Taking into consideration the lack of standards for dynamic bullet and bullet fragments trap with difficult-defined energy, the issue is now solved by individual proposals of these devices. Its security is certainly the priority requirement of the construction. The device commonly ignores the investment cost and also operating cost due to lack of information on sizes of dynamic operational load. In a systematic approach which is leading to the elimination of these negative aspects, it is necessary to perform a wide range of numerical simulation and experiments. They lead to the optimized dynamic bullet trap design proposal, which will be, based on experience obtained, possible to modify for required installation dimensions in particular application in practice. Finally, the concept is designed for environmental friendly approach to waste management.
The purpose of this study was to identify possible causes of longitudinal surface cracks found during early stages of ingot breakdown. However, these cracks need not necessarily form during forging or as a result of poor quality of the surface in metallurgical terms. Under certain conditions, they may occur even as the ingot is being heated in the furnace to the forging temperature. The cracks probably form within a few minutes after placing the ingot in the furnace as a result of the temperature gradient, which is most severe on the ingot surface. A numerical model was created to represent the case of three ingots in a furnace. Upon casting, the ingots are cooled down to no more than 600°C and then placed in a furnace at 1,100 - 1,200°C. Numerical simulations were used to analyse their internal stresses and temperatures.
Efficient machining using wire electrical discharge machining (WEDM) technology is a compromise between cutting speed and resulting surface quality. Typical morphology of the surface machined by WEDM shows a plenty of craters caused by electrospark discharges produced during the cutting process. This work is focused on assessing the impact of machine setting parameters on quantitative and qualitative evaluation of the workpiece surface of aluminium alloy AlZn6Mg2Cu. Using metallography, the surface effects arisen during the process of wire spark erosion on cross-sections of preparations were studied. Using local spot EDX microanalysis, the chemical composition of the surfaces of the samples was studied. The attention was also paid to the highest height of profile of the craters, which were studied using 3D filtered images.
Progressive methods and technologies are the key to the dynamic development of the automotive and electrical-engineering industries. The processes in sheet-metal processing have changed fundamentally since the end of the 1990s. Previously, the operations such as cutting, punching holes, etc., were carried out separately on different press machines. These operations can now be integrated into a single tool on one press machine due to the development of progressive tools and, especially, the fine-blanking technology. The result is an already completed component that can be used for the assembly. The development of progressive tools must be supported with the FEM simulations of sheet-metal processing that are dependent on their inputs. Therefore, only a correct material model can be expected to provide the right results. For the reasons described above, an experimental program dealing with measuring and fitting the data to the models with orthotropic material properties such as rolled sheets was designed and implemented. The aim is to obtain the material models of rolled sheets made of selected aluminum, copper and steel alloys. One of the objectives of the solution is to provide more efficient and more accurate data fitting because the more accurate the input material data are, the more accurate are the simulation results for sheet-metal processing. The optimization script using the simplex method was made for fitting. The main function of the optimization script is to specify the parameters of the material model iteratively and to compare the simulation results and the mechanical-test results. The script was programmed in the Python environment for the MSC.MARC/MENTAT software using the Johnson-Cook plasticity model. Fitting the data from the pressure tests by Rastegaev at different loading speeds is presented. The difference between the measured and simulated curves is less than 1 %. Keywords: FEM simulation, measurement, compression test, fitting, MSC.MARC, Python Napredne metode in tehnologije so klju~ne za dinami~en razvoj avtomobilske in elektro-industrije. Procesi preoblikovanja plo~evin so se bistveno spremenili od devetdesetih let zadnjega stoletja. Prej so se operacije, kot so rezanje, prebijanje lukenj in podobno, izvajale lo~eno na razli~nih strojih. Zaradi razvoja naprednih orodij in {e posebej tehnologije precizijskega {tancanja se te operacije lahko zdru`i v enem orodju na enem stroju. Rezultat je kompletna komponenta, ki je primerna za vgradnjo. Razvoj naprednih orodij mora biti podprt s FEM-simulacijami obdelave plo~evine, kar je odvisno od vhodnih veli~in. Zato samo pravilen model materiala lahko zagotavlja prave rezultate. Iz navedenih razlogov je bil postavljen in uporabljen eksperimentalni program, ki obravnava merjenje in ujemanje podatkov za modele z ortotropnimi lastnostmi materiala, kot je valjana plo~evina. Namen je dobiti modele materiala valjane plo~evine za izbrane aluminijeve in bakrove zlitine ter jekla. Eden od ciljev je zagotoviti bolj u~inkovito in bolj zanesljivo pridobivanje pod...
The purpose of this study was to identify possible causes of longitudinal surface cracks found during early stages of ingot breakdown. However, these cracks need not necessarily form during forging or as a result of poor quality of the surface in metallurgical terms. Under certain conditions, they may occur even as the ingot is being heated in the furnace to the forging temperature. The cracks probably form within a few minutes after placing the ingot in the furnace as a result of the temperature gradient, which is most severe on the ingot surface. A numerical model was created to represent the case of two ingots in a furnace. Upon casting, the ingots are cooled down to no more than 600°C and then placed in a furnace at 1,100 -1,200°C. Numerical simulations were used to analyse their internal stresses and temperatures.
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