Abstract:This contribution is concerned with the embedding of constitutive relations for magneto-active polymers (MAP) into finite element simulations. To this end, a recently suggested, calibrated, and validated material model for magneto-mechanically coupled and rate-dependent MAP response is briefly summarized in its continuous and algorithmic settings. Moreover, the strongly coupled field equations of finite deformation magneto-mechanics are reviewed. For the purpose of numerical simulation, a finite element model … Show more
“…By appropriately considering the micromechanical constitution of magnetoelastic polymers, formulations for coupled field equations using homogenisation techniques have been proposed by Castañeda and Galipeau (2011);Galipeau and Castañeda (2013) and Chatzigeorgiou et al (2014), among others. Phenomenon of energydissipation due to viscoelasticity has been modelled by Saxena et al (2013), Ethiraj and Miehe (2016), and Haldar et al (2016); and anisotropic structure of magnetoelastic polymers has been accounted in the models by Bustamante (2010), Danas et al (2012a), and Saxena et al (2014). However, in this work, we restrict our attention to isotropic and conservative magnetoelastic systems.…”
One common phenomenon native to inflation of membranes is the elastic limit-point instability-a bifurcation point at which the membrane begins to deform enormously at the slightest increase of pressure. In the case of magnetoelastic materials, there is another possible phenomenon which we call magnetic limitpoint instability, a state referring to the non-existence of an equilibrium state -either stable or unstable. In this work, we are concerned with such instabilities in an incompressible isotropic magnetoelastic toroidal membrane with an initial circular cross-section. A non-uniform magnetic field is generated using a circular current carrying loop placed inside the membrane in addition to inflation by a uniform hydrostatic pressure. An energy formulation based on magnetization is used to model the magneto-mechanical coupling along with a Mooney-Rivlin constitutive model for the elastic strain energy density. Computations show that the magnetic field strongly influences the location of elastic limit points and in some cases can cause them to vanish. Multiple equilibrium states are obtained as solutions of the governing equations and a criterion based on second variation is employed to determine their stability. Existence and dependence of magnetic limit point on the magnetic field is demonstrated. While the quantitative results obtained here are specific to the toroidal geometry, the deformation behaviour can be generalised to any magnetoelastic membrane.
“…By appropriately considering the micromechanical constitution of magnetoelastic polymers, formulations for coupled field equations using homogenisation techniques have been proposed by Castañeda and Galipeau (2011);Galipeau and Castañeda (2013) and Chatzigeorgiou et al (2014), among others. Phenomenon of energydissipation due to viscoelasticity has been modelled by Saxena et al (2013), Ethiraj and Miehe (2016), and Haldar et al (2016); and anisotropic structure of magnetoelastic polymers has been accounted in the models by Bustamante (2010), Danas et al (2012a), and Saxena et al (2014). However, in this work, we restrict our attention to isotropic and conservative magnetoelastic systems.…”
One common phenomenon native to inflation of membranes is the elastic limit-point instability-a bifurcation point at which the membrane begins to deform enormously at the slightest increase of pressure. In the case of magnetoelastic materials, there is another possible phenomenon which we call magnetic limitpoint instability, a state referring to the non-existence of an equilibrium state -either stable or unstable. In this work, we are concerned with such instabilities in an incompressible isotropic magnetoelastic toroidal membrane with an initial circular cross-section. A non-uniform magnetic field is generated using a circular current carrying loop placed inside the membrane in addition to inflation by a uniform hydrostatic pressure. An energy formulation based on magnetization is used to model the magneto-mechanical coupling along with a Mooney-Rivlin constitutive model for the elastic strain energy density. Computations show that the magnetic field strongly influences the location of elastic limit points and in some cases can cause them to vanish. Multiple equilibrium states are obtained as solutions of the governing equations and a criterion based on second variation is employed to determine their stability. Existence and dependence of magnetic limit point on the magnetic field is demonstrated. While the quantitative results obtained here are specific to the toroidal geometry, the deformation behaviour can be generalised to any magnetoelastic membrane.
“…To work with the governing equations (29) and (28) in the presence of an azimuthal magnetic field, the non-zero components of the magnetoelastic tensors are A 0iiii , A 0iijj , A 0ijij , A 0ijji , C 0ii2 , C 0i2i , K 0ii for i, j ∈ {1, 2, 3} and i = j. Explicit formulas for these components for the Mooney-Rivlin magnetoelastic material are given in the Appendix.…”
Section: Numerical Resultsmentioning
confidence: 99%
“…Since both EAPs and MREs are polymer based composites, the deformation process is usually dissipative. The effect of the magnetic field on the viscoelasticity has been studied by Bellan and Bossis [24], the effect on the Mullin’s effect studied by Coquelle and Bossis [25], magneto-viscoelasticity of isotropic and anisotropic MREs was studied by Saxena et al [26, 27] and Haldar et al [28] and a micromechanical approach to study magneto-viscoelasticity has been undertaken by Ethiraj and Miehe [29]. A similar case of dissipation in the electro-viscoelastic case has been studied by Ask et al [30], Saxena et al [31] and Denzer and Menzel [32].…”
A thick-walled circular cylindrical tube made of an incompressible magnetoelastic material is subjected to a finite static deformation in the presence of an internal pressure, an axial stretch, and an azimuthal or an axial magnetic field. The dependence of the static magnetoelastic deformation on the intensity of the applied magnetic field is analysed for two different magnetoelastic energy density functions. Then, superimposed on this static configuration, incremental axisymmetric motions of the tube and their dependence on the applied magnetic field and deformation parameters are studied. In particular, we show that magnetoelastic coupled waves exist only for particle motions in the azimuthal direction. For particle motion in radial and axial directions, only purely mechanical waves are able to propagate when magnetic field is absent. The wave speeds as well as the stability of the tube can be controlled by changing the internal pressure, axial stretch, and applied magnetic field that demonstrates the applicability of magneto-elastomers as wave guides and vibration absorbers.
“…Several advanced techniques have been proposed to model additional features of the particle-filled magnetoelastic smart elastomers. For example, Castañeda and Galipeau (2011); Castaneda and Siboni (2012) and Chatzigeorgiou et al (2014) formulated the field equations by coupling magneto-mechanical phenomena at the microscopic level and the use of homogenization; Saxena et al (2013); Ethiraj and Miehe (2016) and Haldar et al (2016) modelled the energy dissipation due to coupled polymer magneto-viscoelasticity; Bustamante (2010); Danas et al (2012) and Saxena et al (2014Saxena et al ( , 2015 modelled the inherent anisotropy and resulting changes in the magneto-mechanical response of these polymers. Several of the above-mentioned models have been useful in computational analysis of instabilities in magnetoelastic bulk media reported by Otténio et al (2008); Kankanala and Triantafyllidis (2008); Rudykh and Bertoldi (2013); Danas and Triantafyllidis (2014); Saxena (2017), and Goshkoderia and Rudykh (2017).…”
We study the inflation of a weakly magnetizable isotropic incompressible circular membrane in the presence of magnetic field generated by a magnetic dipole. Following the approach in recent papers by (
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