Rivet forming using adaptive meshing

Rivets are a type of fastener used to create permanent attachment between two sheets of material. A rivet typically consists of a cylindrical body with a head on one end. It is inserted through a hole in the sheets of material and other end is compressed such as to expand the diameter, pinching the sheets. The traditional Lagrangian formulation fails to give satisfactory solution as mesh becomes distorted extensively near the corner and contact interaction cannot be treated correctly. Therefore ALE adaptive meshing is used to make sure a a high-quality mesh is maintained throughout the analysis. ALE adaptive meshing technique smooths the mesh by re-positioning nodes.

This is a challenging problems as it involves multiple nonlinearities: material nonlinearity, geometric nonlinearity and contact between multiple components. As the geometries and loads are axisymmetric, the rivet forming problem will be analyzed using an axisymmetric model. The analysis is performed using explicit solver.

Note: This exercise is part of the Solving Non-linear Problems with Abaqus course.

The traditional Lagrangian formulation fails to give satisfactory solution as mesh becomes distorted extensively near the corner and contact interaction cannot be treated correctly.

When the ALE adaptive meshing is used, it maintains reasonable element shapes and aspect ratios.  The figure shows the refinement of mesh as deformation takes place at different time increments.

As the punch moves upward, material undergoes high plastic strains. The figure shows the distribution of equivalent plastic strain at the end of the step.

The contour plot shows the distribution of logarithmic strain at the end of forming process.

The following animation shows the evolution of logarithmic strain and equivalent plastic strain as the rivet is deformed.

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