A finite element constitutive update scheme for anisotropic, viscoelastic solids exhibiting non-linearity of the Schapery type

Poon, Harrison; Ahmad, M. Fouad

doi:10.1002/(sici)1097-0207(19991230)46:12<2027::aid-nme575>3.0.co;2-5

Cited by 35 publications

(10 citation statements)

References 15 publications

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“…The final consideration in this material constitutive model is the format of the nonlinear coefficients. Poons & Ahmad [ 40 ] showed that, for material with Schapery-type nonlinearity, the nonlinear coefficients in 3D cases can be taken as

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Section: Materials Modelsmentioning

confidence: 99%

An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

Chen¹,

Ashcroft²,

Wildman³

et al. 2015

Proc. R. Soc. A.

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A method using experimental nanoindentation and inverse finite-element analysis (FEA) has been developed that enables the spatial variation of material constitutive properties to be accurately determined. The method was used to measure property variation in a three-dimensional printed (3DP) polymeric material. The accuracy of the method is dependent on the applicability of the constitutive model used in the inverse FEA, hence four potential material models: viscoelastic, viscoelastic–viscoplastic, nonlinear viscoelastic and nonlinear viscoelastic–viscoplastic were evaluated, with the latter enabling the best fit to experimental data. Significant changes in material properties were seen in the depth direction of the 3DP sample, which could be linked to the degree of cross-linking within the material, a feature inherent in a UV-cured layer-by-layer construction method. It is proposed that the method is a powerful tool in the analysis of manufacturing processes with potential spatial property variation that will also enable the accurate prediction of final manufactured part performance.

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…”

Section: Materials Modelsmentioning

confidence: 99%

An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

Chen¹,

Ashcroft²,

Wildman³

et al. 2015

Proc. R. Soc. A.

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“…Replacing the derivative by finite difference in equation (1), and using the backward Euler scheme, which is known for its stability, the following can be obtained 29 …”

Section: Seat-occupant Femmentioning

confidence: 99%

Development and verification of a multi-body dynamic model for seat-occupant system of manned spacecraft

Zanoosi

Mallakzadeh

Kalantarinejad

2014

Proceedings of the Institution of Mechanical Engineers, Part K:

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The main goal of this study is to develop a novel multi-body dynamic model for seat-occupant system of a manned spacecraft. The seat of a spacecraft and its components has significant effects on an astronaut’s body during flight mission, where sustained accelerations and impact loads are inevitable. Besides, conducting sustained acceleration and shock loads on the body of astronauts during flight missions is the key factor for health conservation. This study develops a new multi-body dynamic model for seat-occupant system of manned spacecraft to investigate the effects of spacecraft seat design. The astronaut is modelled as a four-jointed rigid link placed on a viscoelastic cushion. The cushion is modelled to present polyurethane foam, which is using in almost all automotive and aerospace applications. The equations of motion are derived and the effects of different parameters are investigated. To verify the developed model, a finite element model is presented to implement the same exact multi-body model. The results show that the presented analytical multi-body model is in good accordance with the finite element model. The effects of different parameters such as foam discretisation, foam thickness and geometry of seat frame on the motion of the system are illustrated. This novel model can be used in designing spacecraft seat to preserve an astronaut’s health. It also can be used in seat control applications and where computational efficiency is necessary.

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“…The Schapery model has been extensively applied to isotropic and anisotropic materials. Recently, numerical integration methods of the Schapery model and their implementations in finite element environment have caught much attention among researchers [13,14].…”

Section: ( ) J T δ -Simplified Multiple Integral Representationmentioning

confidence: 99%

Modeling of Nonlinear Viscoelastic Creep of Polycarbonate

2007

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Abstract:The creep behavior of a commercial grade polycarbonate was investigated in this study. 10 different constant stresses ranging from 8 MPa to 50 MPa were applied to the specimen, and the resultant creep strains were measured at room temperature. It was found that the creep could be modeled linearly below 15 MPa, and nonlinearly above 15 MPa. Different nonlinear viscoelastic models have been briefly reviewed and used to fit the test data. It is shown that the Findley model is a special case of the Schapery model, and both the Findley model and the simplified multiple integral representation are suitable for properly describing the creep behavior of the polycarbonate investigated in this paper; however, the Findley model fit the data better than the simplified multiple integral with three terms.

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A finite element constitutive update scheme for anisotropic, viscoelastic solids exhibiting non-linearity of the Schapery type

Cited by 35 publications

References 15 publications

An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

Development and verification of a multi-body dynamic model for seat-occupant system of manned spacecraft

Modeling of Nonlinear Viscoelastic Creep of Polycarbonate

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