Institute of Fundamental Technological Research

The paper deals with experimental attempts for determination of the mechanical resistance of various components subjected to static loading by analysis of displacement values in a 3D coordinate system using a non-contact testing method. The problem is studied on the basis of results from tests of the wheelchair and SUV’s wheel, supported by means of a PONTOS 5M Digital Image Correlation (DIC) system enabling determination of the patterns deflection at discretised facet measuring zones of an element. The objects tested extend a knowledge on the components’ behaviour under static loading within their loading capacity. Data collected in the experiments are expressed by variations of the resultant vector of deflection in the 3D coordinate system and images under loading and unloading stages as well. The results enabled to indicate the weakest zone in the wheelchair and to express an influence of the foot tire on the rim edge, giving necessary knowledge on the mechanical resistance of tested components. In case of the wheelchair a rear side and axle represent the weakest regions, while for the wheel a rim edge is the most loading sensitive region on the tire guard with respect to safety of the operational process. All data captured by DIC system as a function of time can be directly used for modelling and improving a suitability of the selected components since they can be employed as the limit levels during determination of safety factor. The experimental approach applied to the SUV wheel investigation can be also used as a procedure for wheels of other type vehicles tested either in laboratories of research institutions or technical universities.

The paper reports experimental results from tests carried out at room temperature on servo-hydraulic system dedicated for examination of the exploitation properties of rocker arms. The ball joint of this element was modified by an application of composite coating such as the tungsten carbide (WC). To apply cyclic loading to rocker arms the griping system was designed and elaborated. Results from tests performed on the composite coated ball joints were compared with data obtained for typical elements. Variations of the following parameters versus time i.e. force, temperature and surface topography of balls were analysed with respect to exploitation properties of the modified ball joints. An increase of the wear coefficient was achieved for sliding joints of the steel ball-steel cups coated by the WC.

Ball Joint, Composite, Cyclic Loading, Surface Topography, Tungsten Carbide, Wear

Praca przedstawia charakterystyki naprężenie-odkształcenie stali austenitycznej VP159 oraz staliwa austenitycznego LH556, o dużej zawartości azotu, przy różnych prędkościach odkształcania. Do badań w zakresie obciążeń statycznych zastosowano serwohydrauliczną maszynę wytrzymałościową, natomiast w zakresie obciążeń dynamicznych metodę pręta Hopkinsona. Otrzymane rezultaty przedstawiono w formie wykresów naprężenia rzeczywistego w funkcji odkształcenia rzeczywistego. Na podstawie statycznej próby rozciągania wyznaczono również podstawowe parametry badanych materiałów, takie jak: E, R0,05, R0,2, Rm. Na podstawie badań stwierdzono, że stal VP159 ma znacznie lepszą ciągliwość niż staliwo LH556, natomiast pozostałe parametry i charakterystyki były zbliżone. Otrzymane wyniki można wykorzystać do wyznaczenia parametrów równań konstytutywnych opisujących termomechaniczne właściwości materiałów na potrzeby symulacji komputerowych.

mechanika, pręt Hopkinsona, duże prędkości odkształcania, stal wysokoazotowa, charakterystyka naprężenie-odkształcenie

The steels of different carbon content were tested with respect to their microstructural and selected mechanical parameters variations. The original combinatorial method, based on the phase quanta theory, was applied in the quantitative metallographic assessment. Hence, the adequate geometrical parameters of steel microstructure were possible to be determined. Moreover, the selected mechanical parameters of the materials were evaluated using non-destructive and destructive methods. The results enabled to formulate some significant quantitative relationships between microstructure and mechanical parameters.

Steel, phase composition, quantitative metallography, mechanical behaviour

structural components, static loading, markers, displacement, deflection, DIC