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| 2. |
- Ask, Anna, et al.
(författare)
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Electromechanics of polyurethane elastomers
- 2011
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Konferensbidrag (refereegranskat)abstract
- It is well known that electroactive polymers (EAP) deform under electric fields. An advantage of EAP is that it may undergo deformations much larger than those capable by electroactive ceramics, however at comparatively low forces. As common for polymers, EAP exhibit time-dependent material behavior, i.e. an electro-viscoelastic effect. In the modeling the deformation as well as the electric potential are introduced as global degrees of freedom, the internal variables accounting for the viscous response are incorporated at the so-called constitutive level. The proposed model is calibrated against experimental data, and a simple coupled finite element example is studied to show the applicability of the finite deformation electro-viscoelastic formulation proposed.
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| 4. |
- Ask, Anna, et al.
(författare)
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Inverse-motion-based form finding for quasi-incompressible finite electroelasticity
- 2013
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Ingår i: International Journal for Numerical Methods in Engineering. - : Wiley. - 1097-0207 .- 0029-5981. ; 94:6, s. 554-572
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Tidskriftsartikel (refereegranskat)abstract
- This work deals with inverse-motion-based form finding for electroelasticity. The inverse motion problem is formulated for the electroelastic case, and the resulting equations are implemented within a finite element framework. A four-field variational approach is adopted, taking into consideration the typically incompressible behavior of the elastomer materials commonly used in electromechanical applications. By means of numerical simulations, the inverse-motion-based form finding makes it possible to design the referential configuration so that a given set of loads and boundary conditions results in a prespecified deformed configuration. The computational finite element framework established in this work allows for such numerical simulations and testing and thereby the possibility to improve the design and accuracy in electroelastic applications such as grippers, sensors, and seals.
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| 8. |
- Bargmann, Swantje, 1980, et al.
(författare)
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On configurational forces within Green–Naghdi thermo-hyperelasticity
- 2008
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Ingår i: Solid Mechanics and its Applications. - Dordrecht : Springer Netherlands. - 1875-3507. - 9789048134465 ; 17, s. 203-214
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Konferensbidrag (refereegranskat)abstract
- The contribution's main objective is the examination of configurational forces in non-classical nonlinear thermoelasticity based on the approach of Green and Naghdi. In the early 1990s, Green and Naghdi introduced a theory attracting interest as heat propagates as thermal waves at finite speed, does not necessarily involve energy dissipation and fully integrates the classical theory. A wide range of heat flow problems can be modeled and the classical theory is fully embedded. As configurational forces have proven to be well suited for the examination of defect mechanics, a numerical example from that research area is discussed. The numerical realization is based on Galerkin finite elements in space as well as in time.
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| 9. |
- Berthelsen, Berthelsen, et al.
(författare)
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Efficient Simulation of Nonlinear Heat Transfer during Thermal Spraying of Complex Workpieces
- 2014
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Ingår i: World Journal of Mechanics. - : Scientific Research Publishing, Inc.. - 2160-049X .- 2160-0503. ; 4:9, s. 289-301
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Tidskriftsartikel (refereegranskat)abstract
- The quality of coatings, produced by thermal spraying processes, considerably decreases with the occurrence of higher residual stresses, which are especially pronounced for complex workpiece geometries. To understand the occurring effects and to aid in the planning of coating processes, simulations of the highly transient energy flux of the HVOF spray gun into the substrate are of great value. In this article, a software framework for the simulation of nonlinear heat transfer during (HVOF) thermal spraying is presented. One part of this framework employs an efficient GPU-based simulation algorithm to compute the time-dependent input boundary conditions for a spray gun that moves along a complex workpiece of arbitrary shape. The other part employs a finite-element model for a rigid heat conductor adhering to the computed boundary conditions. The model is derived from the fundamental equations of continuum thermodynamics where nonlinear temperature-depending heat conduction is assumed.
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| 10. |
- Berthelsen, Rolf, et al.
(författare)
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Computational homogenisation for thermoviscoplasticity : application to thermally sprayed coatings
- 2017
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Ingår i: Computational Mechanics. - : Springer Science and Business Media LLC. - 0178-7675 .- 1432-0924. ; 60:5, s. 739-766
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Tidskriftsartikel (refereegranskat)abstract
- Metal forming processes require wear-resistant tool surfaces in order to ensure a long life cycle of the expensive tools together with a constant high quality of the produced components. Thermal spraying is a relatively widely applied coating technique for the deposit of wear protection coatings. During these coating processes, heterogeneous coatings are deployed at high temperatures followed by quenching where residual stresses occur which strongly influence the performance of the coated tools. The objective of this article is to discuss and apply a thermo-mechanically coupled simulation framework which captures the heterogeneity of the deposited coating material. Therefore, a two-scale finite element framework for the solution of nonlinear thermo-mechanically coupled problems is elaborated and applied to the simulation of thermoviscoplastic material behaviour including nonlinear thermal softening in a geometrically linearised setting. The finite element framework and material model is demonstrated by means of numerical examples.
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