One degree-of-constraint semi-fusible gearbox mounting link
A mounting link between an engine and a gearbox comprises an engine attachment piece, a gearbox attachment piece, and primary and secondary retention fasteners. The engine attachment piece is rotatably secured to the engine, and the gearbox attachment piece is rotatably secured to the gearbox. The primary retention fastener rigidly constrains the gearbox attachment piece with respect to the engine attachment piece in a single degree of freedom, but is configured to shear at a breakpoint load. The secondary retention fastener constrains the gearbox attachment piece loosely with respect to the engine attachment piece, and can withstand the breakpoint load. The gearbox attachment piece and engine attachment piece abut in a friction fit that provides Coulomb damping.
1. A gearbox-to-engine mounting arrangement comprising:
an engine attachment piece attachable to the engine;
a gearbox attachment piece attachable to the gearbox and slidably movably engaged with the engine attachment piece such that the slidable movement is along a single axis over a selected stroke length; and
a force failing member in operable communication with the engine attachment piece and the gearbox attachment piece preventing the slidable movement until loads on the force failing member have exceeded a selected value;
wherein the stroke length is defined by pins fixed to one of the engine attachment piece and the gearbox attachment piece that move within slots of the other of the engine attachment piece and the gearbox attachment piece.
2. The gearbox-to-engine mounting arrangement of claim 1 , wherein the slidable movement requires overcoming frictional engagement between the engine attachment piece and the gearbox attachment piece.
3. A method of attaching a gearbox to an engine structure along an axis defining a single degree of freedom using the gearbox-to-engine mounting arrangement of claim 1 , the method comprising:
securing the engine attachment piece to the engine structure;
attaching the gearbox attachment piece to the gearbox;
slidably connecting the gearbox attachment piece to the engine attachment piece, such that the gearbox attachment piece is able to move along a single axis over a selected stroke length, with respect to the engine attachment piece; and
fixedly securing the gearbox attachment piece to the engine attachment piece via the force failing member until a load on the force failing member exceeds a selected value.
4. The method of claim 3 , further comprising:
shearing the force failing member under a load of at least the selected value; and
subsequently loosely retaining the gearbox attachment piece with respect to the engine attachment piece in at least the single axis.
5. The method of claim 3 , further comprising:
tightly positioning one of the engine attachment piece and the gearbox attachment piece in an interference fit between sections of the other of the engine attachment piece and the gearbox attachment piece.