The FEM based numerical simulation was used for the determination of stress and strain distribution in V-notched specimens as well as for the calculation of stress concentration and notch-sensitivity factors. Bend fatigue strength of the selected spring steel was then determined considering concentration in the notch. Simultaneously, structural testing of real mono and two-leaf springs for trucks was performed at selected conditions of fatigue and their life time was assessed. The FEM based calculated life-time of the springs is in a good agreement with its real life time.
COBISS.SI-ID: 684202
Fatigue strength of the improved 51CrV4Mo steel was determined in different loading modes for two heat-treatments conditions and two directions of segregations. For determination of S-N curves smooth and notched cylindrical and CVN specimens with different kt factors were used. Microstructural characterisation by LM and SEM of selected steel was performed. The obtained experimental results enabled a better FEM-based fatigue life prediction of leaf springs of the selected geometry; taking into account loading conditions and experimentally determined dynamic properties of spring steel.
COBISS.SI-ID: 824490
The genetic programming method was used to determine the correlation between spring tool life and inclusion size and inclusion location. According to the best genetically developed spring life model it was easily to calculate the critical size of inclusion on the spring surface. This value is 0.14 mm. According to known critical inclusion size value the right spring steel and steel plant technology could be easily selected. The results are compared with more experimentally oriented research.
COBISS.SI-ID: 1439995
The possibilities of the vacuum heat-treatment of spring steel 51CrV4 are presented. Testing has been performed on circumferentially notched and fatigue-precracked tensile specimens. The results of investigation have shown that the use of the proposed method enables to draw tempering diagrams. Metallographic analyses of the specimens used shows in steel the presence of positive and negative segregations. It was found that the width of the segregations and the distance between segregations influence significantly the KIC due to the presence of bainite in the negative segregations.
COBISS.SI-ID: 851370