Polytechnic and design, Vol. 10 No. 2, 2022.
Professional paper
https://doi.org/10.19279/TVZ.PD.2022-10-2-08
INFLUENCE OF GEOMETRIC PROPERTIES OF CROSS SECTION ON STRENGTH OF MACHINE ELEMENTS
Branimir Markulin Grgić
; Zagreb University of Applied Sciences, Zagreb, Croatia
Vladimir Markulin Grgić
; Novamina, d. o. o. Zagreb, Croatia
Antonio Antunović
; Zagreb University of Applied Sciences, Zagreb, Croatia
Miroslav Radaković
; Zagreb University of Applied Sciences, Zagreb, Croatia
Abstract
Proper choice of shape, dimensions and orientation of the cross section of a beam (machine element) is of great importance for meeting the strength criteria with minimal material consumption. The influence of cross section on stresses under basic types of loads is significant, as this paper shows. The properties of the material do not affect the stress distribution and magnitude. The wrong choice of cross section can be compensated only by larger dimensions, i.e. higher material consumption. In all comparisons, the cross sections are of the same surface area and it is shown that drastically different results can be achieved with the same material consumption in terms of strength, but also stiffness, which is not the subject of this paper. In the case of axial tensile load and shear, only the surface A of the cross section is important; in the case of bending, the shape, dimensions and orientation of cross section are important, which is expressed by the axial moment of resistance W; and in the case of torsion, the shape and dimensions are important, which is expressed by the polar moment of resistance Wp. In the case of torsion, we limited ourselves to circular cross sections. There are frequent examples from practice in which, due to the wrong choice of the cross section of the profile, significantly higher material consumption was required to meet the strength conditions. In the considered cross sections, we imagine that there are no stress concentrators, i.e. geometric and material discontinuities that cause a local increase in stress.
Keywords
strength; geometric properties; bending; torsion; moment of inertia
Hrčak ID:
284319
URI
Publication date:
2.5.2022.
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