Publications

More and more players in the German wind energy sector are concerned with the question of how to deal with the aging German wind fleet, as around 5,200 turbines will simultaneously reach the end of the feed-in tariff funding period of the Renewable Energy Sources Act (EEG) for the first time at the end of 2020. Around 8,000 wind turbines will follow by the end of 2025, as shown in Figure 1. Operators of affected wind turbines will then have the choice between (I) continuing to operate the old turbine within the framework of direct marketing on the European Power Exchange, (II) repowering the old turbine by a new and more efficient wind turbine at plant-specific feed-in premium levels tendered in the German renewable energy auctions or (III) decommissioning the respective plant finally.

However, the question of choosing the right option arises not only for the operators themselves, but also for various other players in the wind energy sector:

Project developers, turbine manufacturers, and investors are interested in evaluations of plant-specific repowering potentials in the existing wind turbine fleet in order to provide operators with targeted support in implementing new projects; dismantling contractors and disposal companies particularly search for derivatives of plant-specific dismantling potentials and the associated disposal and recycling flows in order to enable optimal handling of the comprehensive dismantling processes; and regional as well as supra-regional public and political institutions are interested in estimates of changes to the installed wind energy capacity in order to enable optimal control of future capacity expansion under consideration of societal, economic and political aspects.

dismantling, wind turbine

At the end of 2020, around 6,000 wind turbines will simultaneously fall out of the 20-year subsidy under the Renewable Energy Sources Act (EEG) for the first time. Around 8,000 further wind turbines will follow by the end of 2025. Operators of affected wind turbines will then have the choice between continuing to operate the old turbine at the significantly lower spot market prices of the European Power Exchange (EPEX), operating a new and more efficient wind turbine at the site of the old turbine (repowering) at auctioned conditions or finally decommissioning it. Quo vadis 20 years old Wind trubines? Scientists from the Institut für Integrierte Produktion Hannover (IPH) have therefore been working on the "DemoNetXXL" project, funded by the German Research Foundation (DFG), in cooperation with the Institute for Information Systems at Leibniz University Hanover on the selection and design of optimal post-utilisation strategies for wind power plants.

wind turbines, plants repowering, post-use strategies, dismantling

In lightweight automotive construction, hybrid structures made of various materials as well as solid and sheet metal elements are used. By hybrid compound forging, a sheet steel and a solid aluminium part can already be joined in a material-locking manner during the forming process. The Institut für Integrierte Produktion Hannover (IPH) gGmbH and the Institut für Schweißtechnik und Trennende Fertigungsverfahren (ISAF) of TU Clausthal are investigating how solid aluminium bolts and steel sheets can be joined in a material-locking manner. This article explains the decisive forming parameters. Furthermore, the tool design for the joining tests is presented.

lightweight construction, aluminum, compound forging

The joint is the weak point at a hybrid metal semifinished product in tube hydroforming. In real forming processes, a deformation at the joint would be prevented in order to avoid failure. A better knowledge of the forming behavior enables to reduce the effort in process design. Thus, this study investigates in hybrid material combinations and the forming behavior of the joint area regarding their suitability for tube hydroforming.

hydroforming, tube, steel-aluminum, FEA

This paper describes the development and prototypical implementation of an energy self-sufficient sensor for condition monitoring of wet-running steel disc clutches in marine gearboxes. For the precise control of an automated system and the monitoring of its performance, the knowledge about the possible wear is an essential prerequisite. In addition, the storage of sensor data over the life of the system offers the possibility of long-term condition monitoring. The combination with various other technological components creates a solution that enables cost-effective condition monitoring of marine gearboxes. Compared to existing systems, for example, the costs for installation and maintenance are significantly reduced. Both the methodology from the morphological box to the fine concept as well as the first measurements of the sensors are presented.

automated system, condition monitoring, metrology, clutch, gearbox

Lightweight automotive construction increasingly relies on hybrid structures made of steel and aluminium. These materials are currently joined mainly by form locking, for example by riveting. Welding and bonding are also used for joining the two materials. Hybrid composite forging allows to join the two components during the forming process. This shortens the process chain. With the help of zinc as a brazing material, the components are joined to form a material bond. This publication explains the results of the simulative parameter study. It shows how temperature, geometry and speed influence the joining result. Furthermore, first results of practical joining tests are presented.

lightweight construction, aluminum, simulative parameter study

Resource depletion and climate change are the main drivers for the rapid change of power generation structures. The energy transformation is causing an increase in energy prices for manufacturing small and medium-sized enterprises (SMEs). Within the last decade energy prices in Germany have doubled and are expected to grow even further . Metal processing SMEs are already attributing 4.5 percent of their gross production value to electricity costs. The paper shows the possible savings potential of the use of inventory levels as energy storage and provides approaches to an efficient solution of the associated optimization problems.

production program planning, energy costs, inventory level, energy storage

So far, the design of automated guided vehicle systems (AGVS) as well as the disturbance management in AGVS is in need of human experts. In order to design an AGVS or clear an occurring disturbance a system expert has to work through defined process steps manually. This work?ow does not only demand expert knowledge but causes high costs and the proposed solutions are often limited to the experiences of the expert. The following paper introduces the development of a case-based reasoning expert system for an automated proposition of solutions for disturbances in AGVS and discuss related work in the feld of expert systems for the design support of AGVS.

expert system, automated guided vehicle systems, disturbance management

In average, more than 1,275 wind turbines were installed annually since 1997 in Germany and more than 27,000 wind turbines are in operation today. The technical and economic life time of wind turbines is around 20 to 25 years. Consequently, dismantling of aging wind turbines will increase significantly in upcoming years due to repowering or decommissioning of wind farms and lead to millions of costs for operators. An option to supersede the costly and time-consuming dismantling of wind turbines entirely on-site is to establish a dismantling network in which partly dismantled wind turbines are transported to specialized dismantling sites for further handling. This network requires an optimization model to determine optimal locations and an appropriate distribution of disassembly steps to dismantling sites. The challenge is to consider the networks dependency on the trade-off between transportation and dismantling costs which, in turn, depends on the selection of dismantling depths and sites. Building on the Koopmans-Beckmann problem, we present a mathematical optimization model to address the described location planning and allocation problem. To permit a proof-of-concept, we apply our model to a case-study of an exemplary wind farm in Northern Germany. Our results show that the model can assist dismantling companies to arrange efficient dismantling networks for wind turbines and to benefit from emerging economic advantages.

dismantling, wind turbine, optimization model

Structured factory planning is a key to ensure the competitiveness concerning to the increasing pressure from globalization and the high market dynamic. Companies though avoid to do factory planning projects, because of the high effort. For this reason, the processes of factory layout capture and factory layout assessment are in need of improvement in order to increase the efficiency, which will be achieved through new technologies and a semi automation of the processes.

factory planning, drone, photgrammetry, laserscan, image data processing

Black marking as micrometer scaled binary coding applied on shafts by ultrashort pulsed lasers with high contrast and without ablation as a non-contact sensor system for combined measurement of angular position and torque.

laser materials processing, sensors, absorption, image analysis

Constantly increasing quality requirements and ever-stricter conditions pose difficult challenges for the foundry industry. They must produce the high-quality components demanded by the market at a reasonable cost. Modern technologies and innovative methods help to master this challenge. Until recently, production, from the design of the aluminum melting furnace to daily process, relied largely on traditional methods and experience. However, important data and information about the melting process—for example, the temperatures and the shape of the aluminum block in the furnace—can hardly be obtained with conventional experimental methods, as the temperatures exceed 700 °C. Therefore, this research project investigates the method of monitoring a melting process by means of optical sensors for the first time. The purpose of this paper is to predict the surface shape of the block during the melting process, as it is not possible to maintain a constant monitoring due to the heat and energy loss during measurement (Einsatz einer Lichtfeldkamera im Hochtemperaturbereich beim Schmelzvorgang von Aluminium. To generate the necessary data, a 3D light-field camera is installed on top of an aluminum melting furnace in order to monitor the process. The basic idea is to find a general method for curve modeling from scattered range data on the aluminum surface in 3D space. By means of the (x, y, z) data from the 3D camera, the aluminum surface is modeled as a polynomial function with coefficient derived using various interpolation and approximation methods. This study presents an attempt to find the optimal polynomial function model that describes the aluminum surface during the melting process by interpolation or approximation methods. The best method for curve fitting will be extended and implemented for surface modeling. 

melting process light-field, polynomial function, interpolation, approximation, aluminum surface

The development of an ecological logistical impact model for the holistic consideration of the logistics performance should allow companies and especially SMEs to be able to record the CO2 emissions of the logistics transparently. For the development of such a model, the basic influencing factors must be defined and furthermore established as quantitatively assessable criteria. This paper discusses the basic relationships between logistics and ecology. Moreover, the boundaries for an ecological and logistical impact model are discussed and procedures for the definition of the required evaluation criteria are described.

Ecology, Logistics, CO2 calculation, Impact Modell, sustainabilty

A hot forging process allows to produce parts of excellent quality and technical properties. Nevertheless, it is not possible to forge undercut geometries like piston pin bores, it is usually necessary to manufacture them in subsequent processes. Thus, an undercut-forging process was newly developed. Such a process requires a multidirectional forming tool, which is challenging due to a high clamping force of the tool during the process. With the research results, the requirements to the crucial tool components of heavy springs diminish, allowing using standard spring devices instead of large and expensive custom designed devices. The aim of this study is to analyze the clamping force, its origin, and influencing factors in order to facilitate the tool design. Therefore, in forming simulations the input parameters press velocity, initial temperature, and punch shape were investigated, and their effect on the clamping force was statistically evaluated. The press velocity has the major impact on the resulting clamping force. The initial part temperature and the shape of the punch tool showed minor but still significant effects. This combination of input parameters reduces the load and the stress on the tool, enabling to perform the process on smaller forging presses. Eventually, forging trials validated the results.

forging, undercut, FEA, multidirectional, clamping force, tool design

Future factory planning projects are much easier and cheaper than today. With a drone it es possible to scan a factory layout during the flight in a short time. To achieve this benefits, researchers of the IPH are developing a new factory planning method.

drone, threedimensional factory layout, object recognition in point clouds, factory planning

Rotary energy harvesters offer the possibility of generating energy in the center of rotation or outside of the center of rotation. There are both concepts with reference to the outer housing as well as different concepts without a fixed reference. In addition, Energy Harvester solutions are available that provide energy to the housing and generate energy through the rotation of the shaft. The selection of a concept must be made individually for each application and depends on various influencing factors. Decisive in particular are the installation space, the energy requirement of the sensor node and the speed.

energy supply for microsystems, energy harvesting, rotary energy harvester, power management

Currently used methods for factory layout planning are limited in their evaluation methods. Factory evaluation is either qualitative or quantitative, but limited to a few objectives. These deficits were overcome by the development of a quantitative, multidimensional ad hoc factory evaluation method. On this basis, it is now possible to develop a method for factory layout planning that reduces the planning effort and significantly increases the quality of the solution.

facility layout planning, factory planning, operations research, mathematical modelling

For companies it is challenging to identify application scenarios for Industry 4.0 as well as to use the associated potential. This article describes a strategy, which includes methodical and knowledge-based guidelines for decisions, to increase the likelihood of beneficial industry 4.0 transformations.

industry 4.0, strategy, production system

In forging industry, the development of new bulk metal forming technologies still is determined by a separation between construction and simulation. The resulting iterations take a lot of time. In this paper, the data mining method neuronal network is used to predict the forming force of a finite element forging simulation of a flange.

simulation, AI, prognosis, forming force

In lightweight construction, light metals like aluminum are used in addition to high-strength steels. However, a welded joint of aluminum and steel leads to the precipitation of brittle, intermetallic phases and contact corrosion. Nevertheless, to use the advantages of this combination in terms of weight saving composite hybrid forging has been developed. In this process, an aluminum solid part and a steel sheet were formed in a single step and joined at the same time with zinc as brazing material. For this purpose, the zinc was applied by hot dipping on the aluminum in order to produce a connection via this layer in a forming process, under pressure and heat. Due to the formed intermediate layer of zinc, the formation of the Fe-Al intermetallic phases and the contact corrosion are excluded. By determining the mathematical relationships between joining parameters and the connection properties the strength of a specific joint geometry could be adjusted to reach the level of conventional joining techniques. In addition to the presentation of the joint properties, the influence of the joining process on the structure of the involved materials is also shown. Furthermore, the failure behavior under static tensile and shear stress will be shown.

lightweight construction, aluminum, joining properties

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