Frank Mantwill

Efficient Consideration of Contact in Compliant Assembly Variation Analysis

The geometric deviations of real parts pose a major challenge, particularly in the extensively automated mass production of complex assemblies. To meet this challenge, an attempt is made, with the aid of statistical tolerance analysis, to predict dimensional accuracy for various assembly concepts as precisely as possible depending on the individual part tolerances. Most recent developments enable consideration to be given to the deformability of the parts during joining in order to improve the prognostic quality of simulation. The methods that are employed reveal deficits if nonlinear effects such as contact, extensive deformations, or material inelasticities occur. In this work, contact between or with adjacent parts during joining will be investigated, and an efficient and reliable method, which can be unproblematically integrated into existing compliant assembly variation analysis programs, will be developed. To achieve this, the methods of springback calculation according to Liu (1995, “Variation Simulation for Deformable Sheet Metal Assemblies Using Mechanistic Models ,” Trans. NAMRI/SME, 23, pp. 235–241) have been extended and coupled with numerical contact mechanics methods in order to realistically portray the problem, which usually involves intensive computing, with a minimum of additional effort. The method that has been developed will be validated on the basis of two examples with the aid of nonlinear finite element analyses, the results of which can be regarded as state-of-the-art in mechanical problems involving contact. The quality of the results reveals that this method improves the quality of prognosis for a wide range of applications and, consequently, that production problems can be combated during an early development phase.

Patterned CoCrMo and Al2O3 surfaces for reduced free wear debris in artificial joint arthroplasty

Surface wear of corresponding tribological pairings is still a major problem in the application of artificial joint surgery. This study aims at developing wear reduced surfaces to utilize them in total joint arthroplasty. Using a pico-second laser, samples of medical CoCrMo metal alloy and Al2 O3 ceramic were patterned by laser material removal. The subsequent tribological investigations employed a ring-on-disc method. The results showed that those samples with modified surfaces show less mass or volume loss than those with a regular, smooth surface. Using calf serum as lubricating medium, the volume loss of the structured CoCrMo samples was eight times lower than that of regular samples. By structuring Al2 O3 surfaces, the wear volume could be reduced by 4.5 times. The results demonstrate that defined surface channels or pits enable the local sedimentation of wear debris. Thus, the amount of free debris could be reduced. Fewer abrasives in the lubricated so-called three-body-wear between the contact surfaces should result in less surface damage. Apart from direct influences on the wear behavior, less amounts of free debris of artificial joints should also be beneficial for avoiding undesired reactions with the surrounding soft tissues. The results from this study are very promising. Future investigations should involve the use of simulators meeting the natural conditions in the joint and in vivo studies with living organisms.

Visualisation of component deformation for virtual quality assessment

The calculation of deformation with numerical methods such as finite element analysis (FEA) includes the discretisation of the continuous part geometry in simple geometrical elements. This so-called meshing therefore involves a reduction in visualisation quality. With the aid of the DefoVis method, which is presented by Helmut Schmidt University Hamburg and Volkswagen AG, deformation status visualisation in the quality familiar from CAD systems is achieved by combining discrete calculation results with tessellation of the original CAD geometry. In combination with a ray tracing method, a realistic, photograph-like illustration of deformed parts can be generated, enabling virtual assessment of the appearance. As application examples in body development rear lid and bonnet installation are investigated.

Lebenszykluskosten in der Digitalen Fabrik

Kurzfassung Die stetig steigende Komplexität der Anlagenstruktur im Karosseriebau sowie kürzer werdende Planungsphasen stellen eine große Herausforderung an die Planungsabteilung der Automobilhersteller dar. Bei der Ausschreibung von Produktionsanlagen spielen, neben den Anschaffungskosten, die Folgekosten eine immer wichtigere Rolle. Da wesentliche Produkt- und Produktionsfaktoren in der Regel mit Simulationsmodellen vorab untersucht werden, kann durch die Ergänzung um Lebenszykluskosten die Vergabeentscheidung unterstützt werden. Dieser Beitrag stellt ein Konzept zur Unterstützung der Bewertung von unterschiedlichen Lieferanten während der Planungsphase vor.

User Supporting Assistances as a Prerequisite for Developing Tailored CIAs

Automotive manufacturers are challenged by a growing number of product derivatives, decreasing sales figures of each product, shorter product life cycles and increasing market dynamics. There is a strong need for a competitive cost-optimal engineering and production. Therefore multidisciplinary require-ments have to be taken into account in early phases of the product development process. The tool helping to consider these requirements could be a web-based Assistance for the development engineers and other involved people during the process. The Assistance can be embedded in the CAD system or accessed directly with a web-browser. The opportunities of having a user tailored tool working with a web-based interface across different systems where different user groups inside the enterprise are working without waste of time would avoid duplication of effort and might help to develop the Competitive Innovation Advantage (CIA). This paper describes the principle and usage of an Assistance at the field of Standard-Part-Management between product development and production planning.

Lebenszykluskostenbewertungen zur frühzeitigen Produktbeeinflussung im Produktentstehungsprozess

Kurzfassung Steigender Wettbewerbsdruck führt zu hohen Anforderungen an die Produktentwicklung bei einer gleichzeitig wirtschaftlich, ökologisch und technologisch optimalen Herstellung. Die frühe Konzeptphase im Produktentstehungsprozess birgt hierfür ein großes Optimierungspotenzial. Eine frühzeitige Berücksichtigung von Lebenszykluskosten in der Konzeptphase ist durch die zukünftige Produktgestalt auf Basis von Produktionsanforderungen möglich. Der Beitrag beschränkt sich dabei zunächst auf die wirtschaftliche Dimension. So können der Produktentwicklung seitens der Produktionsplanung Lösungsangebote auf Basis von Lebenszykluskostenbetrachtungen bereitgestellt werden. In diesem Beitrag wird ein Ansatz vorgestellt, der bereits in der frühen Konzeptphase Produktionsanforderungen berücksichtigt, um eine optimierte Entscheidungsfindung auf der Grundlage von Lebenszykluskosten zu ermöglichen.

Der modulare Lebenszykluskosten-Baukasten

Kurzfassung Durch den permanenten Kostendruck fokussieren sich Unternehmen zunehmend auf Folgekosten der Produktion. Gerade in einer komplexen Produktionsumgebung der Automobilindustrie spielt die Kostenbeherrschung entlang des Lebenszyklus eine wichtige Rolle. Die Berechnung der Lebenszykluskosten stellt dabei eine große Herausforderung dar, da aktuelle Normen hierzu nur unzureichend Methoden beschreiben. Der folgende Ansatz des modularen Lebenszykluskosten-Baukastens stellt eine Strukturierung von Methoden zur Kostenbewertung vor.

Data Interface Concept for the Connection of Applications to Web-Based Systems

Data exchange between applications and servers is always a risky theme from the IT department point of view, because confidential data has to be kept secure. Usual direct connections make it necessary to get approved by the IT department before they can be used inside of the company what makes it expensive and takes a lot of time. The concept shows the possibilities of an alternative approach by connecting applications via the browser control element to a server and the corresponding opportunities as well as the advantages in saving the main program logic server side.

Know-How Identification, Scoring, and Classifying in Product Development Processes

The following paper describes the development of a method for identifying, scoring and classifying captive process know-how in German enterprises of the automobile industry. Object of study will be the product development process. An initial point is described, in order to illustrate the results of an empirical analysis that lead to the necessity of protecting captive process know-how methodology.

Visualisierung von Bauteildeformationen zur virtuellen Qualitätsbeurteilung

Die Berechnung von Deformationen mit Hilfe von numerischen Methoden wie der Finite-Elemente-Methode (FEM) beinhaltet die Diskretisierung der kontinuierlichen Bauteilgeometrie in einfache geometrische Elemente. Diese sogenannte Vernetzung (Meshing) ist verbunden mit einer Reduzierung der Darstellungsqualitat. Mit Hilfe einer von der Helmut-Schmidt-Universitat Hamburg und der Volkswagen AG vorgestellten Methode namens DefoVis wird durch die Verknupfung von diskreten Berechnungsergebnissen mit einer Tesselierung der ursprunglichen CAD-Geometrie eine Darstellung von Verformungszustanden erzielt, wie sie von der Qualitat her aus CAD-Systemen gewohnt ist. In Kombination mit einem Ray-Tracing-Verfahren wird auf diesem Weg eine fotorealistische Darstellung deformierter Bauteile erzeugt, die eine Beurteilung der Anmutung virtuell erlaubt. Als Anwendungsbeispiele im Karosseriebau werden Heckklappen- und Frontklappeneinbau untersucht.