This project is a close cousin to the drop tower, however it is focused on simpler material geometries but with a higher strain rate. The higher strain rate represents the lower end of ballistic and explosive impact velocities seen in high strain rate applications. The output of the split-Hopkinson bar apparatus is the trace from a wave which travels down the striker bar, and is reflected and transmitted through a small material specimen. These waves have the potential to be analyzed in a manner that provides a stress strain relationship for the material being tested.
One of the most interesting parts of the system is the design of the gas gun that is used to fire the projectile (the striker) at the end of the bars (see picture from Waterloo University). The bars are suspended or placed in low friction bearings when the striker is fired. The striker is fired from a gun using compressed gas. The compressed gas is moved from a large pressurized chamber to the barrel with the striker either by opening a valve or iris very quickly or else through the rupture of a membrane. Design of this key portion of the apparatus is the primary focus of the project. If the membrane or the iris can be designed then the rest of the gun can be built in a reasonable amount of time.
This project is a combination of theory and practice, The successful team will complete the design on paper and develop a full drawing package. Key components of the system will be built and tested, so that any necessary further production and assembly can be completed by less experienced personnel.
Preliminary performance specifications, including pressures and velocities required for operation: 9/22/06
Final design specifications determined and literature reviewed: 10/6/06
Presentation of selected design sketches from researched literature to Umaine Alumnus: 10/12/06
Web page completed including resumes, photos and milestones: 10/13/06
Completed sketches of optional design: 10/27/06
Milestone review: 11/3/06
Final design specifications of air gun: 11/10/06
Preliminary drawings of final design including all components and assembly: 11/24/06
Draft midterm report: 12/08/06
Final drawing package of air gun: 12/15/06
Materials ordered for component test: 12/15/06
Preliminary preformance specifications, including pressures and velocities required for operation.
Final design specifications determined and literature reviewed.
Web page completed including resumes, photos and milestones.
* Final design specifications of air gun.
* Preliminary drawings of final design including all components and assembly.
* Draft midterm report.
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