Load Collectors 
Load Collectors
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Load Collectors |
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Load Collectors |
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Load collectors collect and organize loads and equations. Load collectors are created, edited, and deleted from the Model browser and are shown under the LoadCollector folder.
Loads and equations can be organized into a load collector using the Organize panel. Every load and equation must be organized into one, and only one, load collector and therefore are mutually exclusive to a load collector. Newly created loads and equations are automatically organized into the current load collector.
The current load collector is shown in the status bar and is also bold in the Model browser. The current load collector can be set using the Model browser context menu on a selected load collector within the LoadCollector folder. Load collectors can also be card edited using the Model browser context menu on selected load collectors within the LoadCollector folder.
Load collectors have a display state, on or off, which control the display of all loads and equations organized within the load collector in the graphics area. The display state of a load collector can be controlled using the icons next to the load collector in the Model browser. Geometry and element display states can be controlled separately for load collectors.
Load collectors also have an active and export state. The active state of a load collector controls the display state of the load collector and the listing of the load collector in the Model browser and any of its views. If a load collector is active, then its display state is available to be turned on or off and it is listed in the Model browser and any of its views. If a load collector is inactive, then its display state is turned off permanently and it is not listed in the Model browser or any of its views. If a find operation "finds" an inactive load collector, that load collector will automatically be set to active.
The export state of a load collector controls whether or not that load collector and all loads and equations organized within the load collector are exported when the custom export option is utilized. The all export option is not affected by the export state of a load collector. The active and export states of load collectors can be controlled using the Entity State browser.
Operations performed on a load collector affect loads and equations within the load collector. For example, if you delete a load collector, the loads and equations within the load collector are also deleted.
The data names associated with load collectors can be found in the data names section of the HyperMesh Reference Guide.
A load collector is a repository for loads and constraints. Each load or constraint must belong to a load collector. There are two card images called HISTORY and INITIAL_CONDITION. Loads or constraints that are to be used as history data (under *STEP) should be collected into load collectors with the HISTORY card image. These load collectors also need to be added to the corresponding load steps (*STEP) from the load steps panel. In contrast, loads or constraints for model data should be collected into load collectors with INITIAL_CONDITION card image. They will automatically be written out in the model portion of the Abaqus input deck.
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Load collector information is specified with a required $HMNAME comment card and an optional $HMCOLOR comment card. If an input translator encounters one of these comments while reading a load card, a new load collector is created. For the comments to be valid, they must follow a load keyword or the last line of the previous Structured block. The loads that follow a $HMNAME LOADCOLS comment are read into that collector. If there is a new keyword or structured block, the previous load collector information is ignored. For non-HyperMesh generated input decks, loads are divided into collectors based on classification. The following load collectors are created:
If translational or rotational constraints are defined in the input model, they are placed in a separate load collector named Nodal Constraints. Load collectors are not used by LS-DYNA, but are useful for visualization. Additional load collectors can be defined to describe other entities.
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There are two types of load collectors for Nastran:
Generic load collectors are used to collect loads and constraints for display purposes and to assign an ID to the loads. Specific load collectors are used for specialized loading cards, such as SPCADD, MPCADD, EIGRL, EIGB, EIGC, EIGP, EIGR, FREQ, FREQ1, LOAD, GRAV, RFORCE, and TEMPD. Specific load collectors have card images which can be edited to do the following:
General boundary conditions, such as loads and constraints, should not be collected into specific load collectors. When reading in a Nastran deck, loads that have the same SID are collected into the same load collector. If a load collector already exists in the database with the same SID, one of the following can occur: If overwrite is off (default), the new load collector’s ID is offset and all loads in that collector will have a new SID upon export. If overwrite is on, the new load collector replaces the existing load collector. The original load collector and the loads it contains are deleted.
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Specific load collectors are used for specialized loading cards, such as EIGRL, SPCADD, GRAV, RLOAD, DTABLEi, etc. Specific load collectors have card images, which can be edited to do the following:
General boundary conditions should not be collected into specific load collectors. Organizing loads and constraints into a specific load collector may result in an error termination. The following is a list of OptiStruct cards, which are represented as specific load collectors.
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When working with RADIOSS (Block Format), HyperMesh requires that all the loads be placed in the load collectors with one of the following valid card images:
There are two choices for assigning loads to a load collector: Create individual loads, all of the same type and degree of freedom, and store them in the appropriate load collector. Identify the nodes on which loads/BCs act by selecting them through a set. The selection of the set is possible by editing the card image of the load collector. |
