News Article | April 1, 2016
Engineering departments at large automotive companies today use simulation when conducting virtual tests during the development phase of their new vehicle designs. This involves computing the physical properties of the cars in advance, which significantly shortens the often year-long testing loops with real test vehicles. For example, this is already being done in testing passive safety, acoustics, durability and reliability, and for energy efficiency, fuel consumption and carbon emissions. At present, vehicle can be simulated very well using software tools. However, it is difficult to simulate environmental influences that have a significant effect on the automobile while driving, such as street conditions, weather and driving maneuvers. Experts often work with assumptions rather than with actual data because generating the actual data and making it relevant for simulations is complex and expensive. "For years we have been working closely with automobile and commercial vehicle manufacturers; we have recognized this need and made it our mission to develop cost-effective solutions to include road and environment into simulation based vehicle engineering", says Dr. Klaus Dressler of the Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern. At the Hannover Messe 2016, scientists from the Fraunhofer Institute will be presenting a system that consists of a test vehicle, a geo-referenced database and a vehicle simulator (Hall 7, Stand E11). Using two 360-degree laser scanners, the Road & Environmental Data Acquisition Rover (REDAR) captures enormous amounts of environmental data at normal driving speed. "We call it point cloud data. That means for each 3D coordinate we have environmental data," says Dressler. The ITWM researchers have managed to prepare the terabyte-sized dataset so that it can be used in real time in 3D interactive driving simulations. "The volume of data is so large that the data cannot be easily fed into the memory of a computer system. We have therefore developed an out-of-core method to process only the data necessary for the running time in the simulator." REDAR captures data from the building fronts to the left and right and from the street in front and behind of the vehicle at a distance of 200 meters. It also scans the road's surface with a resolution of less than half a centimeter. An inertial platform eliminates potential movement of the vehicle from the raw data of the laser scanner so that it can be objectively processed by the software. "To build such a complex measurement system and consistently process the data through appropriate algorithms were our biggest challenges," Dressler adds. The test vehicle has been in use since 2015 and has already been collecting data for various customer projects. ITWM's own driving simulator RODOS (Robot-based Driving and Operation Simulator) converts the metrics collected by REDAR. The simulator consists of a cabin system in which a steering wheel, gas and brake pedal can be operated. The driver cabin is connected with a 6-axle robot system that realistically simulates accelerations, braking or driving around tight curves. "The test driver moves through a virtual world that feels very realistic after just a few minutes," explains Dressler. The simulations are supported with data from the database system known as Virtual Measurement Campaign (VMC). The database provides the world's road network with its topography, regulations, weather and additional geo-referenced data. "With the data collected from the data acquistion vehicle we merge real fine-coarsed data with the coarse-grained data from the VMC. Merging the two worlds is an important step in developing test scenarios for the engineering of road-bound vehicles," says Dressler. At the joint stand of the Fraunhofer Society at the Hannover Messe, the researchers will show how REDAR's fine-coarsed data is imported into the coarse-grained world of 3D driving simulations. Manufacturers are adding more and more advanced driver assistance systems in their vehicles. This goes towards autonomous driving, one of the major mega trends in automotive industry. In order for driverless cars to find their way through a maze of streets, they need to continually detect their surroundings using sensors, GPS, etc. to communicate with their environment. "We are currently putting a lot of effort into testing these technologies. Some manufacturers are even considering setting up entire artificial towns in which self-driving test vehicles can communicate with mock buildings, traffic lights and such. It would, of... In addition to the virtual testing of new automation systems, our system lets engineers incorporate emissions and fuel economy regulations more easily into the design process than before. Current test scenarios in the sector have been criticized because they insufficiently represent real consumption and emission. Dr. Klaus Dressler of the Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern: "With the help of VMC, REDAR and RODOS, we can quickly and cost-effectively create for our customers test scenarios suited for autonomous driving as well as consumption and emissions testing under variable environmental and usage conditions."
News Article | November 2, 2015
The new T-shirt is nice and soft, it is comfortable to wear, and the fabric falls loosely. This usually meets the requirements in the field of fashion. The situation is different in the case of technical textiles. They have to meet different requirements. Compression bandages, for example, should put pressure on the human tissue, therefore the stretchability of the material has to be right. Materials for protective jackets need to have a certain bending stiffness: If something hits them, the material should protect the wearer and not yield. Textiles for car seats have to be durable, especially at the edges. Manufacturers of these products have two determining factors with which they can define the properties: the yarns, as well as the structure via which the individual yarns are interconnected – such as special weave patterns or mesh variations. The mechanical properties of the yarns can be identified relatively easily: With a device into which they are clamped. It pulls the fiber and measures how much force is required to stretch it by a predetermined value. It is harder to comment on the properties of the fabric, though: The fabric has to be produced and then tested. However, this can naturally only be done with samples. It would be too costly to produce all conceivable designs with the various yarns. The Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern, Germany has developed a simpler and also more insightful method to improve the properties of textiles. "We simulate the behavior of the materials", says Dr. Julia Orlik, scientist at the ITWM. "In that way, we are able to accurately predict which properties the fabrics have depending on the yarn and structure". The benefits: With the simulation, the researchers can examine all of the conceivable variants of patterns and yarns and analyze which one is optimal for the desired application. All without having to produce the individual textiles. For the first time, they can even simulate the contact between the yarns. How well do the individual threads slide over each other? And how does this in turn affect the entire fabric? A starting point for the simulation are the parameters that the scientists receive from the manufacturers. These relate mainly to the yarns. In terms of contact properties, the question is more difficult: Few manufacturers can determine these parameters. Therefore, the researchers take measurements from selected real pieces of fabric, comparing them to the simulations and adjusting the parameters until the results of the simulation and the experiment match. The researchers do not only analyze individually selected structures; they also change them gradually. "Take the shape of a a single mesh, for example. It resembles a Greek letter Ω somewhat. Now, you can make this Ω longer and narrower, or shorter and wider. We change the mesh shape continuously and see what effect that has on the entire fabric," says Orlik. "In short: We compute the best configuration". In addition, the researchers are investigating the yarns: How do the properties of the fabric change if, say, more stretchable yarn is used? The parameters are provided by the manufacturers. If a manufacturer has already decided upon a certain yarn, for example, the researchers look for the best structure for this yarn.
News Article | December 10, 2015
Day after day, an aircraft hurtles down the runway, slowly lifts from the ground and climbs towards the clouds. To do this for years at a time and still remain safely in the air, jet engine turbines must be precision engineered without even the slightest flaw. That's why, before installation, inspectors examine every single blisk – the turbine disk and its 30 to 60 blades – very carefully for six to eight hours. In this process, they rely exclusively on their practiced eye to spot any problems. Capturing the geometry and analyzing the surface In the future, inspectors will receive technical support via the AMI4BLISK system (Automated Geometrical Measurement and Visual Inspection for Blisks): it measures the blisk's geometry and also automatically examines it for defects. Researchers at the Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern developed the system in close cooperation with Hexagon Metrology GmbH and the Hexagon Technology Center GmbH. The EU project is part of the Clean Sky joint technology initiative. "With our system, inspectors can examine the blisks almost twice as fast as before – and with the same precision," says Markus Rauhut, head of department at ITWM. "What's more, we always have the same recognition rate: the system never gets tired and even night shifts cause no complaint." ust as before, geometric measurement is performed using a coordinate measuring machine. A cantilever arm with a probe touches several hundred points on the blisk. In the future, the machine will also examine surface quality. Instead of just a measuring probe, the cantilever arm will be outfitted with two cameras and a light to ferret out scratches, dents and pressure marks. The corresponding software collects details in a list about the type and exact position of each flaw. An optical sensor developed by Hexagon in turn uses the data to measure the individual defects in more detail. Although it can inspect small areas only of up to one square millimeter in size, the sensor measures more precisely than a camera. Once these investigations have been completed, the human inspector steps in and takes a closer look at any defects detected, using the report generated by the system and a 3D representation of the blisk. Color coding reveals which areas of the turbine the system analyzed automatically. If the camera was unable to identify certain spots – inside a drilled hole, for instance – those areas are marked red on the computer display. "The system doesn't just deliver an objective test report, but also confirms that the entire blisk was examined," explains Rauhut. One of the challenges for the camera system is determining exactly how far away the camera is from the respective blisk part. This is important because the software can't calculate how long or how deep scratches or dents are if the distance information isn't accurate. Otherwise, areas that are further away appear smaller than they actually are. The CAD data for each blisk offers the solution: the software takes the information about the blisk's exact geometry and turns the virtual CAD turbine so that its position in space perfectly corresponds to the test subject's real position. Then for each individual pixel, it calculates the distance from the camera to the point on the blisk. This means the optical sensor's tool can provide exact information about where a defect is located, as well as how long and wide a scratch is. The core system is already complete. Researchers will introduce the AMI4BLISK system at Control 2015, the international trade fair for quality assurance in Stuttgart on May 5–8. You can find it at the Fraunhofer shared exhibition stand, which is coordinated by the Fraunhofer Vision Alliance (Hall 1, Booth 1502). This year, the booth focuses on Industry 4.0. In the next step of the development process, the scientists will aim to have the AMI4BLISK system ready for the market in 2016. Explore further: Quality control at the point of a finger
News Article | March 1, 2017
Non-woven materials are usually well hidden and are therefore not visible. However, if you are looking for them, you can find them everywhere: as a lining in winter jackets, as a padding in sofas, as a soundproofing mat in cars, as insulation in house walls, as a filter in kitchen exhaust hoods, as a cosmetic pad in bathrooms or as a separating layer in electric cables. Highly absorbent non-woven can even be found in the diapers of our little children. It is an extremely versatile and high-performance material which is indispensable in our everyday lives. Accordingly, textile manufacturers and mechanical engineers are interested in keeping its production as efficient and flexible as possible. The Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern has developed special software called the FIDYST tool (Fiber Dynamics Simulation Tool). It simulates the movement of fibers in turbulent air flows. In the production of non-woven materials, the fibers or threads are each stretched with the aid of air and deposited onto a conveyor belt. Depending on the speed and temperature of the air stream, a non-woven product with the desired structure, density and strength results. One widely used application is random web, in which the individual fibers display a diverse orientation, thereby forming a random web which is simultaneously voluminous and firm. How precisely the fibers move in the airflow and in which orientation they land on the conveyor belt is computed by the simulation software FIDYST which the researchers have developed. After simulating the airflow, the user only has to enter the material properties of the fibers in the software. The software then simulates the dynamic behavior of thousands of fibers. Even fiber mixtures can be simulated with the software. The result can be visualized in a three-dimensional representation. Equipped with this data, the manufacturer can then, for example, improve the air flow in a targeted manner. This results in a non-woven fabric with the desired specification while at the same time reducing energy and raw material consumption. The software simulation can calculate that by changing the configuration of the machine, fewer fibers are needed to produce a non-woven fabric with the desired structure and strength. The Fraunhofer tool not only benefits the textile manufacturers who want to precisely configure their machines for every desired non-woven product. "Mechanical engineers can also use it to create machines that are as efficient and flexible as possible," explains Dr. Simone Gramsch, FIDYST Project Manager at ITWM. Despite the complex computing operations, FIDYST does not rely on expensive, high-performance computers or data centers; the tool is content with standard PCs of the upper performance class and runs on both Windows and Linux. After the calculation, the data can be exported in the "EnSight Gold Case" format and then visualized and analyzed. The format is standard in applications that deal with the visualization and analysis of flow dynamics of all kinds, such as in aircraft or automotive engineering, but also in sports or medicine. Behind FIDYST is a real world premier. For the first time, it has been possible to precisely simulate and predict fiber dynamics in air currents. "The development is the result of several years of research as well as a few doctoral theses. It has been worth it, though; with FIDYST, we have a unique feature," says project manager Simone Gramsch. The ITWM licenses the software to mechanical engineers or textile manufacturers. "If necessary, we also offer FIDYST as a service; then, all the simulations are executed on our computers according to the specifications of the customer," says Gramsch. This is useful when it comes to particularly complex and, therefore, computer-intensive projects.
News Article | December 1, 2015
Small and mid-sized companies usually do not have a research department. The expertise of scientists can also create added value for them, though. This is shown by the example of a manufacturer of burglary-resistent house doors from Rhineland-Palatinate in Germany: simulation methods and software tools of the Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern have been helping to construct these burglary-resistent doors such that they are now eligible for a grant from the Kreditanstalt für Wiederaufbau (KfW- Credit Institute for Rebuilding). The new frame construction provides the entire door with an heat transfer coefficient (HTC) of 0.49 W/m²K. In the process, its burglary-resistent properties remain unchanged. "This is a very low value for burglary-resistent doors, considering their complex structure," says Dr. Matthias Kabel from the Department Flow and Material Simulation at ITWM. "Previously, the frame constructions had a value of 2.84 W/m²K. Now, the HTC of the models from the company catalog are less than 1.3 W/m²K. All doors are therefore eligible for funding," says Dr. Kabel. The HTC is a measure of the thermal transmittance of a gas through a solid body. It is expressed in watts per square meter and Kelvin (W/m²K). "We have demonstrated through the project that with the help of complex simulation methods and software tools, we can optimize even our everyday objects – with direct added value for the customer," says Dr. Kabel. The company manufactures burglary-resistent doors and door frames made of aluminum. The problem: aluminum is particularly good at conducting heat. Cold penetrates into the house and interior heat escapes to the outside. "Not an ideal situation for the energy efficiency of the house," says Dr. Kabel. The ITWM researchers compared and tested the design proposals by predicting all the essential functional properties using precise numerical calculation methods. "With the help of computer simulations, we have been able to look at a large number of possible variants and to design the various materials in the area of the door leaf and the frame profile to the exact millimeter," says Dr. Kabel. The manufacturer did not have to build its own prototypes for the individual variants. As a result, it saved time and costs. "With our tools, we were able to quickly pair up information about the door structure and heat transfer with the requirements of the DIN standard for thermal insulation of windows, doors and shutters. This resulted in proposals for optimal design plans of various door models for the company," says Dr. Kabel. In the first step, the scientists showed that they can simulate the real measurements of heat transfer on the computer precisely. "This helped the customer to become more confident in the process. The company does not have a research department and worked intensively with us on product development," says Dr. Kabel. "Without the simulation, the manufacturer would only have had the mean value of the heat loss of the frame. With the help of the computer-assisted illustration, it was possible to determine exactly which part of the frame was responsible for which portion of the heat loss. We made specific proposals about how the design of the frame could be thermotechnically optimised." The researchers adapted their simulation software to the requirements of the problem regarding the doors: among other things, this included selecting the right material parameters, digitally and accurately portraying the physical effects of heat transport in doors, as well as considering the corresponding DIN norm in the simulation software. The thermal insulation of houses is a key component of energy transmission and is promoted in Germany. The federal government of Germany wants to greatly reduce energy consumption in residential buildings by the year 2050. Through the KfW, it is also promoting the installation of thermally-insulated interior and exterior doors. However, only if an HTC of less than 1.3 W/m²K can be verified. Explore further: Heating with the sun
Latz A.,Helmholtz Institute Ulm |
Zausch J.,Fraunhofer Institute for Industrial Mathematics
Electrochimica Acta | Year: 2013
We present an exclusively thermodynamics based derivation of a Butler-Volmer expression for the intercalation exchange current in Li ion insertion batteries. In this first paper we restrict our investigations to the actual intercalation step without taking into account the desolvation of the Li ions in the electrolyte. The derivation is based on a generalized form of the law of mass action for non ideal systems (electrolyte and active particles). To obtain the Butler-Volmer expression in terms of overpotentials, it is necessary to approximate the activity coefficient of an assumed transition state as function of the activity coefficients of electrolyte and active particles. Specific considerations of surface states are not necessary, since intercalation is considered as a transition between two different chemical environments without surface reactions. Differences to other forms of the Butler-Volmer used in the literature [1,2] are discussed. It is especially shown, that our derivation leads to an amplitude of the exchange current which is free of singular terms which may lead to quantitative and qualitative problems in the simulation of overpotentials. This is demonstrated for the overpotential between electrolyte and active particles for a half cell configuration. © 2013 Elsevier Ltd. All rights reserved.
Altmann E.G.,Max Planck Institute for the Physics of Complex Systems |
Portela J.S.E.,Max Planck Institute for the Physics of Complex Systems |
Portela J.S.E.,Fraunhofer Institute for Industrial Mathematics |
Tel T.,Eötvös Loránd University
Reviews of Modern Physics | Year: 2013
There are numerous physical situations in which a hole or leak is introduced in an otherwise closed chaotic system. The leak can have a natural origin, it can mimic measurement devices, and it can also be used to reveal dynamical properties of the closed system. A unified treatment of leaking systems is provided and applications to different physical problems, in both the classical and quantum pictures, are reviewed. The treatment is based on the transient chaos theory of open systems, which is essential because real leaks have finite size and therefore estimations based on the closed system differ essentially from observations. The field of applications reviewed is very broad, ranging from planetary astronomy and hydrodynamical flows to plasma physics and quantum fidelity. The theory is expanded and adapted to the case of partial leaks (partial absorption and/or transmission) with applications to room acoustics and optical microcavities in mind. Simulations in the limaçon family of billiards illustrate the main text. Regarding billiard dynamics, it is emphasized that a correct discrete-time representation can be given only in terms of the so-called true-time maps, while traditional Poincaré maps lead to erroneous results. Perron-Frobenius-type operators are generalized so that they describe true-time maps with partial leaks. © 2013 American Physical Society.
Wagner A.,Fraunhofer Institute for Industrial Mathematics
Energy Journal | Year: 2014
A model for residual demand is proposed, which extends structural electricity price models to account for renewable infeed in the market. Infeed from wind and solar is modeled explicitly and withdrawn from total demand. The methodology separates the impact of weather and capacity. Efficiency is modeled as a stochastic process. Installed capacity is a deterministic function of time. The residual demand model is applied to the German day-ahead market. Price trajectories show typical features seen in market prices in recent years. The model is able to closely reproduce the structure and magnitude of market prices. Using simulations it is found that renewable infeed increases the volatility of forward prices in times of low demand, but can reduce volatility in peak hours. The meritorder effect of increased wind and solar capacity is calculated. It is found that under current capacity levels in the German market wind has a stronger overall effect than solar, but both are even in peak hours. ©2014 by the IAEE. All rights reserved.
Stahl D.,Fraunhofer Institute for Industrial Mathematics |
Hauth J.,Fraunhofer Institute for Industrial Mathematics
Systems and Control Letters | Year: 2011
In this article, a new model predictive control approach to nonlinear stochastic systems will be presented. The new approach is based on particle filters, which are usually used for estimating states or parameters. Here, two particle filters will be combined, the first one giving an estimate for the actual state based on the actual output of the system; the second one gives an estimate of a control input for the system. This is basically done by adopting the basic model predictive control strategies for the second particle filter. Later in this paper, this new approach is applied to a CSTR (continuous stirred-tank reactor) example and to the inverted pendulum. These two examples show that our approach is also real-time-capable. © 2011 Elsevier B.V. All rights reserved.
Schladitz K.,Fraunhofer Institute for Industrial Mathematics
Journal of Microscopy | Year: 2011
In this paper, the field of quantitative microcomputed tomography arising from the combination of microcomputed tomography and quantitative 3D image analysis, is summarized with focus on materials science applications. Opportunities and limitations as well as typical application scenarios are discussed. Selected examples provide an insight into commonly used as well as recent methods from mathematical morphology and stochastic geometry. © 2011 The Author, Journal of Microscopy © 2011 Royal Microscopical Society.