The development process of the knowledge-based engineering (KBE) system for the structural size optimization of external fixation device is presented in this paper. The system is based on algorithms for generative modeling, finite element model (FEM) analysis, and size optimization. All these algorithms are integrated into the CAD/CAM/CAE system CATIA. The initial CAD/FEM model of external fixation device is verified using experimental verification on the real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement transducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on the simulated annealing (SA) method and a local algorithm based on the conjugate gradient (CG) method. The cost function of size optimization is the minimization of the design volume. Constrains are given in a form of clinical interfragmentary displacement constrains, at the point of fracture and maximum allowed stresses for the material of the external fixation device. Optimization variables are chosen as design parameters of the external fixation device. The optimized model of external fixation device has smaller mass, better stress distribution, and smaller interfragmentary displacement, in correlation with the initial model.

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Difference between industrial designer and product designer is not precisely defined. There is a lot of discussions and misunderstandings about these two professions. What is the job of industrial designer and what is the job of product designer? This question if often asked from people, which want to hire someone to design a new product for them. Through this research, same real-life design contest is given to group of students from Faculty of Mechanical Engineering, Department of Mechanical Design, at Industrial design course and to group of students from Academy of Fine Arts, Department of Product Design as product design project. Goal of the contest was to design an upholstered chair for indoor use with a modern and refined style. Goal of this research was to find some unique characteristic of designs from industrial designers and product designers. Resulted designs were evaluated analysing the fulfilment of the requirements criteria defined by contest and analysing additional criteria, which is important for new product design. Analysing the resulted designs some important conclusions are made. Most important conclusion is that industrial designer can be product designer but product designer cannot be industrial designer. For product design, engineering knowledge is not necessary, but for industrial design, it is most important.

The purpose of a car jack is lifting the car and maintaining it at a certain height during different repairs. This paper focuses on the design of car jack, which belongs to the basic equipment of cars. Cars jacks are used mainly for changing tires and small repairs of a car. The aim of this paper was to create a parametric CAD model of a car jack and carry out numerical structural analysis of the car jack using the created parametric CAD model. The development of the parametric CAD model and structural analysis was performed using the CATIA V5 system. This paper describes the modern way of creating more complex mechanisms, which support quick modification of its parameters, and thus the entire design. The whole model of the car jack was parametrized. The stresses obtained by finite element method (FEM) analysis were confirmed with the analytical calculation in characteristic parts of the design, with some exceptions. At the end of the paper, an analysis of the obtained results was performed, on the basis of which specified conclusions were made.