A multiscale numerical model is developed for the simulation of solidification grain structure formation (equiaxed to columnar and columnar to equiaxed transitions) during the continuous casting process of steel billets. The cellular automata microstructure model is combined with the macroscopic heat transfer model. The cellular automata method is based on the Nastac’s definition of neighborhood, Gaussian nucleation rule, and KGT growth model. The microscopic model parameters have been adjusted with the experimental data for steel 51CrMoV4. Simulations have been carried out for different castings.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 1080315We have developed a model of steel hardness with respect to the process parameters of soft annealing based on the genetic programming. The described developments have been used in practice in Štore Steel company. We have increased the productivity of the annealing furnace for more than two times based on the described developments and with this significantly improved the existing productionprocess.
F.10 Improvements to an existing technological process or technology
COBISS.SI-ID: 1066747Artificial neural networks (ANNs) are employed as an alternative to physical modeling for calculation of the relations between the production path process parameters (melting of scrap steel and alloying, continuous casting, hydrogen removal, reheating, rolling, and cooling on a cooling bed) and the final product mechanical properties (elongation, tensile strength, yield stress, hardness after rolling, necking) of steel semi products. They provide a much faster technique of response evaluation complementary to physical modeling. The Štore Steel company process path for production of steel bars is used as an example for demonstrating the new approach. The applied ANN is of a multilayer feedforward type with sigmoid activation function and supervised learning. The entire set of 123 process parameters has been reduced to 34 influential ones and 1879 data sets from the production line have been used for learning. The results of parametric studies performed on the ANN based model seem consistent with the expectations based on industrial experiences. However, further improvements in data acquisition and analytical procedures are foreseen in order to obtain a methodology, reliable enough for use in the everyday industrial practice. The methodology seems to be for the first time applied in the through process modeling of steel production.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 2601467The Pipistrel Taurus G4 plane won NASA Geen Flight Challenge 2011, sponsored by Google. Is currently the largest, heaviest and the fastest electro-powered aircraft, and the only electro-powered four-seater in the world. The article presents the plane path from idea, through planning to implementation, testing and participation in the contest. Published are the facts from background, technical diagrams and the ideology behind the concept of the plane. The authors also disclosed to competitive tactics and knowledge gained in testing procedures. Project design and manufacture of aircraft Taurus G4 lasted a mere 5 months, and it has been necessary to implement innovative approaches such as. rapid prototyping and concurrent development in several areas simultaneously. The theoretical background is multidisciplinary and include all of the aeronautical, mechanical engineering, electrical engineering skills, as weel as the statistics in the analysis and processing data from tests. The capacity of aircraft Taurus G4 correspond to the predictions of simulations within accuracy of few percent (1 to 3%). We demonstrated that we can develop a product in a very short time, based on the simulations, which behaves predictable, although it is not conventional. The Taurus G4 plane has double body design and belongs to the category of so called multi-body aircraft. The advantages of the structure is shown in excellent mass distribution along the wing, while it can achieve substantial lower structural weight of aircraft, the reby also use less energy for a particular purpose. The structural aspect can be used in aircraft of different implementations, where the ability to carry loads is of great importance. We emphasize the importance and usefulness of rapid prototyping, innovative construction solutions, unique aerodynamic solutions and CFD optimization, knowledge of the electric propulsion system, and knowledge for the future design of aircraft with low specific energy use. The findings are useful for engineers and researchers.
F.06 Development of a new product
COBISS.SI-ID: 2174971In the book, published in USA, recent advances in the field of meshless methods are presented by distingushed authors.
C.01 Editorial board of a foreign/international collection of papers/book
COBISS.SI-ID: 1737723