Andrea Bohn

Applications for a new production technology – analysis of linear flow-split linear guides

Within the collaborative research centre 666 “Integral Sheet Metal Design with Higher Order Bifurcations” the innovative manufacturing technologies linear flow-splitting and linear bend-splitting are researched that allow the continuous production of multi-chambered steel profiles in integral style. The massive forming processes create an ultra-fine grained microstructure in the forming area that is characterized by an increased hardness and lower surface roughness compared to as received material. These properties predestine the technology to be used in the production of linear guides. Additionally, the multi-chambered structure of the linear flow-split and -bend components can be used for function integration. To design and evaluate linear guides that use the whole technological potential, the research is focused on a macroscopic and a microscopic point of view.The macroscopic approach is targeting the development of linear flow-split linear guides with integrated functions to provide additional performance values to the established machine parts. Continuously produced guidance systems with innovative functionality can be introduced to a new market with the technology push approach. Preliminary designs of linear flow-split guidance systems and integrated functions are promising. Therefore, an approach to develop new functions for linear flow-split linear guides basing on calculation models and property networks is shown [1]. With this approach, optimized solutions can be created and possible design modifications can be derived. In this contribution, the development and integration of a clamping function for decelerating the slide is presented. Calculation models for analyzing the functionality are presented and validated by finite element models and experiments.The microscopic examination of the profiles aims to investigate the material behavior, particularly of the formed areas. Beside the conventional mechanical and fatigue properties of linear flow-split material ZStE500 [2], the present work focuses on the rolling contact fatigue. This is necessary to evaluate linear flow-split components regarding their eligibility with regard to the rolling contact fatigue behaviour. The Hertz theory for rolling contact fatigue is only valid for homogeneous materials [3]. The flow-split material ZStE500 shows a non-homogeneous behaviour and has to be analyzed with the Finite Element Method in order to determine stresses and strains. In comparison to simulation results with unformed and therefore homogeneous material, the effect of linear flow-split surfaces on the rolling contact behavior is demonstrated. Based on these results, it is possible to start experimental investigations on rolling contact fatigue of linear flow-split components to validate the FE model and determine the performance of linear flow-split flanges for rolling contact fatigue.Copyright

An Approach to Classify Methods to Control Uncertainty in Load-Carrying Structures

Today, a wide variety of methods to deal with uncertainty in load-carrying system exists. Thereby, uncertainty may result from not or only partially determined process properties. The present article proposes a classification of methods to control uncertainty in load-carrying systems from different disciplines within mechanical engineering. Therefore, several methods were collected, analysed and systematically classified concerning their characteristic into the proposed classification. First, the classification differs between degrees of uncertainty according to the model of uncertainty developed in the Collaborative Research Centre CRC 805. Second, the classification differs between the aim of the respective method to descriptive methods, evaluative methods or methods to design a system considering uncertainty. The classification should allow choosing appropriate methods during product and process development and thus to control uncertainty in a systematic and holistic approach.

Developing Robust PSS Offerings

PSS are often used by multiple users as well as under varying conditions. These users do not know the PSS well and therefore are less likely to recognize problems or handle situations that could damage the product. Therefore design of robust product components for PSS is important.

Modellierung von Unsicherheit in der Produktentwicklung

Fur die erfolgreiche Entwicklung von Produkten sind typischerweise eine Vielzahl von Einflussfaktoren zu beruksichtigen. Aufgrund von Unsicherheiten, z.B. fehlenden Informationen oder schwankende Einflussgrosen im Produktlebenslauf, ist eine detaillierte Analyse jedoch haufig schwierig. In diesem Beitrag wird deswegen die Wahrscheinlichkeits- mit der Moglichkeitstheorie verglichen, um die Anwendbarkeit beider Theorien fur eine quantitative Analyse von Unsicherheiten im Rahmen der Produktentwicklung zu untersuchen. Am Beispiel eines Euler-Knickstabes werden die Einschrankungen einer statistischen Analyse sowie die Vorteile der Berechnung einer unscharfen, kritischen Knicklast aufgezeigt. Das Ziel ist eine geeignete Beschreibung relevanter Unsicherheiten als Grundlage fur die Entwicklung robuster Produkte. Die vorgestellten Betrachtungen sind Teilergebnisse des Sonderforschungsbereichs 805 „Beherrschung von Unsicherheit in lasttragenden Systemen des Maschinenbaus“ der Deutschen Forschungsgemeinschaft an der Technischen Universitat (TU) Darmstadt.