Entity

Time filter

Source Type

Erie, PA, United States

Abu-Farha F.,Penn State Erie
JOM | Year: 2011

A custom mechanical stretching setup based on the Nakazima method was designed and built for testing sheet metals at elevated temperatures. Specimens from a fine-grained 5083 aluminum alloy sheet were deformed at various temperatures, spanning between those associated with warm forming (250°C) and hot forming (550°C). Circle grid analysis of the deformed specimens produced the forming limit curves at each of the covered temperatures, hence revealing the great influences of forming temperature on the material's formability limits. Finally, all the curves were combined to construct a unique three-dimensional forming limit surface, which we present here as a more comprehensive map for describing material formability limits at wide-ranging temperatures. © 2011 TMS. Source


Nazzal M.,German Jordanian University | Abu-Farha F.,Penn State Erie | Curtis R.,Kings College London
Journal of Materials Engineering and Performance | Year: 2011

Characterizing the behavior of superplastic materials is largely based on the uniaxial tensile test; yet the unique nature of these materials requires a particularly tailored testing methodology, different to that used with conventional materials. One of the crucial testing facets is the specimen geometry, which has a great impact on the outcome of a superplastic tensile test, as a result of the associated extreme conditions. And while researchers agree that it should take a notably different form than the typical dog-bone shape; there is no universal agreement on the specimen's particular size and dimensions,as evident by the disparities in test specimens used in the various superplastic testing efforts found throughout the literature. In view of that, this article is dedicated to understanding the effects of specimen geometry on the superplastic behavior of the materialduring tensile testing. Deformation of the Ti6Al4V titanium alloy is FE simulated based on a multitude of specimen geometries, covering a wide range of gauge length, gauge width,grip length, and grip width values. The study provides key insights on the influences of each geometrical parameter as well as their interactions, and provides recommendations onselecting the specimen's proportions for accurate and unified tensile testing of superplastic materials. Source


Abu-Farha F.,Penn State Erie | Hector Jr. L.G.,General Motors
Journal of Manufacturing Science and Engineering, Transactions of the ASME | Year: 2011

The formability curves of AZ31B magnesium and 5083 aluminum alloy sheets were constructed using the pneumatic stretching test at two different sets of forming conditions. The test best resembles the conditions encountered in actual hydro/pneumatic forming operations, such as the superplastic forming (SPF) and quick plastic forming (QPF) techniques. Sheet samples were deformed at (400 °C and 1×10-3 s-1) and (450 °C and 5×10-3 s-1), by free pneumatic bulging into a set of progressive elliptical die inserts. The material in each of the formed domes was forced to undergo biaxial stretching at a specific strain ratio, which is simply controlled by the geometry (aspect ratio) of the selected die insert. Material deformation was quantified using circle grid analysis (CGA), and the recorded planar strains were used to construct the forming limit curves of the two alloys. The aforementioned was carried out with the sheet oriented either along or across the direction of major strains in order to establish the relationship between the material's rolling direction and the corresponding limiting strains. Great disparities in limiting strains were found in the two orientations for both alloys; hence, a "composite FLD" is introduced as an improved means for characterizing material formability limits. © 2011 by ASME. Source


Abu-Farha F.,Penn State Erie
ASME 2010 International Manufacturing Science and Engineering Conference, MSEC 2010 | Year: 2010

The merits of warm and elevated temperature hydro/pneumatic sheet metal forming operations, most prominently superplastic and quick plastic forming, have been ever counteracted by two major drawbacks: slow forming rates and non-uniform thickness distribution with potentially severe thinning. Trying to resolve one of the two issues has generally led to escalating the other, so a compromise based on the nature of the part being formed is often targeted. To tackle the latter of the two issues, imposing a pre-thinning reverse bulging step has been shown to ease the problem with specific part geometries that involve large plastic strains and intricate details. The aerospace industry, however, is the prime sector that is able to afford the "seemingly" prolonged forming times associated with this approach. Yet with the lack of adequate details on the implications of utilising reverse bulging, this effort explores some of the hidden merits of the approach. A recently-developed simple monitoring technique for providing a direct feedback on the sheet's advancement during pneumatic forming operations, coupled with an interrupted testing methodology, are utilised to have a closer look at the process. The results reveal significant time-savings that can be achieved with the proper use of reverse bulging, for both simple and complex part geometries. Copyright © 2010 by ASME. Source


Dawood S.,Penn State Erie
International Journal of Project Management | Year: 2014

Project-based work has long been characterized as frenetic, fast-paced, and dynamic. The often competing constraints imposed by schedules, stakeholders, and budgetary restrictions make project activities conflict-laden and highly conducive to work-related stress. Stress is not an end unto itself but instead, is often a precursor for burnout. Burnout is a psychological syndrome of emotional exhaustion, cynicism, and reduced personal accomplishment. This paper reports on the results of a study of burnout among project management personnel. Using the Demand-Control-Support model as our conceptual framework, we analyzed a sample of respondents from four project-intensive organizations. Our findings demonstrated that women tend to experience emotional exhaustion to a greater extent than their male counterparts. Further, control and social support do serve as moderators for the burnout dimensions of emotional exhaustion and cynicism, suggesting limited support for the Demand-Control-Support model. Implications of this study for project management and workplace burnout are discussed. © 2013 Elsevier Ltd. Source

Discover hidden collaborations