Stress Waves through Projectile Joints and Interfaces
Abstract
Studies of the response to stress waves of a hollow cylinder containing a threaded joint used the finite element method of dynamic stress analysis. These types of joints are common in many current cargo-carrying artillery projectiles. Sharp rise-time loads, which generate stress waves, can occur with electromagnetic launch and can occasionally result from a poorly behaved chemical charge (solid and liquid propellant) which creates pressure waves. The joint studied has 2 types of discontinuities: 1) A change of medium - - the interface between aluminum and steel; and 2) A non-closing gap, typically found at a cylindrical joint with two closing faces. Analysis of a bi-metallic rod is performed to verify aspects of the finite element code such as time step, element size and type, and analysis type. Response of a rod to stress waves can be easily compared to well-known analytical predictions. Next, a hollow homogeneous cylinder is analyzed to evaluate radial motion induced by the forcing function. This oscillatory motion disturbs the uniformity of the stress patterns. Only the initial pass of the stress wave is clear, and is similar in appearance to that of the rod. Thereafter, stress gradients through the wall thickness are evident with the onset of vibration modes, excited by the short- duration forcing function and appear to be a function of the duration of the applied transient load. Then, a non-closing notch discontinuity is introduced at the mid section of the hollow cylinder. Stress transmitted through this discontinuity is determined for various notch depths and locations. (EDC)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1989
- Accession Number
- ADA212201
Entities
People
- James M. Bender
Organizations
- Ballistic Research Laboratory