# RD-V: 0100 Impact Momentum

A block impacts a plate and the system is compared to theory.

The impact algorithm is studied by impacting a square plate with a cube. The system momentum after impact is compared to the theoretical system momentum. The time history output of each part and the total system is used.

## Options and Keywords Used

• /INTER/TYPE7
• /INTER/TYPE24
• /INTER/TYPE25

## Input Files

Refer to Access the Model Files to download the required model file(s).

The model files used in this problem are available in:

## Model Description

The plate is 254 mm square and 25.4 mm thick. The cube length is 25.4mm. The parts are modeled using solid elements and linear elastic material. An initial velocity of 5080 mm/s is applied to the block in the z direction. There are no other constraints in the model.

### Simulation Iterations

Three different contact interfaces, /INTER/TYPE7, INTER/TYPE24, and /INTER/TYPE25 are tested to model the impact between the plate and the block. A surface to surface contact is defined for all interfaces. TYPE7 requires two different contact interface definitions in the model whereas TYPE24 and TYPE25 can define surface to surface contact using one definition.

The following system is used: mm, s, Mg.

## Results

The global momentum can be plotted from the time history output. Figure 2 shows that the global z momentum for all interface models exactly matches the theoretical momentum of 0.6452 $\frac{Mg×mm}{s}$.

Figure 3 and Figure 4 show the Z momentum of the impactor and plate for the three different contact interfaces. The results for each interface are not exactly the same because of the differences in the contact stiffness of the interfaces. The TYPE7 contact also includes a contact gap for solid to solid contact and thus the impact occurs slightly before the other two contact interfaces.

### Conclusion

The global z momentum in the model exactly matches the theoretical momentum of 0.6452 Mg*mm/s.

1 Buechler, Miles, Amanda McCarty, Derek Reding, and R. D. Maupin. "Explicit finite element code verification problems." In 22nd SEM International Modal Analysis Conference, Dearborn, MI. 2004.