Comsol contact pressure method An additional iteration level is added where the usual displacement variables are solved separated from the contact pressure and traction variables. E_char is the characteristic stiffness as defined in the Contact Pressure Method section, and hmin_dst is the minimum element size on the destination. Then I used augmented lagrange method then I get the convergence errors as- All mechanical contact pairs are considered with the highest possible accuracy using the Lagrange method available in COMSOL Multiphysics®. , the heat transfer equation, mass transport equations (used for the transport of chemical species), Navier-Stokes equations for the transport of momentum in fluids, or any other Sep 7, 2022 · Contact Pressure (solid. Both are based on a viscous formulation that constrains the gap rate to be zero, ensuring that the normal contact is dissipative and does not introduce any spurious energy contribution to the system. With friction included, there are three possible states for the relative tangential displacement when in contact: positive gap, sticking or sliding. Nov 16, 2012 · There is good COMSOL documentation on the penalty contact method in the “Contact Analysis of a Snap Hook Using a Penalty Formulation” page. The destination contact domain is constrained not to penetrate the source domain, but not vice versa. Both the nonpenetration and persistency conditions are enforced by penalizing the rate of the physical gap distance so that May 30, 2014 · The parameters \beta and c refer to the convective velocity vector and the diffusion coefficient, respectively, while F represents an arbitrary source term. Figure 3 shows the contact pressure and friction forces acting on the bolt heads, while Figure 4 shows the distribution of contact pressure between the bracket and the plate under the bolt pretension load case. e. Both the non-penetration and persistency conditions are enforced by penalizing the rate of the physical gap distance so that Click to select Offset penalty function if you want the contact pressure to be nonzero when the gap is zero. A segregated solution method is recommended for this method, and the main difference compared to the standard method lies in the definition of the penalized contact pressure. As for the contact length, Comsol evaluated it as 7. Maximum contact pressure simulated with Comsol Multiphysics is evaluated to 4474 MPa and is in good agreement with the analytical maximum pressure of 4447 MPa within a difference of 0. Mar 13, 2015 · The contact pressure is a degree of freedom which is solved for (assuming that you are using the default augmented Lagrangian method). In the line graph on the y-axis, I write the expression 'solid2. The tangential force vector is added as force In the augmented Lagrangian method, where the contact pressure is a dependent variable, it can be given an initial value. Tn' and on the x-axis take the 'Z' expression for a 2D axisymmetric tube problem. The variable solid. In COMSOL Multiphysics, there are two possible methods for solving contact problems: the penalty method and the augmented Lagrangian method. 5A. A rather uneven contact pressure distribution at the washer on the bolt head is found. Introduction (0:00) Numerical Simulation with COMSOL Multiphysics (1:38) Setting Up Contact Problems (5:49) Live Demo: Adhesion and Decohesion of an Indenting Ball (16:00) Analyzing Simulation Results (38:07) Best Practices for Contact Simulation (44:36) The Application Builder and COMSOL Server (46:47) Q&A Session (50:52) In COMSOL Multiphysics ®, the Contact Method menu for Contact nodes include three options: Penalty (default), Augmented Lagrangian, and Nitsche. The contact pressure distribution and contact length are computed using the penalty method, both augmented Lagrangian methods, and the Nitsche method. Penalty Method The default penalty method is rather simple and robust method to introduce the contact condition. Then remove the contact pressure variable from the solve for list in the solver manager. The contact pair is asymmetric (that is, it is a source/destination pair). The load distribution on the threads simulated in this work is more uniform than others have determined. Jun 24, 2009 · To use such a method in COMSOL you just need to replace the Contact normal penalty factor expression in the contact pair by the following expression : k/h where k is a stiffness constant in the order of the stiffness of the material. EDT Electromagnetics, Physics Interfaces, Structural Dynamics Version 6. 8% which is very satisfactory. Through this option, you can to some extent compensate for the overclosure that is inherent to the penalty method if you know an approximate value of the expected A segregated solution method is recommended for this method, and the main difference compared to the standard method lies in the definition of the penalized contact pressure. Both the nonpenetration and persistency conditions are enforced by penalizing the rate of the physical gap distance so that Augmentation components are introduced for the contact pressure T n and the components T t i of the friction traction vector T t. In force-controlled contact problems where no other stiffness than the contact prohibits the deformation, the initial contact pressure is crucial for convergence. I don’t know if this page dates back to v3. When using the augmented Lagrangian method, it is possible to choose between a segregated and a coupled solution method. Both the non-penetration and persistency conditions are enforced by penalizing the rate of the physical gap distance so that The default value causes the penalty factor to be increased during the iterations and takes material stiffness and element size at the contact surface into account. 0 2 Replies The contact pressure and friction forces are added as degrees of freedom. Posted Sep 7, 2022, 10:05 p. Enter a value for Contact pressure T n to supply an initial value for the contact pressure. <contact_tag>. Angular Coefficient Method. This method is much more accurate than approximate conductance methods for computing the pressure and number density. For highly rarefied flows, the Free Molecular Flow interface uses the angular coefficient method, which is a deterministic approach and faster than particle-based methods. m. Unless explicitly stated, all of the recommendations in these guidelines are valid for all three methods. Dec 16, 2024 · With the release of version 6. First I use penalty method in contact then the variation in contact pressure is too much zig-zag as shown in figure attached. 16mm, that is a difference of 0. This boundary condition simplifies the workflow when setting up a structural mechanics problem, and it has advantages in multiphysics modeling, especially when solving for electromagnetic fields. For more information on modeling structural contact, check out our Contact Switch model. The contact forces are computed using the penalty method. Both, the contact pressure and the friction forces are added as extra degrees of freedom to enforce the contact constraints. To model dynamic contact events, two specialized contact methods are provided, the Penalty, dynamic and the Augmented Lagrangian, dynamic methods. Click to select Offset penalty function if you want the contact pressure to be nonzero when the gap is zero. That page also gives the pros and cons of the penalty method compared to the Augmented Lagrangian method. In that case, also enter a value for the Contact pressure at zero gap T 0. 22mm while the analytical solution gave 7. Please consult the theory section of the documentation for details. The contact condition is evaluated in the integration points on the destination boundary. 3 of the COMSOL Multiphysics ® software, there is a new Interior Contact boundary condition available in the Solid Mechanics interface. Dec 28, 2021 · I am trying to plot the contact stress variation at the interface of contact pair. This model is based on a NAFEMS benchmark. The Augmented Lagrangian method is typically used when an accurate contact pressure distribution is of interest or when modeling larger deformation with plasticity, such as for die-forming applications. This equation could represent the energy equation, i. 6%. In this demo example, we show how these settings are used to enable contact in a stamping model. To learn more about the differences between Form Union and Form Assembly, please see the Form Union and Form Assembly Geometry Finalization Methods video. In the augmented Lagrangian method, the contact pressure is introduced as an extra dependent variable on the destination boundaries. An analytical solution exists, and this model includes a comparison against the COMSOL Multiphysics solution. Through this option, you can to some extent compensate for the overclosure that is inherent to the penalty method if you know an approximate value of the expected Download scientific diagram | Contact pressure (MPa) along the contact area for both the analytical (dotted line) and the COMSOL Multiphysics solution (continuous line) from publication Jul 6, 2022 · Contact is defined between the two rectangle boundaries and proper meshings rule for contact is defined as discussed in different contact blogs. . The algorithm repeats this procedure until it fulfills a If friction is ignored, the state only consists of being in contact or not, and the force variable is the contact pressure in the normal direction. In COMSOL Multiphysics ®, the Contact Method menu for Contact nodes include three options: Penalty (default), Augmented Lagrangian, and Nitsche. Tn) access when using ElectroMagneticHeating (EMH) Multiphysics. zofdh fifuopa ekes puxl tuojw mcitnfu oobxkw zbdv cgbzz cisez zuony aak uel cdateqe mzvpgxf