MANAGER’S GUIDE Accelerate R&D with Multiphysics Simulation COMSOL® Software An Integrated Platform for Physics-Based Modeling, Simulation, App Design and Deployment

COMSOL Multiphysics® Surpass Design Challenges with Numerical Simulation Product design is a time-sensitive objective requiring the most accurate and comprehensive simulation tools to stay ahead of the competition.

The COMSOL Multiphysics® software is a fully integrated platform for performing powerful simulations and analyses, allowing R&D teams to accelerate development and reduce risk.

Explore your design through a user-friendly interface with a consistent workflow for both single and multiphysics models, regardless of the system of study. COMSOL DESKTOP® FOR NUMERICAL SIMULATION OF PHYSICS-BASED SYSTEMS Consider any number or type of physics, including Develop multiphysics models of any system with the Model Builder, then use electrical, mechanical, fluid, thermal, acoustic, and postprocessing tools to visualize your results. (Image above: Numerical simulation of a chemical effects (Products, p. 18). differential gear mechanism in the COMSOL® software.)

Analyze the performance of a product under varied operating conditions, verify and optimize the design prior to prototyping.

Make use of powerful solver technology to deliver accuracy and speed; run on everything from standard desktop hardware to high-performance clusters and clouds (License options, p. 19).

Visualize results with built-in, intuitive post- processing functionality. Interface with industry standard software for technical computing, CAD, and data analysis, and easily share results and collaborate with colleagues in multiple departments.

COMSOL Server™ Deploy apps throughout your organization Generate specialized, user-friendly apps based on your simulations with the Application Builder included with COMSOL Multiphysics®. Extend the power of simulation to colleagues and customers worldwide.

Run apps in COMSOL Multiphysics directly, or use BRING YOUR SIMULATION TO COLLEAGUES AND CUSTOMERS WITH SIMULATION APPS AND the COMSOL Server™ product to access them from COMSOL SERVER™ Choose which parts of your simulation to share with colleagues, the free-of-charge COMSOL Client for Windows® collaborators, and clients. (Image above: COMSOL app of a finned pipe, used to evaluate the thermal performance of various geometries.) operating system or major web browsers.

© 2014-2017, COMSOL. Manager’s Guide. Accelerate R&D with Multiphysics Simulation is published by COMSOL, Inc. and its associated companies. COMSOL, the COMSOL logo, COMSOL Multiphysics, Capture the Concept, COMSOL2 Desktop, COMSOL Server, and LiveLink are either registered trademarks or trademarks of COMSOL AB. All other trademarks are the property of their respective owners, and COMSOL AB and its subsidiaries and products are not affiliated with, endorsed by, sponsored by, or supported by those trademark owners. For a list of such trademark owners, see www.comsol.com/trademarks. ACCELERATE R&D WITH MULTIPHYSICS SIMULATION Provide Design Teams, Manufacturing Departments, and Other Colleagues with High-Fidelity Models and Simulation Apps

Wolfspeed POWER ELECTRONICS

Simulation apps were used to design semiconductor devices that can withstand extreme temperatures.

4 Multiphysics simulation was used 10 Boeing to design and evaluate aircraft AEROSPACE composite structures containing a protective, electrically-conductive, expanded-metal foil (EMF) layer. Fiat HYBRID VEHICLES

Researchers investigated internal temperature distribution within a battery cell and located 12 problematic hot spots.

Cypress TOUCHSCREENS 6 Researchers use simulation Toyota to develop optimal thermal Engineers use simulation apps management solutions for to improve communication AUTOMOTIVE hybrid vehicles. across development teams and 14 streamline touchscreen design.

mieletec KITCHEN APPLIANCES

Researchers at mieletec used COMSOL® to resolve 8 Multiphysics simulation was used crucial design challenges. Sharp to optimize LED designs, and reduce the number of design DISPLAYS & LIGHTING iterations required. We16 welcome your questions and comments. Contact us at [email protected]. 3 Boeing Simulates Thermal Expansion in Protective Coatings for Aircraft Composites

èLIGHTNING STRIKE PROTECTION OF AIRCRAFT STRUCTURES The Boeing 787 Dreamliner is innovative in that it is comprised of more than fifty percent carbon fiber reinforced plastic (CFRP) due to the material’s light weight and exceptional strength. Although CFRP composites inherently have many advantages, they cannot mitigate the potentially damaging electromagnetic effects from a lightning strike. To solve this At left is the composite structure layup from the COMSOL Multiphysics® software problem, electrically conductive model and, at right, the geometry of the expanded metal foil. SWD and LWD expanded metal foil (EMF) can be correspond to short way dimension and long way dimension. The mesh aspect ratio, added to the composite structure SWD/LWD, is one of the parameters varied in the study. layup to rapidly dissipate excessive current and heat for lightning protection of CFRP in aircraft. Physics leading the simulation, Dr. èREDUCING RISKS AND Over time, however, stress Patrice Ackerman from Sealants and MAINTENANCE COSTS accumulates in the protective coating Electromagnetic Materials leading The objective at BR&T is to improve of the composite structure as a result the testing, and Technical Fellow overall thermal stability of the of thermal cycling due to the typical Quynhgiao Le from Manufacturing protective coating and therefore ground-to-air flight cycle. This stress Technology Integration. In their work, reduce the risks and maintenance costs may cause the protective coating the EMF design parameters are varied associated with damage to the coating to crack providing an entrance for in order to investigate the relative or composite system during service. moisture and environmental species difference in displacement in each Greegor and his colleagues that can cause corrosion of the layer of the composite structure layup. qualitatively regard even the smallest EMF, thereby reducing its electrical projected increase in displacement conductivity and ability to perform its protective function. Designing an EMF layer that can perform optimally under these conditions involves realizing a balance between current carrying capacity, displacement due to thermally induced movement of the protective layers, and weight. To better understand the impact of the EMF design on thermal stress and displacement in the protective coating, the engineers at Boeing Research and Technology (BR&T) are using multiphysics simulation in addition to physical measurements. Contributing to the research effort at BR&T are project lead Jeffrey Morgan from Sealants and Electromagnetic Materials, Associate Technical Research team at Boeing Research and Technology, from left to right: Patrice Fellow Robert Greegor from Applied Ackerman, Jeffrey Morgan, Robert Greegor, and Quynhgiao Le.

4 Photo micrographs of the composite structure layups after exposure to moisture and thermal cycling. At left, the results for the copper EMF and at right, the aluminum. as an increased risk for developing COMSOL Multiphysics® software. In structure layup as experienced upon cracks in the protective layers since the surface protection scheme, each descent in an aircraft. Final and initial mechanical stress due to thermal layer including the paint, primer, temperatures were defined in the cycling accumulates over time. corrosion isolation layer, surfacer, model to represent the ground and Experimental evidence supports EMF, and the underlying composite altitude temperatures, respectively. this logic as shown in the photo structure contribute to the buildup The results of the micrograph cross-sections of surface of mechanical stress in the protective COMSOL Multiphysics simulations protection schemes with aluminum coatings over time as they are subject were analyzed to quantitatively or copper EMF. The images were to thermal cycling. determine the stress and acquired after prolonged exposure In this study, EMF design displacement in each layer upon to moisture and thermal cycling in parameters including the height, heating and for varied properties of an environmental test chamber. The width of the mesh wire, aspect the expanded metal foil. It was found layup with the copper EMF shows no ratio (SWD/LWD), and metallic that, due to the lower impact on cracks, whereas the aluminum EMF led composition were varied to evaluate displacement, increasing the mesh to cracking in the primer, visible edge their impact on thermal performance width or decreasing the aspect ratio and surface cracks, and substantial throughout the entire structure. The are better strategies for increasing cracking in mesh overlap regions. metallic composition of the EMF was the current carrying capacity of the Over the same temperature either aluminum or copper, where EMF for lightning strike protection.v range, the experimental results an aluminum EMF requires additional References correlate well with the results from fiberglass between the EMF and 1. R.B. Greegor, J.D. Morgan, Q.N. Le and the simulations that consistently the composite to prevent galvanic P.K. Ackerman, Finite Element Modeling and Testing of Expanded Metal Foils Used for show higher displacements in the corrosion. Lightning Protection of Composite Aircraft protective layers for the aluminum In the CTE model, the Thermal Structures, Proceedings of the 2013 ICOLSE EMF. Both simulation and experiment Stress multiphysics interface couples Conference, Seattle, WA, September 18-20, 2013. indicate that the layup with copper solid mechanics with heat transfer 2. J.D. Morgan, R.B. Greegor, P.K. Ackerman EMF is a better choice from the to simulate thermal expansion and and Q.N. Le, Thermal Simulation and Testing of Expanded Metal Foils Used for Lightning durability performance perspective of solve for the displacement throughout Protection of Composite Aircraft Structures, the protective coating. Multiphysics the structure. The simulations were SAE Int. J. Aerospace 6(2), 371-377, 2013, simulation is therefore a reliable confined to heating of the composite doi:10.4271/2013-01-2132. means to evaluate the relative impact of the EMF design parameters on stress and displacement to better understand and reduce the likelihood of crack formation.

èEVALUATING THERMAL EXPANSION IN AIRCRAFT COMPOSITE STRUCTURES To evaluate the thermal stress and displacement in each layer of the composite structure layup, a coefficient of thermal expansion Relative stress in arbitrary units was plotted through the depth of the composite (CTE) model was developed by structure layups containing either aluminum (left) or copper EMF (right). Greegor1,2 and his colleagues using

Boeing, Dreamliner, and 787 Dreamliner are registered trademarks of The Boeing Company Corporation in the U.S. and other countries. 5 Simulation-Led Topology Optimization for Improved Cooling in Toyota Hybrid Vehicles

èREINVENTING THE ELECTRONICS at TRI-NA explains that, “the goal for the reengineered cold plate. COOLING SYSTEM was to come up with a combination Research on the novel heat sink Toyota hybrid vehicles have jet-impingement and channel-flow design, which earned the team an sophisticated electrical systems based cold plate with optimally R&D 100 award in 2013, was carried comprised of many power designed branched cooling channels out as part of TRI-NA’s mission semiconductor devices such as diodes to uniformly remove the most to conduct accelerated advanced and insulated gate bipolar transistors heat and with the least pressure research in the areas of energy and (IGBTs) that are used for power drop.” The primary challenge environment, safety, and mobility conversion and management. For for Dede and his colleagues was infrastructure. thermal regulation of the devices, to create the branched cooling they are mounted on aluminum heat channel design, where testing the èCOOLING SOLUTION FOR HYBRID sinks, or cold plates, through which thermal performance of many VEHICLES a water/glycol coolant mixture is possible topologies could require “Many researchers working on pumped via cooling channels. a prohibitively large number of diverse applications have identified As the technology roadmap prototypes. jet impingement as an attractive for these power components calls way to cool surfaces,” said Dede. for them to shrink to less than half èACCELERATED WORKFLOW FOR “But while jet impingement their current size while dissipating AWARD-WINNING INNOVATION performs well with respect to heat the same amount of power, their To save the time and expense dissipation close to the jet, it’s less heat flux will increase. With space associated with analytical design than optimum as you move away already at a premium in the engine methods and trial-and-error physical from the orifice.” Consequently, compartment, using a larger, more prototyping, Dede and his colleagues their solution combines single-phase powerful pump to force more used numerical simulation and jet impingement cooling in the coolant through the cold plates is not multiphysics topology optimization plate’s center region with integrated a viable solution. to design and test the possible hierarchical branched cooling Researchers from the Toyota prototypes of a novel heat sink for channels to cool the periphery. Research Institute of North America future hybrid vehicle generations. “It’s in your interest to make those (TRI-NA) in Ann Arbor, MI focused Their workflow included simulation channels short to keep pressure drop on reengineering the cold plate. Dr. in COMSOL Multiphysics® software to a minimum,” Dede explained. Ercan (Eric) Dede, a manager in the enabling the efficient design of the Simulation in COMSOL Multiphysics Electronics Research Department branched cooling channel topology using the CFD Module and

Representative optimal cooling channel topology with fluid streamlines colored blue (left); normalized temperature contours (center); and normalized pressure contours (right).

6 Prototype aluminum cold plates with (left) and without (right) a representative hierarchical microchannel topology.

Heat Transfer Module was essential that separate the cooling channels some nice functionality that allows for optimizing the branched cooling could be incorporated and was you to actively link to CAD design channel topology for efficient, investigated in a separate parametric tools, and it was easy to import uniform heat transfer throughout the sizing study. Simulation results various structures from SOLIDWORKS® cold plate. Additionally, demonstrated that the channels software back into COMSOL® LiveLink™ for MATLAB® enabled efficiently distribute coolant software to verify pressure drop and Dede to run simulations for design throughout the plate to produce heat transfer,” says Dede. “I think this is really the future of simulation, “...this is really the future of simulation, to be able to link your CAD tool to be able to link your CAD tool to to your simulation tool so that you can streamline development through your simulation tool so that you can fast, accurate design iterations.” streamline development through fast, accurate design iterations.” Using the optimization from within his relatively uniform temperature and designs created in the SOLIDWORKS® MATLAB® software code to examine pressure distributions that are a software, prototypes were fabricated how the cooling channel topology function of branching complexity. from aluminum using standard influenced steady-state convection- Therefore, this fractal-like topology micromachining techniques. The diffusion heat transfer and fluid flow, was used to guide the design of reengineered power electronics cold for example. a physical cold plate prototype in plate now offers up to 70% better Once an initial channel topology SOLIDWORKS® software. heat transfer and is only one-quarter was derived, the height of the fins “LiveLink™ for SOLIDWORKS® has the size of those currently in use.v

The Toyota Research Institute of North America’s topology optimization team includes (from left) Ercan Dede Ph.D., Manager; Jaewook Lee Ph.D., Assistant Professor at Korea Aerospace University (former TRI-NA researcher); and Tsuyoshi Nomura Ph.D., Sr. Researcher at Toyota Central Research and Development Labs (former TRI-NA researcher).

SOLIDWORKS is a registered trademark of Dassault Systèmes SolidWorks Corp. MATLAB is a registered trademark of The MathWorks, Inc. 7 Multiphysics Software, a Versatile, Cost-Effective R&D Tool at Sharp

Left: The LCD pixel geometry used in Sharp displays was imported from ECAD software into COMSOL Multiphysics® software. Right: Mesh generated for the high aspect ratio structures of the LCD pixels.

èUNDERSTANDING DIVERSE our research staff, including materials TECHNOLOGY IN PRODUCT scientists, chemists, physicists, optical DEVELOPMENT designers, electronic engineers, and Today’s electronic products are software developers,“ says Chris sophisticated, highly integrated Brown, research manager for SLE’s systems containing technology Health & Medical Devices Group. such as processors, light and power For product lines such as LED sources, analog and passive devices, lighting systems, researchers face displays, and microelectromechanical challenges in optimizing electrode systems (MEMS). Understanding the designs to prevent hot spots that interactions within and among each can disproportionately reduce the system component requires that efficiency of the entire device. To product developers draw on multiple improve the image quality and scientific and engineering disciplines reduce the power consumption right from the outset of a project in of LCD displays, versatile tools are ® order to meet functionality, quality, required to extract and analyze the COMSOL software simulation cost, and time-to-market goals. electrical characteristics of individual results showing the surface electric potential in the LED. Nowhere has this multidisciplinary pixels. Other development initiatives approach to product design taken in the healthcare and energy arenas toolbox needed to address these root more firmly than in the R&D involve understanding the interaction challenges, aiding product developers laboratories of Osaka, Japan- between fluid flow, heat transfer, across multiple engineering based Sharp Corporation. At Sharp and electrical properties to design disciplines in improving device Laboratories of Europe (SLE), an systems that are more accurate and functionality and product design affiliate of Sharp Corporation, efficient. workflow while reducing costs. technology for lighting, displays, In regard to their research in medical tools, and energy systems is èIMPROVING DEVICE LED systems, the team found that under development. PERFORMANCE, QUALITY, AND their model incorporating both “A common feature of much TIME TO MARKET the electrical and thermal behavior of our work is its multidisciplinary Each application presents unique produced an accurate match nature, as reflected by the broad challenges for the engineers at SLE. between simulation and experimental range of scientific specialties across Multiphysics simulation offers the results. Brown explains that with

8 multiphysics simulation they “were able to optimize LED designs for improved performance and reduced time to market.” The benefits of using multiphysics simulation to evaluate product design and performance were numerous and varied depending on the application. When it comes to LCDs, “the versatility and degree of control over the meshing procedure in COMSOL® software have allowed us to successfully analyze high-aspect Researcher Matthew Biginton using COMSOL to simulate LCD pixel capacitances. ratio structures for the first time,” says Brown. “This modeling ability the process of design translation and development across the company’s gives us a more accurate starting minimize the risk of translation errors.” many engineering disciplines and point for experiments…reducing the SLE also provides technical support product lines. Brown expects number of design iterations required, to Sharp’s display business where multidisciplinary research activities which in turn helps us to reduce the LCDs are used in products such as to be ongoing at SLE and that R&D prototyping time and cost.” “COMSOL Multiphysics will continue “This modeling ability gives us a more accurate starting point for to play an important role, both as a research tool and as a product experiments…reducing the number of design iterations required, which development tool.”v in turn helps us to reduce the R&D prototyping time and cost.”

èMULTIPHYSICS SIMULATION AS A smartphones and televisions. As part PRODUCT DESIGN SOLUTION of SLE’s workflow for electronic circuit SLE applies the same rigorous design, they use the AC/DC Module approach to the purchase, to extract the electrical characteristics configuration, and use of its tools of each pixel in addition to the as it does to its R&D explorations parasitic resistance and capacitance of with COMSOL software. “SLE’s use the electrical wiring throughout the of COMSOL Multiphysics® software entire thin film LCD. has grown over the last five years, For the diverse range of projects having started out in the LED area Chris Brown is the Research Manager at SLE, multiphysics simulation has of the Health & Medical Devices and then expanding to the other empowered successful research and Group. research themes by way of internal recommendations,” says Brown. Each team has a license for COMSOL in addition to relevant application- specific add-on modules. Multiphysics simulation was used initially to maximize heat dissipation from LEDs to create a uniform temperature distribution and improve device efficiency. For this application, Brown says they “use LiveLink™ for SOLIDWORKS® with COMSOL Multiphysics® to simplify LED modules from Sharp (www.sharpleds.com).

SOLIDWORKS is a registered trademark of Dassault Systèmes SolidWorks Corp. 9 High Performance Power Packages and Multiphysics Applications

èRETHINKING THERMAL (GaN) and silicon carbide (SiC), which size: “With parametric modeling, you MANAGEMENT IN POWER operate stably at high frequencies and can find out exactly what’s influencing ELECTRONICS temperatures. Simulation was integral the system the most and get the best Billions of people use products from to finding the best combination of compromise among performance, the power electronics industry: geometric and material properties to complexity, and cost,” he added. modern cars, smartphones, tablets, optimize weight, switching frequency, and other wireless devices. Thermal and power density in the new power èSIMULATION RESULTS DRIVE management heavily influences modules. “Wolfspeed specializes in SEMICONDUCTOR SOLUTIONS device performance; temperatures high power density products, which McPherson successfully optimized the higher than the specified operating need a lot of precise testing before thermal and electrical performance conditions may cause overheating or they’re perfected. It’s very valuable of his power packages; his COMSOL increased electrical resistance, lower to be able to simulate something results showed that the two new switching frequencies, and threshold before you invest money and time designs exhibited lower inductance drifts. These effects diminish into prototyping and building it,” he and lower thermal resistance than efficiency and controllability and commented. the TO-254, a common commercial can eventually lead to failure. With In the COMSOL® software, transistor. After applying boundary the current trend toward minimizing McPherson was able to model Joule conditions for temperature and the size and weight of electronics heating, analyze the heat generated voltage and examining the resulting products, thermal management in the conductors, and study the inductance, thermal resistance, and becomes even more challenging. effects of changing geometric current density, he made design There is a growing need, therefore, aspects such as the substrate and adjustments to optimize current- for power packaging to control heat base plate thickness. He also set up carrying capacity and footprint. The transfer and current so that electronics parametric sweeps to show how final Wolfspeed packages designed can operate stably at high frequencies thermal resistance changed according using multiphysics simulation have and temperatures. Engineers at to substrate conductivity and device greatly improved thermal management Wolfspeed, A Cree Company and can operate under much more have begun designing new power extreme conditions than before— packages that offer more robustness including temperatures over 225° C. and flexibility than those currently on the market. Their greatest challenges èDISTRIBUTING SIMULATION are to minimize thermal resistance THROUGHOUT THE ORGANIZATION and the parasitic inductances that COMSOL is also an application cause voltage spikes. Their power design environment. By using the packages, aimed at improving thermal The new Wolfspeed power package Application Builder in management and device lifespan, is slightly larger than a quarter. contain the die (device), contacts, interconnects, surrounding housing, and base components.

èSAVING TIME AND MONEY WITH SIMULATION For Brice McPherson, a Sr. Staff Engineer at Wolfspeed, COMSOL Multiphysics® software simulations proved especially helpful for saving time and money during the design stage. He based his new Simulation results show the current densities in the SiC (left) and GaN (right) power designs on two wide-bandgap modules. The SiC package has a lower current density (preferable for high currents), semiconductors, gallium nitride with the greatest current shown in the wire bonds. The GaN module shows a higher average current density, but has more available area for conduction (preferable for lower inductance). 10 COMSOL Multiphysics, McPherson was able to extend his simulations Simulation results comparing the thermal resistance of the TO-254 package to to applications—making it easy to McPherson’s SiC (left) and GaN (right) packages. share models and results among colleagues, including those without heavily driven by the geometry of an engineering background. His COMSOL Server™ license. Users of the wire and the loop,” McPherson McPherson’s application can easily explained. “Now we can have a determine the maximum allowable “It’s very valuable to be able to clean, simple application to get the current, see how the peak temperature simulate something before you necessary data without requiring is influenced by the number of wires, invest money and time into an engineer.” He also expects the and determine the number of bonds of prototyping and building it.” Application Builder to expedite their a given diameter required for specific design process in other ways. “We current inputs, temperatures, and write many grant proposals that latest app studies the ampacity and geometric setup. By using multiphysics typically require an engineer to spend fusing current of wire bonds, used to simulation and applications created a day running first pass analyses… connect semiconductor devices with from his models, McPherson has the Application Builder will be hugely packages like the new SiC and GaN successfully and easily redesigned the important there as well.” modules. “We constantly have to be thermal management in Wolfspeed’s McPherson’s application can be run mindful of how much current we can power electronics packaging.v in any major web browser by using the transfer through these wires…it’s

The application showing the temperature change in the wire bonds. The end user chooses the bond length, loop height, current level, and number of bonds.

11 Fiat Improves Thermal Management of Li-Ion Battery Packs

èDESIGNING FOR MAXIMUM work well due to problems with heat, design, they determined that a less EFFICIENCY AND SAFETY then it has a negative impact on the powerful fan was required, which Given the long development cycle for entire pack. helped reduce costs. “With the vehicles, automobile manufacturers It is important that the maximum help of the model, we were able must plan their upcoming lines far in temperature differential does not to cut our design time by 70%. We advance. And with growing emission exceed 5 °C across all cells in a pack. estimate that instead of needing regulations and the rising cost of gas, In addition, if the temperature of the 1000 hours for the design of a full electric and hybrid vehicles are pack as a whole is too low, it limits battery pack, we could cut it down expected to become more attractive the amount of charge extracted. If to roughly 300 hours,” says Michele and grow in market share. the temperature is too high, there Gosso, a researcher with Fiat. At the Fiat Research Center in is the risk of thermal runaway, Orbassano, Italy, researchers develop which can mean a jump directly to èBATTERY PACK DESIGN FOR electric and hybrid vehicles using electrolyte emission, smoke, or in the HYBRID VEHICLES lithium and lead-acid batteries as worst case, fire. In Li-ion batteries, heat is produced well as supercapacitors. Fiat currently through both Joule heating and has several light trucks that run èSIMULATION PROVIDES CRITICAL chemical reactions, which was on electric drives in addition to an ANSWERS AND REDUCES COSTS electric version of the Fiat 500 that is By developing a model using presently available to the US market. COMSOL Multiphysics® software, While Fiat Research Center does the researchers at Fiat were able to not manufacture the individual find the hot spots on a cell and also lithium-ion battery pouch cells, they investigate its internal temperature “We estimate that instead of needing 1000 hours for the design of a battery pack, we could cut it down to roughly 300 hours.”

are responsible for combining as distribution. This provided invaluable many as 100 of them into battery information that cannot be achieved packs that generate the requisite 350 via other methods due to the difficulty volts. Sufficient cooling is necessary involved in embedding thermocouples while keeping the packs as small and in battery pouches and attaining Surface temperature of a pouch cell light as possible. Because the cells reliable results from them. from a lithium ion battery pack – the are wired in series, if one cell doesn’t Additionally, by simulating their uniform distribution is an important parameter.

Three types of lithium-ion batteries. Fiat uses a series of 100 or so of the pouch cells to power their vehicles.

12 evaluated from an expression dependent on the current density. In their designs, Gosso and his colleagues opted for convective cooling and used multiphysics simulation to study the resulting temperature distribution on the cell surface. The model divides each surface of the pouch cell into nine areas that correspond to the thermocouples on the cell itself. The temperature distribution was examined at several Results from using an infrared camera and thermocouples to measure the temperature charge/discharge rates to verify that on the surface of a pouch cell. the model was consistent with reality, as measured by thermocouples and space and also cuts weight because the other extreme conditions for infrared heat cameras. Here, they a smaller frame can be used. This Li-ion battery packs, particularly at found that the results were within makes it easier to insert the battery temperatures below freezing where 1 ºC of the measurements. pack into a larger variety of vehicles, it can be difficult to charge these With the knowledge gained from which is important in order to adapt types of batteries. But by leveraging the model, they were able to reduce battery powertrains to vehicles the Joule heating effect and through the size of the physical channels already on the market. innovative design, it may be possible between the cells. Doing this reduces A future project will look at to solve this problem as well.v

A comparison of model and experimental results for one of the thermocouples on the surface of the lithium cell. The results show a maximum difference of 1°C between the two.

13 Improving Production Processes for Customized Touchscreens

èDEVELOPING AN EFFICIENT in which it is used, each touchscreen TOUCHSCREEN DESIGN PROCESS stack-up and electrode pattern In many of today’s technologies, must be customized for its intended touchscreens are becoming more environment. This requires studying and more ubiquitous. Cypress a variety of environmental conditions Semiconductor, the leading and ways in which a consumer supplier of capacitive touchscreen will interact with a touchscreen. technologies, designs and Peter Vavaroutsos, a member of manufactures touchscreens for a the modeling group at Cypress, variety of applications, including designs TSPs for different consumer smartphones, mp3 devices, laptops, products. “For these designs, I must automotive environments, industrial take into account such factors as applications, home appliances, and how interactions with a horizontally Example design box showing a touch more. Because of the diverse uses mounted GPS, for example, will differ sensor with electric field lines modeled of touchscreens and the nature from a smartphone, which can be using the AC/DC Module, an add-on product to COMSOL Multiphysics® of the products in which they are held and interacted with in a myriad software. used, many of the designs Cypress of different ways.” produces must be created individually In addition to consumer products, Thomas, an R&D engineer on the on a case-by-case basis. an automotive group at Cypress automotive team. Capacitive touchscreens consist of designs touchscreens for use in Because of the challenges varying layers of transparent lenses, applications such as an automobile’s involved in creating so many custom substrates, adhesives, and horizontally center console or rear seat and designs, multiphysics simulation and and vertically aligned indium-tin-oxide overhead entertainment systems. “In simulation apps have emerged as key (ITO) electrodes. Together, these the automotive group, our designs tools at Cypress for ensuring effective elements are known as touchscreen are more customer-driven and are product development. panels (TSPs) or stack-ups. often created on a case-by-case basis Depending on the type of product for a specific product,” says Nathan èDESIGN CAPABILITIES FOR THE ENTIRE ORGANIZATION Multiphysics modeling allows designers to predict and optimize numerous device designs without the need to build multiple physical prototypes. The Cypress R&D engineers create multiple electrostatic simulations using the COMSOL Multiphysics® software in order to study the performance of different device geometries, which are referred to as “design boxes”. Recently, Cypress R&D engineers have been using the Application Builder in COMSOL Multiphysics to create simulation apps based on their models. Whether for smartphone designs, automotive applications, or other industrial processes, these Typical touchscreen sensor stack-up, which contains an LCD layer followed by simulation apps allow their support a substrate, a pattern of horizontally and vertically aligned diamond-shaped ITO engineers, sales teams, and others to electrodes, and finally an optically clear adhesive layer that bonds the glass cover onto experiment with designs that would the screen.

14 otherwise have required the expertise of an R&D engineer. Simulation apps have been particularly valuable for designing customer-specific products. “We’re using the Application Builder to build simplified user interfaces over our models, which allows us to communicate more effectively with our customer support teams,” says Vavaroutsos. “Before we started using simulation apps, any time a customer wanted a design that was slightly outside of the standard design box, we’d have to be involved again to run simulations for minor parameter changes. A lot of times, a sales engineer might try to run the simulations themselves, even though they had little experience using the Simulation app based on a COMSOL® software model used to support the design of COMSOL® software. Not only would touch-based capacitive sensors. The app user can change design parameters ranging from we have to check the simulations, the finger location to the thickness of different layers in the sensor. A drop-down list can but they also took up a seat on the be used to select a solution corresponding to the excitation of different sensor traces. software license as well.” Using the apps, sales engineers, field technicians, and others are able engineer—or use a seat up on our parameters such as the thickness of to quickly recalculate a model based COMSOL Multiphysics license.” layers or the location of a virtual finger on a customer’s specific needs. This touching the screen. The app then gives them the ability to provide èUSER-FRIENDLY SOLUTION FOR calculates the electric field distribution timely support for their customers, DEVICE DESIGN and the capacitance matrix, an even for cases that would have Each design space—and its integral piece of information for previously fallen outside the range of multiphysics model—will vary capacitive sensor design, and can a design box. depending on the intended generate a detailed report on the “We’re finding that letting application. Different designs might study. Simulation apps are shared our support teams have access to include, for example, multiple using a COMSOL Server™ license, multiphysics simulation results is electrode layers, layers in different which makes the apps accessible ® hugely helpful,” says Vavaroutsos. orders, or varying thicknesses or through either a Windows -native “We can control which parameters patterns for each layer. Each will also client or a web browser. are accessible to the app user so that cover a variety of parameter ranges “We’ve been creating simulation we know the apps are delivering in order to enable the precise analysis apps that our field engineers can accurate results, while also letting our of a certain system, and allows the apply directly to the task at hand engineer to predict and optimize the without having to go through us to create the simulation for them,” “I can foresee simulation apps becoming the primary tool used by our says Thomas. “While this is still field engineers in the automotive group in the near future.” a new technology for us, I can foresee simulation apps becoming support engineers experiment with electrical performance of the device. the primary tool used by our field thousands of different design options One app created at Cypress, engineers in the automotive group in without the need to involve an R&D based on such a simulation, allows the near future.”v the user to change various geometric

15 Multiphysics Simulation Helps Miele to Optimize Induction Stove Designs

èDEVELOPING AN EFFICIENT èREDUCED DEVELOPMENT TIME DESIGN PROCESS WITH FEWER PROTOTYPES Induction stoves have several At mieletec, engineers relied on advantages over traditional ones: simulation and the multiphysics they provide faster heating and are approach to improve, verify, and known for extremely high efficiency, optimize their induction stove where over 90% of the energy goes designs. Because their simulations directly into heating food. Induction in COMSOL® software accurately heating is used to heat a pot placed demonstrated how the prototypes on the stove, rather than heating the would perform, they saved stove itself, by passing an alternating development time and reduced the current through copper coils to number of experiments needed generate a magnetic field. This to finalize their designs by 80%. induces currents in the metal of the They were able to simulate the pot, causing Joule heating. entire system, improving the energy efficiency of the stove and optimizing “...they saved development time their results so that when the first and reduced the number of prototypes were built, they already had a clear idea of how they would experiments needed to finalize perform. Tests that in practice last for their designs by 80%.” a few days took only a few hours to The stovetop remains cool; in fact, the achieve when simulated. ice cubes are hardly melting, while the However, the process for water inside the pot is boiling. designing an induction stove was, èSIMULATION-LED OPTIMIZATION until recently, quite demanding. FOR HIGH-QUALITY STOVE DESIGN electromagnetics to optimize and It required trial and error for Simulating the induction heating determine the best operating estimating parameters such as the process involved solving heat conditions. Using COMSOL allowed ideal frequency, coil size, and power transfer simultaneously with researchers at mieletec to optimize output. Designers also tackled more unusual challenges, such as silencing the high-pitched noise produced by electric currents flowing through the metal, or the side effect of pots moving around on the stovetop because of magnetic forces. Researchers at mieletec FH Bielefeld, a joint research laboratory between Miele & Cie. KG and the University of Applied Sciences Bielefeld, Germany, have used computer simulation to close the gap between the concept and production stages of building induction stoves. With the help of COMSOL Multiphysics® software, they have created a breakthrough cooktop for Miele, a world leader in domestic appliances and commercial machines. Comparison between results from COMSOL Multiphysics® software (magnetic flux density norm) and experimental field lines can be used to test other coil designs before building a prototype.

16 the coil setup, settling on a combination of current frequency and coil geometry that would produce noise at a frequency higher than the human ear can pick up ­­— silencing the high-pitched squeal created by the eddy currents. To prevent pots from moving across the stovetop, they used simulation to analyze how the properties of different materials used in cookware respond to thermal and electromagnetic effects. Eddy currents in the paramagnetic metals that induction pots are made of produce a magnetic field when they interact with the magnetic field generated by the coil. This creates the magnetic forces that can cause the pot to move. From their results, the team optimized the coil design to ensure that pots would stay put, would provide the right amount of power for cooking, and would not produce noise audible to the human ear, all while retaining the high efficiency characteristic of induction stoves. The result? A development process aided and hastened by Setup of a test campaign performed by staff scientists Werner Klose (left) and Mikhail multiphysics simulation, and a Tolstykh (right). The stovetop has been removed, showing the internal workings of the stove. high-quality stove created and optimized for efficient, fast, reliable performance.v

Experimental results (left) and simulation results (right) showing the x-component of the magnetic flux density for a special coil design.

17 ADDITIONAL RESOURCES

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COMSOL COMSOL HANDBOOK SERIES Specialized Techniques HE MLIHSICSN SIMLAIONEWS MAAINE for Postprocessing and Visualization in ® MULTIPHYSICS COMSOL Multiphysics Sponsored by FROM STUDENTS TO ENTREPRENEURS SIMULATION University at Bu alo Special Advertising Section to: PAGE 32

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ABB EXTENDS CHARGING LIFETIME OF POWER Check out our many events that provide TRANSISTORS AT WITRICITY PAGE 20 PAGE 8 attendees with opportunities to learn more PUBLICATIONS & PRODUCT DOCUMENTATION about the COMSOL Multiphysics® software and Get to know the powerful simulation tools its capabilities. COMSOL offers, and read how simulation experts across many industries use COMSOL® software to • Webinars – Learn about how others in your industry resolve design challenges. are using COMSOL Multiphysics in a live or archived webinar. Browse the full list at comsol.com/webinars. • COMSOL News, Multiphysics Simulation • Web Workshops – Learn to build a multiphysics model • Introductory books to COMSOL Multiphysics and while you follow along from your own computer. Contact Application Builder us to schedule a demo and download a free trial. • Handbooks • COMSOL Days – Take part in regional 1-day training • Whitepapers events featuring hands-on courses and invited talks by experienced COMSOL users, product managers, and applications engineers. VIDEOS • COMSOL Conference – Attend these 2 and 3 Watch step-by-step tutorials, user presentations, day annual events featuring as many as thirty and topic-specific videos to learn how to model minicourses, poster and oral presentation sessions, your system with COMSOL. keynote presentations, exhibition, and social events. • Training courses – Advance your skills and boost your productivity at our 2-day COMSOL Multiphysics Intensive Training Course, or one of our topic-specific courses. BLOG Browse our blog to get inspiration and guidance for SUPPORT your own simulation work. You will find: Support engineers at COMSOL answer questions • Tutorials and how-tos and offer suggestions. The online discussion forum provides you with a widespread network of users • Simulation best practices modeling a diverse range of applications. • User research

PRODUCTS

› COMSOL Multiphysics® › COMSOL Server™

ELECTROMAGNETICS STRUCTURAL & FLUID & HEAT CHEMICAL INTERFACING › AC/DC Module ACOUSTICS › CFD Module › Chemical Reaction › LiveLink™ for MATLAB® › RF Module › Structural Mechanics › Mixer Module Engineering Module › LiveLink™ for Excel® › Wave Optics Module Module › Subsurface Flow Module › Batteries & Fuel Cells › CAD Import Module › Ray Optics Module › Nonlinear Structural › Pipe Flow Module Module › Design Module › Plasma Module Materials Module › Microfluidics Module › Electrodeposition Module › ECAD Import Module › Semiconductor Module › Geomechanics Module › Molecular Flow Module › Corrosion Module › LiveLink™ for SOLIDWORKS® › MEMS Module › Fatigue Module › Heat Transfer Module › Electrochemistry Module › LiveLink™ for Inventor® › Multibody Dynamics › LiveLink™ for AutoCAD® Module MULTIPURPOSE › LiveLink™ for Revit® › Rotordynamics Module › Optimization Module › LiveLink™ for PTC® Creo® Parametric™ › Acoustics Module › Material Library › LiveLink™ for PTC® Pro/ENGINEER® › Particle Tracing Module › LiveLink™ for Solid Edge® 18 › File Import for CATIA® V5 PRODUCT FAQ

What is the COMSOL Multiphysics® software? What is COMSOL Server™? • An integrated software environment for creating • A software product for running apps built with physics-based models and simulation apps. COMSOL Multiphysics and the Application Builder. • A particular strength is its ability to account for • It is like COMSOL Multiphysics, but… coupled or multiphysics phenomena. »» With a web interface for running applications • Add-on products expand the software environment from a web browser. for electrical, mechanical, acoustic, fluid flow, »» With administrator tools for creating and thermal, and chemical simulations. managing user accounts. • Interfacing tools enable the integration of COMSOL® »» Without the builder tools: Model Builder, Application Builder, and Physics Builder. simulations with all major technical computing and CAD tools on the market. What are the advantages to COMSOL Server™? What are the advantages to COMSOL Multiphysics®? • Run apps in a web browser (or COMSOL Client for Windows® operating system) from anywhere in the • Powerful and extensive multiphysics functionality world, sharing application libraries. enables high-fidelity modeling of real world systems. • Administrator tools for user accounts, privileges, and • A consistent, easy-to-learn interface across all user sessions. application modules means a shorter learning curve, and enhanced productivity. • Much lower license fee (a cost-effective way of running apps built with COMSOL). • Increase everyone’s productivity by converting your COMSOL model into an easy-to-use custom • Install anywhere – on a server, cluster within an simulation app with the Application Builder tool. organization, on a laptop, or on a desktop computer for offline use. What are the advantages of custom simulation apps? • The web browser or COMSOL Client running on • App users do not need any experience in numerical the user’s device does not do any computations. All simulation to benefit from the power of multiphysics computations are done on your server computer(s). analysis. • Simulation apps can be deployed to colleagues and customers with a local installation of the COMSOL Server™ product for seamless collaboration.

LICENSE OPTIONS The table below is a summary of the different license types available.

License Multiple Multiple Client/ Cluster Network World- Type Computers Users Server Computing Access wide

Named Single * User License (NSL)

CPU-Locked Single User License (CPU)

Floating Network ** License (FNL)

COMSOL Server ** License (CSL)

* The software may be installed on 4 machines at one time, and may be run on 2 of those 4 machines at any given time. ** Pay per concurrent user.

19 www.comsol.com