelastic phase of composite materials undergoing large deformations. The details of the micromechanical analysis, based on a tangential formulation, for composites with periodic microstructure are presented. The derived micromechanical analysis includes the capability to model a possible imperfect bonding between the composite’s constituents and to provide the field distribution in the composite. The micromechanical method is verified by comparison with analytical and finite difference solutions for porous hyperelastic materials that are valid in some special cases. Results are given for a rubberlike matrix characterized by softening hyperelasticity, reinforced by unidirectional nylon fibers. The response of the composite to various types of loadings is presented up to the onset of loss of static stability at a location within the hyperelastic rubber constituent, and initial failure envelopes are shown.

Finite Element Analysis by Using Hyper-Elastic Properties for Rubber Component

2011 ◽  
Vol 488-489 ◽  
pp. 190-193
Author(s):  
Chang Su Woo ◽  
Hyun Sung Park ◽  
Wae Gi Shin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Element Analysis ◽  
Energy Functions ◽  
Hyper Elastic ◽  
Rubber Component ◽  
Strain Energy Functions

The material modeling of hyper-elastic properties in rubber is generally characterized by the strain energy function. The strain energy functions have been represented either in term of the strain in variants that are functions of the stretch ratios, or directly in terms of the principal stretch. Successful modeling and design of rubber components relies on both the selection of an appropriate strain energy function and an accurate determination of material constants in the function. Material constants in the strain energy functions can be determined from the curve fitting of experimental stress-strain data. The uniaxial tension, equi-biaxial tension and pure shear test were performed to acquire the constants of the strain energy functions which were Mooney-Rivlin and Ogden model. Nonlinear finite element analysis was executed to evaluate the behavior of deformation and strain distribute by using the commercial finite element code. Also, the fatigue tests were carried out to obtain the fatigue failure. Fatigue failure was initiated at the critical location was observed during the fatigue test of rubber component, which was the same result predicted by the finite element analysis.

scholarly journals Biaxial estimation of biomechanical constitutive parameters of passive porcine sclera soft tissue

2021 ◽  
Author(s):  
Zwelihle Ndlovu ◽  
Dawood Desai ◽  
Thanyani Pandelani ◽  
Harry Ngwangwa ◽  
Fulufhelo Nemavhola
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Model ◽  
Test Data ◽  
Element Model ◽  
Finite Element Models ◽  
Anisotropic Model ◽  
Material Models ◽  
Material Parameters ◽  
Constitutive Parameters

This study assesses the modelling capabilities of four constitutive hyperplastic material models to fit the experimental data of the porcine sclera soft tissue. It further estimates the material parameters and discusses their applicability to a finite element model by examining the statistical dispersion measured through the standard deviation. Fifteen sclera tissues were harvested from porcine’ slaughtered at an abattoir and were subjected to equi-biaxial testing. The results show that all the four material models yielded very good correlations at correlations above 96 %. The polynomial (anisotropic) model gave the best correlation of 98 %. However, the estimated material parameters varied widely from one test to another such that there would be needed to normalise the test data to avoid long optimisation processes after applying the average material parameters to finite element models. However, for application of the estimated material parameters to finite element models, there would be needed to consider normalising the test data to reduce the search region for the optimisation algorithms. Although the polynomial (anisotropic) model yielded the best correlation, it was found that the Choi-Vito had the least variation in the estimated material parameters thereby making it an easier option for application of its material parameters to a finite element model and also requiring minimum effort in the optimisation procedure. For the porcine sclera tissue, it was found that the anisotropy more influenced by the fiber-related properties than the background material matrix related properties.

Finite Element Modeling of Grain Aspect Ratio and Strain Energy Density in a Textured Copper Thin Film

1996 ◽  
Vol 436 ◽  
Author(s):  
R. P. Vinci ◽  
J. C. Bravman
Keyword(s):  
Finite Element ◽  
Energy Density ◽  
Aspect Ratio ◽  
Finite Element Modeling ◽  
Strain Energy Density ◽  
Driving Force ◽  
Strain Energy ◽  
Interface Energy ◽  
Element Modeling ◽  
Grain Aspect Ratio

AbstractWe have modeled the effects of grain aspect ratio on strain energy density in (100)-oriented grains in a (111)-textured Cu film on a Si substrate. Minimization of surface energy, interface energy, and strain energy density (SED) drives preferential growth of grains of certain crystallographic orientations in thin films. Under conditions in which the SED driving force exceeds the surface- and interface-energy driving forces, Cu films develop abnormally large (100) oriented grains during annealing. In the elastic regime the SED differences between the (100) grains and the film average arise from elastic anisotropy. Previous analyses indicate that several factors (e.g. elimination of grain boundaries during grain growth) may alter the magnitude of the SED driving force. We demonstrate, using finite element modeling of a single columnar (100) grain in a (111) film, that changes in grain aspect ratio can significantly affect the SED driving force. A minimum SED driving force is found for (100) Cu grains with diameters on the order of the film thickness. In the absence of other stagnation mechanisms, such behavior could cause small grains to grow abnormally and then stagnate while large grains continue to grow. This would lead to a bimodal grain size distribution in the (100) grains preferred by the SED minimization.

Strain energy functions for filled elastomers

1965 ◽  
Vol 9 (7) ◽  
pp. 2565-2579 ◽  
Author(s):  
M. Shinozuka ◽  
A. M. Freudenthal
Keyword(s):  
Strain Energy ◽  
Energy Functions ◽  
Filled Elastomers ◽  
Strain Energy Functions
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