Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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PowerGrasp: Development Aspects for Arm Support Systems

2022 , Goppold, J.-P. , Kuschan, J. , Schmidt, H. , Krüger, J.

Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).

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Business model development in European aerospace start-ups: The case of the spaceup project

2021 , Steinhöfel, Erik , Singer, Katrin

In their quest for market establishment and organizational maturity, business model development (BMD) plays a crucial role for start-ups. After foundation, primary focus is no longer on generating promising business ideas, but on commercializing a start-upâs inherent potential. This particularly applies to innovative, technology-based start-ups. Here, superior functions in relation to existing solutions resulting from advancements in technologies and the value associated with such functional superiority are center of entrepreneurial activity and BMD. This study presents the BMD methodology applied for supporting 60 technology-based, aerospace-related start-ups on their path to becoming leading companies in their field and the results of its application in the frame of the SpaceUp project. The methodology was carried out in a two-stage process. First, a questionnaire was provided to the start-ups to capture and assess their business model (BM). In a second step, based on the information provided, a detailed evaluation of the start-upsâ BM was carried out and starting points for further development were generated. In order to assess the relevance and usefulness of the results generated by applying the methodology, a quantitative survey was conducted among the start-ups. The survey showed that the generated results were perceived as beneficial by the start-ups and that the application of the methodology therefore proved successful in the project.

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Sensor integration in hybrid additive manufactured parts for real-time monitoring in turbine operations

2021 , Uhlmann, Eckart , Polte, Julian , Kersting, Robert , Brunner-Schwer, Christian , Neuwald, Tobias

Real-time monitoring of operation conditions such as tempeatures and vibrations enables efficiency enhancement for maintenance tasks. In energy industry monitoring of critical components such as turbine blades is essential for the operation safety. But the effective recording of critical process data is a challenging task due to the extreme operating conditions. With a hybrid processing approach combining two additive manufacturing technologies new classes of self-monitoring components become possible allowing data acquisition directly inside the component. Using the example of a turbine blade, the hybrid process chain is described. The turbine blade blank is produced via Laser Powder Bed Fusion (L-PBF) with channels for the integration of high temperature sensors. After integration cavities were closed by Laser Directed Energy Deposition (L-DED) followed by classical milling operations for part finishing. The data acquisition is integrated in state-of-the-art product l ifecycle monitoring (PLM) software to create a digital twin. Evaluation shows that temperature could be successfully monitored at conditions of Π= 550°C.

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Effects on part density for a highly productive manufacturing of WC-Co via laser powder bed fusion

2021 , Polte, Julian , Neuwald, Tobias , Gordei, Anzhelika , Kersting, Robert , Uhlmann, Eckart

The additive manufacturing of parts made from difficult-to-weld materials through the usage of preheating temperatures of up to Î0 ⤠500 °C is enabled by newest L-PBF machine tools, such as the RenAM 500Q HT from the company RENISHAW PLC, Wottun-under-Edge, UK. This work aims to delevop processing parameters for the dense and crack-free manufacturing of tungsten-carbide cobalt (WC-Co) via this off-the-shelf machine tool. Therefore the laserpower and scanning speed were varied between 80 W ⤠PL ⤠350 W and 140 mm/s ⤠vS ⤠650 mm/s respectively. Furthermore the influence of a continuous and pulsed laser mode was analysed. A focus was set on the identification of parameters that enable a highly productive manufacturing while maintaining a high part density. A parameter set for relative density rel. > 94 % and a buildup rate v = 0.59 mm3/s was developed.

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Cutting edge preparation of monolithic ceramic milling tools

2021 , Uhlmann, Eckart , Polte, Mitchel , Polte, Julian , Hocke, Toni

Due to international competition, continuous increases in productivity, product quality and reduction of production costs are required. Especially, the development of milling tools made of innovative cutting materials and application-specific tool geometries for the machining of brittle materials are in focus to overcome these challenges. One approach to improve the performance and the tool behaviour concerning milling of graphite is the use of monolithic ceramic milling tools. Unfortunately, the high brittleness of the ceramic leads to breakouts on the cutting edge during the grinding process. This results in an increased maximum chipping of the cutting edge, which has a significant influence on the milling process. To improve the breakout behaviour, a cutting edge preparation with the immersed tumbling process was applied. To enable a process reliable cutting edge preparation, a suitable lapping medium, the influence of the processing time as well as the depth of imme rsion were investigated. Besides the maximum chipping of the cutting edge, the rounded cutting edge radius was also analysed. The results show that a process reliable cutting edge preparation of monolithic ceramic milling tools with a maximum chipping of the cutting edge RS,max ⤠3 µm and a rounded cutting edge radius of rβ ⤠7 µm could be realised. In future investigations, the experimental applicability of monolithic ceramic milling tools will be proved.

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Photocatalytic effect of TiO2-coated surfaces on the pathogenic microorganisms E.coli and S.aureus

2021 , Uhlmann, Eckart , Hein, Christoph , Brehmer, Annika

The use of titanium dioxide as a strong photocatalytic substance can have a large effect in combating the spread of pathogens through heavily contaminated surfaces. For this purpose, various materials, such as metal, glass, and polymer were coated with rutile- and anatase-rich titanium dioxide by sol-gel method. The contact angle and photocatalytic activity of the coated surface were measured under UV irradiation. The anatase-rich titanium dioxide showed higher photocatalytic activity, which further increased with the coating thickness. The process temperature had an effect on the photocatalytic activity due to the temperature-dependent conversion of anatase to rutile crystal conformation. The coated surfaces had strongly reduced contact angles compared to the uncoated material. In particular, the anatase-rich surfaces resulted in superhydrophilic properties. Photocatalytically induced antibacterial activity against pathogenic microorganisms in liquid environments was d emonstrated, especially for gram-negative Escherichia coli bacteria.

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Development of a Conceptual Understanding of the term Technological Capability

2021 , Hecklau, Fabian , Kidschun, Florian , Kohl, Holger , Hizal, Gamze Gül

The term "technological capability" has been studied for almost 40 years. It is an important component of technology strategy that contributes to the success and strengthening of organizations competitiveness. There are numerous attempts to define the term in the literature, but it is always used in different contexts. Thus, the definition of technological capability varies depending on the researcher's perspective and objectives. Therefore, the main objective of this research is to develop an own definition and interpretation of the term technological capability. To this end, an extensive literature review will be conducted to examine the basic concepts and management areas of technological capability and to analyze the individual definitions of the term. The subsequent goal is to derive an understanding of what technological capability is in terms of research and technology organizations.

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Application of tool electrodes oxidised with humid and dry air during the electro-discharge drilling of MAR-M247 alloy

2021 , Uhlmann, Eckart , Polte, Mitchel , Streckenbach, Jan , Camin, Bettina , Chocholaty, Ondřej , Dinh, Ngoc Chuong

The requirements and challenges of machining advanced materials in the field of aerospace, automotive and tool industry are increasing constantly. Due to their mechanical properties, cutting of high-strength materials such as superalloys is severely limited. Electro-discharge drilling can be used for the manufacturing of holes in hard to machine materials. Although electrical discharge machining (EDM) is successfully applied to the machining of holes in turbine blades, a lack of performance and challenges concerning the geometrical accuracy still remain. By applying inner flushing, the resulting electrically conductive debris is flushed through the lateral working gap, increasing the probability of arcs and short circuits. The resulting increased tool wear, conicity of the hole, limited hole depth and process instabilities are still challenging in electro-discharge drilling. In order to decrease the effects of the arcs and short circuits, a surface modification is appli ed to increase the electrical resistance of the lateral surface of the tool electrode. As a result, the mentioned impairments occur less frequently due to decreased occurrence of arcs and short circuits in the lateral working gap. For the present investigation copper tool electrodes were thermally oxidised in dry and humid air with different durations and used afterwards for electro-discharge drilling of MAR-M247. The tests were carried out on the machine tool AGIETRON Compact 1 from the company GF AgieCharmilles, Losone, Switzerland. Holes with a depth of t = 11 mm were drilled using various surface-modified tool electrodes with a diameter of d = 2 mm. Oxidation with dry air and a extended oxidation time resulted in a 18 % lower erosion duration, accompanied by an increase of the linear wear of the tool electrode Île below 10 %.

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A contribution to the interpretation of organizational resilience (Or) based on the analysis of key drivers and conceptual elements

2021 , Hecklau, Fabian , Kidschun, Florian , Kohl, Holger , Hizal, Gamze Gül

Organizations are increasingly confronted with unexpected events, which can occur within or outside the organization and relate to various dimensions or aspects. The significance and extent of its impact on the organization can be quite surprising (Duchek 2020). Despite the fact that academic interest in this subject area has grown steadily in recent years, its conceptualization is not yet fully developed. There is no consensus on the meaning of resilience and the elements it contains. This paper contributes to the understanding and need for organizational resilience (OR) and also reveals gaps in its conceptualization. Resilience is understood as the ability of an organization to repel, prepare for, consider, absorb, recover from and adapt ever more successfully to actual or potential adverse events. Those events are either catastrophes or processes of change with catastrophic outcome which can have human, technical or natural causes.(Thoma 2014) In order to survive in an uncertain environment and promote future success, organizations must be able to deal with all these manifestations of the unexpected and catapult themselves out of the crisis. They have to develop a capacity for resilience that enables them to react appropriately to unexpected events and to make capital from events that could potentially threaten the survival of an organization (Lengnick-Hall et al. 2011; Duchek 2020; Denyer 2017; Aguilar 1967). In literature and practice, there are various approaches to OR, which consist of phase models that also allow an assessment of an organization as resilience using a maturity model. From the examined methods in this paper it follows that the resilience capability is questioned only after occurrence of an adverse event and no "preparation phase" according to the Fraunhofer resilience cycle exists. This ex post approach endangers not only the competitive position, but also the existence of an organization.

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Validation of Immersive Design Parameters in Driving Simulation Environments

2021 , Lyga, Yvonne , Lau, Merle , Brandenburg, Elisabeth , Stark, Rainer

Driving simulators are used for the prospective validation of technical systems in the automotive sector. The design of simulation environments can affect drivers and should be considered in investigations of driver-vehicle interactions. The aim of this research is to minimize the gap between driving simulators and real car studies by integrating immersive parameters into simulated driving environments. Stereoscopy, surround sound and motion feedback were analyzed with regard to driver behavior and experience and were then compared to data of a real drive from a previous investigation. The authors conducted a study with N = 48 participants performing a dual-task scenario in a driving simulator. Results reveal significant effects of immersive design parameters on gaze behavior and mental workload. Findings provide guidance for an efficient and cost-effective development of driving simulation environments.

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