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21.09.2021

Virtual Quality Inspection Optimizes Production of Filter Nonwovens

Nonwoven production received more attention than ever before from the general public in Corona times, because the technical textile is crucial for infection protection. The ultra-fine nonwoven products are manufactured in so-called meltblown processes. A cross-departmental team at the Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern is optimizing the entire production chain in the »ProQuIV« project. Simulations help to guarantee the product quality of the filter material despite fluctuations in production.

Nonwoven production received more attention than ever before from the general public in Corona times, because the technical textile is crucial for infection protection. The ultra-fine nonwoven products are manufactured in so-called meltblown processes. A cross-departmental team at the Fraunhofer Institute for Industrial Mathematics ITWM in Kaiserslautern is optimizing the entire production chain in the »ProQuIV« project. Simulations help to guarantee the product quality of the filter material despite fluctuations in production.

The abbreviation »ProQuIV« stands for »Production and Quality Optimization of Nonwoven Infection Protection Clothing«. This is because bottlenecks in the production of these materials were particularly evident at the beginning of the Covid 19 crisis. For the meltblown nonwovens, this optimization of the product quality is also particularly difficult because the textiles react very sensitively to fluctuations in the manufacturing processes and material impurities.

Digital Twin Keeps an Eye on the Big Picture
»Meltblown« is the name of the industrial manufacturing process whose ultra-fine fiber nonwovens are responsible for providing the crucial filtering function in face masks. In this process, the molten polymer is forced through nozzles into a forward-flowing, high-speed stream. It is stretched and cooled in a highly turbulent air flow.

»The overall process of filter media production – from the polymer melt to the filter medium – presents a major challenge in simulation,« explains Dr. Konrad Steiner, head of the »Flow and Materials Simulation« department. »In the project, we kept the big picture in mind and developed a completely integrated evaluation chain as a digital twin. In doing so, we take several key components into account at once: We simulate the typical production processes of nonwovens, the formation of the fiber structures and then the material properties – here, in particular, the filter efficiency. This allows us to quantitatively evaluate the influences of the manufacturing process on the product properties.« In each of these individual areas, Fraunhofer ITWM and its experts are among the leading research groups internationally.

Homogeneity of the Material – Fewer Clouds in the Simulation Sky
In the meltblown process, a key factor is the behavior of the filaments in the turbulent, hot and fast air flow. The properties of the filaments are strongly influenced by this air flow. The quality of the filaments – and thus the quality of the nonwovens – is influenced by many factors. Dr. Dietmar Hietel, head of the »Transport Processes« department, knows what this means more precisely in practice. His team has been working at Fraunhofer ITWM for years on the simulation of various processes involving filaments, threads, and fibers. »The focus of the project is the so-called cloudiness, i.e. the non-uniformity of the fiber distributions in the nonwoven,« explains Hietel. »We are investigating the question: How homogeneous is the fabric? Because the quality of the products can be greatly improved if we increase the uniformity. Our simulations help figure out how to do that.«

Objective Evaluation of the Homogeneity of Nonwovens
The researchers also use appropriate image analysis techniques to quantify this cloudiness. The power spectrum plays a special role here. »The cloudiness index (CLI) describes homogeneity complementary to local basis weight and its variance,« describes Dr. Katja Schladitz. She brings her expertise in image processing to the project. »Our CLI ensures a robust assessment of the homogeneity and can thus be used for different material classes and imaging techniques to be used as an objective measure.« The frequencies that go into the CLI calculation can be chosen so that the CLI is meaningful for the particular application area.

Filtration: How Efficient Are the Filters?
For the upscaling to industrial processes such as mask production, the ITWM expertise in filters is also included in the project. The »Filtration and Separation« team led by Dr. Ralf Kirsch has been working for years on the mathematical modeling and simulation of various separation processes.

»What's special about this project is that we calculated the efficiency of the filters for fluctuations of varying degrees in the fiber volume fraction,« emphasizes Kirsch. »This allows us to specify up to what level of cloudiness the required filter efficiency can be achieved at all.« As a current example of this, the figure depicts in the graphic the efficiency of a filter material for N95 masks as a function of the inhomogeneity of the nonwoven.

ITMW Methods Support Across the Entire Process Chain
In »ProQuIV«, digital twins and calculations from Fraunhofer ITWM support a holistic view and better understanding of the processes. The production of technical textiles thus not only becomes more efficient, but the nonwovens can be developed virtually without having to realize this in advance in a test facility. In this way, production capacities can be increased while maintaining or even increase the quality. Together with long-term partners from industry, the research can be put into practice quickly and efficiently.

Simulations save textile companies experiments, allow new insights, enable systematic parameter variations and solve upscaling problems that can otherwise lead to bad investments during the transition from laboratory plant to industrial plant. However, virtual implementation of nonwoven production also opens up new opportunities for optimization at other levels. For example, acoustic insulating nonwovens or even hygiene nonwovens can also be optimized in terms of their product quality precisely with regard to the material properties to be achieved – while taking into account the process fluctuations that occur.

The project is part of the Fraunhofer-Gesellschaft's »Fraunhofer versus Corona« program and was completed in April 2021. The results will flow into several follow-up projects with the nonwovens industry.

(c) Fraunhofer ITWM
27.07.2021

Simulation Software TexMath - Simulating Technical Textiles realistically

From high-performance textiles to compression and sportswear: The modular software program »TexMath« of the Fraunhofer Institute for Industrial Mathematics ITWM enables both the simulation of mechanical material properties and the optimization of textile products.

Accelerated development and optimized design of technical textiles while reducing experiments? The demand for techniques that can realize this is especially high in areas such as the sports, medical, and clothing industries. The »Technical Textiles« team of the  »Flow and Material Simulation« department at Fraunhofer ITWM has taken up this challenge and is developing simulation methods that allow efficient prediction of textile behavior under stretching, shear, bending, torsion, or compression. It is also possible to simulate wrinkling under stretching as well as shrinkage of yarns or critical shear angles throughout the manufacturing process.

From high-performance textiles to compression and sportswear: The modular software program »TexMath« of the Fraunhofer Institute for Industrial Mathematics ITWM enables both the simulation of mechanical material properties and the optimization of textile products.

Accelerated development and optimized design of technical textiles while reducing experiments? The demand for techniques that can realize this is especially high in areas such as the sports, medical, and clothing industries. The »Technical Textiles« team of the  »Flow and Material Simulation« department at Fraunhofer ITWM has taken up this challenge and is developing simulation methods that allow efficient prediction of textile behavior under stretching, shear, bending, torsion, or compression. It is also possible to simulate wrinkling under stretching as well as shrinkage of yarns or critical shear angles throughout the manufacturing process.

The »TexMath« simulation software they developed ensures that process chains in production can be adapted to new materials in advance. Complicated patterns and layers can be mapped with the help of the software and a direct connection to the textile machine can be made. Desired woven, knitted and warp-knitted products are accurately simulated with the software and their material properties computed. In addition to evaluating a particular textile design using simulation, the tools also provide optimization of performance characteristics for different design variations. The goal of the software, according to team leader Dr. Julia Orlik, is to »realize the design according to product properties and target criteria.«

TexMath consists of several components: »MeshUp«, »FibreFEM« and »FIFST«. Each of the components included in TexMath has its specific field of application. In addition, the tools have interfaces to each other as well as connections to the software »GeoDict®« of the Fraunhofer spin-off Math2Market, which can be used, for example, to perform fluid mechanical simulations on the textiles.

One area of application for the TexMath software is the optimization of compression textiles for the medical sector or for sports. For optimal effectiveness, the fit of the material is particularly important. For example, the knitting process can be simulated with TexMath to create a bandage with predefined compression properties and thus design the optimal knitted fabric. This virtual bandage is then loaded in another simulation and put on a virtual arm or leg. Thanks to TexMath, the calculated pressure profile makes it possible to evaluate the compression properties of the bandage in advance and also to directly control the knitting machine according to the optimal design.

»TexMath can also be used to design spacer textiles, such as those used for the upper material of sports shoes and for the production of high-performance textiles, and to optimize them in advance in terms of structure and fluid mechanics,« say Dr. Julia Orlik and department head Dr. Konrad Steiner, naming further areas of application for the software.

The newly developed input interface is particularly user-friendly. The textile class (i.e. knitted, warp-knitted, woven and spacer fabrics) can be easily set. The new graphic interface allows simple and fast configuration.

MeshUp for Structure Generation of Woven Patterns and Stitches
Knitted and woven fabrics are produced with the aid of knitting or weaving machines. Each textile is based on a looping diagramm, which is read into the machine or is firmly pre-defined in the machine. MeshUp is the software module of TexMath, in which looping diagramm for various woven and knitted fabrics with different types of binding, the yarn path and all contact points between different yarns are created, graphically displayed and translated into the corresponding input formats for further simulations in TexMath with FISFT and FiberFEM. In addition, MeshUp also provides the geometry as volume data (voxel format) for calculation tools such as GeoDict and FeelMath.

FiberFEM to Calculate Effective Mechanical Properties of a Periodic Textile Structure
With FiberFEM, woven and braided textiles, spacer fabrics, scrims and trusses can be calculated and optimized regarding their effective mechanical material properties. A special feature of FiberFEM is that, in addition to tensile and shear properties, effective bending and torsional properties of textiles can also be determined based on their textile structure and yarn properties.

As input variables FiberFEM requires the microstructure description from MeshUp, the fiber cross-section geometry, as well as mechanical fiber properties such as tensile stiffness and friction. As output the effective mechanical textile quantities are calculated. Besides the calculation of the effective mechanical material properties for already existing woven or knitted textiles for technical and medical applications, the approach also offers the potential for the targeted design and optimization of new textiles with a given mechanical property profile.

For example, the relaxation behavior of a textile can be determined from the weave or knit pattern and the yarn relaxation times for viscoelastic yarns. Coefficients of friction between the yarns are also taken into account and are directly included in the simulation of the effective properties or identified from the experimental validation with the fabric.

FIFST to Calculate the Deformation and Load of Textiles
The tool FIFST is specialized for dynamic simulations of stretchable knitted fabrics and teir production. For example, the knitting process can be simulated, the pull-off from the knitting machine, the shrinkage to a relaxed textile and also the further deformation during tightening can be calculated. This means that the design of the knitted fabric can also be adapted to predefined tension profiles and individualized machine control is possible for the production of personalized textiles or product-specific designs.

The numerical implementation uses the finite element method with non-linear truss elements, which has been extended for contact problems by an additional internal variable - the sliding of threads at contact nodes. The friction law is implemented with the Euler-Eutelwein model, which was extended by an additional adhesion term. Adhesion thus allows different pre-strains in the respective meshes. The elastic energy is calculated directly from the yarn force-elongation curves.  

One of the most important unique selling points of FIFST is the special technology of assigning several elements to specific threads and their arrangement in the thread as well as the simultaneous contact sliding at millions of nodes. Thus FIFST enables multi-scale simulation of large knitted or woven shell components, taking into account the local textile structure.

Another functionality of the software is to virtually drag textiles over a surface triangulation given in STL format. In the video, woven mask (knitted is also possible) is extended in the plane at 6 points and pulled against the face surface. Its knots are projected onto the face and continue to slide on the surface until the mask is fully in place. If you know frictional properties of yarns on the face, you can investigate further folding formation and also influence it specifically. As a further potential for optimization, FIFST allows to minimize pore sizes of dressed textiles on particularly curved surface areas. This can be achieved by increasing the pre-tension in yarns or by modifying the lapping diagram or the binding cartridge.


For a Test demoversion, please contact

Fraunhofer Institute for Industrial Mathematics ITWM
Fraunhofer-Platz 1
67663 Kaiserslautern

Phone: +49 631 31600-4342

texmath@itwm.fraunhofer.de    

Source:

Fraunhofer Institute for Industrial Mathematics ITWM

(c) Porsche AG
04.05.2021

Fraunhofer: Lightweight and Ecology in Automotive Construction

  • The “Bioconcept-Car” moves ahead

In automobile racing, lightweight bodies made from plastic and carbon fibers have been standard for many years because they enable drivers to reach the finish line more quickly. In the future, lightweight-construction solutions could help reduce the energy consumption and emissions of everyday vehicles. The catch is that the production of carbon fibers is not only expensive but also consumes considerable amounts of energy and petroleum. In collaboration with Porsche Motorsport and Four Motors, researchers at the Fraunhofer WKI have succeeded in replacing the carbon fibers in a car door with natural fibers. This is already being installed in small series at Porsche. The project team is now taking the next step: Together with HOBUM Oleochemicals, they want to maximize the proportion of renewable raw materials in the door and other body parts - using bio-based plastics and paints.

  • The “Bioconcept-Car” moves ahead

In automobile racing, lightweight bodies made from plastic and carbon fibers have been standard for many years because they enable drivers to reach the finish line more quickly. In the future, lightweight-construction solutions could help reduce the energy consumption and emissions of everyday vehicles. The catch is that the production of carbon fibers is not only expensive but also consumes considerable amounts of energy and petroleum. In collaboration with Porsche Motorsport and Four Motors, researchers at the Fraunhofer WKI have succeeded in replacing the carbon fibers in a car door with natural fibers. This is already being installed in small series at Porsche. The project team is now taking the next step: Together with HOBUM Oleochemicals, they want to maximize the proportion of renewable raw materials in the door and other body parts - using bio-based plastics and paints.

Carbon fibers reinforce plastics and therefore provide lightweight components with the necessary stability. Mass-produced natural fibers are not only more cost-effective but can also be produced in a considerably more sustainable manner. For the “Bioconcept-Car” pilot vehicle, researchers at the Fraunhofer WKI have developed body parts with 100 percent natural fibers as reinforcing components.

“We utilize natural fibers, such as those made from hemp, flax or jute. Whilst natural fibers exhibit lower stiffnesses and strengths compared to carbon fibers, the values achieved are nonetheless sufficient for many applications,” explained Ole Hansen, Project Manager at the Fraunhofer WKI. Due to their naturally grown structure, natural fibers dampen sound and vibrations more effectively. Their lesser tendency to splinter can help to reduce the risk of injury in the event of an accident. Furthermore, they do not cause skin irritation during processing.

The bio-based composites were successfully tested by the Four Motors racing team in the “Bioconcept-Car” on the racetrack under extreme conditions. Porsche has actually been using natural fiber-reinforced plastics in a small series of the Cayman GT4 Clubsport since 2019. During production, the researchers at the Fraunhofer WKI also conducted an initial ecological assessment based on material and energy data. “We were able to determine that the utilized natural-fiber fabric has a better environmental profile in its production, including the upstream chains, than the fabric made from carbon. Thermal recycling after the end of its service life should also be possible without any problems,” confirmed Ole Hansen.

In the next project phase of the "Bioconcept-Car", the researchers at the Fraunhofer WKI, in collaboration with the cooperation partners HOBUM Oleochemicals GmbH, Porsche Motorsport and Four Motors, will develop a vehicle door with a biogenic content of 85 percent in the overall composite consisting of fibers and resin. They intend to achieve this by, amongst other things, utilizing bio-based resin-hardener blends as well as bio-based paint systems. The practicality of the door - and possibly additional components - will again be tested by Four Motors on the racetrack. If the researchers are successful, it may be possible to transfer the acquired knowledge into series production at Porsche.

The German Federal Ministry of Food and Agriculture (BMEL) is funding the “Bioconcept-Car” project via the project-management agency Fachagentur Nachwachsende Rohstoffe e. V. (FNR).

Background
Sustainability through the utilization of renewable raw materials has formed the focus at the Fraunhofer WKI for more than 70 years. The institute, with locations in Braunschweig, Hanover and Wolfsburg, specializes in process engineering, natural-fiber composites, surface technology, wood and emission protection, quality assurance of wood products, material and product testing, recycling procedures and the utilization of organic building materials and wood in construction. Virtually all the procedures and materials resulting from the research activities are applied industrially.

 

  • EU Project ALMA: Thinking Ahead to Electromobility

E-mobility and lightweight construction are two crucial building blocks of modern vehicle development to drive the energy transition. They are the focus of the ALMA project (Advanced Light Materials and Processes for the Eco-Design of Electric Vehicles). Nine European organizations are now working in the EU project to develop more energy-efficient and sustainable vehicles. Companies from research and industry are optimizing the efficiency and range of electric vehicles, among other things by reducing the weight of the overall vehicle. The Fraunhofer Institute for Industrial Mathematics ITWM is providing support with mathematical simulation expertise.

According to the low emissions mobility strategy, the European Union aims to have at least 30 million zero-emission vehicles on its roads by 2030. Measures to support jobs, growth, investment, and innovation are taken to tackle emissions from the transport sector. To make transport more climate-friendly, EU measures are being taken to promote jobs, investment and innovation. The European Commission's Horizon 2020 project ALMA represents one of these measures.

Emma4Drive (c) Fraunhofer ITWM
03.11.2020

EMMA4Drive - Dynamic human model for more safety and comfort in autonomous vehicles

  • DFG and Fraunhofer support trilateral project on autonomous driving

For many employees, it is an inviting vision of the future: to drive to work in their own car and still make good use of the travel time: Reading news, checking e-mails or relaxing and enjoying the first coffee of the day. In the future, passengers of autonomous vehicles will be able to pursue new activities. However, this will require new (software) tools to understand customers’ expectations, strengthen trust and demonstrate safety. With the EMMA4Drive project, the German Research Foundation (DFG) and the Fraunhofer-Gesellschaft are funding the development of a dynamic human model for the development of (partially) autonomously driving vehicles.

  • DFG and Fraunhofer support trilateral project on autonomous driving

For many employees, it is an inviting vision of the future: to drive to work in their own car and still make good use of the travel time: Reading news, checking e-mails or relaxing and enjoying the first coffee of the day. In the future, passengers of autonomous vehicles will be able to pursue new activities. However, this will require new (software) tools to understand customers’ expectations, strengthen trust and demonstrate safety. With the EMMA4Drive project, the German Research Foundation (DFG) and the Fraunhofer-Gesellschaft are funding the development of a dynamic human model for the development of (partially) autonomously driving vehicles.

Researchers from the Fraunhofer Institute for Industrial Mathematics ITWM and the company fleXstructures are developing a muscle-activated human model together with scientists from the Institute for Engineering and Computational Mechanics (ITM) at the University of Stuttgart.

This model dynamically simulates the interaction of human body parts and the vehicle seat during driving maneuvers. The resulting software prototype, EMMA4Drive, will be used as a digital image of the passenger and will analyze and evaluate his safety and ergonomics during driving maneuvers.

Realistic movements instead of quasi-static investigations
So far, human models have been used either in crash simulations to estimate the risk of injury or in ergonomic analyses. In crash analyses, detailed, computationally intensive models are used for calculations in the millisecond range, which are not suitable for the simulation of dynamic driving maneuvers, because here longer processes have to be simulated. In contrast, human models for ergonomics analysis are based on the simplified kinematics of a multi-body model and so far, only allow quasi-static investigations. Realistic postures and movements during new activities can only be modeled with a lot of effort using these models.

"The by us developed prototypical human model EMMA uses an optimization algorithm to automatically calculate new postures and movement sequences with the associated muscle activities," explains Dr. Joachim Linn, head of the department "Mathematics for the Digital Factory" at the Fraunhofer ITWM, the special feature of EMMA. "This means that the new motion sequences for (partially) autonomous driving can be implemented and examined comparatively easily in the simulation model - for example when the driver takes over the steering wheel."

EMMA4Drive thus enables a comparatively simple implementation of new movement patterns and an efficient virtual examination of safety, comfort and ergonomics in (partially) autonomous driving. "Our goal is to have a further developed prototype of our digital human model EMMA available at the end of the project, which we can use to investigate and improve seating and operating concepts when driving semi-autonomous or fully autonomous vehicles," Joachim Linn explains.

DFG and Fraunhofer support six trilateral projects with EUR 5 million
In the trilateral project EMMA4Drive, the University of Stuttgart contributes extensive experience in the fields of active human modeling, vehicle safety and model reduction. The Fraunhofer ITWM contributes expertise in multibody-based human modeling and motion optimization by means of optimal control. The company fleXstructures develops, distributes and maintains the software family IPS including the digital human model IPS IMMA, which simulates motion sequences during assembly work.

"EMMA4Drive - Dynamic human model for autonomous driving" is one of six projects funded by the DFG and Fraunhofer. The aim of the EUR five million funding is to involve companies in research innovations at an early stage. Three project partners each from universities, Fraunhofer Institutes and industry are cooperating on the basis of a joint working program. The Fraunhofer experts take the lead in the exploitation of the project results for the application partners or other interested parties from industry.

Source:

Fraunhofer Institute for Industrial Mathematics ITWM

Cost-effective Ways to minimize Risks in the Supply Chain Photo: Pixabay
28.07.2020

Fraunhofer ITWM: Cost-effective Ways to minimize Risks in the Supply Chain

  • Algorithms for optimized supply chains

The coronavirus pandemic has hit the economy hard. What lessons can be learned from this experience? And what’s the best way for companies to protect themselves against this kind of crisis in the future? The answer will certainly involve a combination of different approaches – but new mathematical methods developed by the Fraunhofer Institute for Industrial Mathematics ITWM look likely to be a very promising piece of the puzzle. These methods aim to calculate how the risks posed by supply shortages can be reduced significantly at very little extra cost.

  • Algorithms for optimized supply chains

The coronavirus pandemic has hit the economy hard. What lessons can be learned from this experience? And what’s the best way for companies to protect themselves against this kind of crisis in the future? The answer will certainly involve a combination of different approaches – but new mathematical methods developed by the Fraunhofer Institute for Industrial Mathematics ITWM look likely to be a very promising piece of the puzzle. These methods aim to calculate how the risks posed by supply shortages can be reduced significantly at very little extra cost.

 Nobody ever expected hospitals to be struggling to get hold of the face masks and other personal protective equipment they need. The supply chain had always run smoothly in the past, yet the coronavirus crisis has now caused shortages of these products on multiple occasions. Previously, these supply chains had worked well – but the necessary restrictions on the global flow of goods led them to collapse.In many cases, for example, Chinese suppliers were unable to make deliveries even while factories in Germany were still working as normal, a situation that had a knock-on effect on goods production in Germany. And viruses are not the only potential risk: international suppliers can be paralyzed by all kinds of unforeseen factors, from natural disasters such as tsunamis, earthquakes, storms and floods to strikes or other unexpected political developments. If a company chooses to rely on just one supplier for its production needs in order to reduce costs, this can have devastating consequences that may even bring production to a complete standstill. It can take a very long time indeed for other suppliers to ramp up their production and start delivering the required products.
 
Analyzing and safeguarding supply chains
This is where methods developed by Fraunhofer ITWM come into play. “The algorithms analyze how diversified the supply chains are in different areas of the company and thus how great the risk is of running into critical supply problems in an emergency, in other words in the event of regional or global disruption,” says Dr. Heiner Ackermann, deputy head in the Department of Optimization at Fraunhofer ITWM in Kaiserslautern. “The question is how you can minimize the risk of supply shortfalls without incurring significant additional costs.” The dilemma is similar to that of buying a house: Is it best to opt for the lowest possible interest rates, even though there is a risk that follow-up financing will offer much worse rates? Or is it best to play safe and pay slightly higher interest rates from the start if that means having the reassurance of reasonably priced financing for the entire term?
 
Companies also have to get the right balance between risk and costs. If a company chooses to rely solely on the cheapest supplier, they are taking a major risk. But if they procure a raw material from multiple suppliers at the same time, that risk drops significantly. “And in this case the difference in cost is much lower than the difference in risk,” says Ackermann. In other words, the risks fall dramatically even when a company increases its costs by just a few percent – so it is possible to eliminate much of the risk by accepting just a slight rise in costs. Companies can use the algorithm to discover what would work best in their particular situation. “This method lets companies optimize their supply chains based on multiple criteria, helping them to find the optimal balance between costs and risks,” says Ackermann. “The underlying algorithms work equally well whether you are dealing with supply shortages caused by an earthquake or a virus. So, unlike existing software solutions, we don’t try to make assumptions as to the likelihood of any particular scenario.” With this new method, a company starts by entering various parameters – for example areas in which they think disruption could be likely and how long that disruption might last. The algorithms then calculate various cost/risk trade-offs for this exact raw material, including the possible allocations of suppliers that would correspond to each point on the scale. They even take into account options such as storing critical products in order to cushion any temporary supply shortfalls.
 
Substituting raw materials during supply shortages      
Another option the algorithms take into account is whether a raw material could potentially be replaced by different materials in the event of a supply bottleneck. If so, this can be taken into consideration from the start. Essentially, the method calculates the costs and risks of different courses that a company can follow in regard to their suppliers. Procter & Gamble is already using a software-based variant of this methodology which has been specially tailored to its needs.

Source:

Fraunhofer Institute for Industrial Mathematics ITWM

Photo: Pixabay
28.04.2020

Meltblown Productive: Fraunhofer ITWM vs. Corona - With Mathematics Against the Crisis

  • Meltblown Productive – ITWM Software Supports Nonwoven Production for Infection Protection

Simulations by the Fraunhofer Institute for Industrial Mathematics ITWM make processes in the manufacturing of nonwovens more efficient. Within the anti-corona program of Fraunhofer the production of infection protection is optimized.
 
Nonwovens production is currently attracting more attention than ever before from the general public, because in times of the corona pandemic, nonwovens are vital for infection protection in the medical sector and also for the protection of the entire population. Disposable bed linen in hospitals, surgical gowns, mouthguards, wound protection pads and compresses are some examples of nonwoven products.

  • Meltblown Productive – ITWM Software Supports Nonwoven Production for Infection Protection

Simulations by the Fraunhofer Institute for Industrial Mathematics ITWM make processes in the manufacturing of nonwovens more efficient. Within the anti-corona program of Fraunhofer the production of infection protection is optimized.
 
Nonwovens production is currently attracting more attention than ever before from the general public, because in times of the corona pandemic, nonwovens are vital for infection protection in the medical sector and also for the protection of the entire population. Disposable bed linen in hospitals, surgical gowns, mouthguards, wound protection pads and compresses are some examples of nonwoven products.

IEspecially in intensive care and geriatric care, disposable products made of nonwovens are used due to the special hygiene requirements. At the moment there are clear bottlenecks in the production of these materials. For the meltblown nonwovens class, however, it is difficult to increase production efficiency because meltblown processes are highly sensitive to process fluctuations and material impurities.
 
Although nonwovens are not all the same, the rough principle of their production is relatively similar to all industrially manufactured nonwovens: molten polymer is pressed through many fine nozzles, stretched and cooled down in an air stream and thus deposited into the typical white webs. "Meltblown" stands for the submicron fiber process whose nonwovens are responsible for the decisive filter function in face masks.
 
With meltblown technology, nonwoven fabrics are produced directly from granules. A special spinning process in combination with high-speed hot air is used to produce fine-fibered nonwovens with different structures. The fibers are highly stretched by the turbulent air flow. During this process they swirl in the air, become entangled and fall more or less randomly onto a conveyor belt where they are further consolidated - a very complex process. Nonwovens manufacturers around the world are striving to massively increase their production capacities.
 
Digital Twin Optimizes Meltblown Process    
This is where the software of the ITWM comes into play. "Our Fiber Dynamics Simulation Tool FIDYST is used to predict the movement of the fibers, their falling and the orientation with which they are laid down on the conveyor belt. Depending on the process settings, turbulence characteristics are generated and thus nonwoven qualities are created that differ in structure, fiber density and strength," explains Dr. Walter Arne from the Fraunhofer ITWM. He has been working at the institute for years on the simulation of various processes involving fibers and filaments.

The methodology is well transferable to meltblown processes. In these processes, one of the specific features is the simulation of filament stretching in a turbulent air flow - how the stretching takes place, the dynamics of the filaments and the diameter distribution. These are all complex aspects that have to be taken into account, but also the flow field or the temperature distribution. The simulations of the scientists at the Fraunhofer ITWM then provide a qualitative and quantitative insight into the fiber formation in such meltblown processes - unique in the world in this form when it comes to simulate a turbulent spinning process (meltblown).

Nonwoven Manufacturers benefit from Simulation
What does this mean for the industry? The production of technical textiles becomes more efficient, but the nonwovens can also be developed without having intensive productions tests in a real facility. This is because the simulations help to forecast and then optimize the processes using a digital twin. In this way, production capacities can be increased while maintaining the same product quality. Simulations save experiments, allow new insights, enable systematic parameter variations and solve up-scaling problems that can lead to misinvestments during the transition from laboratory to industrial plant.

Making a Contribution to Overcome the Crisis With Many Years of Expertise
"We want to demonstrate this in the project using a typical meltblown line as an example - for this we are in contact with partner companies," says Dr. Dietmar Hietel, head of the department "Transport Processes" at the Fraunhofer ITWM. "Within the framework of Fraunhofer's anti-corona program, we want to use our developed expertise and our network to contribute to overcome the crisis", reports Hietel. His department at the Fraunhofer ITWM has been pursuing research in the field of technical textiles for around 20 years. Due to its current relevance, the project not only got off to a quick start, but the implementation and results should now also be implemented quickly: The project is scheduled to run from April 15th 2020 to August 14th 2020. The kick-off meeting took place on April 17th 2020 via video conference.
 
The project "Meltblown productive" and the results are certainly interesting for nonwoven producers. The production of many mass products has often been outsourced to Asia in the past decades; the nonwovens manufacturers remaining in Germany and Europe tend to focus more on high-quality technical textiles. In the medium and longer term, this will also be a scientific preliminary work when production capacities in Germany and Europe are expanded by new plants. One lesson to be learned from the crisis will also be to reduce the dependence on producers in Asia, especially as a precautionary measure for crisis scenarios.

Source:

Fraunhofer Institute for Industrial Mathematics, ITWM