327 research outputs found
A constitutive model for the superplastic material ALNOVI-1 including leak risk information
For some applications, it is important that a formed sheet of material is completely gas tight, therefore it is beneficial to be able to predict whether a formed sheet will be leak tight for gases or not. Superplastic materials show the ability to attain very high plastic strains before failure. These strains can only be reached within a small range of tempera-ture and strain rate. In thecase of the alu-minium alloy ALNOVI-1 by Furukawa Sky Aluminium, the optimum superplastic be-haviour is found at 520 °C and at strain rates roughly between 10-4 to 10-2 s-1. Under these conditions, the mechanical behaviour of the material is highly strain rate depend-ent. This article describes a proposal for the constitutive model of ALNOVI-1, as can be incorporated into an FE code (like a user-defined material UMAT in ABAQUS), in which the leak risk can be implemented, as function of the cavity volume fraction. This will be done in a phenomenological way, using the results of uniaxial tensile and biaxial bulge experiments
Phenomenologizing McDowell:Book review of C. B. Christensen's <i>Self and World - From Analytic Philosophy to Phenomenology</i>
Symbolism in the middle paleolithic:a phenomenological account of practice-embedded symbolic behavior
The existence and extent of symbolism among Middle Palaeolithic pre-modern humans present a significant point of controversy. As with any scientific dispute, there is a substantial conceptual component to these discussions, here in particular concerning the concept of symbolism, which is often poorly defined. The present chapter approaches the problem from a different, philosophical, angle. It opens with a brief reflection on the phenomenological method in philosophy and its largely unexplored potential for paleoanthropology and evolutionary psychology. The midpart develops a phenomenological framework involving separate levels of expressive and symbolic behavior. It is argued that Middle Palaeolithic pre-modern humans, given the current evidence, are best understood as capable of symbolic behavior, but that symbol use is still tied to expressive behavior and shared practices in the so-called living present. It is further argued that such âpractice-embedded symbolismâ represents a necessary stage in the evolution of symbolism in the hominin lineage, as its use and interpretation are significantly less cognitively demanding than the free symbolic activity of behaviorally modern humans. The final section reviews evidence for the decorative use of pigment and beadwork in Middle Palaeolithic communities. It is argued that while their production plausibly relied on practice-embedded symbols, free symbolism in the modern sense need not be presupposed, and it is unlikely that either pigment or beadwork had itself a symbolic function
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