Hot working of aluminum alloy 7075
Large deformation, constant true strain rate, isothermal compression tests have been conducted on the aluminum alloy 7075 at strain rates which ranged from 103 to 1 sec1 and temperatures which spanned the practical forging temperature range of 3250C 4250 C. In this strain rate and temperature regime the stress-strain curves show very little strain hardening or softening, and the relationship between the (visco) plastic strain rate iP, the absolute temperature T, and the flow stress a can be represented well by the classical one-dimensional equation:
Finite-Element Simulation and Experimental Investigation of Isothermal Backward Extrusion of 7075 Al Alloy
This paper reports on an experimental and finite-element analysis of a backward extrusion process of 7075 Al alloy. The influence of punch speed and billet temperatures on the backward extrusion process was investigated. DEFORM-3D software was used for finite-element simulations. A backward extrusion die was designed and manufactured for the purpose of experimental research. From simulation, the forming load and stress/strain distribution of the billet were obtained. The simulation results show that the effective stress/strain distributions are inhomogeneous in the deformed billet. Finite-element method has been used successfully to predict the backward extrusion load, indicating the good accuracy of the simulation results. In this study, the effects of the different temperatures and punch speeds on the effective stress/strain distribution and forming load during forming process were investigated.
Old English Manuscripts in the Early Age of Print: Matthew Parker and his Scribes
Covering the first dedicated program in the study of and publication of Anglo-Saxon texts, my dissertation examines the sixteenth-century origins of medieval studies as an academic discipline. By placing recent scholarship on media, materiality, cognition, and intellectual history in conversation with traditional paleographical methods on medieval and renaissance manuscript culture, I argue for a new way of understanding how early modern scholars studied and presented the medieval past. I take as my focus a corpus of emulative Anglo-Saxon manuscript transcriptions produced under Elizabethan Archbishop Matthew Parker. Equal parts facsimile and edition, these transcriptions are a unique example of early modern scholars navigating the often competing demands of late sixteenth century manuscript and print culture. This dissertation is, in part, an attempt to catalogue and document the extent of Parkerian Anglo-Saxon manuscript transcriptions. Temporally displaced from their source texts, Parker and his scribes directly modified many of the medieval manuscripts they recovered by editing, rebinding, cropping, and annotating them according to their own interpretive desires and publication needs. These transcriptions place Parker’s early modern scribes into the textual community of early medieval scribal culture, but their printed manuscript editions are an attempt to bring medieval documents into contemporary discourse. They developed new typefaces modeled on manuscript exemplars and attempted to reframe the printed version of a medieval text as an authoritative surrogate