Processing of Multilayer Propellants Through Concentric Extrusion Dies
Durand Simon (1), Dubois Charles (2)*, Lafleur Pierre G. (2)
(1) GD-OTS Canada - Valleyfield - Canada, (2) École Polytechnique Montreal - Montreal - Canada
The primary purpose of this effort is to establish the criteria that enable the extrusion of
in concentric cylindrical dies. The use of segregated propellants formulations with
results in a more progressive pressure-time curve during the propellants combustion,
improved ballistic performances. In a first step, the materials and the range of
multilayer propellant sticks was determined from closed vessel combustion data and
For a given set of layer composition, the optimal geometry of the propellant sticks
acceleration for the maximal weapon system internal pressure capacity.
Secondly, the flow properties of selected polymer based propellants formulations were
measurements by using both rotational and capillary rheometers. This characterization
behaviours that needed to be accounted for during the die design. More specifically, we
enables the maximum variation of the power law flow index “n” while keeping the flow
challenge originated from the unconnected flow between the inner and outer sections
A finite element modeling and simulation approach based on the COMOSL MultiPhysics
code was retained for the die design process. The results obtained by finite elements
experimentally. The study considered die design iterations where angles and channel
optimize and regulate each propellant layer flow rates. Results emphasize the relevance
the shear thinning behavior of this type of polymer based propellant in the design process of the extrusion dies.