PSI - Issue 38

Ronald Schrank et al. / Procedia Structural Integrity 38 (2022) 30–39 Author name / Structural Integrity Procedia 00 (2021) 000 – 000

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4.2. Identify constant load directions

Direction of force resultants at interface points in relation to the control arm vary over time at reference / full test. This is mainly caused by large displacements (vertical stroke) of the wheel suspension. The simplified test prevents large displacements (no vertical stroke) and requires the definition of constant load directions. Constant load direction is defined by direction vector ⃗ (normalized). Reference load ⃗⃗⃗⃗⃗⃗⃗⃗ whose direction varies over time is projected to ⃗ . The projected force magnitude is: = ⃗⃗⃗⃗⃗⃗⃗⃗ ∙ ⃗ There is a residual force which is neglected for the simplified test:

Fig. 6. Force projection to a time-constant load direction. Constant load direction ⃗ is defined in a way that is minimized in relation to over all time points. This is done by a graphical iterative approach. Resulting from the determination of constant load directions, 5 independent load channels remain for further processing.

→ F Res minimized → Optimum

Fig. 7. F Res vs. F Proj for two exemplary constant load directions, damping strut attachment

Note, that there´s no significant constant load direction for the knuckle force components identifiable, so both knuckle force components ( , ; , ) will be kept.

Fig. 8. 5 force components remain after identification of constant load directions