Global trends in automotive industry for weight reduction drives an interest for casting of structural aluminum parts. High pressure die casting (HPDC) is chosen for this purpose since it enables manufacturing of large series parts where complexity and repeatability is demanded. Aluminum alloys have hence been developed through the years to obtain suitable mechanical properties for high strength parts. These alloys have been investigated to predict the types of potential failure mechanisms during HPDC in order to determine die life through simulations. Die life prediction was performed through simulations in MAGMAsoft 5.4 with the help of a die life module, which is based on thermal stresses generated in the die material during casting cycles. Fatigue data at elevated temperature obtained from literature review of AISI H11 tool steel was complemented to the Wöhler curve in the software database. Comparison of two aluminum alloys showed that chemical composition had a major influence on die life. Chemical composition had a direct impact on solidification time and with longer solidification time, the thermal load on the die increased. Since the stress range on the die is temperature dependent, the ability of heat transfer over time proved to be critical for die life results. The most crucial process parameter to achieve a longer die life was constant cooling by tempering channels, due to their high potential to remove heat. Tempering channels and die spray also prevent the die from exceeding a critical temperature resulting in soldering formation. Mold erosion was consistently observed in the same location for all simulations.

The aim of this thesis was to assess the degree of conformity between the mechanical properties evaluated by numerical simulation in software MAGMA5 and the measured values of hardness and ultimate tensile strength of lamellar graphite iron castings. The theoretical part of this thesis deals with the classification of cast iron, structural components of lamellar graphite iron, and the factors defining the resulting mechanical properties of the material. The practical part presents an attempt to find empirical dependencies between input parameters and results evaluated by simulation software. At the end, an analysis of the correlation between reality and simulation software is performed.

The aim of this work is comparing three casting process simulation programs for porosity and microstructure prediction capabilities for die-casting. After confronting these results with experimentally measured data taken from real castings it could be said that simulation is pretty accurate for DAS microstructure prediction and hot-spot areas. Amount of measured porosity could not be compared with predicted values because specimens were not taken from the exact hot-spot areas.

The dissertation work focuses on the design and optimization of the castings and foundry technology and the production a particular model for the casting. The technology proposal and the pattern set building in 3D using CAD system. The casting simulation in CAE MAGMAsoft® system and evaluation of the proposed casting technology. Production of the pattern using CAD/CAM software and CNC machine tools with a focus on 3-axis and 5-axis machining. The economic benefits for the company.

Tensile strength modelling is usually done to predict the mechanical properties of lamellargraphite iron considering microstructural features. This work attempts to create a simplifiedmodel incorporating cooling rate and solidification time without considering themicrostructural features. This model will save time and cost in industry with the presence of acommercially available software such as Magmasoft which simulates solidification time andcooling rate. A plate model was designed for this purpose as the test geometry to createvariation in solidification time and cooling rate. By altering fraction solid, thermalconductivity, specific heat capacity in Magmasoft, a good fit was created between simulatedcooling curve and experimental cooling curves. The experimental UTS data of samples fromthree moulds were investigated and a regression model was created using statistics toolMinitab. The effect of solidification time and alloying on the graphite length Lmax was studiedfor twelve samples from each mould. Quantification of the effect of cooling rate and alloyingon the pearlitic properties of grey iron like matrix microhardness, pearlite inter-lamellarspacing was also investigated in this work.The developed model has sixty three percent correlation and explains UTS well in terms ofsolidification time and cooling rate. Microhardness measurements show that there is an almostlinear relationship between the cooling rate and microhardness of the matrix structure.Microhardness data also provides an overview of the pearlite fineness/interlamellar spacing.Analysis of the outliers showed that the presence of free ferrite on a fully pearlitic structurereduces the UTS significantly. Comparison of the regression model obtained from this workwith previous work showed that, there is a reduction in the predicted strength with this model.The effort to identify the reason for this reduction was not successful and needs furtherinvestigation. Pearlite inter-lamellar spacing measurement was not accurate. The relationshipbetween pearlite interlamellar spacing and matrix microhardness needs to be investigated inthe future using a better technique for pearlite spacing measurement. This will be useful tounderstand the effect of cooling rate on pearlite spacing and consequently on the UTS of greycast iron. / Draghållfasthetsmodellering görs vanligtvis för att förutsäga de mekaniska egenskaperna av lamellärt grafitjärn. Detta arbete har försökt att skapa en förenklad modell som innehåller kylhastighet och stelningstid utan att överväga mikrostrukturella egenskaper. Modellen kommer att spara tid och kostnad i industrin tillsammans med kommersiellt tillgänglig mjukvara som Magmasoft som simulerar stelningstiden och kylningshastighet. En plattformig modell utformades för detta ändamål som testgeometrin för att skapa variation i stelningstid och kylningshastighet. Genom att ändra fraktion fast fas, termisk konduktivitet och specifik värmekapacitet i Magmasoft skapades en bra anpassning mellan simulerade och experimentella kylkurvor. Experimentella draghållfasthetsdata (UTS) för prover från tre gjutningar undersöktes och en regressionsmodell skapades med hjälp av statistikverktyg Minitab. Effekten av stelningstid och legeringshalt på grafitlängden Lmax studerades för tolv prover från varje form. Effekten av kylhastighet och legering på de perlitiska egenskaperna hos grått järn som matrismikrohårdhet och perlitlamellavstånd undersöktes också i detta arbete.  Den utvecklade modellen har sextiotre procent korrelation och förklarar UTS väl med avseende på stelningstid och kylningshastighet. Mikrohårdhetsmätningar visar att det finns ett nästan linjärt förhållande mellan kylhastigheten och mikrohårdheten hos matrisstrukturen. Mikrohårdhetsdata ger också en översikt över perlitens finhet/interlamellära avstånd. Analys av outliers visade att närvaron av fri ferrit på en fullständigt perlitisk struktur minskar UTS betydligt. Jämförelse av regressionsmodellen erhållen från detta arbete med tidigare arbete visade det att det finns en minskning av den förutsagda styrkan med denna modell. Ansträngningen att identifiera orsaken till denna minskning var inte framgångsrik och behöver ytterligare undersökas. Perlit mellan lamellär avståndsmätning var inte korrekt. Förhållandet mellan perlitens interlamellära avstånd och matrismikrohet måste undersökas i framtiden med hjälp av en bättre teknik för perlit-avståndsmätning. Detta kommer att vara användbart att förstå effekten av kylhastighet på perlitavståndet och följaktligen på UTS av grå gjutjärn

This work presents a study and implementation of the simulation of residual stresses in castings. The objects of study are a cast iron truck Hub part (provided by the company Volvo 3P) and an optimized version of the Hub resulting from the application of a topology optimization process. The models are solved through an uncoupled thermo-mechanical solidification analysis, performed both in the FE commercial software Abaqus and the FD commercial software Magmasoft and the results are compared. First, a thermal analysis is carried out where the casting is cooled down from a super-heated temperature to room temperature. The thermal history obtained, is then used as an external force to calculate the residual stresses by means of a quasi-static mechanical analysis, using a J2-plasticity model. The simulation procedures are explained through a simplified model of the Hub and then applied to the geometries of interest. A results comparison between the original Hub and its optimized version is also presented. The theoretical base is given in this work as well as detailed implementation procedures. The results shows that the part subjected to the topology optimization process develop less residual stresses than its original version.

<p>This work presents a study and implementation of the simulation of residual stresses in castings. The objects of study are a cast iron truck Hub part (provided by the company Volvo 3P) and an optimized version of the Hub resulting from the application of a topology optimization process. The models are solved through an uncoupled thermo-mechanical solidification analysis, performed both in the FE commercial software Abaqus and the FD commercial software Magmasoft and the results are compared. First, a thermal analysis is carried out where the casting is cooled down from a super-heated temperature to room temperature. The thermal history obtained, is then used as an external force to calculate the residual stresses by means of a quasi-static mechanical analysis, using a J2-plasticity model. The simulation procedures are explained through a simplified model of the Hub and then applied to the geometries of interest. A results comparison between the original Hub and its optimized version is also presented. The theoretical base is given in this work as well as detailed implementation procedures. The results shows that the part subjected to the topology optimization process develop less residual stresses than its original version.</p>