Fatigue life estimation of notched elements with use of non-local volumetric method

• The threshold value of energy parameter depends on number of cycles.
• The volume of material, depends on level of load and number of cycle.
• Volume of material which were assumed for averaging is greater for tension–compression than for bending.
• Wide range of experimental tests and calculation allows to determine value of volume in which averaging should be done.

The work presents non-local fatigue computations method together with volumetric approach, in which energy parameter has been used. Proposed model has been used for simulation computations, based on experimental testing of unnotched (smooth) and notched specimens subjected to two types of loads, i.e. tensile – compressive and oscillatory bending. Computations of energy parameter value have been done based on results of FEM elastic–plastic analysis for cyclic properties of a material. Averaging operation was performed for assumed constant threshold value, resulting in averaged value of energy parameter, on the grounds of which fatigue life has been read off from characteristics of unnotched specimens. The threshold value assumed depends on load type, and the volume within which averaging is performed depends on load level.