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Example 12a – Taylor bar impact revisited (6)<br />

• Performance comparison:<br />

Case<br />

Time<br />

Integr.<br />

Steps<br />

Cycles<br />

Maximum<br />

frequency<br />

Elements *<br />

cycles<br />

CPU (s)<br />

Speedup<br />

(theor. / actual)<br />

BAMD01<br />

AUTO<br />

59886<br />

—<br />

—<br />

14,971,750<br />

55.7<br />

—<br />

BAMD03<br />

PART<br />

1162<br />

85537<br />

128<br />

1,296,171<br />

6.6<br />

11.6 / 8.4<br />

• To activate the partition, simply add:<br />

OPTI PART<br />

107<br />

Domain Decomposition<br />

References: see A. Combescure (ENS Cachan), B. Herry,<br />

A. Gravouil, N. Bousquet, V. Faucher (2000-2004)<br />

Goal: multi-scale problems in time and space.<br />

• Use appropriate time integration step in each s/d:<br />

– Couple s/d’s with different (and variable) time steps<br />

• Use appropriate time integration scheme in each s/d:<br />

– Any of the Newmark “beta” time schemes may be coupled<br />

– Explicit-explicit or explicit-implicit coupling is possible<br />

• Open the way to special techniques:<br />

– E.g.: combine modal analysis (linear vibrations) with<br />

direct time integration<br />

108<br />

– Treat vibrating parts in large rotations (rotating machinery)<br />

54

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