טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentShapira Guy
SubjectFracture of 1045 Steel under Various Levels of Stress
Triaxiality, at Quasi-Static and Dynamic Loading
A Numerical and Experimental Study
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Daniel Rittel
Dr. Raruch Karp
Full Thesis textFull thesis text - English Version


Abstract

The effect of the triaxiality on the fracture strain has been experimentally investigated using the Shear-Compression Disk (SCD) specimen. The specimen is designed to assure constant level of triaxiality along the complete loading path, thus minimizing any possible effect of triaxiality history on the fracture strain obtained. The investigation included both the quasi-static and the dynamic loading regimes. A hybrid experimental-numerical methods were used to determine the state of stress and the plastic strains inside the specimen’s gauge section at fracture initiation.

A series of experiments was carried out under quasi-static loading conditions in the region of low negative (-0.7 to .1) stress triaxiality on heat-treated SAE 1045 steel specimens. Another set of dynamic experiments was performed on SCD specimens using Split-Hopkinson-Pressure-Bar, in the stress triaxiality range of -0.7 to -0.3. A linear relationship was observed between the strain at fracture initiation and the stress triaxiality within the investigated range. However, the dynamic slope is lower than that of the previous quasi-static experiments on the same material and specimens.

Finally, a comparison to literature-reported experimental results is presented in the discussion, outlining any agreements and contradictions with the current work.