Experimental research on influence on single overloadon fatigue life of constructional steels under complex load

The paper presents the results of fatigue life tests under complex load conditions (proportional bending with torsion) with single overload for the different overload ratios (kj=1.5; kj = 2). Specimens of square sections made of costructional steels: 10HNAP and 18G2A with unilateral sharp notches were tested. The tests were performed at the fatigue test stand MZGS-100; amplitude of resultant moment was Ma=16 N.m (proportion of bending and torsion moments was Mag/Mas =1.73). Fatigue crack growth was measured with a microscope magnifying 25x. It was found that a single overload causes an essential change of fatigue life. It has been shown that the overload factor strongly influences those changes

Fatigue life of constructional materials under bending with torsion for crack propagation

The paper presents description of the equivalent range of the stress intensity factor in the case of bending with torsion of specimens where initiation and propagation of fatigue cracks are observed. Calculations with the Matlab-Simulink program were performed in order to estimate fatigue life. The calculations were realized for variable amplitudes of the resultant moment 13 and 16 N×m. The Forman’s relation was also used for the calculations. It has been shown that the Forman’s relation is suitable for description of fatigue life in the tested range of fatigue crack propagation

Analysis of thread coil effort in the screw-nut joint

Przedmiotem artukułu jest optymalizacja śrub w zespole korbowód-stopa korbowodu silnika SW 680 Leyland, z uwagi na równomierny rozkład obciążenia na wszystkie zwoje gwintu. Optymalizacja geometrii śruby polegała na częściowym stoczeniu zwoi gwintu pełnego pod określonym kątem. Obliczenia stanu naprężenia prowadzono metodą elementów skończonych, przy użyciu programu Nastran/Patran. Wykazano, że optymalnym kątem częściowego stoczenia pełnego zarysu gwintu okazał się kąt 3⁰, przy którym obciążając śrubę siłą rozciągającą 29 kN, uzyskano obniżenie naprężenia redukowanego o 12% oraz bardziej równomierny rozkład obciążenia zwoi gwintu w porównaniu do śruby klasycznej o pełnym zarysie gwintu.The paper concerns optimization of screws in the unit including connecting-rod – connecting rod big end of the SW 680 Leyland motor related to uniform distribution of loading on all the thread coils. Optimization of screw geometry insists in partial turning of the thread coil at a determined angle. The stress state calculations were performed with the finite element method and the Nastran/Patran program. It has been shown that the angle 3⁰ is the optimum angle of partial turning of the thread contour. At that angle, when the screw was loaded by the tensile force 29 kN, we obtained the reduced stress decreased by 12%, and more uniform distribution of the thread coil as compared with the traditional screw (not optimized)

Numerical analysis of stress state and deflection perforated plates with concentrated force

Przedmiotem artykułu jest numeryczna analiza stanu naprężenia i ugięcia w utwierdzonych oraz swobodnie podpartych, perforowanych płytach prostokątnych obciążonych centralnie siłą skupioną. Obliczenia prowadzono metodą elementów skończonych. Uzyskano rozkłady naprężeń wokół otworów na całej powierzchni płyty perforowanej. Wyniki obliczeń numerycznych w przypadku płyty utwierdzonej na brzegach porównano z rezultatami uzyskanymi dla identycznej płyty swobodnie podpartej.The work is the numerical analysis of the state of stress and deflection in restrained and simply supported perforated rectangular plates loaded centrally concentrated force. Calculations were carried out by finite element method. Obtained stress distribution around the holes on the entire surface of the perforated plate. The results of numerical calculations for the plate clamped at the edges compared. Results obtained for identical plate simply supported