How to use comsol multiphysics to fit your experimental data to hyperelastic material models. Mooneyrivlin constants are generated using a curvefitting routine and are based on raw stressstrain data from lab tests. In previous articles, we have introduced arrudaboyce, neohookean, mooneyrivlin, yeoh, gent, blatzko and other hyperelastic models that often used in nonlinear finite element analysis. I have looked into software called hyperfit that appears to do everything i need, however its relatively expensive and the license is only available for a limited time. Hyperelastic material an overview sciencedirect topics. Curve fitting parameter estimation of two parameters that define a nonlinear mooneyrivlin material model in solid mechanics to measured data. Hyperfit software for calibration of hyperelastic material models. Since the applied load is equal for both axes, the stress on each axis is defined as. Constitutive modelling mooneyrivlin model in assessing the mooneyrivlin model constants, equation 4 has been employed in this parametric study with the variation in c 1 and c2 value. The analysis involved large deflections, nonlinear contact, and hyperelastic strains greater that 250%. Fitting measured data to different hyperelastic material. We can now solve the above problem and estimate material parameters by fitting our uniaxial tension test data against the uniaxial neohookean material model. I looked at my hyperelastic data to see what behaviour the material shows at this critical strain of approximately 25%. An online curvefitting solution making it easy to quickly perform a curve fit using various fit methods, make predictions, export results to excel,pdf,word and powerpoint, perform a custom fit through a user defined equation and share results online.
They are merely curvefits of various polynomials to test data. Predicting the dynamic material constants of mooneyrivlin. I plan to perform simple shear test on the rubber and my questions. The mooneyrivlin material properties are listed below. My mesh settings are also all default adaptive and i indeed have a thin structure. As a special case of the polynomial model, a three parameter mooneyrivlin model may be. If it is a rivlinsaunderstype model in ansys it is called mooneyrivlin type and assuming incompressibility, you will arrive at a linear leastsquare problem for uniaxial tensile tests. A versatile model that can be used for rubber, polymer, and biological tissues. Because higherorder mooneyrivlin has many parameters, the parameters are relatively difficult to obtain from the manual or literature, which needs curve fitting of experimental data.
Since one or more experimental stressstrain curves are used for the calibration, the. During the curvefitting state, a oneelement test is carried out in fea softwares like abaqus and ansys. Hyperelastic material curve fitting ansys student community. The software allows you to determine the parameters of hyperelastic constitutive models. However, despite supporting higher order constitutive. As a special case of the polynomial model, a three parameter mooneyrivlin model may be fitted, too. Elastomer rubber fea finite element analysis finite. For detailed instructions on setting up the global leastsquares objective branch, take a look at the mooney rivlin curve fit tutorial, available in our application gallery. Mooneyrivlin model an overview sciencedirect topics. There are a number of material curve fitting routines that are commercially available for performing this function. This presentation shows how to use the optimization module to fit a material model curve to experimental data. Fitting measured data to different hyperelastic material models. The mooneyrivin constants are automatically computed when the use curve data to compute material constants option in the material dialog box is selected. Mooneyrivlin curve fit software di simulazione comsol.
The comparison showed that the lower order yeoh and polynomial model parameters from the scilab scripts and the commercial fea software match perfectly. To specify the complete hyperelastic material model it is necessary to first select a constitutive model, and then find the material parameters by calibrating the material parameters to experimental data. Material parameters can be identified from your experimental data. Fitting hyperelastic models to experimental data r. It is based on the hyperelastic mooneyrivlin material model example given in the structural mechanics users guide. Not suitable for the deformation that exceeds 150%. An animation of onequarter of the seal while the pressure is ramped up is shown in figure 2 pipe walls removed for clairity. Hi everybody,i want to simulate a hyperelastic material named ptfe to obtain contact pressure via simulation. The material model does not differentiate between a 1st time strain and a 100th time straining of the part under analysis. Question for curve fitting of mooney rivlin in nx cae. Click the curve fit button on the element material specification dialog to use the curve fitting routine. Its important to understand that mooneyrivlin models do not give any special insight into material behavior. Mooneyrivlin model is a special form of polynomial model.
The process flow of this parametric study was illustrated in figure 1. Keep in mind that no solution will fit the test data exactly. The curve fit is used to determine the constants for the mathematical material model by performing a bestfit calculation of the usersupplied stressstrain data for the material. When n 1, the polynomial model is reduced to 2parameter mooneyrivlin. This routine calculates the material constants using measured stressstrain data. Ogden hyperelastic model for nonlinear finite element. Meanwhile an answer for the questions regarding the material data fitting.
Mooneyrivlin material properties simulation mechanical. With software tools, it is possible to study many prototypes rapidly, accelerating the understanding of the. Why does the tabulated data plot not match the input data set. Curve fitting is the process of constructing a curve, or mathematical function, that has the best fit to a series of data points, possibly subject to constraints. So i want to use neohookean model but i cant find the definition in solidworks. Most commercial fea software packages use a curvefitting procedure to generate the material constants for the selected material model. Hyperelastic simulation settings ansys student community. Mooneyrivlin models are popular for modeling the large strain nonlinear behavior of incompressible materials, i. The software ansys offers a curve fitting module for hyperelastic material models. Click the curve fit button on the element material specification dialog to use the curve fitting. The material property input dialog box for the hyperelastic and foam material models include a curve fit routine.
I have a question for curve fitting of mooney rivlin in nx cae, how to perform curve fitting of mooney rivlin model in nx cae, if i only have test data. As far i know, i need to do do curve fitting on stress strain data to obtain the material constant. Hyperelastic material model in explicit dynamics cfd. The input to the curvefitting procedure is the stressstrain or stressstretch data from the following physical tests. Screenshot of curve fitting setup top and samples of uniaxial. A chemical solution is pumped through a catalytic reactor where a solute species reacts in contact with the catalyst surface. Advanses offers a complete range of finite element analysis fea consulting services for polymers and elastomers. The mooneyrivlin material model is a hyperelastic material model and is available for 2d, brick, tetrahedral, membrane, and shell elements. I suggest that you keep every 3rd data point in your stressstrain curve and eliminate the rest of the data.
Mooneyrivlin coeffcients for silicon rubber solidworks. Now we will be discussing a special and widely applied hyperelastic model. If i use the neohookean model i can calculate the constants needed, but for the case of mooneyrivlin its not that straightforward because i need to know some experimental data that i dont have. For detailed instructions on setting up the global leastsquares objective branch, take a look at the mooneyrivlin curve fit tutorial, available in our application gallery. I see that there is a curve starting around that strain percentage. Because your stressstrain curve has 293 points, the tabular data only shows the first. The stress strain functions in the model are stable. Material testing and hyperelastic material model curve. I have noticed after doing the curve fit the software shows a plot of tabulated and fitted curve. I have been working on a model of a polymer using experimental uniaxial data and curve fitting to a mooney rivlin model. Curve fitting can involve either interpolation, where an exact fit to the data is required, or smoothing, in which a smooth function is constructed that approximately fits the data. The source code can be downloaded from so that programmers can edit the drivers for their own needs or compile individual subroutines. Simfit is a completetly free, opensource package, distributed as 32bit or 64bit binaries. Yet when i extract data from the equibiaxial region of my planar biaxial simulation, ansys estimates stresses not in line with the curve i used to generate the coefficients.
Ansys seems to curve fit biaxial stressstrain data very well up to 90% and calculate representative coefficients for the mooney rivlin model. Computation from test data of the hyperelastic material coefficients. Elastomer rubber fea finite element analysis material constants for mooneyrivlin, ogden, and viscoelastic prony series. Hi i have engineering loaddisplacement curve from experimental data of a foam structure. Mooney rivlin plot hi everyone, i am trying to do a curve fit to a set of stress stain data. Cristopherson and jazar 2006 used mooneyrivlin model in fe modeling of a passive hydraulic engine mount and determined the mooneyrivlin constants by curve fitting on uniaxial experimental stressstrain data. The mooney rivlin model obtained by fitting tensile data is quite inadequate in other modes of deformation, especially compression. Biaxial mooneyrivlin coefficient of silicone sheet by.
Mooneyrivlin hyperelastic model for nonlinear finite. Plots, curvefitting, and data modeling in microsoft excel this handout offers some tips on making nice plots of data collected in your lab experiments, as well as instruction on how to use the builtin curvefitting routines in microsoft excel. Simfit is a computer package for simulation, statistical analysis, curve fitting and graph plotting, using models from a compiled library or from ascii text files supplied by the user. The material constants on the material dialog are not updated until you finish the curve fitting. Hyperelastic seal simulation with ansys mechanical fea. In addition to these properties, it may be necessary to define some isotropic material properties. Mooney rivlin and prony shear response material model. Sgura abstract this paper is concerned with determining material parameters in incompressible isotropic elastic strainenergy functions on the basis of a nonlinear least squares optimization method. The constants are saved in a text file with the extension. The curve fitting algorithms presented in this study allow fitting of compressiontension and simple shear test data to any order ogden models, any order yeoh models and second as well as first order polynomial models. Material testing and hyperelastic material model curve fitting scilab. Mooneyrivlin polynomial ogden arrudaboyce gent yeoh ogden foam blatzko anisotropic. Excel is a good utility program for data recording and plotting, and is actually used a lot by. Can i use the stress strain data from simple shear test to perform curve fitting for mooney rivlin material model 3 parameters.
1470 354 761 1139 1427 1414 52 993 24 23 1237 1001 78 288 450 467 286 778 1617 969 403 577 300 248 1383 23 891 1498 1573 987 101 628 825 829 1324 979 694 1258 1231 765 750 457 494 1430 779 715 1039 636