RD-V: 0100 Impact Momentum

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

図 1.

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


Input Files

The following input file is used in this example:


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.


The global momentum can be plotted from the time history output. 図 2 shows that the global z momentum for all interface models exactly matches the theoretical momentum of 0.6452 M g × m m s MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca WGnbGaam4zaiabgEna0kaad2gacaWGTbaabaGaam4Caaaaaaa@3CB8@ .

図 2. Global model Z momentum
図 3 and 図 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.

図 3. Impactor Z momentum

図 4. Plate Z momentum


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.