The Finite Element Method is used to investigate the dynamic large plastic deformation response of a spherical pressure vessel with nozzle attachments. Material and geometrical non-linearltles are incorporated In the development of the solution procedure. The system Is loaded by detonating a 3.2 kg Trimonlte charge In an off-centre position, generating a peak pressure of 24 MPa. To minimise the excessive CPU demand a single symmetry is assumed and only half the system modelled. As the charge Is detonated off centre and because the resulting pressure wave travels with a finite velocity, the pressure front arrives at different places on the Inner surface of the vessel at different times. This arrival phase lag Is Incorporated In the solution algorithm to obtain a more realistic response and the pressure peak value Is modified to take Into account the off centre location of the charge.
Scaled-down laboratory experiments are often used to help develop an understanding of explosive forming processes such as welding, surface hardening, shaping, powder compaction and shock focusing for cutting purposes. Of course, for the sake of personnel safety and to prevent unwanted damage, it is extremely important that a secure and reliable confining chamber be available. One such chamber is in use at the Applied Mechanics Division of the Department of Mechanical Engineering at the University of Manchester Institute of Science and Technology. The chamber is spherical in shape with three nozzle access ports of different sizes. The geometrical details of the vessel and its attachment, together with its material characteristics are given elsewhere (Gill et ai, 1970 and Lazari et ai, 1991). Experiments with this vessel are conducted either under static loading by internal pressurisation (Gill et ai, 1970) or under dynamic loading by the detonation of an explosive charge of up to 141g (Lazari et al, 1991).
