IV.1.4.1 Loads
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.