Periodica Polytechnica Mechanical Engineering 

About: Periodica Polytechnica Mechanical Engineering is an academic journal published by Budapest University of Technology and Economics. The journal publishes majorly in the area(s): Finite element method & Heat transfer. It has an ISSN identifier of 0324-6051. It is also open access. Over the lifetime, 838 publications have been published receiving 4218 citations. The journal is also known as: Periodica polytechnica. Mašinostroenie.

Stability of the milling process

Abstract: A new technique for determining the stability conditions of delayed differential equations with time-periodic coefficient is presented. The method is based on a special kind of approximation of the delayed term. As a practical application, the stability of the milling process with respect to the technological parameters is analysed, and an unstable zone in the domain of high cutting speed is shown.

Bisection method in higher dimensions and the efficiency number

Abstract: Several engineering applications need a robust method to find all the roots of a set of nonlinear equations automatically. The proposed method guarantees monotonous convergence, and it can determine whole submanifolds of the roots if the number of unknowns is larger than the number of equations. The critical steps of the multidimensional bisection method are described and possible solutions are proposed. An efficient computational scheme is introduced. The efficiency of the method is characterized by the box-counting fractal dimension of the evaluated points. The multidimensional bisection method is much more efficient than the brute force method. The proposed method can also be used to determine the fractal dimension of the submanifold of the solutions with satisfactory accuracy.

Applicability of friction stir welding in polymeric materials

Abstract: The applicability of friction stir welding has been studied on polypropylene sheets. The joint strength has been analysed in terms of rotation and translation speed. It has been demonstrated that in addition to the judicious selection of welding parameters the proper construction of the welding tool is also very important. The crystallinity of the seam and its neighbourhood has been analysed by DSC, the structure of the seam border region has been analysed by optical and by scanning electron microscopy. It was found, that the seam has undergone embrittlement, as a result of non-satisfactory homogenization. Having analysed the flow circumstances during welding on seams produced by proper tool geometries it has been demonstrated that homogenization and, consequently the joint strength can be substantially improved.

Basalt fiber as a reinforcement of polymer composites

Abstract: The applicability of basalt fibers as reinforcing materials has been examined in a polypropylene (PP) matrix. The brittle basalt fibers have been mixed with the PP fibers by carding combined with needle punching and the composite sheets have been produced by pressing. SEN-T fracture mechanical specimens have been cut out of the sheets and the sensitivity to crack propagation has been examined in the composites. It has been proven that fracture toughness increases as a result of reinforcing. The toughness of the composite increased compared to the matrix due to the gravels appeared at the end of basalt fibers. It has been pointed out that the gravels are results of the Junkers production technology. The observations have also been proven by electron microscopic images. A model has been outlined for investigation of influence of change of technological parameters on basalt fiber production.