Browsing by Author "Allwood, J. M."

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Citation - WoS: 130
The Increased Forming Limits of Incremental Sheet Forming Processes
(Trans Tech Publications Ltd, 2007) Allwood, J. M.; Shouler, D. R.; Tekkaya, A. E.
incremental sheet forming is known to give higher forming limits than conventional sheet forming processes, but investigation of this effect has been impeded by the computational cost of process models which include detailed predictions of through thickness behaviour. Here, a simplified process is used to gain insight into the mechanics of a broad class of incremental forming processes. The simplified process is described and shown to give increases in forming limits compared to a conventional process with the same geometry. A model of the process is set up with a commercial finite element package, validated, and used to trace the history of a 'pin' inserted perpendicularly into the workpiece. The history of the deformation of the 'pin' demonstrates sifnificanat through thickness shear occurring in the direction parallel to tool motion. This insight is used to modify an existing analysis used to predict forming limit curves. The analysis shows that for a sheet with uniform proportional loading, the forming limit is increased when through thickness shear is present, and this is proposed as an explanation for the increased forming limits of incremental sheet forming processes.
Citation - WoS: 125
Citation - Scopus: 158
Incremental bulk metal forming
(Elsevier, 2007) Groche, P.; Fritsche, D.; Tekkaya, E. A.; Allwood, J. M.; Hirt, G.; Neugebauer, R.
Incremental bulk forming is the oldest known technique in metal working. Many developments in this field have dramatically changed our society. Today incremental bulk forming processes are applied to quality products in small and large series production. Numerous advances have been realized. The motivation for using these processes is presented here. After a general definition of incremental processes and a classification of incremental bulk forming in particular, some innovative product and process examples are given that show the potential. Finally recent progress and challenges are illustrated in detail. This includes the development of new machinery for incremental bulk forming, advanced methods for process planning, occurrence of failure modes and the properties of finished products.