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In impact simulations, the instantaneous change of velocity in the contact area can lead to artificial oscillations. These oscillations might significantly influence the results, especially when nonlinear and rate dependent constitutive formulations are used.
In this work, a nonlinear penalty formulation similar to a soft contact formulation is presented.
In this work an approach for smoothing the oscillations of normal contact is presented. On the other side a higher order time discretization scheme in association with a higher order spatial discretization, like the spectral element method, is used. The contact constraints are reformulated in order to get an explicit equation for the motion.
In this work an approach for smoothing the oscillations of normal impact is presented. In addition, a higher order time discretization scheme in association with a higher order spatial discretization, like the spectral element method, is investigated regarding its convergence rates.
Coupling of an isogeometric surface and bulk finite element discretization for contact problems
(2018)
The finite element (FE) framework is a standard tool for the simulation of mechanical problems providing advantages like automated meshing algorithms and effcient quadrature rules. However, for contact problems, the FE discretization is - due to the C0 continuity at element intersections - characterized by a non-smooth normal feld.
Conversely, isogeometric discretizations provide a smooth normal feld also at interelement borders and were recently applied to contact mechanical problems using the mortar method. The application of isogeometric analysis for complex volumetric problems has not reached the same level of automation as the FE-framework, i.e. due to the intricate mesh generation.
This work aims at combining the advantages of both discretization procedures by coupling an isogeometric contact surface with a bulk FE-discretization. The isogeometric contact interface is represented by a NURBS surface, which is tied to the FE mesh. For the discretization of the bulk parts, higher order spectral elements are used. The contact problem is discretized with the mortar method and a penalty approach is used to enforce the contact constraints. Two different types of coupling of the NURBS surface and the bulk part are considered: mortar and pointwise mesh tying. The mortar mesh tying approach shows accurate results, whereas the pointwise tying leads to large oscillations in the contact stresses. Element-based quadrature is applied for mortar tying, as well as for mortar contact discretizations. Using an isogeometric layer, the related quadrature error can be effciently reduced by a higher degree interpolation or increased integration order.
Coupling of an isogeometric surface and bulk finite element discretization for contact problems
(2018)
This work aims at combining the advantages of both discretization procedures (IGA and FEM) by coupling an isogeometric contact surface with a bulk FE-discretization. The isogeometric contact interface is represented by a NURBS surface, which is tied to the FE mesh. For the discretization of the bulk parts, higher order spectral elements are used. The contact problem is discretized with the mortar method and a penalty approach is used to enforce the contact constraints. Two different types of coupling of the NURBS surface and the bulk part are considered: mortar and pointwise mesh tying. The mortar mesh tying approach shows accurate results, whereas the pointwise tying leads to large oscillations in the contact stresses. Element-based quadrature is applied for mortar tying, as well as for mortar contact discretizations. Using an isogeometric layer, the related quadrature error can be efficiently reduced by a higher degree interpolation or increased integration order.