Week 5 Sphere pressing on a plate

CHALLENGE: Analysis is to be carried out to simulate a sphere pressing on a plate and experiencing plastic deformation on the plate

OBJECTIVE: To perform the analysis to simulate a sphere pressing on a plate. Use Structural stel for both sphere and plate but the material of the plate must be Non Linear. Press the sphere onto plate 4mm downwards and retract it. Capture the plastic deformation of the plate.

Materials Used:

Contacts: The default contact regions are deleted and a new contact pair is defined between the sphere and plate. Sphere is the contact body and the Plate is the target body. The defined contact is Frictional. Since impact is involved, the coefficient of friction of 0.74 is obtained by referring to the Roymech Tribology table. The Behavior of contact pair and Formulation are defined as PROGRAM CONTROLLED.

Symmetry Regions: Since this is a symmetric geometry and the loads applied are equally distributed along all faces, we can simplify our design and use only a quarter portion of the geometry. To calculate the complete effect, symmetric regions are then defined along the respective axes.

Meshing: I have adopted an overall mesh sizing of 1mm for this case. Since we

Analysis Settings and Boundary Conditions: The load will be defined in 4 steps. The Solver type is selected as DIRECT and Large Deflection as ON. The rest of the features are kept PROGRAM CONTROLLED as the solver will select optimum values for them

RESULTS

Stress

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Directional Deformation

Strain

• Plastic deformation of the plate is achieved as visible in the results. The plate is permanently strained beyond elastic limits and strain energy is stored in the molecules by absorbing the work done by the sphere.

• Max Equivalent stress acts on the plate at the bottommost point of impact, just before the sphere starts to retract.