Date of Award
Mechanical, Automotive, and Materials Engineering
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The main focus of this research was to investigate force/displacement response and energy absorption performances of axially loaded AA6061-T4 and -T6 circular aluminum alloy extrusions under cutting deformation mode.
Quasi-static experimental investigation on load/displacement and energy absorption characteristics under cutting deformation mode was completed utilizing specially designed heat-treated 4140 steel alloy cutters and two different geometries of the cone-shaped deflectors, namely, straight and curved. An almost constant force during cutting was observed, which eliminated high peak crush force associated with progressive folding or global bending deformation modes. The average mean cutting force, as a result of the cutting deformation, was observed to be 29.8 kN and 43.2 kN for the AA6061-T4 and -T6 extrusions with a wall thickness of 3.175 mm respectively. For the extrusions with a wall thickness of 1.587 mm, the average mean cutting force was observed to be 14.9 kN for T4 temper and 19.6 kN for T6 temper tubes under the cutting deformation.
Additionally a dual stage cutting process was initiated using two cutters in series in this research. In addition to cutters and deflectors, spacers of different geometries between the cutters were also incorporated in this study. The force/displacement responses illustrated that the dual stage cutting was the superposition of two single-stage cutting processes. As spacing between the cutters increased the stability of the cutting progress degraded.
Additionally, controlling the load/displacement response through varying extrusions wall thickness along the length of the specimens was investigated. Results from the experimental testing illustrated that the force/displacement response was dependent upon the extrusion thickness and an almost linear relationship was observed to exist between wall thickness and the steady state cutting force.
Finally to this research, a numerical study of the axial cutting deformation process was simulated employing an Eulerian and Smoothed Particle Hydrodynamic (SPH) methods. Good predictive capabilities of the numerical model employing the Eulerian element formulation were observed.
Majumder, Amitabha, "Characteristics of AA6061-T4 and -T6 extrusions under cutting deformation" (2008). Electronic Theses and Dissertations. 8115.