The accuracy of the implant’s post-operative position and orientation in reverse shoulder arthroplasty is known to play a significant role in both clinical and functional outcomes. Whilst technologies such as navigation and robotics have demonstrated superior radiological outcomes in many fields of surgery, the impact of augmented reality (AR) assistance in the operating room is still unknown. Malposition of the glenoid component in shoulder arthroplasty is known to result in implant failure and early revision surgery. The use of AR has many promising advantages, including allowing the detailed study of patient-specific anatomy without the need for invasive procedures such as arthroscopy to interrogate the joint’s articular surface. In addition, this technology has the potential to assist surgeons intraoperatively in aiding the guidance of surgical tools. It offers the prospect of increased component placement accuracy, reduced surgical procedure time, and improved radiological and functional outcomes, without recourse to the use of large navigation or robotic instruments, with their associated high overhead costs. This feasibility study describes the surgical workflow from a standardised CT protocol, via 3D reconstruction, 3D planning, and use of a commercial AR headset, to AR-assisted k-wire placement. Post-operative outcome was measured using a high-resolution laser scanner on the patient-specific 3D printed bone. In this proof-of-concept study, the discrepancy between the planned and the achieved glenoid entry point and guide-wire orientation was approximately 3 mm with a mean angulation error of 5°.

Blechumformung ist traditionell ein hochaufwendiger Prozess, der teurer Werkzeuge und Formen wie Gesenke oder Patrizen und zugehöriger Stempel bedarf, die erst bei hohen produzierten Stückzahlen rentabel werden. Aus diesem Grund beschränkt sich im Bauwesen der Einsatz umgeformter Stahlprodukte bisher auf die Verwendung von Halbzeugen wie z. B. Walzprofilen. Die inkrementelle Blechumformung (IBU), ein neuartiges Umformverfahren, arbeitet auf ganz andere Weise. Statt eines einstufigen Pressvorgangs, bei dem das Blech in Form gebracht wird, fährt ein Umformwerkzeug die Bauteilkontur in einem sequenziell ablaufenden Prozess mit lokaler Verformung ab, der sich mit einfachen Mitteln an die individuell herzustellenden Blechformen anpassen lässt. Die IBU stellt insofern einen hochflexiblen Prozess dar, der es möglich macht, Serien von geometrisch unterschiedlichen Bauteilen bei hoher Effizienz zu fertigen. Sie verspricht ein ideales produktionstechnisches Mittel für die Umsetzung des Leichtbauprinzips von Raumfaltwerken und mehrlagigen Faltungen zu sein, auf dessen Basis selbsttragende Hüll-und Fassadenkonstruktionen aus Feinblech für die Architektur und den Ingenieurbau gebaut werden können. Die tatsächlichen Eigenschaften und Bedingungen der konstruktiven und praktischen Umsetzung einer mit Hilfe der IBU hergestellten, frei geformten zweilagigen Hüllfläche wurde im Rahmen eines Forschungsprojekts zwischen dem Lehrstuhl für Tragkonstruktionen (TRAKO) und dem Institut für Bildsame Formgebung (IBF) an der RWTH Aachen untersucht.Free-formed, self-supporting folding structure made of metal sheets using the incremental sheet forming (ISF). Sheet forming is traditionally a costly process that requires expensive tools as well as forms such as winds or dies with customized punches, which are only profitable when producing high quantities. However, the incremental sheet forming (ISF), a novel forming technique, works highly differential. In contrast to the common single-stage jacking process, the incremental metal forming is a sequential process in which a forming instrument circumscribes the part contour and warps the sheet repeatedly. This process can easily be adjusted to a variety of individual thin sheet forms. In view of this fact, the ISF is a highly flexible process that allows to craft series of geometrically different components efficiently. ISF appears to be an ideal production-related instrument to realize the principle of lightweight constructions in space folding structures and multilayer folding structures that form the basis of self-supporting building envelopes or facades made of thin sheet. The actual characteristics and conditions of the constructive realization of a free-shaped, two-layered envelope formed with the incremental metal forming procedure has been analyzed during a research project

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In the architecture and construction sector the trend for individualization is often expressed in complex-shaped freeform buildings. Due to missing universal and mature construction methods for freeform buildings, they are usually realized with customized solutions that often include massive, material-consuming substructures, while the visible skin has neither structural nor functional properties. In this context a new concept for self-supporting lightweight structures for the realization of free-form surfaces and the production of the corresponding components has recently been proposed. Taking into account the large part dimensions and the varying part geometries in this application a flexible production chain based on incremental sheet forming has been developed and optimized. It has been validated by producing six-sided large-scale pyramids in 140 similar variants which were assembled to a self-supporting free-form demonstrator. Two-point incremental sheet forming (TPIF) was used with a universal partial supporting tool with the goal to produce all variants without dedicated tooling. Although the majority of pyramids was produced successfully with the applied TPIF strategy, there was a small number of parts with a very asymmetric shape that showed severe buckling in the side walls. For a detailed analysis of this observation the asymmetry was quantified using a wall angle ratio. Subsequently, a single-point incremental sheet forming (SPIF) strategy was successfully applied as an approach to avoid buckling. The results confirm the assumption that the circumferential expansion in SPIF suppresses buckling due to tensile stresses in the side walls, whereas the circumferential compression in TPIF triggers buckling due to the compressive stresses in the side walls.

Der Einsatz von Stahl im Bauwesen war über viele Jahre von engen Vorgaben hinsichtlich der einsetzbaren Halbzeuge geprägt und verlieh Stahlkonstruktionen häufig den Charakter von „Baukastensystemen“. Die Modernisierung der Bearbeitungsmethoden veränderte diese Gegebenheiten. Im digitalen Zeitalter ist es nunmehr möglich, nicht nur aufseiten der Produktion, sondern auch aufseiten des Entwurfs, der Darstellung, der Planung und der Konstruktion eine Prozesskette zu erstellen, mit deren Unterstützung hoch individualisierte Stahlbauteile erzeugt werden können, die Teil wiederum von individualisierten Bauwerken sind. Mit diesen Mitteln lassen sich Leichtbaukonstruktionen aus Blech mit individuellem Design erstellen, wie zwei Prototypen, die an der RWTH Aachen in Kooperation des Lehrstuhls Tragkonstruktionen mit dem Institut für Bildsame Formgebung entstanden sind, eindrücklich demonstrieren. Die neuartige Bauweise aus Feinblech erschließt einen für den Stahlbau bisher eher unzugänglichen Formenkanon und erweist sich als äußerst materialsparend und liegt so im Trend des nachhaltigen Bauens unserer Zeit.

Product development is complex due to the manifold requirements resulting from various perspectives, such as design, production, safety and sales. A concurrent engineering (CE) approach permits to respect all perspectives in the early development stage. However, in the architecture and construction sector for example, CE is particularly difficult to realize, because the central steering for this collaboration process is missing. Thus, the application of CE in the research sector can promote technical progress and cost reduction. In the specific field of freeform architecture, in most cases an individual shape of single components is unavoidable and the use of standard components impossible. Due to missing universal and mature construction concepts for freeform buildings, they are mostly realized with customized solutions often including material-consuming substructures, while the visible skin has only limited structural and functional properties.In this context the present paper proposes a novel universal panel system made of double-curved sheet metal layers enabling the assembly of self-supporting lightweight structures for the realization of freeform surfaces. The panel system has been developed in cooperation of architects, construction and production engineers, successfully applying an interdisciplinary CE approach. As a result, the concept allows for material and cost efficient solutions applicable for a wide range of freeform applications. The detailed development of the panel system is still in progress.Besides the general panel concept, the paper presents in particular the corresponding manufacturing chain and the tooling concept. Accounting for the varying part geometries in this application a flexible manufacturing chain based on the combination of stretch forming and incremental sheet forming has been developed. The entire production process is implemented in a single machine setup and successfully tested on a small-scale prototype.