In today’s car manufacturing industry, sheet metal forming is a important process that takes preparation, which is time consuming and complex when new processes are made. When new metal grades and alloys are provided to the industry, tests are conducted to determine it’s behaviour and strengths. This gives the data for complex material models that can approximate the metal behaviour in an accurate way in a simulation environment. One of the unknown factors from tests is the friction coefficient on the sheet metal. The software Triboform is able to provide an adaptable friction coefficient model that depends on multiple simulation and user input conditions. The problems that occur when acquiring data for the material model is that testing is time consuming and the friction model has to be adjusted to give accurate results. At Volvo Cars there are two material models used with their different advantages, BBC 2005 and Vegter 2017.The purpose with this work is to compare the two material models using the Triboform friction models implemented to see if any combination provides accurate simulation results and then create recommendations for which model is best suited for different cases. Some side studies is also done with an older Vegter model, a strain rate sensitive BBC 2005 model and a Triboform model on all simulation parts.The purpose is achieved by implementing the Triboform model in Autoform and run a simulation of a Limiting Dome Height (LDH) test with both material models and compare the results with experimental data for several different materials. The data that is directly compared from the LDH test is the major and minor strain from two perpendicular sections at four different stages and also the force from the punch tool. The material models will be evaluated by how it manages to mimic the strain behaviour of the metals and how it estimates the punch force.The results point towards an improvement of the accuracy for most of the metals tested and BBC 2005 is the better model if there’s available biaxial data from tests, Vegter 2017 is decent if there’s not. However Vegter 2017 is not a good option for aluminum alloys simulations when the punch force is compared. Side study also shows that Vegter 2017 is bit of a downgrade when it comes to strain values, compared to the old Vegter.The work, in summary shows a dynamic friction model can improve the accuracy for strain predictions in the simulation process. If there’s biaxial yield data available for the metal or if it’s an aluminum alloy, BBC 2005 is the superior choice, but if only tensile tests are available for metals, Vegter 2017 is a decent choice for some cases. / I dagens bilindustri är plåtmetalformning en viktig process som kräver förberedelser som är tidskonsumerande och komplex när nya processer tillkommer. När nya metallslag kommer in till industrin, så utförs tester för att avgöra dess egenskaper och styrka. Denna testdata används till materialmodeller som kan approximera metallens beteende på ett noggrant sätt i en simuleringsmiljö. Den okända faktorn från dessa test är friktionskoefficienten på plåten. Programvaran Triboform är kapabel att göra en dynamisk friktionsmodel som beror på användar- och simuleringsdata. Problemen som uppstår vid framtagning av data är att det är tidskonsumerande och flera simuleringar måste göras för att bestämma friktionen. Volvo Cars använder sig av två modeller med olika fördelar, BBC 2005 och Vegter 2017.Syftet med detta arbete är att jämföra de två materialmodellerna med Triboform modeller implementerat för att se om de påverkar noggrannheten i simuleringar och sedan förse rekommendationer för vilken modell passar bäst för olika fall. Några sidojobb i studien som görs är en jämförelse med gamla Vegter modellen, ett test med en modell som är känslig för töjningshastighet och test med att implementera Triboform modellen på alla pressverktyg.Detta utförs med att implementera Triboform modellerna i Autoform och köra en simulering på ett LDH-test med båda materialmodeller och jämföra resultaten med experimentell data för flera olika metaller. Data som skall jämföras från LDH-testet är första och andra huvudtöjningen i två vinkelräta sektioner i fyra processsteg och stämpelkraften genom hela processen. Modellerna kommer evalueras genom hur de lyckas imitera töjningens beteende och hur den estimerar stämpelkraften.Resultaten pekar mot en förbättring när Triboform är implementerat i simuleringar för de flesta metaller som ingår i testen och BBC 2005 är den model som föredras om det finns tillgänglig biaxiel spänning data från tester, Vegter 2017 är en duglig modell om dessa data inte finns. Vegter 2017 är dock inte ett bra alternativ när det kommer till jämförelse av töjning och stämpelkraften för aluminium. Sidojobb med gamla Vegter visar att den nya Vegter 2017 inte är en direkt förbättring med hänsyn till noggrannheter av krafter och töjningar.Arbetet visar att en dynamisk friktionsmodel kan förbättra prediktering av töjningar i simuleringar. Om det finns biaxiel data för metallen eller om det gäller att simulera aluminium är BBC 2005 det bättre altermativet, om det endast finns dragprovsdata för metallen så är Vegter 2017 duglig för vissa fall.

This thesis engages on the differences between the numerical simulations of sheet metal drawing process performed using AutoForm software from AutoForm Engineering, Swiss company and actual results measured using non-contact measurement system Argus from German GOM company. This work used DC06 material (whose mechanical properties were determined at Technical University of Liberec) for comparison. The calculated results of simulations were compared to measured results of actual plate thickness.

In today's automotive industries, many different simulation programs are used to optimize parts before they come into production. This has created a market for complex material models to get the best possible approximation of reality in the simulation environment. Several industries are still using older material models that can’t give an acceptable accuracy for the materials currently in use as they are based on much simpler and older materials. The problem with material models is that there is no direct comparison between the material models which leads to several sheet metal forming companies still holding on to older models like Hill`48.   The purpose of this work is to create a comparison of sheet material models from a user perspective to be able to provide recommendations of material models. Different models will be tested for different materials and will be based on AutoForm's recommendations. AutoForm is a FEM based sheet metal forming simulation program used by large names in the automotive industry. These recommendations are Vegter2017, BBC2005 or Hill`48 for steel and Vegter2017, BBC2005 or Barlat`89 for aluminum.   This work is achieved by comparing experimental data from a Limiting Dome Height (LDH) test with a simulation of this test for all material models and then comparing the results. The data that will be compared consists of the major and minor strain in the sheet as well as the punch force. These parameters are chosen as they give an overview of the model’s applicability as well as accuracy. The test will be performed on all materials available in Volvo Cars material library to create a broader overview of all material models. The material models will also be evaluated depending on their user-friendliness by analyzing what types of data are required to perform a simulation.   The result from these tests showed that BBC 2005 should be recommended for aluminum and steel for companies that have access to biaxial data and for people who put optimization in focus. Hill`48 proved far too deviant in the results for steel and should not be used if other models are available. Vegter 2017 proved perfect for steel simulations as the result were great as well as the necessary material data can be obtained through standardized tensile tests. The result also showed that Vegter2017 should not be used for aluminum since the result was too deviant from the experimental data in aspect for both form approximation and strain magnitude. Barlat`89 gave accurate results with only data from a tensile test which makes it a preferred model when working with aluminum.   The conclusion from this work is that the choice of material model is very dependent on what conditions you have as very few industries have access to the tests required by the BBC 2005 model. Another conclusion may be drawn for Barlat`89 with aluminum and Vegter 2017 with steel as they can be preferred when working with a small timeframe as well as when few test data is available. / Inom dagens bilindustri används det många olika simuleringsprogram för att optimera delar innan de kommer ut i produktion. Detta har då skapat en marknad för komplexa material modeller för att få en så bra approximation av verkligheten som möjligt. I flera industrier använder man sig fortfarande av äldre materialmodeller som egentligen inte håller måttet för dagens material då de är baserade på simplare material. Problemet som har skapat denna situation är att det inte direkt finns en konkret jämförelse mellan materialmodellerna vilket leder till att flera plåtformnings företag fortfarande håller kvar vid äldre modeller som t e x Hill`48.   Syftet med detta arbete är att skapa en jämförelse av plåt materialmodeller från ett användarperspektiv för att kunna ge konkreta bevis till rekommendationer av materialmodeller. Olika modeller skall testas för olika material och baseras på AutoForms rekommendationer. AutoForm är ett FEM baserat plåtformningssimulerings program som används av stora namn inom bilindustrin. Dessa rekommendationer är då att köra Vegter2017, BBC2005 eller Hill`48 för stål samt att köra Vegter2017, BBC2005 eller Barlat`89 för aluminium.   Detta arbete utförs genom att jämföra experimentella data från ett Limiting Dome Height (LDH) test med en simulering av detta test för alla material modeller och sedan jämföra resultaten. Jämförelsen mellan den experimentella och simuleringsdatan kommer att involvera major och minor strain i plåten samt stämpelkraften. Dessa parametrar har valts då de ger en bra översikt över materialmodellernas applicerbarhet och noggrannhet. Testen kommer att utföras på samtliga material som finns tillgängliga i Volvo Cars materialbibliotek för att skapa en breddare syn på samtliga modellers applicerbarhet. Materialmodellerna kommer även att utvärderas beroende på deras användarvänlighet samt vilka typer av data krävs för att använda modellen.   Resultatet visade att BBC 2005 skall rekommenderas för aluminium samt stål till de företag som har tillgång till biaxiella data samt lägger optimering i fokus. Hill`48 visade sig alldeles för avvikande för stål och bör inte användas om andra modeller är tillgängliga. Vegter 2017 visade sig perfekt för stål då resultatet var bra samt att den nödvändiga materialdatan kan införskaffas genom standardiserade dragprov. Resultatet visade även att Vegter 2017 inte bör användas för aluminium då resultatet var för avvikande. Barlat`89 gav bra resultat med endast data från dragprovstest vilket ger att den är att rekommendera för aluminium.   Slutsatsen från detta arbete är att valet av materialmodell är väldigt beroende av vilka förutsättningar som finns då väldigt få industrier har tillgång till de tester som krävs för att använda BBC 2005. I större delar av industrin där minimala optimeringar inte anses som väsentliga är Barlat`89 och Vegter 2017 att föredra då detta leder till snabbare processer.

As competition in the car market increases, the techniques for car manufacturing are developed and becomes more advanced to be able to keep up with the pace. The development process of car body components has shifted over the years to involve more simulation driven testing than ever before to save time and money in the early stages of development. As the importance of reliable sheet metal forming simulations grows, inconsistencies between simulations and physical stamping can be detrimental to the development time if stamping dies need to be reworked because of poor correlation between physics and simulations.                        The aim of this study is to improve the coherence between physical stamping and the simulation software used by Volvo Cars. The coherence is determined by studying different properties of the result in simulations and comparing them to measurements taken on the corresponding physical stamped parts. A comparison was done between the current standard simulation software, Autoform Forming R8 and a beta version of Autoform Forming R10. The objectives of this study were to compare the sheet thickness, strain, draw-in and ability to predict material failure between the two simulation software to see which of them correlate best to the physical measured parts.                       The workflow consisted of initially setting up the simulations in Autoform Forming R8. Some of the simulations could begin testing right away, while others required needed some geometry rework as the physical tested parts had been stamped with modified stamping dies. When the simulation setups were completed copies of the simulations were taken and run on Autoform Forming R10 to compare with. The simulations were run with a varied Triboform friction models and some of the simulations were run using symmetry to reduce the simulation time. When data was compared Autoform Forming was used when possible and when additional tools were needed the simulated geometries were exported and compared in software such as SVIEW and GOM Correlate.                       The result showed relatively low differences in the comparisons of sheet thickness and major and minor strain as neither of the simulations seemed to give more accurate values compared to the measurements. A slight improvement in the draw-in comparison was found for the Autoform Forming R10 compared to the R8 simulation. In the material failure prediction a major difference was found where the Autoform Forming R10 simulations were better at determining splits than R8. However the splits were only discovered with 2 of the 4 tested friction models in the R10 simulations while the 1 of the 4 simulations indicated risks for a split in the R8 simulation.                       In conclusion the simulations run on Autoform Forming R10 seem to be better at predicting splits and draw-in dimensions while no major differences were found in the comparisons of strain and sheet thickness.

Dual-Phase (DP) steels, part of the group of Advanced High Strength Steels (AHSS), are used by car manufactures due to its large strength to weight ratio. The high strength of the DP steel does have a negative impact on the formability during sheet metal forming and stretch forming, e.g. fractures often appear in shear cut edges during forming of blanks made of DP steel.   The main objective with this thesis is to develop a new punch for Volvo Cars that concentrates the strain to the sheared edges of a test specimen made from different types of DP steel. This is done to be able to measure and obtain maximum fracture strain during stretch forming tests in a press. The newly developed test method is called CTEST (Concentrated Trim Edge Strain Test).   The tests are performed with DP steel specimens with three different qualities of the shear cut edges; fine cut, medium cut and worn cut. DP steels tested are DP600GI, DP600UC and DP800GI from three different suppliers. 10 different types of DP steels are tested in this study with different thickness. Thickness of specimens tested are 1 mm, 1.1 mm, 1.5 mm and 2 mm and all specimens tested have a lengthwise (RD) rolling direction.   The quality of the sheared cut edge has a great impact to the formability and maximum fracture strain of the specimen. A specimen with a fine cut endures higher fracture strain than medium cut and a worn cut for all types of DP steel with different thickness. A 1 mm thick specimen endures a lower fracture strain than 1.5 mm and 2 mm specimen for all cut qualities.   Further, the impact of the orientation of the burr zone of a shear cut edge is studied. With the burr zone facing upwards from the CTEST punch the formability of the specimens is decreased compared to a burr zone facing downwards, especially for a worn cut specimen with micro cracks and imperfections in the edge surface.   ARAMIS Digital Image Correlation (DIC) system is used to analyze the specimen edges during press experiments. The ARAMIS results unveil that several small fractures appear in the sheared edges of a specimen just before the specimens split into two pieces. This phenomenon was seen for specimen with worn and medium shear cut qualities.   Finite Element (FE) simulations of the CTEST is performed in AutoForm to determine maximum values of the true strain for the three different cut qualities. The simulation in AutoForm does show a slightly higher value of the force and press depth than the value from the press test before maximum fracture strain in reached. The small fractures seen in ARAMIS just before the specimen split into two pieces cannot be seen in the simulation in AutoForm.