Launch 2
This model uses full solid elements rather than shell and beam elements and provides a clearer picture of the bending forces on the stays. The animation represents a pressure load model cycling from zero to a pressure of 1.25 N/mm2 (180 psi).
The geometry was automatically translated from the Onshape CAD system and elements added by hand. The automatic mesh generation system tends to generate a more cumbersome analysis model and, in any case, refused to work with the imported geometry in this case.
The red and green areas have exceeded design stresses but the stay positions have not been optimised yet. This is especially obvious around the back end of the inner longitudinal stay.
This model also exhibits the crown stay behaviour explored in the Launch 1 (Consuta) models and a next step in this study was to build a similar bread slice section and investigate whether the stay positions can be moved to improve support of the firebox crown.
The slice model shows that a 100 mm spacing of stays across the wrapper has a beneficial effect on stress levels. The next animation uses angled stays.
The angled stays make a marginal improvement to the pressure induced stresses but these improvements are overshadowed by higher thermal stresses. It looks as though a flanged firebox tubeplate and backhead could be of benefit.
