The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.
The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques.
This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material’s forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.
Finite Element (FE) simulations have become a powerful tool for optimizing process parameters in the metal forming industry. The reliability of FE simulation results is dependent on the accuracy of the material definition, input in the form of flow stress data or constitutive equations, and the assignment of the boundary conditions, such as the friction coefficient and the heat transfer coefficient. In the past few years, advanced FE simulations have been developed via the implementation of user-defined subroutines, which have significantly broadened the capability of FE software.
The use of such advanced FE simulations in the design of forming processes for structural components has been investigated by both the aviation and automotive industries, with the intention of producing lightweight structures that reduces operating costs and CO2 emissions. Particular focus has been placed on the replacement of steel components with lower density materials, such as aluminum alloys and magnesium alloys. However, these alloys, especially the stronger variants, offer limited formability at room temperature and thus complex-shaped components cannot be manufactured using the conventional cold stamping process. Therefore, advanced high temperature forming technologies, such as warm aluminum forming 1-4, hot stamping of aluminum alloys 5-9 and hot stamping of high strength steels 10, have been developed over the past decades to enable complex-shaped components to be formed. In general, high temperature forming processes involve significant temperature variations, strain rate and loading path changes 11, which would, for instance, cause inevitable viscoplastic and loading history dependent responses from the work piece materials. These are intrinsic features of high temperature forming processes and may be difficult to represent using conventional FE simulation techniques. Another desirable feature would be the ability to predict the tool life over multiple forming cycles in such processes, since they require low friction characteristics achieved through coatings that degrade with each forming operation. To represent all these features via the implementation of user-defined subroutines would be computationally very expensive. Moreover, the development and implementation of multiple subroutines would require excessive multi-disciplinary knowledge from an engineer conducting the simulations.
In the present work, a novel Knowledge Based Cloud FE (KBC-FE) simulation technique is proposed, based on the application of modules on a cloud computing environment, that enables an efficient and effective method of modeling advanced forming features in conjunction with conventional FE simulations. In this technique, data from the FE software is processed at each cloud module, and then imported back into the FE software in the relevant consistent format, for further processing and analysis. The development of these modules and their implementation in the KBC-FE is detailed.
KBC-FE simulering teknik muliggør avancerede simuleringer, der skal udføres off-site ved hjælp af dedikerede moduler. Den kan køre funktionelle moduler på en sky miljø, der linker op noder fra forskellige specialer, at sikre, at processen simuleringer udføres så præcist som muligt. De kritiske aspekter i KBC-FE simulering kan involvere uafhængighed af FE-koder, effektivitet af beregningen, og nøjagtigheden af de funktionelle moduler. Realiseringen af hvert avancerede funktion i et modul ville være afhængig af udviklingen af en ny model og / eller en ny eksperimentel teknik. For eksempel er den danner grænse modul udviklet baseret på den nye forenet danner grænse forudsigelse model 11, og friktionen standtid forudsigelse modul er i øjeblikket blevet udviklet af gennemførelsen af den interaktive friktion model 20. KBC-FE simulering teknik giver også funktionen af selektiv beregning, dvs. kun elementer opfylder udvælgelsekriterier udvælges til nærmere vurdering i de enkelte moduler. For eksempel værktøjets levetid forudsigelsesmodulet vælger automatisk de elementer, for hvilke den hårde coating tendens til opdeling, ved at rangordne slidhastigheden af alle elementerne i 1. formningscyklussen, således sædvanligvis mindre end 1% af de elementer vil blive udvalgt til yderligere værktøj liv evalueringer under multi-cyklus belastningsforhold. I nærværende forskning, kan værktøjet liv forudsigelse efter 300 danner cyklusser være afsluttet inden for 5 min.
Ved at udføre de relevante test og kalibrering i overensstemmelse hermed, kan den danne grænsen model anvendes til at skabe proces simuleringer til dermed bestemme de optimale parametre til fremstilling af en komponent fra sådanne legeringer med succes, og med ingen tilfælde af indsnøring. Dannelsen grænse forudsigelsesmodel blev udviklet som en sky modul, der var uafhængig af FE-software, der anvendes, og kan anvendes på enhver FE software til at vurdere formbarhed af et materiale underformning, uden komplicerede underrutiner 17. Ved at importere de relevante data i modellen, kan beregninger udføres for at afgøre, om fiasko ville opstå, i områder af den komponent, som brugeren kunne angive, spare på it-ressourcer. Imidlertid bør det bemærkes, at som de stress-strain kurver er input til FE software gennem en simpel opslagstabel, kan det være vanskeligt fuldt ud repræsentere materialeegenskaberne ved forskellige temperaturer og belastningsgrader under simulering.
I standtid forudsigelse modul, kan den friktions opførsel under formningen forudsiges ved at importere de nødvendige deformation historiske data i den verificerede friktion modul 20, og derefter importere de diskrete datapunkter beregnet af cloud-modulet for hvert element tilbage i FE-softwaren. Dette sikrer, at den avancerede friktion modul kan anvendes af alle FE-koder, uanset deres evne til at inkorporere bruger-subrutiner. Derudover module kunne køre parallelt for yderligere at reducere beregningstiden. Den interaktive friktion / slid model antages fraværet af slid partikler under indledende glidende, og som et resultat, vil det være rimeligt at forvente en konstant startværdi på friktionskoefficient 0,17 20. Selv om denne model viste udviklingen i friktion distribution, friktionsmæssige adfærd under en formende proces er meget kompliceret, og det er vanskeligt fuldstændigt at integrere komplekse friktionsmæssige adfærd fra skyen modul i FE simulering.
Som en fremtidig teknologi, vil KBC-FE simulering stole på udviklingen af dedikerede og robust internetbaserede FE simulation softwarepakker, som ville kræve en yderst rentabel, men helt anderledes forretningsmodel, der fastsættes af softwareudviklere. Desuden skal bygges inden for de kollaborative parter til at sikre datasikkerhed og kontrol pålideligheden af det industrielle system et dedikeret interne netværk. </p>
The authors have nothing to disclose.
The financial support from Innovate UK, Ultra-light Car Bodies (UlCab, reference 101568) and Make it lighter, with less (LightBlank, reference 131818) are gratefully acknowledged. The research leading to these results has received funding from the European Union’s Seventh Framework Program (FP7/2007-2013) under grant agreement No. 604240, project title ‘An industrial system enabling the use of a patented, lab-proven materials processing technology for Low Cost forming of Lightweight structures for transportation industries (LoCoLite)’. Significant support was also received from the AVIC Centre for Structural Design and Manufacture at Imperial College London, which is funded by Aviation Industry Corporation of China (AVIC).
AA6082-T6 | AMAG | Material | |
AA5754-H111 | AMAG | Material | |
1000 kN high-speed press | ESH | Forming press | |
ARGUS | GOM | Optical forming analysis | |
PAM-STAMP 2015 | ESI | FE simulation software | |
Matlab | MathWorks | Numerical calculation software | |
Gleeble 3800 | DSI | Uniaxial tensile test | |
High Temperature Tribometer (THT) | Anton Paar | Friction property test | |
NewViewTM 7100 | ZYGO | Surface profilometer | |
Magnetron sputtering equipment | Coating deposition | ||
Microhardness tester | Wolpert Wilson Instruments | ||
Nano-hardness indenter | MTS |