PSI - Issue 57

Ahmad Qaralleh et al. / Procedia Structural Integrity 57 (2024) 649–657 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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fully elastic and elastic-plastic simulations were conducted on the model, enabling the estimation of material fatigue life at a later stage. The material properties for the fatigue parameter S-N curves, obtained from strain-controlled experiments with constant amplitudes and incremental step tests, are summarized in Table 3.

Fig. 8 Steering knuckle geometry and mesh with a focus on the radius

Table 3 Material properties for the P RAM and P RAJ damage S-N curves obtained from strain-controlled experiments with constant amplitudes and the Incremental Step Test

Maximum strain amplitude [%]

Support factor of the damage curve at N=1 [MPa]

Damage parameter

Source of cyclic properties

The slope of the damage curve

P RAM P RAJ

2743 1773 2760 2746 2761 1296 1773 1296

-0.138 -0.589

Strain controlled test

-

0.4 0.6 0.8 0.4 0.6 0.8

P RAM

-0.138

Incremental Step Test

P RAJ

-0.559

Table 4 presents the characteristic and calculated values obtained from the elastic Finite Element Analysis of the steering knuckle for the stress hypotheses von Mises and the 1st Principal stress. Additionally, the plastic form factor (K p ) is found to be 3.9 based on an elastic-ideal plastic simulation. K p factor is a dimensionless parameter that characterizes the plastic deformation capability of a material.

Table 4 Characteristic values from elastic FE calculation of the steering knuckle for the stress hypotheses according to von Mises and the 1 st Principal stress.

Relative stress gradient [1/mm]

Highly stressed volume [mm3]

Elastic transfer factor [MPa/N]

Material support number

Stress hypothesis

1 st Principal von Mises

0.38 0.50

14.1 15.0

0.0386 0.0343

1.173 1.186