Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

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Oasys LS-DYNA Environment: User Guide (Version 8.1) OASYS D3PLOT version 8.1 Oasys D3PLOT 8.1 contains a number of new features and some enhancements to the existing features. The major enhancements include : ` Improved blanking menu. ` “Quick Pick” options for blanking, setting colours, transparency and colours. ` Modified screen layout to improve ease of use. ` Viewing of nodes from node to surface contacts. (via ‘ZTF’ file created by PRIMER) ` Viewing of nodal constraints and restraints (via ‘ZTF’ file created by PRIMER) ` Identification of *MAT_SPOTWELD beam elements (via ‘ZTF’ file created by PRIMER) For more details on the new features available in D3PLOT consult either Volume 2 of the version 8.1 manuals or the Update and Release notes. OASYS T/HIS version 8.1 Oasys T/HIS 81 is a minor update to the version 8.0 software. For more details on the new features available in T/HIS consult either Volume 2 of the version 8.1 manuals or the Update and Release notes. The enhancements include : ` New MINimum, MAXimum and AVERage functions. ` Improved FFT function. ` New WINDOW function. ` Support for DEFORC, NODOUT, RCFORC and SBTOUT optional LS-DYNA ASCII output files. ` Identification and labelling of minimum and maximum curve values. ` Automatic generation of T/HIS command files from an ASCII input file. ( see FAST-TCF manual for more details.) Page 1.2
Oasys LS-DYNA Environment: User Guide (Version 8.1) 2.0 PARALLEL VERSIONS Two separate versions of LS-DYNA are currently under development for use on parallel computers; the PVP version (Parallel Vector Processing) and the MPP version (Massively Parallel Processing). The PVP version is a shared memory version and is available for use on most machines. The MPP version is a distributed memory version and runs on the Cray T3D, T3E, IBM SP2, HP and Intel Paragon machines. PERFORMANCE OF PVP VERSION The parallel performance of the PVP version of LS-DYNA is not linear with the number of processors used to solve the problem. At best it is expected that the current PVP version will show a speed up of 2.5 over 4 CPU's and that using more than 4 CPU's will not achieve any substantial gain. This drop in parallel performance is due to the large complexity of LS-DYNA meaning that it has not yet been possible to parallelize the whole code. The best parallel performance of LS-DYNA can be obtained on problems involving only a few element types, material models and contacts. In general a problem with many options, e.g. contacts, constraints, rigid bodies and airbags, can only be carried out in parallel 80% of the time. Table 2.1 obtained from Amdahl's law gives a rough indication of the speed up that can be expected in optimal cases. Parallel Fraction Number of Processors 2 4 8 16 75% 1.60 2.29 2.91 3.34 82% 1.69 2.60 3.54 4.32 95% 1.90 3.47 5.93 9.14 RESULTS CONSISTENCY Table 2.1 - Theoretical Parallel Speed-ups When running LS-DYNA in parallel on different numbers of CPU's, in both the PVP and MPP versions, some results will differ. Not only will these results vary with the number of processors but they will vary if the same analysis is run on the same number of processors at a different time. The magnitude of these differences will vary with the type of problem, they can be so small that unless people check very carefully results appear identical. For most structural applications these differences are in the range of a couple of percent but for some applications some results could Page 2.1
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Oasys LS-DYNA Environment 8.1 VOLUME 3 ... - Oasys Software

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