References of "Plapper, Peter 50002870"
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See detailCorrelation of Optical Signal During Laser Fusion Welding of Copper to Aluminum
Mathivanan, Karthik UL; Plapper, Peter UL

in Journal of Laser Applications (2021, January 05), 33(1),

Laser joining of dissimilar metals, copper and aluminum, allows for the precise delivery of laser energy and high process speed. The keyhole-based process is very efficient for welding Al–Cu, considering ... [more ▼]

Laser joining of dissimilar metals, copper and aluminum, allows for the precise delivery of laser energy and high process speed. The keyhole-based process is very efficient for welding Al–Cu, considering the high reflectivity and thermal conductivity of the materials joined. For the Al–Cu system, the formation of detrimental intermetallic compounds is the main issue. Fusion welding with laser as a heat source involves the melting of metals. However, the high speed of the laser welding process is advantageous for terminating the excessive melting of Al and Cu and eventually controlling the detrimental intermetallic phases. Therefore, information pertaining to melted material is an important criterion for achieving joint strength. In this paper, the photodiode signal measured during the laser welding of Cu to Al is investigated as a process monitoring technique. In welding from Cu to Al, the melting of Al (bottom sheet) is very critical for joint strength. The amount of Al material that can be intermixed in Cu depends on the solubility limit of the Al–Cu system. The plasma plume emission during laser welding is used to extract the rapid melting of Al. This study shows the correlation of the Al characteristic peak at a wavelength of 396 nm with the shear strength of the joint. [less ▲]

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See detailEVALUATION OF THE JOINT BASED ON DIFFERENT SURFACE CONDITIONS FOR ALUMINUM-POLYAMIDE LASER WELDING
Amne Elahi, Mahdi UL; Koch, Marcus; Plapper, Peter UL

in Journal of Laser Applications (2021)

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface ... [more ▼]

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface treatment of the metal has a decisive effect on the joint quality and thus on the mechanical properties. In the present study, different mechanical and laser-based surface treatments have been investigated to develop diverse surface conditions on aluminum. Abrasive blasting and laser ablation were used to increase the surface roughness, while abrasive polishing and laser polishing were applied to minimize the surface roughness. In contrast to abrasive surface treatments, laser-based ones were implemented to create artificial oxide layers on the aluminum surface. The surface structures of pretreated samples have been studied with scanning electron microscopy and roughness test. The laser welding of pretreated aluminum with polyamide was achieved with the heat conduction joining technique. To enlarge the welding area and control the heat input, spatial and temporal modulations of the laser beam were implemented. Finally, a single lap tensile-shear test, microscopic analysis of fractured surfaces, and welding cross sections were employed to evaluate the joints. Results show that the presence of an artificial aluminum oxide layer and low roughness are essential to achieve a superior joint between aluminum and polyamide (improvement of approximately 58% in the shear load of the joint compared to as-received welded samples). The cross section of the superior joint which is the laser-polished aluminum welded to polyamide is studied with transmission electron microscopy. [less ▲]

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See detailHolo Study – Mixed Reality Framework for Industrial Engineering Education and Training
Minoufekr, Meysam UL; Plapper, Peter UL

in Trends in Technical & Scientific Research (2020), 4(5), 0131-0135

Nowadays, students struggle with understanding complex production processes and kinematics of machine tools and robots. While professors mostly have been dealing with these subjects for many years ... [more ▼]

Nowadays, students struggle with understanding complex production processes and kinematics of machine tools and robots. While professors mostly have been dealing with these subjects for many years, students have only short time to be introduced to the complex nature of these topics. Mixed Reality allows students to engage hands-on in their subjects to reach new dimensions of understanding. Making challenging topics for students accessible by creating a more visual and tactile experience. The applications for entertainment and gaming are off the charts, but the implications for augmented reality in education and science are also undoubtedly massive. The project focusses on making education as interactive as possible, which helps both, teachers and students receive a unique tool for communicating phenomena and processes that are difficult to describe verbally. As a result, a complex knowledge becomes simple, an involvement of students grows, the quality of education increases [less ▲]

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See detailA Survey of Information Entropy Metrics for Complex Networks
Omar, Yamila UL; Plapper, Peter UL

in Entropy (2020)

Information entropy metrics have been applied to a wide range of problems that were abstracted as complex networks. This growing body of research is scattered in multiple disciplines, which makes it ... [more ▼]

Information entropy metrics have been applied to a wide range of problems that were abstracted as complex networks. This growing body of research is scattered in multiple disciplines, which makes it difficult to identify available metrics and understand the context in which they are applicable. In this work, a narrative literature review of information entropy metrics for complex networks is conducted following the PRISMA guidelines. Existing entropy metrics are classified according to three different criteria: whether the metric provides a property of the graph or a graph component (such as the nodes), the chosen probability distribution, and the types of complex networks to which the metrics are applicable. Consequently, this work identifies the areas in need for further development aiming to guide future research efforts. [less ▲]

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See detailWELDING COPPER TO ALUMINIUM WITH GREEN LASER WAVELENGTH OF 515 NM
Mathivanan, Karthik UL; Plapper, Peter UL

Scientific Conference (2020, October 19)

Joining copper and aluminum sheets is difficult because of brittle intermetallic phases (IMP) formed in the joint, which results in reduced performance. The traditional approach to overcome this issue is ... [more ▼]

Joining copper and aluminum sheets is difficult because of brittle intermetallic phases (IMP) formed in the joint, which results in reduced performance. The traditional approach to overcome this issue is to irradiate the laser beam from Aluminum (Al) to control the weld depth and mixing of Cu in Al. The laser welding approach from the copper side (Cu on top) to Al is very sparse in the literature. In this paper, the welding approach from copper (top sheet) to aluminum is studied with green laser (515 nm) due to improved absorption at this wavelength. The objective of irradiating the laser beam from the copper side (Cu on top) is to exploit the higher solubility of Al in Cu (about 18%), which is significantly higher than Cu in Al. Therefore more Cu and Al can be melted and mixed in the joint for copper sheet placed on the top. From the tensile shear test, a strong joint is obtained with a fracture on the heat-affected zone (HAZ) of Al. Detailed microstructure and composition of Al and Cu in the joint is performed by Energy-dispersive X-ray spectroscopy (EDS) to investigate the composition in the joint. The EDS analysis indicates that a large amount of beneficial Cu solid solution and Al-rich phases is formed in the joint. The detrimental phases are intermixed in between the ductile phase composition i.e Al-rich and Cu solid solution. Therefore the effect of detrimental intermetallic phases is mitigated by intermixing with large ductile phases. With this paper, the fusion welding approach for joining Cu and Al system with a significant level of Cu and Al melting is shown. [less ▲]

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See detailMULTI-LEVEL INFORMATION VALUE STREAM MAPPING
Mangers, Jeff UL; Thoussaint, Lou; Minoufekr, Meysam UL et al

in Proceedings of the 9th International Conference on Mass Customization and Personalization - Community of Europe (MCP-CE 2020) (2020, September 25)

Digitalization and automation of the production according to Industry 4.0 opens new opportunities for companies to develop more efficient value chains. In the context of mass customization, it is ... [more ▼]

Digitalization and automation of the production according to Industry 4.0 opens new opportunities for companies to develop more efficient value chains. In the context of mass customization, it is promising to examine more closely the complete internal value chain of companies, from the first customer contact to the delivery of the finished product, prior to provide digital configurations for customized products. A critical aspect for internal inefficiencies and complication of an aspired automation are the interfaces of departments due to inconsistent and non-uniform information transfer. This article presents a versatile approach to visualize the internal information flow at inter-departmental level as well as at intra-departmental level. The described multilevel information value stream mapping method perfectly suits as prerequisite for a digitalization or automation of internal information flows. As framework for the time capturing and visualization, ISO 22468 is used, and an industrial use case exemplifies the research findings. [less ▲]

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See detailAugmented Reality in Manual Assembly Processes
Kolla, Sri Sudha Vijay Keshav UL; Sanchez, Andre UL; Minoufekr, Meysam UL et al

in Kolla, Sri Sudha Vijay Keshav; Sanchez, Andre; Minoufekr, Meysam (Eds.) et al Augmented Reality in Manual Assembly Processes (2020, September 23)

Augmented Reality (AR) is a novel technology that projects virtual information on the real world environment. With the increased use of Industry 4.0 technologies in manufacturing, AR has gained momentum ... [more ▼]

Augmented Reality (AR) is a novel technology that projects virtual information on the real world environment. With the increased use of Industry 4.0 technologies in manufacturing, AR has gained momentum across various stages of product life cycle. AR can benefit production operators in many manufacturing tasks such as quality inspection, work instructions for manual assembly, maintenance, and in training. This research presents not only a typical architecture of an AR system but also both its software and hardware functions. The architecture is then applied to display virtual assembly instructions in the form of 3D animations on to the real world environment. The chosen assembly task in this research is to assemble a planetary gearbox system. The assembly instructions are displayed on a mobile device targeting a static tracker placed in the assembly environment. [less ▲]

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See detailPre and post-treatments to improve weldability and mechanical properties of Aluminum-Polyamide laser welded specimens
Amne Elahi, Mahdi UL; Koch, Marcus; Heck, Mike et al

in Procedia CIRP (2020), 94

The laser polishing surface treatment is a prerequisite for enhanced weldability that is enabled by superior adhesion between the weldments. The paper describes the laser polishing process of the aluminum ... [more ▼]

The laser polishing surface treatment is a prerequisite for enhanced weldability that is enabled by superior adhesion between the weldments. The paper describes the laser polishing process of the aluminum surface to develop a relatively thick and porous artificial aluminum oxide layer. Microscopic observation shows the laser polishing process significantly improves the adhesion of molten polyamide to the aluminum surface. Besides, the shear load of the pretreated joints is much higher than that of as-received ones. However, for the majority of the welded samples, the failure happens at the polyamide near the interface of aluminum/polyamide due to the thermal effect and structural changes of polyamide during the welding process. By applying the post-treatment of the welded specimens with different cycles, the mentioned failure mechanism is not observed anymore. Therefore, the mechanical properties of the joint will be improved and reach to the limits of the base materials. [less ▲]

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See detailDigitizing of Research and Teaching
Plapper, Peter UL

Scientific Conference (2020, September 05)

The current Covid-19 crisis impacts all manufacturing areas and new processes are sought. This presentation provides the audience with three examples related to assembly work instructions, logistics data ... [more ▼]

The current Covid-19 crisis impacts all manufacturing areas and new processes are sought. This presentation provides the audience with three examples related to assembly work instructions, logistics data handling and manufacturing education, for which innovative ways to obtain access to context sensitive data based on digital tools are investigated. Augmented Reality (AR) and Virtual Reality (VR) facilitate access to relevant manufacturing information. In order to provide logistic warehouse workers with immediate access to shipping documents, to avoid paper print-outs, and to eliminate error-prone typing of information, critical information should be handled digitally and hands-free. To support logistic workers to efficiently document, register and trace receipt, storage or delivery of goods, the presented solution is built on hands-free digital tools with AR technology in commercially available smart glasses. Similarly, workers who execute complex assembly operations frequently require either assistance or support for the next assembly step. Depending on the context, relevant assembly process information is automatically displayed together with the environment in the AR smart glass. Thus, the operator is supported by the presented hands-free-tool to complete the next challenging tasks. Currently, teaching is being transferred from physical class-room teaching to remote or hybrid education. For this purpose, Virtual Reality (VR) provides a very welcome opportunity to complement in-presence teaching with exposure to examples of real manufacturing operations captured in videos of industrial case studies. Students apply learnings from theoretical classes to manufacturing case studies by identifying best practices and also recognizing waste. The presentation shares experience in teaching of lean methods based on AR technology to graduate engineering students. [less ▲]

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See detailHighlighting chemical bonding between nylon-6.6 and the native oxide from an aluminum sheet assembled by laser welding
Hirchenhahn,, Pierre; Alsayyad, Adham Ayman Amin UL; Bardon, Julien et al

in ACS Applied Polymer Materials (2020)

Polymer/metal hybrid assemblies are well suited for automotive and biomedical applications because of their ability to create lightweight structures with a wide range of design possibilities. Laser ... [more ▼]

Polymer/metal hybrid assemblies are well suited for automotive and biomedical applications because of their ability to create lightweight structures with a wide range of design possibilities. Laser welding is a promising technique for joining dissimilar materials thanks to its quickness, freedom of design and absence of adhesives. Still, the fundamental causes of adhesion in hybrid laser welding remain not well understood. Therefore the present work aims at highlighting a chemical bonding between a polymer, nylon-6.6 and a metal, aluminum. To access the interface information, the samples were first broken, leaving a residue on the surface, which was dissolved afterwards. The chemical reactive sites of nylon molecule able to react with aluminum surface were suggested and the feasibility of these reactions was analyzed in the light of the results obtained by means of X-ray photoelectron spectroscopy (XPS) and Time of flight secondary electron microscopy (ToF-SIMS). [less ▲]

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See detailAgent-based, hybrid control architecture for optimized and flexible production scheduling and control in remanufacturing
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Journal of Remanufacturing (2020), (2020),

Introduction: Motivated by high ecological and economical potentials and driven by new laws, remanufacturing is receiving increasing attention as a process that puts used products into “as good as new or ... [more ▼]

Introduction: Motivated by high ecological and economical potentials and driven by new laws, remanufacturing is receiving increasing attention as a process that puts used products into “as good as new or better” condition. Within this process, there are many challenges, which are unseen in manufacturing, such as the uncertainties resulting from unknown conditions of the used products. This places special demands on the control of the remanufacturing system (RS). Methodology: To handle these uncertainties an agent-based hybrid control architecture comprising centralized and decentralized components is presented. In the former, the scheduling takes place including the consideration of the use of automated guided vehicles (AGV) to realize flexible material handling within the RS. The scheduling of machines and AGVs is thereby considered simultaneously and not separately, as it is the case in currently available control systems. For the optimization of the simultaneous scheduling Constraint Programming (CP) is used. In the decentralized component, all participants within the RS will be networked as a cyber-physical system and controlled by respective agents. These agents can communicate with each other in order to find solutions. The architecture is implemented as a multi-agent system. Results: Simulation results, using benchmark instances, show that simultaneous scheduling results in a 19.7% reduction of the makespan. Furthermore, the CP-based approach delivers the best results, compared to other approaches for simultaneous scheduling, which are also achieved in a significantly shorter computing time. [less ▲]

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See detailMensch-Roboter-Kollaboration in der Domäne Refabrikation – State-of-the-Art und Ausblick
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Jäkel, Jens; Thiel, Robert (Eds.) Tagungsband AALE 2020 Automatisierung und Mensch-Technik-Interaktion (2020, March 05)

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See detailAgentenbasierte, hybride Steuerungsarchitektur für cyberphysische Refabrikationssysteme
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Jäkel, Jens; Thiel, Robert (Eds.) Tagungsband AALE 2020 Automatisierung und Mensch-Technik-Interaktion (2020, March 05)

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See detailNew opportunities by laser joining of dissimilar materials
Plapper, Peter UL

Scientific Conference (2020, February 13)

The presentation gives an overview about research projects at UL related to laser welding of dissimilar materials. Literature reference at the end enables the reader to dig deeper in case some specific ... [more ▼]

The presentation gives an overview about research projects at UL related to laser welding of dissimilar materials. Literature reference at the end enables the reader to dig deeper in case some specific projects are of interest. [less ▲]

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See detailLaser joining of titanium alloy to polyamide: influence of process parameters on the joint strength and quality
Alsayyad, Adham Ayman Amin UL; Lama, Prashant; Bardon, Julien et al

in International Journal of Advanced Manufacturing Technology (2020)

Laser-assisted metal–polymer joining (LAMP) is a novel assembly process for the development ofminiaturized joints in hybrid lightweight products. This work adopts a design of experiments (DoE) approach to ... [more ▼]

Laser-assisted metal–polymer joining (LAMP) is a novel assembly process for the development ofminiaturized joints in hybrid lightweight products. This work adopts a design of experiments (DoE) approach to investigate the influence of several laser welding parameters on the strength and quality of titanium alloy (Ti-6Al-4V)–polyamide (PA6.6) assembly. Significant param- eters were highlighted using the Plackett Burmann design, and process window was outlined using the Response Surface Method (RSM). A statistically reliable mathematical model was generated to describe the relation between highlighted welding param- eters and joint strength. The analysis ofvariance (ANOVA) method was implemented to identify significant parametric interac- tions. Results show the prominence offocal position and laser power, as well as significant interaction between laser power and beam speed, on the joint strength. The evolution ofweld defects (bubbles, excessive penetration, flashing, titaniumcoloring, weld pool cavities, and welding-induced deflection) along the process windowwas investigated using optical microscopy. The resulted deflection in titaniumwas quantified, and its relationship with welding parameters was mathematically modeled. Robust process window was outlined to maintain insignificant deflection in the welded joints. Results showed that the growth ofweld defects correlates with a decline in joint strength. Optimal parameters demonstrated a defect-free joint, maximizing joint strength. [less ▲]

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See detailCreation of an ISO Standard at the Example of Value Stream Management Method
Plapper, Peter UL; Mangers, ; Minoufekr, Meysam UL et al

in Jakobs, Kai (Ed.) Shaping the Future Through Standardization (2020)

The main objectives of this chapter are to elucidate the necessity of a standardized Value Stream Management (VSM) and to clarify how this standard can effectively increase corporate performance within ... [more ▼]

The main objectives of this chapter are to elucidate the necessity of a standardized Value Stream Management (VSM) and to clarify how this standard can effectively increase corporate performance within cross-enterprise supply chain networks (SCNs). VSM is an effective tool to collect, evaluate and continuously improve product and information flows within companies in a common and standardized manner. The findings of this chapter are not only valid for consistent product and information flows, but are representative for the relevance of standards in general. In a globalized economy, standards need to be generally accepted and valid for all countries. Thus, corporate or national standards, only have limited impact. The International Standardization Organization (ISO) provides the means to develop, negotiate and communicate standards, which are globally binding. This chapter shares the experience of ISO 22468 standard development within ISO/TC 154 WG7 and proves its applicability by an administrative use case. [less ▲]

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See detailInfluence of Aluminum Laser Ablation on Interfacial Thermal Transfer and Joint Quality of Laser Welded Aluminum–Polyamide Assemblies
Al Sayyad, Adham UL; Bardon, Julien; Hirchenhahn, Pierre et al

in Coatings (2019), 9(11),

Laser assisted metal–polymer joining (LAMP) is a novel assembly process for the development of hybrid lightweight products with customized properties. It was already demonstrated that laser ablation of ... [more ▼]

Laser assisted metal–polymer joining (LAMP) is a novel assembly process for the development of hybrid lightweight products with customized properties. It was already demonstrated that laser ablation of aluminum alloy Al1050 (Al) prior to joining with polyamide 6.6 (PA) has significant influence on the joint quality, manifested in the joint area. However, profound understanding of the factors affecting the joint quality was missing. This work investigates the effects of laser ablation on the surface properties of Al, discusses their corresponding impact on the interfacial thermal transfer between the joining partners, and evaluates their effects on the joint quality. Samples ablated with different parameters, resulting in a range from low- to high-quality joints, were selected, and their surface properties were analyzed by using 2D profilometry, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). In order to analyze the effects of laser ablation parameters on the interfacial thermal transfer between metal and polymer, a model two-layered system was analyzed, using laser flash analysis (LFA), and the thermal contact resistance (TCR) was quantified. Results indicate a strong influence of laser-ablation parameters on the surface structural and morphological properties, influencing the thermal transfer during the laser welding process, thus affecting the joint quality and its resistance to shear load. [less ▲]

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See detailOptimized and flexible scheduling of AGVs and process machines in Re- manufacturing 4 .0 Systems using multi-agent technology and simultaneous scheduling
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Ramírez Fernández, Francisco Javier; Honrubia Escribano, Andrés (Eds.) Abstracts III International Workshop on Autonomous Remanufacturing 2019 (2019, October 02)

In remanufacturing processes the condition of the used products is unknown. This leads to many challenges which are special to the domain of remanufacturing and not known from manufacturing. One of these ... [more ▼]

In remanufacturing processes the condition of the used products is unknown. This leads to many challenges which are special to the domain of remanufacturing and not known from manufacturing. One of these challenges is the stochastic routing of products based on the unknown product conditions. This problem in particular requires a flexible scheduling and control system for the remanufacturing system as well as the intralogistics. The aim of this research is to optimize the scheduling and control of remanufacturing systems considering the flexible material transport by AGVs. Therefore the networking of all resources is organized as an embedded system treating the remanufacturing system as a cyber-physical system in the context of industry 4.0. The scheduling and control of the remanufacturing system will be achieved by a combination of multi-agent technology to deal with unexpected events and the optimization of the schedule by simultaneous scheduling of machines and AGVs. Machine scheduling and transport scheduling have been vastly studied by many researchers, but most of the works address both problems separately. However, these two problems are closely linked and influence each other. By looking at them together, it is possible to achieve an improvement in the overall schedule. In the first step of the research work, the simultaneous scheduling of machines and AGVs has been compared with the currently used sequential scheduling within a simulation study. For this purpose, benchmark instances known in the literature were used. The simulation results show the superiority of the simultaneous scheduling of machines and AGVs. [less ▲]

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