Taško Maneski

Numerical and experimental determination of stress concentration factor for a pipe branch model

The subject of this paper is testing of complex geometrical structures, i.e. stress analysis of a pipe branch model of A6 third pipeline at Hydropower Plant Perucica, Niksic. Analysis of pipe branch model stress distribution was carried out by using finite element method and experimental methods. Finite element method defined 3D pipe branch model. Numerical calculation defined critical locations on model, i.e. locations with the greatest stress concentration. Strain gauges were placed on identified critical locations. Measured stress values confirmed values obtained by using numerical calculation. Experimental measurements were also taken by using new digital image correlation (DIC) method. DIC method is an optical non-contact method that can provide full 3D stress field and enables better understanding of complex structures such as pipe branches. The aim of this paper was to determine stress concentration factor for the pipe branch model by using numerical and experimental analysis.

GROUP THEORETICAL FORMULATION OF NONSYMMETRICAL SYSTEMS BY THE GROUP SUPERMATRIX PROCEDURE

Abstract The group supermatrix procedure, developed by Zlokovic for systems with symmetry properties described by groups, can be also applied to systems without symmetry. Transformation of a nonsymmetrical system into a system with symmetry properties is accomplished by symmetrization of support conditions, by adding fictitious structural parts and by removing existing ones. The generalized displacements and forces in the above symmetrized system coincide with corresponding values in the nonsymmetrical system. The group supermatrix procedure performs the analysis for each G -invariant subspace separately, using only a part of the structure. This provides, in comparison with conventional methods, a drastic reduction in the amount of data input, computation and necessary memory space of the computer.

Numerical analysis of local and global buckling of a stiffened beam-column

Preliminary communication The linear buckling phenomenon is obviously very important for stability of compressed supports. The determination of buckling resistance is an important characteristic of the design of steel structure. Besides, the presence of stiffeners in structural plate elements has a vital role in order to increase critical buckling load capacity. However, these stiffeners cause a redistribution in buckling behaviour in terms of local and global buckling. In this paper the transverse and longitudinal stiffeners were employed on a real beam-column structure to maximize the critical buckling loads. The objective is to find the optimum geometry of stiffeners. Based on the finite element method, a numerical model is made using the Abaqus program in order to observe the critical buckling capacity. The results showed that the local critical buckling has been significantly affected by stiffeners position in the case of transverse stiffeners, but little effect is observed on the critical local and global buckling in the case of longitudinal stiffeners.

Analysing Displacement in the Posterior Mandible using Digital Image Correlation Method

Background: Knowing the biomechanical consequences of the stresses generated to the supporting bone during occlusal loading is significant for improving design and clinical planning process in partial edentualism therapy. The objective of this study was to analyze the surface displacement field on partial dentate mandible rehabilitated with removable partial denture and to compare it to displacement field on partial dentate mandible rehabilitated with cantilever fixed partial denture. Material and Methods: The experimental models were partial dentate mandible with full-arch PFM crowns and removable partial denture and partial dentate mandible rehabilitated with full-arch cantilever fixed partial denture. Displacement were measured using Digital Image Correlation Method. Results: Displacement values of the removable partial denture-model were ranging from 0-1.50 mm. Analysis of the fixed partial denture-model results showed displacement values from 0.05-0.69 mm. Conclusion: Higher displacements of bone tissue were observed below the removable partial denture, especially in the region of distal abutment and distal portion of the free-end saddle. Displacements within bone and the bonedenture contact area were mostly influenced by the teeth and denture vertical movements.