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Item type:Publication, Access status: without files , 194 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Friction-induced vibrations during tightening of bolted joints : analytical and experimental results(Multidisciplinary Digital Publishing Institute (MDPI), 2018-12-05); ; Bolted joints are one of the most used machine elements. Holding together structures of all sizes, the integrity rests on their shoulders. Thus, an accurate and reliable assembly of the joint is crucial. While it is the aim to not experience friction-induced vibrations at all, at some situations, it is unavoidable. These cases, however, have yet been out of the focus of control algorithms due to the volatile nature of the process. This contribution delivers analytical and experimental results for the occurrence of friction-induced vibrations during tightening of bolted joints. Previous findings of system characteristic constants could be validated, which can be used to monitor the tightening process even while strong vibrations during the tightening process occur. Additionally, a real-time algorithm is presented which allows for an advanced process monitoring and control by identifying process characteristics based on which predictions of the process can be made. These measures significantly improve the capabilities to reach the target values of the tightening process.Publicationtype: Journal Article281 364 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Friction-induced vibrations during tightening of bolted joints: insights from a multi-body model(American Society of Mechanical Engineers (ASME), 2017); ; The tightening process of bolted joints shows a highly dynamic behavior, which depends on numerous factors and can therefore be challenging to be adequately quantitatively reproduced. The presented model solves this problem by combining a multi-body model of the joint with the sophisticated LuGre friction model. This allows for a detailed simulation while simultaneously reducing the computational work in comparison to a standard finite element simulation. We demonstrate that, with a constant tightening angular velocity, the progression of the tightening torque and the preload force can be described by three constants. The model further allows to implement custom torque sources, screw types, and materials to further extend its capabilities. In this contribution, we focus on the basic relationships of acting torques on the joint and friction-induced vibrations during the tightening process. Furthermore, effects of typical geometric and material changes on the stick-slip frequency are demonstrated and discussed.Publicationtype: Conference Paper109 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Evolutionary-based design and control of geometry aims for AMD-manufacturing of Ti-6Al-4V parts(Elsevier, 2016-09-16); ; ; ; Additive Metal Deposition (AMD) is an additive manufacturing process building parts based on a nozzle-fed powder by laser assisted solidification. The AMD technology offers unique advantages for the production of near net-shape parts. In contrast to the powder bed-based technologies it provides a high productivity grade. Today AMD lacks reproducible process strategies manufacturing large parts in narrow tolerances. The building height of a single layer and the geometrical shape of a whole part alter progressively with increasing part dimensions - consecutively leading to a higher effort in the manufacturing-process development for such parts. To reduce this effort, in this paper first an iterative identification of optimal process parameters is performed by following an evolutionary algorithm under varied BC. Based on the geometry-related parameter sets, tolerances are defined. The process strategies and tolerances are validated for a prototype application considering the defined quality aims. Finally the results are discussed and summarized in an a-priori process design guideline for AMD Ti6Al4V-parts.Publicationtype: Journal ArticleScopus© Citations 15 299 486