3 CASE HISTORY modefrontier Community Sommario - Contents 5 Virtual Prototyping and PIDO in the Spotlight 10 Optimization of an automotive door panel acting on injection molding process parameters 16 Il fenomeno del Flutter per Ponti di Grande Luce: uno studio numerico 21 Software to Meet the Toughest Challenges in Design of Composite Structures 22 La sperimentazione navale nell ingegneria nautica in Victory Design 24 Piastra Raffredata da Microfori: Funzionamento e Tracciamento di Particelle 27 Progetto STAR (Simulation Technology Aeronautic Research) 32 La simulazione delle lavorazioni meccaniche delle Superleghe 38 FORGE - Release Notes 40 FRAMMENTI DI FEM:Flessione secondaria nei recipienti in pressione in parete sottile 43 EnginSoft e il progetto CEFEN 44 Enginsoft è presente alla conferenza annuale di ANSYS a Pittsburgh 45 Nuove offerte formative per l addestramento alle tecnologie CAE nel Education and Research for Excellence in Engineering 49 A reliability analysis with a Monte Carlo approach using modefrontier 52 The failure behavior of glass mat reinforced thermoplastics (GMT) - optimization of the parameters slim and erods 53 modefrontier at TUBITAK-SAGE in Turkey 54 Why students join the modefrontier university program 55 modefrontier Event Calendar Newsletter EnginSoft Anno 5 n 3 - Autumn 2008 Per ricevere gratuitamente una copia delle prossime Newsletter EnginSoft, si prega di contattare il nostro ufficio marketing: Tutte le immagini utilizzate sono protette da copyright. Ne è vietata la riproduzione a qualsiasi titolo e su qualsiasi supporto senza preventivo consenso scritto da parte di EnginSoft. Copyright EnginSoft Newsletter. Pubblicità Per l acquisto di spazi pubblicitari all interno della nostra Newsletter si prega di contattare l ufficio marketing: Luisa Cunico - EnginSoft S.p.A BERGAMO Via Galimberti, 8/D Tel Fax FIRENZE Via Panciatichi, 40 Tel Fax PADOVA Via Giambellino, 7 Tel Fax MESAGNE (BRINDISI) Via A. Murri, 2 - Z.I. Tel Fax TRENTO fraz. Mattarello - via della Stazione, 27 Tel Fax SOCIETÀ PARTECIPATE COMPANY INTERESTS ESTECO TRIESTE Area Science Park Padriciano 99 Tel Fax CONSORZIO TCN TRENTO Via della Stazione, 27 - fraz. Mattarello Tel Fax ESTECO GmbH - Germany ESTECO UK - United Kingdom EnginSoft France - France ESTECO Nordic - Sweden Aperio Tecnologia en Ingenieria - Spain ASSOCIAZIONI PARTECIPATE ASSOCIATION INTERESTS NAFEMS International TechNet Alliance STAMPA - PRINTING Grafiche Dal Piaz - Trento Newsletter EnginSoft Anno 5 n 3-3 DIRETTORE RESPONSABILE - RESPONSIBLE DIRECTOR Stefano Odorizzi - NEWSLETTER EnginSoft è un periodico trimestrale edito da EnginSoft SpA The EnginSoft NEWSLETTER is a quarterly magazine published by EnginSoft SpA Autorizzazione del Tribunale di Trento n 1353 RS di data 2/4/2008
4 4 - Newsletter EnginSoft Anno 5 n 3 EnginSoft Flash In autumn 2008, EnginSoft has launched several initiatives that we regard as milestones in the development of our organization and network. First of all, our three major CAE Conferences in Venice are approaching. On 16th & 17th October, experts from various industries, research & academia, software development will come together and unify the industrial and scientific worlds of Simulation. The Conference Program of TCN CAE 2008, which has gone online in early September, features technical contributions from around the world, on such topics as, medicine, materials and methods, process integration and multi-objective design optimization. Furthermore, management, technical and open sessions on industrial applications, relevant to automotive, aerospace, energy and consumer goods are included in the agenda. The uniqueness of the TCN event is also reflected by such futureoriented topics as education and co-funded research projects. In 2008, the EnginSoft Users Meeting celebrates its 15th anniversary as an annual occasion for those responsible for CAE and Virtual Prototyping in industry. The conference focuses on the innovation of the industrial design process featuring CAE as an indispensable tool for competitiveness. As such, the event showcases the modefrontier, ANSYS, LS-DYNA, MAGMASOFT, Flowmaster, ESAcomp technologies. The ANSYS Italian Conference 2008 will take place within the frame of the EnginSoft Conference as in previous years underlining EnginSoft s status as the official ANSYS distributor in Italy. ANSYS expert users from all over the country will capture their audience under the motto of the 2008 Worldwide ANSYS Conferences: Inspiring Engineering. The modefrontier international users meeting traditionally takes place in Trieste where the ESTECO headquarter is located. The dates of the meeting, 14th & 15th October, have been chosen to allow the many delegates from abroad to conveniently combine their stay for the following CAE events in Venice. ESTECO is proud to offer a top-class program with speakers from BMW, EADS, Volkwagen, VOLVO, ABB and many more esteemed organizations. modefrontier users from around the world will meet with software developers and experts to discuss applications, latest developments and the capabilities and diversity of modefrontier. The Venice and Trieste events will offer unique CAE occasions for our audiences to exchange experiences and latest knowledge, find new business partners, renew existing relations, and to get inspiration for the year ahead. A major step forward in EnginSoft s commitment to education and research is the launch of our Training & Recruitment Initiative in September Based on our conviction that a full understanding of new complex technologies and the necessary permanent development of expertise requires a modern working Ing. Stefano Odorizzi General Manager EnginSoft environment, we have elaborated a structure for a series of Training Courses which will commence in February Course Graduates will be invited to enter into assignments with EnginSoft or its partners in Europe. We also invite our readers to follow the contributions on modefrontier, specifically the article which demonstrates the successful coupling with Moldflow or the reliability analysis with a Monte Carlo approach. This issue also includes a contribution from The Institute of Polymer Engineering, University of Applied Science Northwestern Switzerland and their work in optimization. The Software News this time feature the ESAComp s 4.0 version and the design of composite structures. One of the key competences of our Civil Engineering Team is the design of longspan suspended bridges, and this issue includes an article on the challenges related to flutter phenomena. We introduce Victory Design, their work with the ANSYS software and Virtual Prototyping in naval engineering. The Newsletter also provides Projects News, this time on our activities linked to CEFEN and STAR, as well as the latest modefrontier News and Event Calendar. The EnginSoft Team looks forward to the pleasure of welcoming our readers to Venice (16th & 17th October) and Trieste (14th & 15th October) to share our enthusiasm for excellence in Engineering! Stefano Odorizzi Editor in chief
5 Newsletter EnginSoft Anno 5 n 3-5 Virtual Prototyping and PIDO in the Spotlight In mid-october 2008, four closely linked conferences will bring together and melt the industrial and scientific worlds of simulation, offering their audiences state-of-the-art technologies and deep insights into future developments. Leading players and well-known speakers from the fields of virtual prototyping, process integration, and multi-objective optimization, various industries, research, software development, academia, and consultancies will come together to offer the most promising, inspiring and largest event of its kind in Italy - with wide international participation. The Conferences that will take place concurrently in Venice on 16th and 17th October are: TCN CAE 2008 International Conference on Simulation Based Engineering and Sciences EnginSoft Conference 2008 CAE Technologies for Industry ANSYS 2008 Italian Users Meeting The NH Laguna Palace Hotel in Venice/Mestre will provide a made-tomeasure location for the fusion of the three main conferences. The stunning venue boasts Europe s biggest transparent glass roof and a marina that links the hotel with all canals of the world-famous historic city of Venice, built on water. The state-ofthe-art conference center and central exhibition area, with software and hardware vendors from around the globe that await our audiences, will unify the three conferences to a notto-be-missed CAE occasion. Prior to the Venice Conferences, on 14th and 15th October, in nearby Trieste, the bi-annual modefrontier international users meeting 2008 will be hosted by ESTECO srl, the program developers. All these events will offer a unique forum in which enabling technologies, as well as industrial applications will be presented and discussed from a business-value perspective, allowing the participants to plan their path through the various sessions and contributions, and hence to take the maximum advantage of these unique CAE occasions. Various independent technological studies say that computer modelling and simulation are key elements for achieving progress in engineering and science in the 21st century. Today, we are facing an enormous expansion in our ability to model and simulate an almost limitless variety of phenomena and industrial processes. However, and at the same time, the challenges of making progress are as substantial as the benefits. Certainly, it is crucial for all involved in the technology circle, from researchers to industrial practitioners, to understand better the working methods and directions of their developments, implementations and the use of the various technologies. Conferences like those organized in Venice and Trieste, will help exploring ways on how to integrate virtual prototyping across multiple disciplines, including mechanics, dynamics, CFD, crash, durability and fatigue, acoustics, process simulation, control systems. In addition, the Conferences will address questions on how to: Qualify and quantify the value of computational techniques Implement virtual prototyping early in the design process Manage virtual prototyping across the supply chain Integrate and manage trade-offs between simulation and test & measurement Qualify cost-benefits of high performance computers Overcome barriers for data sharing and interpolation. Furthermore, the agendas will include business management issues, such as: Cost-benefit analysis Organizational challenges Knowledge capture Design methodologies and training Deployment of virtual prototyping across the supply chain Reduction of testing Supporting infrastructures Staff skills profiles Management of data Failure scenarios Investment protection and similar TCN CAE 2008 International Conference on Simulation Based Engineering and Sciences TCN Consortium is a private company with the primary objective to provide state-of-the-art training to those people involved in fostering company innovation and competitiveness. During the course of the year, TCN offers training at different levels and through various methods, for disciplines related to CAE, Virtual Prototyping and Testing, as well as to complementary disciplines which are bound to statistics, data structures, information technologies and software engineering in general. The aim is to
6 6 - Newsletter EnginSoft Anno 5 n 3 make the corresponding software technologies usable for industry with particular emphasis on the production context. Ever since its foundation in 2001, TCN has experienced a growing demand for its different initiatives including: Short courses (more than 80 courses are on offer in 2008) Web-based courses (more than 50 courses with a unique set-up) Mini-Masters (TCN Mechatronics has become a sort of trademark ) Research on education and educational methods, specifically for EU-funded pilot projects in the frame of the Leonardo da Vinci Programme and one Marie-Curie Project, where TCN acts as coordinator, about 500 fellowships could be established within the frame of this initiative Bi-annual TCN-CAE Conferences. Since TCN CAE s first edition in Sardinia, 2nd-5th October 2003, the International Conference has received recognition for its unique approach: to build a bridge between research & academia, technology providers, industrial practitioners and managers. With the same perspective, the 2008 conference is featuring: A plenary session, with keynotes addressing the topics of the subsequent program parts Three separate sessions on enabling technologies designed around the themes of medicine, materials and methods, process integration and multi-objective design optimization Four separate management, technical and open sessions on industrial applications, relevant to sectors such as automotive, aerospace, energy and consumer goods; A separate session on education and co-founded research (mainly EU co-founded projects). Keynote Speakers include such distinguished personalities from university, research, industry and technology as: Giulio Maier, Professor Emeritus of Structural Engineering at the Technical University of Milan, and Rector of the International Centre of Mechanical Sciences of Udine, who will address the problem of Inverse Analysis Procedures for Mechanical Characterization of Materials and Diagnosis of Structures Roberto Cingolani, Professor of General Physics at the University of Salento and Invited Professor at Tokio University, as well as Director of the prestigious National Nanotechnology Laboratory at Salento University, who will present an overview on Nanomaterials with Enhanced Mechanical and Chemical Performances Thomas Gasser, Department of Solid Mechanics of the Royal Institute of Technology in Stockholm, who will speak about A Simulation based Diagnostic System for the Abdominal Aortic Aneurysm Nevio Di Giusto, General Manager and CEO of Centro Ricerche Fiat. and Elasis S.C.p.A (Fiat Research is a co-founder and current member of TCN), who will discuss CAX Systems as enabling Instruments for Automotive Innovation Christophe Behar, Director of the Research Centre CEA/DAM-Ile de France, who will introduce The High Performance Computing Center at CEA as well as its Applications and Perspectives Dan Nagy, Program Director of the IMS International Research and Development Initiative Further keynote speakers will open the parallel sessions of the conference. TCN CAE 2008 will meet the expectations generated by its predecessor meetings and provide the ideal international forum for best possible interaction and exchange between attendees, exhibitors, sponsors and patrons! The EnginSoft Users Meeting CAE Technologies for Industry The EnginSoft Users Meeting celebrates its 15th anniversary as an annual occasion for those responsible for CAE and Virtual Prototyping in industry. In fact, the conference is focused on the innovation of industrial design (and production) processes, identifying CAE as the indispensable tool to improve quality, efficiency and efficacy towards competitiveness. The conference will strive to provide answers to such key questions as: What are the possible solutions for manufacturers to overcome organizational and technological challenges and obstacles in order to realize the full potential of virtual prototyping? How can analysis and product design be linked together more closely? Are there any available processes and tools that can coordinate and manage the data and workflow resulting from integrated design and analysis? What are the best methods for deploying and managing virtual
7 Newsletter EnginSoft Anno 5 n 3-7 dedicated to the main software that EnginSoft supports and distributes ANSYS, modefrontier, LS-DYNA, MAGMASOFT, Flowmaster, ESAcomp among others. Highlights will be new software developments and applications! prototyping across dispersed enterprises and supply chains? Will the investments made by technology providers lead to higher quality and more productive solutions? How can virtual prototyping technologies be cost-justified when payback may be expected in years ahead in the future? How should CAE and virtual prototyping be deployed throughout the product development process to ensure the greatest possible impact on costs, time and quality? How can we efficiently provide suitable and ongoing training for new technologies? The event will be opened by a plenary session with keynote addresses from: Stefano Odorizzi, General Manager and CEO of EnginSoft on The impact of CAE on the Innovation of the Design Process in Industry Professor Carlo Poloni, General Manager and CEO of Esteco on modefrontier, a Tool for Process Integration and Multi-objective Collaborative Design Optimization, and Jim Cashman, President and CEO of ANSYS, Inc. The plenary part will be followed by four parallel sessions representing the four main industrial areas: automotive, aerospace, energy, consumer goods. Moreover, the conference program will feature workshops and courses The ANSYS 2008 Italian Conference. As EnginSoft is the Italian distributor for the ANSYS suite of software technologies, the EnginSoft Conference 2008 hosts also the ANSYS 2008 Italian Conference. Both events are highly interconnected, specific ANSYS applications will be presented in all four parallel sessions of the EnginSoft Conference. Case histories and CAE experiences contributed by outstanding Ansys expert users from all over Italy will perfectly underline the motto of the 2008 Worldwide ANSYS Conferences: Inspiring Engineering. More specifically, the multiphysics approach - a unique solution and comprehensive coupled physics tool combining structural, thermal, CFD, acoustics and electromagnetic simulation capabilities in a single software product - will be highlighted. The multiphysics context was actually pointed out at the 2007 EnginSoft Conference, and it was on this occasion that Keith Hanna, Corporate Marketing Director Europe, ANSYS, Inc., interviewed Stefano Odorizzi. The interview focused on Stefano s viewpoints and visions on the evolution of multiphysics solutions as well as future challenges to overcome. The interview will appear shortly in the ANSYS Advantage magazine. Some words taken from the interview are worth to be mentioned here, since they anticipate key topics of the discussions at the upcoming conferences. Excerpt from ANSYS Advantage Magazine, edition 3/2008 published by ANSYS, Inc. Remarks by Stefano Odorizzi, EnginSoft S.p.A. made during an interview with Keith Hanna, ANSYS, Inc.
8 8 - Newsletter EnginSoft Anno 5 n 3 As multiphysics and advanced modeling methods become more advanced, simulation-based engineering and science will be indispensable in meeting the technological challenges of the twenty-first century. The process will not be simulation as usual for narrow studies of individual parts and assemblies but rather will be focused on complex, inter-related engineering systems and on analysis results that meet specified standards of precision and reliability. Hence engineering simulation will develop new methods, technologies, procedures, processes and planning strategies. All these will be key elements for achieving progress in engineering and science. To reap these benefits, however, four significant obstacles must be overcome: First, we must revolutionize the way we conceive and perform simulation. In this respect, the mass success of computerbased engineering simulation may be its own worst enemy, because the knowledge base, methods and practices that enabled its achievements to date now threaten to stifle its prospects for the future because of organizational inertia and a reluctance to implement new approaches. Second, we must make significant advances in supporting technologies, including those for structuring the way in which models are built and organized. These technologies have a huge impact on the complexity, solution time and memory capacity required, and even today, some of the most complex turbulent-flow problems cannot be currently solved on the world s largest and fastest computers. If progress continues at the rate of Moore s Law, such solutions may not become practical for decades unless effective multiscale modeling technologies are developed to represent the entire range of complexities from minute individual component details up to broad system-level characteristics. Third, meaningful advances in simulation-based engineering and sciences will require dramatic changes in education. Interdisciplinary education in computational science and computing technology must be greatly improved. Interdisciplinary programs in computational science must be encouraged, and the traditional boundaries between disciplines in higher education must be dissolved for information to be exchanged smoothly between scientists and engineers collaborating within teams from multiple disciplines. Fourth, because of the interdisciplinary character and complexity of simulation, we must change the manner in which research is funded. Incremental, shortterm research efforts are inadequate and instead should be replaced by long-term programs of high-risk research. Moreover, progress in such research will require the creation of interdisciplinary teams that work together on leading-edge simulation problems. Should applied mathematics and computer science methodologies be focused on computational science at this broad scale in overcoming the above barriers, there is ample evidence that developments in multiphysics and related new disciplines could significantly impact virtually every aspect of human experience. Stefano s concluding thoughts in the interview said: Also, among the world s leading CAE software suppliers, ANSYS, Inc. has the right long-term vision and is making significant investments both in the core disciplines of science and engineering and in the development of algorithms and computational procedures for dynamic multiscale, multiphysics applications. Do I personally think we will get to a point of science fiction becoming science fact within the next decade or two, where design engineers focus most of their efforts imagining product variants and product innovations while computers churn away in the background spitting out predictions in real time? I really do think these dreams will become reality in my lifetime. The modefrontier International Users Meeting 2008 To stay competitive and gain market share, companies are forced to continuously improve the quality of their products. While this has been a longtime-held belief for most managers, only in recent years has it become clear that achieving higher quality is not necessarily at odds with efforts to reduce cost and time-tomarket. The modefrontier International Users Meeting traditionally takes place at the Mediterranean, in the beautiful city of
9 Trieste, where ESTECO s headquarter is located. The dates of the meeting, 14th & 15th October, have been chosen to guarantee smooth onward travels for delegates from abroad to nearby Venice for the following CAE events on 16th & 17th October. After all, it is only a convenient journey of about 1,5h by car or train from Trieste to Venice, the world-famous city built on water. The 2008 modefrontier event features top-class speakers from BMW, EADS, Volkwagen, VOLVO, ABB and many more esteemed organizations. modefrontier users from around the world will meet with software developers and experts to discuss applications, latest developments, new features, and the capabilities and diversity of modefrontier, one of the best multidisciplinary & multiobjective design optimization tools available on the market today. As in previous years, the accompanying exhibition in the Foyer will serve as a platform for exhibitors, including EnginSoft, and attendees to meet and share technical know-how, experiences and visions for the future. The conference s plenary session features keynotes from: Bombardier on the optimization of the Zefiro High-Speed Train Fiat on their optimizations and Advanced Simtech on the application of modefrontier in real world collision reconstruction. The 10 subsequent parallel sessions are designed around the main themes and applications of: Automotive Aerospace Civil Engineering Electromagnetism and antenna related applications and challenges Further topics will touch fuel cells, BGA, welding processes, pump design, composite structures and other. The plenary sessions that follow are interconnected with the main conference topics and will wrap-up the discussions and offer further and more general overviews on the impact and potential of the PIDO. Be Inspired about Optimization - Come and meet us in Trieste on 14th and 15th October 2008! CONCLUSIONS The word Inspiration naturally brings up many good thoughts. In the CAE context, certainly the motto of the 2008 Worldwide ANSYS Conferences comes up in our minds: Inspiring Engineering. We are confident that our attendees that we are delighted to welcome to Venice and Trieste will be inspired about the technical programs, the discussions, the social evenings and the venues we have chosen. It was inspiration for excellence in engineering and for making investments for the future of CAE and Virtual Prototyping that has guided us to include the topics of Education and Knowledge Transfer into the conference agendas. We want to pass on and share our inspiration for engineering, computational science and computing technologies with the next generation of engineers. The EnginSoft Training & Recruitment Initiative offers unique opportunities for interdisciplinary education in simulation to young people with inspiration for engineering! Additional info on 2008 Conferences: Conference Guides for each of the events will be handed out to the attendees at the Welcome Desks. The Guides provide a variety of useful information, such as conference programs, exhibitor lists, logistic details and more. Electronic Conference Proceedings will be available, also for those who could not participate! We encourage anybody who was not on-site, but would like to have insights into the range of worldclass technical presentations, to contact EnginSoft and/or Esteco to receive a free copy of the Proceedings! Newsletter EnginSoft Anno 5 n 3-9 Dedicated web sites: SPONSORS
10 10 - Newsletter EnginSoft Anno 5 n 3 Optimization of an automotive door panel acting on injection molding process parameters Ottimizzazione di un pannello per porta d automobile agendo sul processo di stampaggio a iniezione Il caso studio in oggetto si riferisce all analisi del processo di stampaggio a iniezione e della progettazione dello stampo del pannello della Grande Punto. La configurazione iniziale dello stampo è stata fornita da Johnson Control Italy (JCI), che ha preso parte a questo lavoro. Dati la geometria del pannello, il materiale, le caratteristiche della macchina e la procedura di stampaggio, Fig. 2 The optimization process, automated by modefrontier Fig. 1 Door Panel model ambizioso progetto sono stati Moldflow MPI, con cui è stato costruito il modello ed elaborati i parametri del processo di stampaggio a iniezione, e modefrontier, con cui sono stati controllati e processati i parametri e gli obiettivi dell ottimizzazione. In una fase successiva si è proceduto all integrazione di Moldflow MPI con la strategia di ottimizzazione, così da ricercare la miglior combinazione tra i parametri iniziali che soddisfacesse le condizioni date. I risultati, visualizzati ed analizzati con gli strumenti di postprocessing disponibili in modefrontier, hanno fornito utili indicazioni: con soli 44 tentativi, e l integrazione di Moldflow/modeFRONTIER (ed in particolare grazie all efficienza dell algoritmo MOGT) è stato possibile ridurre, contemporaneamente, la forza di chiusura del 30% ed la deformazione del 29%. sono stati fissati degli obiettivi qualitativi da raggiungere rispettando alcuni vincoli operativi. Come spesso accade per problemi ingegneristici, anche questa sfida si è prefissa di ottenere contemporaneamente miglioramenti e performance tra loro in conflitto, riducendo al contempo i costi di produzione. Gli strumenti utilizzati per questo Fig. 3 Mesh of the model The challenge The present work refers to the study of an injection molding process and the mold design of a door panel (front medallion 3 doors car) from the Fiat
11 Newsletter EnginSoft Anno 5 n 3-11 MPI by using a midplane model, including about triangular elements. The hot runner system has been defined by beam elements. The mesh of the panel and of the hot runners is shown in fig. 3. Mesh diagnostics commands have been used to detect and fix model errors, such as high aspect ratio or overlapping elements. Fig. 4 Typical packing profile Grande Punto 199 Project. The initial mold design is from Johnson Control Italy (JCI), which co-operated to realize this work. The door panel geometry is shown in fig. 1: its dimensions in the XY plane are approximately 1050 mm (width) and 550 mm (height), and it is injected by a hot runner system. The used injection molding machine is a tandem machine, capable of injecting two molds at the same time. In the present case, the right and left panel are injected by the same machine. The material used for this part is a Polypropylene with 10% mineral filler. JCI provided indications on the characteristics of the injection molding machine: an important aspect to be considered is that the clamp force value for this part should be under 1350 tons. A few preliminary Moldflow The goal is to increase part quality while respecting some manufacturing constraints. To achieve these objectives, output values, such as Z- axis deformation (warpage), material flow pattern and weld line positions, have to be improved. Simultaneously, the clamp force should be reduced in order to cut the cost of the process. This scenario represents a typical challenge in engineering, with various and often conflicting objectives. Fig. 5 Position and number of valve gates The tools available to achieve the given objectives are Moldflow MPI for the injection molding simulations, and modefrontier for the automation of the multi-objective optimization, and as data post-processor. The Moldflow MPI model and the process assumptions The part has been modeled in Moldflow Fig. 6 Desired position for the last point to fill.
12 12 - Newsletter EnginSoft Anno 5 n 3 Fig. 7 modefrontier optimization workflow (with under development version of the Moldflow MPI node, updated at the present paper first release). MPI analyses clarified that it is extremely difficult to respect such clamp force limits when using only three injection points for the mold. This is mainly due to the relatively long flow lengths within the part when using only 3 gates: hence the maximum pressure, and particularly the clamp force, are too high for the considered machine. Therefore, the number of injection points has been set to a constant value of five in the subsequent optimization, even though it is possible to consider the number of injection points as a variable within a modefrontier project. The thickness of the part is approximately constant around 2.8 mm: such a value was obtained by the customer itself as a good compromise between cost, structural and processing needs. For this reason, thickness has not been included as a free parameter to be investigated, even though it would be possible within a modefrontier optimization. Optimization parameters Among all the process parameters controlling part quality and clamp force, 8 have been selected as the most sensitive ones, and subsequently set up as input variables in the modefrontier optimization workflow linked to the Moldflow MPI model. The packing profile has been parameterized giving modefrontier the opportunity to control the packing pressure, packing time (time during which constant packing pressure is applied) and decay time (time from packing pressure to zero pressure). A typical packing profile is shown in fig. 4. This is important not only with respect to the clamp force, but also in order to control the warpage of the part. JCI recommended to use a packing pressure of about MPa for this material. To better study the influence of packing pressure on design objectives, packing pressure values between 20 and 50 MPa have been considered. The total cycle time has been determined after a few introductive analyses, taking into account the characteristics of the injection molding machine: its value is around 45s, including approximately 14s of mold opening time. Since the order of magnitude of the filling time is about 5s, as found out after some preliminary analyses, about 26s are consequently available for the packing and the cooling of the part. Considering also other characteristics of the process (such as re-dosing time), it has been decided to investigate the influence of the total packing time on the design objectives (in particular with the aim to achieve warpage reduction), by assigning two independent input variables to the packing time and the decay time, both can span from 0 to 20s, without exceeding a maximum of 20s together. This is possible in the modefrontier workflow by assigning a constraint to the sum of the independent variables. In this case, the positions of the injection points (see fig. 5) could not be changed significantly, due to customer requests and constraints related to the mold and part geometry. Instead, it was possible to use hot runners with valve gate control, and hence search for the optimal valve gates opening times. Considering that in general, it is not convenient that a single valve gate opens before the flow front reaches the valve itself (to avoid weld line forming) and that injection starts from gate1, the delayed opening times of valve gates number 2-5 were controlled by modefrontier as independent input variables. This allowed the optimizer to control the flow pattern and the balance of fill without changing the injection gates positions. Delay time ranges for gates 2 and 3 were set to 0-2s, the ones for gates 4 and 5 to 0-1.5s. Moreover, the melt temperature has been considered as an input variable, because of its influence on flow pattern, clamp force (melt temperature influences viscosity of material and hence injection pressure and clamp force during filling) and warpage of the part. The melt temperature has been set free to vary between 220 and 260 C. Mold temperature has been set as a constant of 40 C, since all the preliminary analyses proved that any change of mold temperature in the material s recommended range had only secondary effects on the results of interest, with respect to the other variables. Optimization objectives In order to describe and control the part quality, besides warpage minimization, another important parameter to consider is a proper filling pattern. Controlling flow pattern and positioning weld lines in the least sensitive areas are important design objectives which allow to obtain good quality parts. In the present case, it
13 has been agreed with the customer to control the position of the last zone to fill: it is important to note that this part (where a weld line is likely to form) is located in an hidden area of the medallion after having been assembled into the whole door structure. The zone recommended by the customer is shown in fig. 6: Within modefrontier it is possible to extract from any Moldflow MPI analysis the position of the last-filled-point, shots in the most serious cases. In the modefrontier project, a constraint has been assigned to the minimum flow front temperature result: if more than 10 C lower than melt temperature, the solution is going to be penalized within the optimization loop. In summary, the following 8 independent input variables have been set: Newsletter EnginSoft Anno 5 n 3-13 out-of-plane (Z direction) deformation; minimize the distance of the last filled node from the desired zone. Additionally, a constraint has been set to the difference between minimum flow front temperature and melt temperature; some small bosses with low thickness, present in the part, were not included in this verification. The representation of the whole optimization process is the modefrontier workflow depicted in fig. 7. Fig. 8 Initial design and selected optimal solution within the two main objectives space. and to assign as objective the minimization of the distance of such node from the wanted zone. Another important result from the Moldflow MPI analyses is the flow front temperature which provides important indications on the quality of the part. A big difference between minimum flow front temperature and melt temperature can lead to bad quality weld lines, flux hesitations and short packing pressure; packing time and decay time; melt temperature; delay times for valve gates 2-5; while the 3 objectives to be pursued simultaneously by the multi-objective optimizer have been: minimize the clamp force in Z direction (mold open direction); minimize the difference between maximum and minimum value of Tab. 1 Comparison between the initial design and the selected optimal solution, as input variable values and as objective improvements. Integration of Moldflow MPI and optimization strategy After the creation of the workflow of fig. 7, modefrontier is ready to search for the best combination of input parameters, building and driving automatically several Moldflow MPI studies towards the optimum. In particular, the link between the Moldflow MPI project and modefrontier has been managed via Moldflow s API, and hence without any ASCII file creation. In this way, it is possible to let modefrontier control - as input parameters - virtually any process parameter defined in the Moldflow study, as well as other entities, such as gate numbers and positions, shape and thickness of some parts, eventually linking any external CAD system. The multi-disciplinary nature of modefrontier allows the user to set up mixed optimizations, connecting to the process simulation also other analyses, such as fiber orientations, FEM analyses, and so on - thus linking in other commercial CAE tools or in-house codes in the same optimization loop. Despite of the fact that the optimization described here, only involves process parameters, the space of the possible solutions combining the 8 defined parameters is wide, actually in the range of 1016 different responses. Therefore, due to a time constraint of one weekend on a single processor machine as total optimization time, a very efficient
14 14 - Newsletter EnginSoft Anno 5 n 3 Fig. 9 Initial design (left) and selected optimal solution (right), Z axis deflection Fig.10 Initial design (left) and selected optimal solution (right), clamp force the variables to be optimized from one player to another, dynamically during the progress of the optimization, and accordingly to the statistical influence analysis of each variable. The result is a robust stochastic algorithm able to approach the Pareto Frontier (the whole set of nondominated solutions of multi-objective problems) within a few attempts which is extremely useful for engineering problems with a limited solution time. In the described project, a maximum number of Moldflow studies of about 60 was available by leaving the solver to work automatically, driven by modefrontier s MOGT, all over a weekend using a single processor workstation. Optimization results The results obtained by the MOGT algorithm have been visualized by applying the modefrontier post processing charts. With regard to the two main objectives, the minimization of warpage and clamp force, the scatter chart shown in Fig. 8 has been particularly useful. It represents each of the Moldflow study results by means of a marker. Each green bubble shown Fig. 11 Initial design (left) and selected optimal solution (right), filling time plot optimization stochastic algorithm, available in modefrontier, has been chosen. This algorithm, named MOGT (Multi- Objective-Game-Theory), is based on the work of John Nash on the game theory. In a competitive game, there may be several conflicting objectives to be achieved. Each player can optimize a certain variable subset assigned to him/her with respect to the unique objective, using a fast mono-objective strategy. In any case, all the variables that are not under his/her own control, are the result of a previous optimization step carried out by all the other players. Hence, they obviously influence his/her search. The solution is an equilibrium point that occurs when the choices of the two players do not change in the following steps. This choice represents the best compromise for the objectives: it is a unique solution, however, this solution depends on the way the variables space has been split among the players. For this reason, the modefrontier s MOGT implements an adaptive mechanism that allows to redistribute Fig. 12 Correlation indexes for each input parameter (lines) over the two main objectives (columns), modefrontier s correlation matrix.
15 Newsletter EnginSoft Anno 5 n 3-15 shows that decreasing this last factor has not a huge but still a negative effect on the warpage (-0.22 correlation). The reduction of the warpage is widely controlled by the packing time (increasing is beneficial) and by the gates delay times. The melt temperature, within the assigned variation limits, appears not to be a primary factor with regard to both the objectives. Fig. 13 Interaction effects on the warpage of the two factors melt temperature and packing pressure, modefrontier interaction chart is a solution respecting assigned constraints on total packing time and minimum flow front temperature, while a yellow marker does not. The green dotted line groups the most interesting solutions. In particular, number 44 was selected as the most interesting compromise between the two main objectives. Table 1 illustrates the comparison between the initial solution and the optimized one. As shown right, the improvements were considerable and simultaneously obtained with respect to all the three objectives. On the left, we can see the peculiar parameters combination which guarantees such results. Packing pressure has been reduced (beneficial in reducing clamp force) with respect to the initial design, but not abated to the minimum allowed in the defined range. In the same way, the total packing time has been increased but not up to the maximum allowed, testifying again the conflicting nature of the objectives. A peculiar combination of delay times for the controlled gates has been detected. This is to control the flow pattern with respect to the flow front temperature, pressure and deflection. Fig.9 shows the improvements obtained with the warpage behavior of the part, mainly due to deformation reduction in the highlighted critical zones. Fig.10 compares the clamp force history of the initial and optimized process: a reduction of the peak value is clear. Fig.11 shows how the last-filled zone (grey cells) has been moved towards the ideal orange box defined for aesthetic reasons. Parameter sensitivity analyses and optimization data post processing After an optimization process, the visualization and exploitation of all the collected data represents a key issue. For example, a major topic is detecting sensitivities, main effects and interactions of the various parameters on the major outputs/objectives. modefrontier offers several powerful tools to meet these challenges. In particular, the plot in fig. 12 shows the result of a correlation analysis over a reduced factorial Design of Experiment plan performed as part of the same study described in the previous chapters. Correlation indexes are normalized between 1 (perfect positive correlation) and 1 (perfect negative correlation). Therefore, if an input parameter has an absolute index value close to 0 regarding a particular output, it means that its first-order influence on the same is quite negligible, as it follows from the correlation definition: While the clamp force is dominated by the packing pressure value, the chart Interactions analysis can also be performed. In this case, the response is a rather strong interaction between melt temperature and packing pressure (see fig. 12), which from fig. 11 seem to be the least effective parameters over the warpage itself, if varied separately. In fact, the interaction chart highlights how a simultaneous increase of melt temperature amplifies the effect of a simultaneous increase of packing pressure in terms of reduction of warpage. modefrontier provides many other modules, that allow the designer to take decisions and find satisfactory tradeoffs between several objectives, but also tools to cluster and group multi-dimensional data, to perform robust design analyses, and to speed up the optimization campaigns integrating meta-modelling techniques (Response Surfaces). Conclusions Moldflow MPI and modefrontier have been coupled in a multi-objective optimization. Thanks to the efficient MOGT algorithm, the initial design has been improved, with only 44 attempts (Moldflow calculations) reducing clamp force by 30% and warpage by 29% - simultaneously. modefrontier couples easily Moldflow MPI with any CAD, FEM or other inhouse CAE software to drive the process and/or product design towards a multicriteria optimal solution. Luca Fuligno, Maurizio Facchinetti, Sergio Sarti - EnginSoft S.p.A. Andrea Piussi - Esteco srl Alastair Tweedie, Pierluigi Colombo Johnson Controls Inc.
16 16 - Newsletter EnginSoft Anno 5 n 3 Il fenomeno del Flutter per Ponti di Grande Luce: uno studio numerico The flatter phenomenon on longspan suspended bridges: a numerical study The present work aims at analysing the flutter phenomenon on long-span guyed and suspended bridges, due to the action of the wind. This study has been carried out through the weak Figura 5 - Rappresentazione a mappe di colore per la pressione totale e la norma della velocità - Angolo di attacco pari a -16. Figura 1 - Configurazione di maglia per flusso parallelo alla direzione globale X. Figura 2 - Prima configurazione di maglia per flusso relativo ad angoli di attacco variabili. Figura 6 - Rappresentazione a mappe di colore per la pressione totale e la norma della velocità - Angolo di attacco pari a -4. Figura 3 - Seconda configurazione di maglia per flusso relativo ad angoli di attacco variabili. Figura 7 - Vettori di velocità in prossimità della parete di impalcato e nella zona di spigolo con flusso incidente. Figura 4 - Terza configurazione di maglia per flusso relativo ad angoli di attacco variabili. coupling of structural and fluiddynamic behaviour. The Great-Belt East Bridge (Denmark) has been used as reference point for the construction of the finite element model, since all necessary information about its dynamic and aeroelastic behaviour can be extracted from its rich bibliography. The main steps of this articulated analyses are presented in this article, based on the following phases: the investigation of the fluiddynamic behaviour of the deck transversal section though numerical simulation; the determination of the instability critical velocity due to
17 Newsletter EnginSoft Anno 5 n 3-17 flatter and the frequency analysis of the system; the creation of a three dimensional model for a suspended bridge (with known characteristics and configuration) using beam elements; the estimation of the critical velocity due to flutter for the suspended bridge considering also geometrical non-linearity effects. The use on ANSYS ICEM CFD 11.0 has allowed to carry out several simulations to investigate the parameters effects on the final results. Figura 8 - Andamento del coefficiente di Drag. Figura 9 - Andamento del coefficiente di Lift. Scopo del lavoro Il presente approfondimento tratta il fenomeno di instabilità da flutter causato dall azione del vento su ponti strallati e sospesi di grande luce. L analisi è stata svolta con l approssimazione di accoppiamento debole tra comportamento strutturale e fluidodinamico e si è articolata nei seguenti punti: a. Studio del comportamento fluidodinamico della sezione trasversale dell impalcato per differenti angoli di attacco, mediante simulazione numerica. b. Determinazione delle velocità critica di instabilità da flutter attraverso un modello piano di comportamento che risolve le equazioni del moto della sezione soggetta al carico da vento con logica al passo. c. Analisi in frequenza del sistema a 2 d.o.f debolmente accoppiato al fine di stimare la velocità critica di flutter. d. Creazione di un modello tridimensionale ad elementi Beam per un ponte sospeso di configurazione e caratteristiche note. e. Stima della velocità critica da flutter per il modello ad elementi finiti del ponte sospeso con inclu- Figura 10 - Andamento dei coefficiente di momento Cm al variare del polo i punti notevoli della sezione di impalcato. Figura 11 - Modello a 2 g.d.l. per la sezione del ponte Grealt-Belt.
18 18 - Newsletter EnginSoft Anno 5 n 3 accordo con l ipotesi di incomprimibilità. Tramite la variazione parametrica della velocità indisturbata, la variazione dell angolo di attacco è stata analizzata tramite la sola variazione delle condizioni al contorno, lasciando inalterata la mesh del dominio fluido. Per ciascuna delle configurazioni di maglia precedentemente esposte, sono state condotte 20 analisi separate ad intervalli di 2, partendo da un valore iniziale di -20 e finale pari a 20. Figura 12 - Andamento temporale della traslazione verticale - Rapporto di smorzamento 1%. Le figure 5 e 6 illustrano alcuni risultati in termini sia di pressioni totali che di campo di moto. La figura 7 illustra il campo vettoriale delle velocità in prossimità della parete di impalcato; si nota l andamento logaritmico tipo dello strato limite laminare. Viene inoltre visualizzato il campo di velocità in prossimità dello spigolo di incidenza della vena fluida. I grafici in figura 8 e 9 illustrano gli andamenti dei coefficienti aerodinamici ottenuti in funzione dell angolo di attacco. Figura 13 - Andamento temporale della rotazione - Rapporto di smorzamento 1%. sione degli effetti di non linearità geometrica. L opera strutturale scelta come riferimento per la creazione del modello ad elementi finiti di un ponte sospeso e relativa analisi di stabilità è stato il Great-Belt East Bridge sito in Danimarca ed avente una luce centrale pari a 1924 m. Per tale struttura è a disposizione una vasta bibliografia relativa al comportamento dinamico ed aeroelastico. Studio fluidodimanico delle forze da vento sull impalcato Nel presente studio sono state condotte diverse simulazioni al fine di investigare l effetto dei differenti parametri di maglia sul valore finale delle forze aerodinamiche agenti sulla sezione trasversale. Il software utilizzato per la costruzione delle maglie è stato ANSYS ICEM CFD Si noti come tutte le mesh utilizzate abbiano una dimensione della mesh di parete tale da permettere la risoluzione dello strato limite laminare, necessaria per l utilizzo di un modello di turbolenza di tipo k-ω. Le figure 1, 2, 3, 4 illustrano alcune delle configurazioni di maglia utilizzate. La simulazione fluidodinamica viene svolta in condizioni di regime; i numeri di Reynolds che interessano il fenomeno oggetto di studio, sono in La figura 10 illustra l andamento del coefficiente aerodinamico di momento relativo alla simulazione numerica ed ai risultati sperimentali. Sono stati riportati gli andamenti relativi a tutti i poli notevoli della sezione dell impalcato. Calcolo della velocità critica di flutter con modello a 2 g.d.l. L implementazione di un programma in Delphi ha consentito di risolvere il sistema di equazioni differenziali del moto di un sistema a 2 g.d.l. tramite il metodo di Newmark. Si noti che la non linearità della forzante è integrata esattamente e quindi alcun procedimento di linearizzazione (a parte quella della rigidezza verticale e rotazionale costante dell impalcato) è stato effettuato. La figura 11 illustra una schematizzazione grafica della trattazione del
19 Newsletter EnginSoft Anno 5 n 3-19 Figura 16 - Vista complessiva del modello globale unifilare per il "Great Belt East Bridge". problema di instabilità da flutter tramite modello a 2 g.d.l. Figura 14 - Andamento delle frequenze fondamentali al variare della velocità del vento incidente Caso non smorzato. Le figure 12 e 13 illustrano l andamento degli spostamenti verticale e delle rotazioni per una velocità incidente del vento pari a 50 m/s. Si nota chiaramente l andamento divergente del moto. Soluzione linearizzata in frequenza per la stima della velocità di flutter Un approccio alternativo per il calcolo della velocità di flutter a partire dalle caratteristiche aeroelastiche della sezione dell impalcato risulta essere quello in frequenza. All aumentare della velocità della vena fluida incidente si nota la diminuzione della frequenza propria rotazionale fino al raggiungimento della sincronizzazione. Figura 15 - Andamento delle frequenze fondamentali al variare della velocità del vento incidente Smorzamento 1%. I grafici in figura 14 e 15 illustrano il comportamento del sistema dinamico allo studio in assenza di smorzamento, ovvero con uno smorzamento pari all 1%. Figura 17 - Andamento della velocità del vento in ingresso. Analisi della risposta tridimensionale aeroelastica del ponte sospeso Il presente studio si conclude con l approfondimento del comportamento aeroelastico di un ponte sospeso reale caratterizzato da un modello unifilare tridimensionale. Tale modello simula la presenza dei seguenti componenti strutturali: Impalcato a cassone metallico monocellulare a piastra ortotropa con diaframmi interni. Piloni a telaio in calcestruzzo armato. Funi principali di sospensione centrali.
20 20 - Newsletter EnginSoft Anno 5 n 3 Elementi verticali di appensione. Elementi infinitamente rigidi di collegamento tra gli elementi principali. La figura 16 illustra una vista del modello globale del ponte sospeso oggetto di studio. Uno smorzamento di circa l 1% è stato inserito con modalità alla Rayleigh; la simulazione viene condotta nel dinamico transitorio non lineare con inclusione degli effetti della configurazione geometrica spostata. La figura 17 illustra il profilo della velocità in ingresso, con valore a regime pari a 90 m/s. Figura 18 - Andamento dello spostamento laterale di impalcato nella sezione centrale del ponte. Le figure 18, 19 e 20 illustrano gli spostamenti laterali, verticali e rotazionali del ponte durante l analisi condotta. Francisco Garcia Lorente, Università di Siviglia Alberto Lovison, Università di Padova, ESTECO Daniele Schiavazzi, EnginSoft S.p.A. Figura 19 - Andamento dello spostamento verticale di impalcato nella sezione centrale del ponte. "L articolo è tratto da un lavoro di tesi compiuto dallo studente Francisco Garcia Lorente della Università di Siviglia, nell ambito di un progetto di tirocinio formativo presso la sede di Padova di Enginsoft s.p.a. Si ringraziano Alberto Lovison di Esteco per la stima lineare in frequenza della velocità di flutter e l ufficio di Bergamo di Enginsoft s.p.a. per i preziosi consigli sullo svolgimento delle analisi fluidodinamiche". Figura 20 - Andamento della rotazione di impalcato nella sezione centrale del ponte.