P. Beňo, D. Kozak, P. Konjatić Optimizacija tankostjenih konstrukcija u CAE sustavu ANSYS ISSN 1330-3651 (Print), ISSN 1848-6339 (Online) UDC/UDK [621-462:539.413/.414]:519.6 OPTIMIZATION OF THIN-WALLED CONSTRUCTIONS IN CAE SYSTEM ANSYS Pavel Beňo, Dražan Kozak, Pejo Konjatić Original scientific paper Solving optimization problems from the standpoint of structural stresses and strains can be carried out scientifically on the example of telescopic jib. It is mainly due to the fact that despite a broad spectrum of the telescopic jib utilization there are no generally valid, scientifically proven and presented theoretical principles for their designing. From the viewpoint of the classification of mechanics, the arm of telescopic jib as a subject of study can be ranked among thin-walled constructions. In fact, it is a case of enclosed thin-walled bars stressed in operation by a combination of bending and torsion moments. Applying the Finite Element Method (FEM) in connection with the CAE system ANSYS, it is possible to design an optimum shape of the cross-section of the telescopic jib arm. Comparing the calculated values of stresses and deformations with the values obtained by experimental measuring, it is possible to evaluate the effectiveness of the optimization process. Keywords: ANSYS, CAE system, Finite Element Method, optimization, thin-walled constructions Optimiranje tankostjenih konstrukcija u CAE sustavu ANSYS Izvorni znanstveni članak Znanstveni pristup rješavanju problema optimiranja sa stanovišta naprezanja i deformacije u konstrukciji provedeno je u ovom radu na primjeru teleskopske ruke. To je uglavnom zbog činjenice da, unatoč širokom spektru uporabe teleskopskih ruku, ne postoje općenito valjana, znanstveno dokazana i prezentirana teorijska načela za njihovo projektiranje. Sa stajališta mehanike, krak teleskopske ruke, kao predmet istraživanja može se svrstati u tankostjene konstrukcije. U stvari, riječ je o zatvorenom tankostjenom presjeku opterećenom kombinacijom savojnih i torzijskih momenata. Primjenjujući metodu konačnih elemenata (MKE) povezanu s CAE sustavom ANSYS moguće je projektirati optimalan oblik poprečnog presjeka poluge teleskopske ruke. Uspoređujući izračunate vrijednosti naprezanja i deformacije s vrijednostima dobivenim eksperimentalnim mjerenjima, moguće je procijeniti učinkovitost procesa optimiranja. Ključne riječi: ANSYS, CAE sustav, metoda konačnih elemenata, optimizacija, tankostjene konstrukcije 1 Introduction The telescopic jib presents a unique design solution through which it is possible to reach a wide range of work positions of the equipment at a high accuracy of the work cycle. Its universal utilisation is just that feature which predetermines it to be used in manipulators, building, earth-moving and agricultural machines. It is mainly due to the fact that a relatively wide assortment of working equipment can be attached to the end of telescopic jib arm. Individual types differ from one another in their structure mainly because they are designed for various operating conditions and different equipment. The individual producers´ team of designers use mostly their own know-how which is a subject of patent protection in many cases. The application of the optimization module, which is part of the majority of high-end CAE software, allows designing the construction of technical parameters for so general utilisation as possible. From the functional point of view the telescopic jib presents a constructional arrangement of components which are called “guiding” in the technical practice. In fact, it is a system in which the movable part is attached to the stationary part and it moves along geometrically precise and predetermined paths. Its main parts are the outside arm, inside arm and the guiding elements. In addition, it includes also other components which ensure e.g. mutual shift of the arms and working equipment. It is also necessary to consider the effect of the axial rotation mechanism, although it is not often part of the telescopic jib subsystem. The thing is that it affects the design and calculation themselves mainly by its dynamic impacts. On the basis of the above mentioned facts, we can state that the force proportions are necessary to be evaluated from the viewpoint of static load and with the effect of dynamic load. On the one hand, the questions of force proportions can be evaluated within complex loading, but at the same time they can be observed separately, i.e. from the viewpoint of statics or dynamics. The relations concerning particular cases of load are evaluated in two reciprocally perpendicular planes: in the plane of jib stroke (vertical plane) and in the plane of rotating around the vertical axis (horizontal plane). Within the analysis of loading forces in the vertical plane it is possible to appraise two basic operation modes: when lifting the jib or when backing it to the support plate on which the equipment is placed. In the process of lifting the bearing structure, the jib is loaded by the mass of particular components, by reactions activated in the places of jib locations and by forces of lifting mechanism activity. From the viewpoint of stressing, forces of the greatest impact are those ones arising as a result of external force application on the working equipment which is usually fixed at the end of the extensible arm. If it concerns the using of the telescopic jib when lifting a certain load, then the external loading is mass of the given load. Generally, it is interaction of working equipment and the object of work cycle of the given equipment. In the case of backing the working equipment to the support on which is placed the equipment, mass of the load does not act. The jib is loaded by pressure force arising as an effect of the mechanism acting and its running in the vertical plane. If it concerns mobile working equipment, the analysis of external loading in a simplified case is reduced to solving of the classic task of balance of moments. In both cases (lifting or holding down), it is assumed that stabilizing moments equal tilting moments (Fig. 1), where N and Q are vertical external Tehnički vjesnik 21, 5(2014), 1051-1055 1051