The basis for performing a thermo-mechanical staggered coupled heat source analysis of a welding simulation is implemented into LS-DYNA. In this report, three methods for initiating the heat source’s mechanical motion during girth and tubular joint welding are developed and evaluated. The first method is a reformulation of the equations used at Det Norske Veritas, the second is an incorporation of the equations into excel and the third is a standalone third party software. The most efficient of the developed methods turned out to be the software which creates k-files which are implemented into the main k-file using LS-PrePost. All methods have been visually and numerically evaluated using Excel, LS-DYNA and LS-PrePost.

The idea to use finite element (FE) models to reconstruct accidents for humans is becoming more popular the last years. They represent the human body very accurately and indicate well changes in shape, size and biomechanical properties. FE models are useful when looking at complex factors in the human body in a more systematic way and when the approach is too complicated for conventional setups. Positioned child models from PIPER were used in the process and then rotated in LS-PrePost according to impact points and impact velocities from a given literature data where information from witnessed fall accidents of children was given. The simulations were finally run in LS-Dyna and the purpose was to investigate if the resulting brain injuries were similar to the real life data. From the literature, the falling distance from lowest point of the body to the ground, the age of the child, gender, type of ground and results from CT scans were all known. To compare the results to the literature data, section cuts of the brain were taken at four locations with different time steps. Biomechanical injury predictors such as brain strain, acceleration, rotational angular acceleration and rotational angular velocity were observed and helped with the comparison. In total, 12 cases were reconstructed which ended as 22 simulations. Due to uncertainty regarding the falling height when the children fell from a swing, each swing case had 3 scenarios. Overall the comparison of predicted injury locations from LS-Dyna to real injury locations from CT scans indicated that 7 out of 12 cases compared relatively well. The comparison of a 23-month-old girl to the same case reconsructed with CRABI-18 showed similar outcomes of the angular acceleration and the angular velocity. The linear acceleration and HIC were however much higher with LS-Dyna. Comparison between the swing cases of a 10-, 12- and 13-year-old resulted in similar results for the 12- and 13 year-old girls but the 10 year boy had lower values for all biomechanical parameters except the angular velocity which was a bit higher. With more detailed information about real accidents and precise scaling of PIPER child models, reconstruction with LS-Dyna could be useful in the future to design safer playgrounds for children and to obtain injury criterion for children after fall incidents. / Användande av finita element (FE) modeller för att rekonstruera olyckor har blivit allt populärare de senaste åren. De representerar människokroppen mycket noggrant och indikerar väl förändringari form, storlek och biomekaniska egenskaper. FE-modeller är användbara när man tittar på komplexa faktorer i människokroppen på ett mer systematiskt sätt och när tillvägagångssättet är för komplicerat för konventionella metoder. PIPER barnmodellerna positionerades i enlighet med islagpunkter och islaghastigheter från en given databas där informationen från vittnade fallolyckor av barn gavs. Simuleringarna kördes slutligen i LS-Dyna och syftet var att undersöka om predikteringarna liknade de resulterande hjärnskadorna. Från databasen var fallhöjd från kroppens lägsta punkt till marken, barnets ålder, kön, typ av mark och resultat från CT skanningar kända. För att jämföra resultaten med litteraturdata togs sektionsavsnitt av hjärnan på fyra platser med olika tidspunkter. Biomekaniska skadeprediktorer såsom hjärntöjning, acceleration, vinkelacceleration och vinkelhastighet extraherades och användes i jämförelsen. Totalt, rekonstruerades 12 fallolyckor med totalt 22 simuleringar. På grund av osäkerhet om fallhöjden när barnen föll från en gunga, hade varje fall från gunga 3 scenarier/fallhöjder var. Sammantaget indikerar jämförelsen av förväntade skadepredikteringar från LS-Dyna till observerade skador från CT-skanningar att 7 av 12 fall korrelerade relativt bra. Jämförelsen av en 23 månader gammal tjej i samma fall som tidigare också rekonstruerades med en CRABI-18 docka visade liknande resultat av vinkelaccelerationen och vinkelhastigheten. Linjär acceleration och HIC var emellertid mycket högre med LS-Dyna simuleringarna. Jämförelse mellan fallen från gunga hos en 10-, 12-och 13-åring resulterade i liknande resultat för 12- och 13-åriga flickor, medan 10-åringen hade lägre värden för alla biomekaniska parametrar utom den vinkelhastighet som var lite högre. Med mer detaljerad information om verkliga olyckor och exakt uppskalning av PIPER barnmodeller kan rekonstruktion med LS-Dyna vara användbar i framtiden för att utforma säkrare lekplatser för barn och för att få skadeskala för barn efter fallhändelser.

Diploma thesis is focused on the description of the parameters of nonlinear material models of concrete, which are implemented in a computational system LS-DYNA, interacting with performance of nonlinear test calculations in system LS-DYNA on selected problems, which are formed mainly by simulations of tests of mechanical and physical properties of concrete in uniaxial compressive and tensile on cylinders with applying different boundary conditions and by simulation of bending slab, with subsequent comparison of some results of test calculations with results of the experiment. The thesis includes creation of appropriate geometric models of selected problems, meshing of these geometric models, description of parameters and application of nonlinear material models of concrete on selected problems, application of loads and boundary conditions on selected problems and performance of nonlinear calculations in a computational system LS-DYNA. Evaluation of results is made on the basis of stress-strain diagrams and load-displacement diagrams based on nonlinear calculations taking into account strain rate effects and on the basis of hysteresis curves based on nonlinear calculations in case of application of cyclic loading on selected problems. Verification of nonlinear material models of concrete is made on the basis of comparison of some results of test calculations with results obtained from the experiment.