Multiphysics modelling of the coupled behaviour of precision-guided projectiles subjected to intense shock loads
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Multiphysics modelling of the coupled behaviour of precision-guided projectiles subjected to intense shock loads X. W. Yin • P. Verberne • S. A. Meguid
Received: 17 March 2014 / Accepted: 26 April 2014 Ó Springer Science+Business Media Dordrecht 2014
Abstract Precision-guided projectiles (PGPs) typically deployed in smart munitions are operated and guided by highly sophisticated embedded electronic systems (EES). These PGPs are subjected to severe shock loads resulting from the ignition of the propellant during their launch. These shock loads, which are typically characterised by high intensity, short duration and wave reflections at varied frequencies, often lead to the failure of the EES. It is the objective of this work to conduct a comprehensive multiphysics analysis of the launch process of PGPs accounting for coupling and interaction effects between the different media (propellant, PGP, confined volume and free space). Specifically, we investigated the entire launch process that include the ignition of the propellant to observe local and global features of the setback, set forward pressure and acceleration histories using explicit axisymmetric Lagrangian–Eulerian finite element simulations. In this work, we also examine the severity and frequency of the reflected waves as well as the springback of the PGPs resulting from these local oscillations as they exit the muzzle. In addition, the flight state transition due to muzzle exit in terms of pressure and flow velocity is also discussed. Our
X. W. Yin P. Verberne S. A. Meguid (&) Mechanics and Aerospace Design Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Rd, Toronto, ON M5S 3G8, Canada e-mail: [email protected]
results reveal the complex phenomena associated with the dynamic response of the PGPs and pressurization process resulting from the ignition of propellant during launch that are characterized by high oscillatory pressure profiles and projectile springback. Keywords Precision-guided projectile Propellant FEM Shock loads Pressure history Acceleration history Embedded electronic system Wave reflection
List of symbols A Internal cross-sectional barrel area B Hardening constant b0 Burn rate constant _b Burn-rate C Total propellant mass Strain rate constant C0 c Growth reaction exponent cp Propellant specific heat D Reaction constant Dw Propellant web size Eproj Projectile kinetic energy Eprop Propellant kinetic energy eg Propellant specific energy F Web fraction G Reaction growth constant Gp Shear modulus for projectile Kg Bulk modulus for propellant Kp Bulk modulus for projectile
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l m ms(t0) ms(t) n n0 P P1 Pc Pg Tm U V(t) W(t) x xc b C h k qg qp qs ry /_ /(t)
Effective chamber length Thermal softening exponent Initial solid propellant mass Solid propellant mass Burn rate exponent Hardening exponent Base pressure Average pressure Base pressure at burnout Pressure of reaction product Material melting temperature Effective chamber volume Projectile
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