22 research outputs found
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Modeling the effects of friction and geometry on deformation path during hot rolling of aluminum
In this work, a parametric study of hot rolling is conducted. The effect of friction model, friction coefficient, roll gap geometry and temperature on the deformation rate field is demonstrated. This parameter space is restricted to a region which is tractable, yet provides considerable variety in the features of non-uniform deformation developed in rolling. The degree and nature of redundant work (shearing) is contrasted for different stream-line locations within the bite. Recommendations for the application of material models in analysis of rolling is made with consideration of the simulation predictions
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Sensitivity of Simulated Anisotropy to Initial Texture Definitions
Free compression tests were performed on 0.040 inch thick 5754 aluminum sheet stock producing a slight in-plane anisotropy. A visco-plastic self-consistent (VPSC) deformation modeling code was used to model the mechanical properties and resultant deformation textures. Calculations using a discretized description of the initial texture simulated the deformation texture very closely. Simulation of the mechanical properties were also captured nicely with one exception. The direction of simulated in-plane anisotropy was reversed from the experimental results. Simulation of the impact of various texture components on the anisotropy indicted that the shift of texture toward stronger brass, {l_brace}110{r_brace}<112>, and Goss, {l_brace}110{r_brace}<001>, components led to the reversal of anisotropy. The simulated deformation texture was more intense than the experimental texture in the brass and Goss positions. This result suggests that the more intense simulated texture components may be responsible for the reversal of an isotropy
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Does supplemental feeding of white-tailed deer alter response of palatable shrubs to browsing?
The impact on palatable shrubs when herbivores have access to high-quality food is unclear. We determined if providing high-quality food and increasing white-tailed deer (Odocoileus virginianus) density reduced growth and altered nutritional quality of two palatable shrub species. We maintained target densities of 13, 31, or 50 deer km-2 in six 81-ha-1 enclosures on each of two ranches. We provided nutritious, dry feed ad libitum in one of each pair of enclosures with similar densities on each ranch. We measured height and width of Texas kidneywood (Eysenhardtia texana Scheele) and spiny hackberry (Celtis ehrenbergiana [Klotzsch] Liebm), measured hackberry thorns, and estimated crude protein. Plants were protected from browsing with wire exclosures in 2005; a similar-sized unprotected plant was paired with each protected plant. We estimated density of shrub species using twenty 3 × 50mbelt transects/enclosure June 2005, 2007-2012. Growth of protected and unprotected kidneywood was similar (P ≥ 0.88) at 13 deer km-2, but growth was reduced (P ≤ 0.05) by higher deer densities. Protection from browsing and increasing deer density did not influence (P ≥ 0.25) size of spiny hackberry. Browsed kidneywood plants had a 34% lower crude protein (P ≤ 0.01) compared with protected plants when deer did not have access to feed. Spiny hackberry protein was greater (P ≤ 0.05) in unprotected plants compared with protected plants at 50 deer km-2. Response of Texas kidneywood density at > 1.5-mtall to deer density depended on year (P=0.04), with no effect of deer density (P ≥ 0.10) on spiny hackberry density. Density of both shrubs was similar (P > 0.14) with and without supplement. Access to feed does not alter effects of browsing on these sympatric shrubs; however, responses to increasing herbivore density contrast. Texas kidneywood is less tolerant of herbivory than spiny hackberry. © 2016 The Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
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Experimental evaluation of a contact area evolution model
Experiments designed to simulate boundary lubrication conditions during sheet forming were performed and evaluated. The results are compared to a model for contact area evolution caused by flattening of surface asperities. Microscopic observations and estimates of the area fraction in boundary contact agree reasonably well with the model. The effect of microstructural features on the accuracy of continuum models is also discussed. 8 refs., 15 figs
The formation of complex microstructures after different deformation modes in advanced high-strength steels
The microstructure of transformation induced plasticity (TRIP) and dual phase (DP) multiphase steels after stamping of an industrial component at different strain levels was investigated using transmission electron microscopy. The TRIP steel microstructure showed a more complex dislocation substructure of ferrite at different strain levels than DP steel. The deformation microstructure of the stamped parts was compared to the deformation microstructure in these complex steels for different "equivalent" tensile strains. It was found that the microstructures are similar only at high levels of strain (>10 pct) for both steels. © 2014 The Minerals, Metals & Materials Society and ASM International
Strain hardening behavior of dual-phase steels
A detailed qualitative and quantitative examination of the microstructure and mechanical properties of three different classes of DP600 and DP450 dual-phase (DP) steels was carried out. The tested DP steels are characterized by different alloying elements: aluminum, boron, and phosphorus. Among them, aluminum DP steels showed the lowest percentages of hard phases, while phosphorus DP steels exhibited the highest resistance values. The Hollomon, Pickering, Crussard–Jaoul (CJ), and Bergstrom models were used to reproduce the strain hardening behavior of DP steels. Relationships that correlate the fitting parameters with the chemical composition and the thermal cycle parameters were found, and the predictive abilities of different models were evaluated. The Pickering equation, among the tested models, is the best one in the reproduction of the experimental stress-strain data