One makes the distinction between load cases corresponding to quasi-static accelerations or forces applied on the structure and thermo-elastic loads cases.
First, three load cases corresponding to quasi-static accelerations applied to the entire satellite structure are defined in file “unit_accel.bdf”. These accelerations are defined by Nastran “GRAV” cards and are oriented in directions X, Y and Z. Their Load identifiers are 601001, 601002 and 601003 respectively.
Then loads corresponding to quasi-static acceleration on parts of the structure are created by defining the appropriate force fields. The method used to defined those force fields is explained in the example presented in section IV.2.5.1. Six files contain these force fields:
In file “force1_PAN_PZ.bdf”, one defines a force field corresponding to a unit acceleration one the panel +Z and on the instrument. The force field corresponds to load id 616001. Similarly, one defines force fields in directions Y and Z with ids 616002 and 616003 respectively.
Similarly on defines unit acceleration fields on the upper part of the structure in files “force*_UPPER.bdf” (the upper panel, the struts and the fittings). These force fields correspond to load IDs 617001, 617002 and 617003 respectively.
One also defines temperature fields for thermo-elastic load cases calculations:
In files “temp_M100_PAN_PZ.bdf” and “temp_M100_PAN_PZ.bdf” one defines temperature fields on the +Z panel. The two files correspond to a temperature of -100 C and +120 C respectively. The corresponding load ids are 621001 and 621002.
In files “temp_M100_PAN_PANLAT.bdf” and “temp_M100_PAN_PANLAT.bdf” one defines temperature fields on lateral panels. The two files correspond to a temperature of -100 C and +120 C respectively. The corresponding load ids are 622001 and 622002.
In files “temp_GRAD_X.bdf”, ‘temp_GRAD_Y.bdf” and ‘temp_GRAD_Z.bdf”, on defines three temperature gradients of 100 C/m on the entire structure in directions X, Y and Z respectively. The corresponding load ids are 623001, 623002 and 623003.
The method used to defined these temperature fields is explained in the example presented in section IV.2.5.2.