The ALE-method with triangular elements: direct convection of integration point values

The arbitrary Lagrangian-Eulerian (ALE) finite element method is applied to the simulation of forming processes where material is highly deformed. Here, the split formulation is used: a Lagrangian step is done with an implicit finite element formulation, followed by an explicit (purely convective) Eulerian step. The purpose of this study is to investigate the Eulerian step for quadratic triangular elements. To solve the convection equation for integration point values, a new method inspired by Van Leer is constructed. The new method is based on direct convection of integration point values without intervention of nodal point values.\ud The Molenkamp test and a so-called block test were executed to check the performance and stability of the convection scheme. From these tests it is concluded that the new convection scheme shows accurate results. The scheme is extended to an ALE-algorithm. An extrusion process was simulated to test the applicability of the scheme to engineering problems. It is concluded that direct convection of integration point values with the presented algorithm leads to accurate results and that it can be applied to ALE-simulation

Modelling of aluminium sheet material at elevated temperatures

The formability of Al–Mg sheet can be improved considerably, by increasing the temperature.\ud At elevated temperatures, the mechanical response of the material becomes strain rate dependent. To accurately\ud simulate warm forming of aluminium sheet, a material model is required that incorporates the temperature\ud and strain-rate dependency. In this paper hardening is described succesfully with a physically based material\ud model for temperatures up to 200 ◦C. At higher temperatures and very low strain rates, the flow curve deviates\ud significantly from the model. Strain rate jumps still pose a serious problem to the model

The digital medieval manuscript:approaches to digital codicology

This thesis explores how digitisation affects the way we perceive, handle, encounter, keep, preserve, and understand medieval manuscripts. With digitisation gaining ever-more importance, today, we encounter medieval manuscripts mostly in their digital form. This study reflects on how medieval manuscripts function and move as cultural (devotional, historical, archival, heritage) objects in an increasingly digital culture. Chapter 1 comprises a theoretical and methodological framework which discusses relevant ideas about codicology, (digital) materials and materiality, reproduction and copying. This thesis uses digital codicology to analyse the core case studies’ material elements, its place as cultural object and carrier of knowledge and tradition, and its position in history, in relation to the physical manuscript. Chapter 2 explores the Bury Bible (CCCC, ms. 2) and looks into how the digital facsimile is made and what digitisation practices mean for how the Bury Bible is revealed to or obscured for the audience in digital space. The chapter considers how the manuscript’s material properties are presented the digital object, and what this brings to light about its intellectual, cultural and institutional contexts. Chapter 3 looks at a Der naturen bloeme manuscript (KB, KA16), focusing on the ways in which digitisation facilitates fragmentation and the hyper-expansion of the manuscript, fostering re-use and appropriation in social media environments. The chapter thinks about how the digital manuscript functions in larger cultural narratives and how it is used once it enters seemingly unbound digital space. Chapter 4 details the prayer book of Mary of Guelders (SBB-PK, ms. germ. qu. 41 and ÖNB, cod. 1908) explores ideas about fragility, looking at how the manuscript is sustained in digital space, and how, in turn, the fragile material of the digital object is often disregarded. It studies the relationship between digitisation and preservation practices, and how this affects meaning and value we ascribe to the manuscript and the digital facsimile."This thesis was supported by the University of Groningen PhD scholarships; the St Leonard's College European doctoral scholarships; the Prins Bernhard Cultuurfonds scholarship grant (40016097/MAK/ILE); the Vereniging Rembrandt, Claudine de With scholarship grant; the Arts, Books and Collections scholarship grant." -- Fundin