Generic Knuckle Concept Model for Wheel Suspension Performance
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The knuckle is a wheel suspension component that transfers the forces acting upon
the tires through the linkages to the vehicle’s sub-frame. The coordinates, or joints,
where the knuckle and linkages connect are the outer hardpoints and the joints
where the linkages and vehicle’s sub-frame connect are the inner hardpoints. The
position of hardpoints in 3D space will determine the motion of the wheels during
different maneuvers.
In the concept phase of the suspension system development, the hardpoints are computed
and analyzed iteratively for optimum kinematics and compliance behavior.
The suspension knuckle is developed based on the hardpoints. However, optimizing
the knuckle design based on stiffness and weight targets for different test cases is
time-consuming. Therefore, a quick computation of the knuckle’s approximate stiffness
right after the iteration of hardpoints in the concept phase will speed up the
suspension development process.
This quick approximation of the stiffness, using the concept of 3D-frame analysis,
is computed using the Direct Stiffness Method. The frame structure is formed by
joining the outer hardpoints using 3D beam elements of uniform and linearly varying
cross-sections. The four-link suspension system is mathematically modeled to
compute the reaction forces at the outer hardpoints for the applied force at the tire
contact patch. The deformation of the nodes at each knuckle hardpoint is calculated
based on the reaction forces and appropriate constraints. This mathematical
model is validated using NX Finite Element software using 1D elements of uniform
and varying cross-sections. Upon validation, the mathematical model is compared
against the finite element model of the knuckle for camber and aligning torque stiffness.
Beskrivning
Ämne/nyckelord
Non-prismatic 3D beam, four-link suspension, knuckle compliance, frame structure