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Fig. 26 from the 1997 modejump paper. This slide shows a history of the axial strain at a particular location in the PANDA2-optimized PANEL I (PANDA2 mode-jumping constraint turned off during optimization cycles).
The maximum strain in the panel occurs at the top and bottom surfaces of the panel skin next to the blade stiffener.
Mode jumping occurs at a load factor, PA, close to 0.7, and the vertical line of data points there represents a large number of closely spaced data points obtained from a STAGS transient run that simulates what happens during the mode jump, which is a dynamic phenomenon.
PA = 1.0 is the design load.
The three phases of the STAGS analysis are:
1. initial nonlinear static analysis with STAGS load factor PA in the range 0 < PA < 0.7013
2. nonlinear transient analysis with STAGS load factor PA held constant at 0.7013
3. post-transient nonlinear static analysis with STAGS load factor PA in the range 0.7013 < PA < 0.943
STAGS predicts that the panel collapses at load factor, PA - 0.943. The load factor for which the panel was previously optimized by PANDA2 is the design load factor, PA = 1.0.
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