The CAD geometry was uploaded as a STEP file consisting of 4 solid bodies
A mesh type:‘Tetrahedralization with Refinements’ was selected and mesh refinement was done at the rope-carabiner frictionless contact zones.
Plastic material behavior was considered for this model.
Source: Mechanical Behavior of Precipitation Hardened Aluminum Alloys Welds (R.R. Ambriz and D. Jaramillo)
The simulation was run as a Solid Mechanics Dynamic Analysis using Code Aster. The 3 boundary conditions are as follows:the bottom rope was fixed in all directions, the top rope was displaced in the x- and y- direction along the strong axis of the carabiner, and a plane contraint was imposed to prevent movement in the z-direction.
Augmented Lagrange contact was used for the frictionless contacts between the ropes and carabiner. Contact smoothing was used to improve the solution results.
A bonded contact was enforced between the faces of the carabiner and lock to prevent separation.
The yield strength of aluminum is 276 MPa. Based on the graph below, the maximum vonMises stresses in the carabiner exceed the yield strength starting at .2 seconds. Since the top rope dispacement was implemented as a function of time, .2 seconds corresponds to a .42 mm tensile displacement in the direction of the strong axis of the carabiner
vonMises stress: .42 mm displacement
vonMises stress: 1.05 mm displacement