טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBrill Alon
SubjectThe Influence of Hydrostatic Pressure on the Dynamic Failure
of PMMA
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Daniel Rittel
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

The static and dynamic mechanical behavior of confined commercial polymethylmethacrylate (PMMA) is reported. Cylindrical specimens are confined by means of a tightly fit metal sleeve. The rate and pressure sensitivity of PMMA are characterized over strain rates ranging from. The response of this polymer is described using a fitted rate-dependent Drucker-Prager pressure-sensitive model. The failure mode consists of axial splitting and fragmentation at the lower strain rates and confinement pressures. But, at higher strain rates and confinement pressures, the failure mode changes and becomes adiabatic shear formation of a comical plug. This previously unreported failure mode transition is can be explained by the fact the confinement delays the operation of damage micromechanisms, as evidenced from the post-peak slope. As for other brittle materials, the addition of a confining pressure to PMMA turns this brittle material into a ductile one. It is found that the rate and pressure dependence of the mechanical behavior of PMMA can be simply expressed by: for