ULiege - Aerospace & Mechanical Engineering http://metafor.ltas.ulg.ac.be/dokuwiki/ 2026-05-25T02:45:28+00:00 http://metafor.ltas.ulg.ac.be/dokuwiki/ http://metafor.ltas.ulg.ac.be/dokuwiki/_media/logo.png text/html 2016-03-30T13:23:04+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/def?rev=1459344184&do=diff Defining contact elements Defining contact element is done is the same way as volume elements. First, a contact material is defined (without friction, sticking, ...), then the material is included in an ElementProperties (Contact2DElement ou Contact3DElement text/html 2017-06-21T08:07:30+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/elements?rev=1498032450&do=diff Contact elements Contact[2|3]DElement For rigid-defo contact: Contact[2|3]DElement defines contact between a rigid entity under a given displacement (unmeshed geometric entity) and a meshed geometric entity which is part of the surface of the mesh. This element is therefore a one node element, called the slave, having 2/3 dofs in 2/3D. text/html 2025-04-09T08:57:17+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/interactions?rev=1744189037&do=diff Contact Interactions Contact elements are generated on the mesh using Interactions described below, in the same way as volume elements. Rigid-Defo contact Interaction between a rigid body (die), meshed or not, and a deformable meshed entity. ci = RdContactInteraction(number) ci.setTool(gObject1) ci.push(gObject2) ci.setSmoothNormals(bool) ci.addProperty(prp) interactionset.add(ci) text/html 2016-03-30T13:23:04+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/lag_aug?rev=1459344184&do=diff Augmented Lagrangian Method The Augmented Lagrangian method is used to iterate several times over a single time step, to correct contact forces (augmentation) to get a gap $g$ smaller than a given tolerance (defined by the parameters PRECONNORMALGAP and $i$$$ F = L_i + k_N\,g $$$k_N$$L_i$$$ L_{i+1} = L_i + k_N\,g $$ text/html 2025-04-29T13:37:11+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/laws?rev=1745933831&do=diff Contact materials Description For all contact materials, a penalty along the normal direction and a depth at which contact is detected are required. Contact can be: * positively unilateral (UNILATERAL_POSITIF), contact for $\mbox{gap} \geq 0$ (by default) * negatively unilateral ($\mbox{gap} \leq 0$$\mbox{gap} \geq 0$$\mbox{gap}\leq 0$$m\,\sigma_0\,/\sqrt{3}$$\sigma_0$$q_{N}$$$q_{N} = h_c \left(p_{N} \right) \left(T^{S} - T^{M}\left(\bf{\xi}^{S}\right)\right), $$$p_{N}$$T^{S}$$T^{M}\left… text/html 2016-03-30T13:23:04+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/rigid_matrices?rev=1459344184&do=diff Rigid matrices Defining rigid matrices In Metafor, any geometric entity can be defined as rigid Contact Matrices. No additional definition is required. However, the orientation of the entity is relevant. It defines the area considered as the die, where a penetrating node will experience a contact force. By convention, the normal vector is pointing inside the die.$\boldsymbol{n}$$\boldsymbol{t} \wedge \boldsymbol{n} = (0,0,1)$ text/html 2016-03-30T13:23:04+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/start?rev=1459344184&do=diff General Points Contact using penalty method text/html 2021-09-24T13:35:33+00:00 Anonymous (anonymous@undisclosed.example.com) http://metafor.ltas.ulg.ac.be/dokuwiki/doc/user/elements/contact/stationnaryrotatingtool?rev=1632490533&do=diff Stationary Rotating Tool A stationary rotating tool is a rigid contact tool that rotate around a given axis but with a geometry fixed in space. It is usefull, for example, to make models of rolling process where cylinders are deformed by the contact between the sheet and the rolls. As the process is quasi stationary, the deformation of the roll stay fixed in space, but it is the friction on the rotating roll that make the sheet moving forward.