ISSN 1232-308X See larger image ISSN 2299-3649	Polish Academy of Sciences Computer Assisted Mechanics and Engineering Sciences Polish Academy of Sciences Computer Assisted Methods in Engineering and Science HOME EDITORIAL BOARD ALL CONTENT CURRENT ISSUE INSTRUCTIONS FOR AUTHORS SUBSCRIPTION SEARCH HOME EDITORIAL BOARD ALL CONTENT CURRENT ISSUE INSTRUCTIONS FOR AUTHORS SUBSCRIPTION SEARCH CAMES 1994-2011

This paper presents a fluid-structure interaction simulation applicable for evaluating and optimizing hydraulic valve designs. A special emphasis is placed on shim stack valve commonly used in automotive and railway shock absorbers. For simplicity, the problem was effectively reduced to a two-dimensional (2D) problem. This was accomplished by introducing section-lines along which the pressure profile was computed to find and evaluate the global minimum. The global minimum was then treated as the design ranking measure. This ranking function provided a means to choose an optimal design from a set of available design variants. In the presented results, the ranking is problem-specific as it identifies and localizes low pressure zones that are the root causes of both aeration and cavitation effects. The damping force performance was experimentally evaluated for both the baseline and optimized valve design using a shock absorber level test on a servo-hydraulic test rig.


Keywords: valve system, aeration, cavitation, computational fluid dynamics, fluid-structure interactions, simulation, optimization.

This paper presents an approach to optimize the structure of a micro-drill for reducing its lateral vibration, which has a strong effect on the quality of drilled holes during the cutting process. The micro-drill and the spindle of a micro-drilling spindle system are modeled as Timoshenko's beam elements. Each element with five degrees of freedom at each node comprehensively includes the effects of continuous mass eccentricity, shear deformation, gyroscopic moments, rotational inertia with external thrust force and torque, and coupling torsional and lateral effect. The finite element method is used to determine the lateral amplitude response at the micro-drill point, which is considering the objective function during the optimization of the micro-drill by the interior-point approach. The diameters and the lengths of drill segments are chosen as the design variables with nonlinear constraints in the constant mass, mass center location, and torsional deformation of the drill. The in-house finite element code-integrated optimization environment is implemented in MATLAB to solve the optimal problem. The results showed that compared with the original micro-drill, the lateral amplitude response at the drill point of the optimal one is reduced by 91.89% at an operating speed of 50 000 rounds per minute (r/min), and its first critical speed and the corresponding amplitude response exceed those of the original one.


Keywords: nonlinear constrained optimization, finite element analysis, micro-drilling spindle, continuous eccentricity.

A significant influence of explosive charge geometry is frequently observed during experimental testing. In this paper, the effect of explosive charge shape, along with its material properties, on the generated blast waves is studied. The FEM analysis was conducted for six different explosive materials and three different cylindrical shapes, with geometrical proportions of length L to diameter D varying between 2, 1 and 0.25 and constant charge mass. We found that the blast wave generated by detonation is susceptible to shape changes. However, the different explosive materials were influenced by the charge shape in almost the same way, with only insignificant differences resulting from the material properties.


Keywords: blast wave, FEM, ALE.

This article presents possibilities of using one of network analysis tools for public transport optimization. The work focuses on presenting the transport system as a research polygon for analysis of its geographical information system (GIS). The article covers both a cognitive and methodological application approach. The first is achieved on a wider scope through discussing research regarding public transport in the GIS environment and in a narrower focus on the methodology where the vehicle routing problem (VRP) tool is referred to in detail. The city of Łódz, Poland and its system of night bus connections were used as a case study to illustrate how GIS solutions may be used to manage public transport. The simulation using the VRP tool conducted on a large urban center meets the work's methodological assumptions and may present an indication for local transport managers of how the spatial information systems can boost their organizational operations.


Keywords: vehicle routing problem, network analyst, accessibility, public transport, city.