Isight optimization of material parameters used in the abaqus worldwide. The viscosity is modeled by a prony series applied to all shear parameters. The other prony series parameters g i, i are identified as the optimization parameters. Time domain viscoelasticity abaqus analysis users manual v6. The focus is on the use of the hyperelastic and viscoelastic prony series representation in the abaqusstandard and abaqusexplicit simulation software. For simplicity, the constitutive parameters of the material were from the example in the abaqus example problem manual article 26,27. There is no restriction on the number of terms that can be used. Combining stress relaxation and rheometer test results in modeling a polyurethane stopper.
Effect of prony series parameters on fracture behavior of. Help modeling a viscoelastic material in abaqus imechanica. Since the dynamic properties of rubber are more or less nonlinear, it is not entirely appropri8. Highlights in this work we developed a new method for determination of the parameters of the prony series of rubber compounds. Abaqus performs a nonlinear least squares fit of the test data to determine the from finite ele meng101 at xian jiaotong university.
Determining a prony series for a viscoelastic material from time varying strain data abstract in this study a method of determining the coefficients in a prony series representation of a viscoelastic modulus from rate dependent data is presented. Finite element software abaqus has been used with time dependent prony series parameters. You can prepare a model, simulate it using onpremise or cloud resource, monitor during solution, perform dataextraction, and optimize with a. Defining parameters for concrete damage plasticity model. How does abaqus convert the frequency data to the prony series i am using abaqus for simulating viscoelastic materials. The parameters of the resulted spectra are often expressed in the form of a prony series. All answers 11 im not an expert in this field but if you want to use abaqus in time domain then you need 15 to 20 prony series in order to describe a mastercurve for e. Check the stability of the abaqus material model at extreme strains obtain the best possible material constants from the available test data. For the ve model, the intrinsic abaqus linear prony series method was employed. Prony series representation finite strain linear viscoelasticity relaxation and creep test data prony series data. Abaqus technology brief material model calibration using. You can use prony series, but as far as i remember, you are limited to 12 characteristic times.
A prony series expansion implemented in abaqus code, is used to express the materials behavior. Pdf implementation of generalized viscoelastic material model in. There is a mesh sensitivity problem when cracking failure in not distributed evenly. Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. In this paper, using the fourier transform of the time domain prony series, a nonlinear constrained least square problem based on prony series representations of storage and loss modulus, for the considered material, is analyzed. The parameters necessary to fully model the timedependent volumetric and shear. Quick guide to abaqus cae method of finite elements ii dr. Id like to model a viscoelastic material in prony series terms in abaqus 6. Determination of the parameters of the prony series in. The other prony series parameters gi, i are identified as the optimization parameters. It is also shown in abaqus user guide that anisotropic. Thus, a short prony series, which can accurately represent the material, is desirable. Implementation of abaquss viscoelasticity modeling in a cartilage tissue. The experimental data are fitted to a prony series using a userchosen number of terms represented by two coefficients.
Hello everybody, im using prony series to model viscoelasticity of an asphalt material in a pavement. Viscoelasticity is an important characteristic of gussasphalt mixtures. Set time prony to define a linear, isotropic, viscoelastic material by giving the parameters of the prony series representation of the relaxation moduli. Nothing is detailed in the documentation of abaqus. This phenomenon exists when there is no reinforcement in significant regions of the model.
The abaqus software is inherently complex, and the examplesand procedures in this manual are not intended to be exhaustive or to apply to any particular situation. This manual is a complete reference for all of the capabilities of both abaqusstandard and abaqusexplicit and contains a description of the elements, material models, procedures, input specifications, etc. How does abaqus convert the frequency data to the prony. Set time creep test data if the prony series parameters are to be computed by abaqus from data taken from shear and volumetric creep tests.
Damping characteristics of viscoelastic damping structure. The normalized shear stress relaxation modulus is often represented by a series expansion in exponential terms. Abaqus then uses the normalized shear modulus and normalized bulk modulus in a nonlinear leastsquares fit to determine the prony series parameters. A viscoelastic constitutive model can accurately represent entire creep indentation tests of human patella cartilage. Optimal discretetime prony series fitting method for. Beijing, china abstract drop test simulation plays an important role in investigating impact behaviors and identifying weak points of a cellular phone at design stage. Combining stress relaxation and rheometer test results in. An inverse method for determining the spatially resolved. Abaqus finite element mesh, undeformed top and deformed bottom for solid elastomers, a reasonable assumption can be made that there are no rate effects in the dilatational response. The master curves for each test were fit to the appropriate prony series and all coefficients are tabulated for reuse. Modeling and simulation of relaxation in viscoelastic open. Com have the following abaqus cel distortion book available for free pdf abaqus example problems manual, vol2 abaqus 6. Conversion tables, constants, and material properties. Viscoelastic massachusetts institute of technology.
The combination of the hyperelastic models with a viscoelastic equation can predict real mechanical behaviour of the rubbers. Impact analysis of a cellular phone 1wei liu, 2hongyi li beijing feaonline engineering co. Prony series, in time domain, are normally used to determine constitutive parameters for viscoelastic materials. Savvas triantafyllou institute of structural engineering, eth page 1 of 9 quick guide to abaqus cae. This study firstly derives the explicit prony series form of the shear relaxation modulus of viscoelastic material from laplace transformation. Lumbar spine component experimental test and model. I am trying to find prony series coefficeints using dma. Abaqus references for additional information on the abaqus capabilities referred to in this brief. The software described in this document is furnished under license and may be used or copied only in accordance with the terms of such license. A viscoelastic constitutive model can accurately represent. Abaqus performs a nonlinear least squares fit of the test. Prony series to model viscoelastic behaviour dassault. If only dynamic frequency data is available for a material then the prony series can be determined from the following implicit equations see the abaqus theory manual for a. The frequency dependence can also be obtained from a time domain prony series description of the dimensionless shear and bulk.
I have defined the material properties through timedomain prony series in abaqus. Time domain viscoelasticity abaqus analysis users guide 6. Abaqus can determine prony series parameters from creep or stress relaxation test data. If a relaxation time is associated with only one of the two moduli, leave the other one blank or enter a zero. Linear orthotropic viscoelasticity model for fiber. The prony series parameters were fitted by the optimization method. How to input maxwell parameters of a viscoelastic material. The response becomes asymptotic, showing that the maximum stress at time equal to 1,000 seconds decreases to nearly half of the maximum stress at the beginning of the solution, as expected. Isight optimization of material parameters used in the. The information in this document is subject to change without notice and should not be construed as a commitment by abaqus, inc. However, if you use only sine loads, so in frequency domain, the huetsayegh model is quite convenient see the viscoelastic program veroad. Plot used for manual fitting of creep prony coefficients 33 figure 44. For the vevp model, the prony series was combined with a.
In the discrete finite element model, each term in the prony series adds a substantial number of global variables. In abaqus, i create a material in terms of general density, mechanical\elasticity\elastic youngs modulus and poissons ratio and. Note that relaxation starts to occur at the beginning of the solution, and this model experiences a multiaxial state of. In this work, four material constitutive models were evaluated. If only dynamic frequency data is available for a material then the prony series can be detercjorgen s.
Set time frequency data if the prony series parameters are to be computed by abaqus from frequencydependent cyclic test data. The aim of this study is to find the correct viscoelastic material parameters of the novel gussasphalt applied in the 4th yangtze river bridge based on the modified burgers model. Determining a prony series for a viscoelastic material. Calculation of prony series parameters from dynamic. Pdf an accurate description of behavior of bituminous mixes is necessary to adequately predict. If you plan to input the prony series as a function of frequency it may be easier to fit the prony series to the complex modulus instead of the loss and storage separately. I am simulating a viscoelastic material with abaqus and need to implement prony parameters. The abaqus code was used in conjunction with a neldermead simplex optimization method. You can specify the prony series parameters directly for each term in the prony series. Abaqus will compute the terms in the prony series automatically from a given set of normalized shear creep compliance data, which can be derived by adding the instantaneous compliance. The material parameters of the first order mooneyrivlin viscous material law law17 in pamcrash used by snedeker et al. Viscoelastic models based on prony series are usually used due to easy implementation in finite element analysis codes.
The prony series parameters, and can be defined directly for each term in the prony series. The implementation follows the abaqus manual pretty closely, extensions and modifications concern cubic material symmetry. Abaqus assumes that the time domain viscoelasticity is defined by a prony series expansion. Impact analysis of a cellular phonewei liufeaonline. Alternatively, abaqus can calculate the terms in the prony series using timedependent creep test data, timedependent relaxation test data, or frequencydependent cyclic test data that you provide. Viscous materials, like water, resist shear flow and strain linearly with time when a stress is applied. The second paper suggests a method to id entify the material parameters of. Frequency domain viscoelasticity abaqus analysis users guide. Usage information is provided for both the keyword and the abaquscae interfaces. The numerical example shows the good agreement between the present results and those from analytical. Nonlinear regression methods can help with determining a short and accurate. In case of a large displacement analysis, remember to check the.
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