Multiaxial fatigue assessment of crankshafts by local stress and critical plane approach
Journal Title: Frattura ed Integrità Strutturale - Year 2016, Vol 10, Issue 38
Abstract
For multiaxially-loaded parts several stress-based fatigue assessment concepts are applicable mostly taking uniaxial test results as basis. These approaches work well in case of proportional loading states, but on contrary, for non-proportional stress conditions, implying a change of the principal stress direction, deviations in the fatigue life estimation may occur. The aim of this study is to evaluate the cyclic multiaxial material behavior experimentally and to proof the applicability of stress-based methods to assess the fatigue strength. The investigated base materials incorporate the commonly applied crankshaft steels 50CrMo4 and 34CrNiMo6 without surface-layer post-treatments. Extensive fatigue tests with small-scale specimens are performed to evaluate the material behavior under cyclic loading. The experiments include basic uniaxial characterizations, such as notch stress sensitivity and effect of loading type, including tests under tension, rotating bending, and torsion loading. Additionally, combined loading tests with proportional and non-proportional situations are presented to reveal the fatigue resistance for multiaxial stress states. Significant loading conditions, such as proportional stress under rotating bending and torsion, and further on, non-proportional effects like phase shifts and varying frequency ratios are presented. The local fatigue strength assessment is performed on the basis of the critical plane approach, whereat the normal and shear stresses are transformed in numerous cutting planes. Equivalent stress hypotheses are applied and compared with the experiments showing that the Huber-Mises-Hencky criterion fits well to the test results in case of proportional rotating bending and torsion loading
Authors and Affiliations
M. Leitner, Z. Tuncali, R. Steiner , W. Chen
Keywords
Related Articles
- EP ID EP138960
- DOI 10.3221/IGF-ESIS.38.06
- Views 63
- Downloads 0
Fatigue crack tip damaging micromechanisms in a ferritic-pearlitic ductile cast iron
Due to the peculiar graphite elements shape, obtained by means of a chemical composition control (mainly small addition of elements like Mg, Ca or Ce), Ductile Cast Irons (DCIs) are able to offer the good castabili...
The effect of steady torsion on fatigue crack growth under rotating bending loading on aluminium alloy 7075-T6
Axles and shafts are of prime importance concerning safety in the transportation industry and railway in particular. Design rules for axles and shafts are mainly based on endurance curves for the material used ac...
Fatigue cracking of aluminium alloy AlZn6Mg0.8Zr subjected to thermomechanical treatment
The paper presents the results of experimental test of the fatigue of aluminium alloy type AlZn6Mg0,8Zr exposed to various low temperature thermomechanical treatment. Basquin’s characteristics of fatigue have...
An analysis research of the stiffness characteristics of hospital building materials
This paper primarily aims to introduce different stiffness ratio requirements for hospital buildings of various structural styles, to achieve a new standard. The requirements of each stiffness ratio are analyzed,...
Random accumulated damage evaluation under multiaxial fatigue loading conditions
Multiaxial fatigue is a very important physical phenomenon to take into account in several mechanical components; its study is of utmost importance to avoid unexpected failure of equipment, vehicles or structures...