06-04-2012, 11:34 AM
Vehicle Structure Analysis
Lecture on Vehicle structure.pdf (Size: 2.05 MB / Downloads: 69)
Load Analysis
Ensure the structure will not fail in service.
2. Ensure satisfactory fatigue life
Objectives
Load Analysis
If the structure can resist the (rare) worst possible loading
which can be encountered,
Vertical Asymmetric Load Case
Asymmetric loading is specified by the
maximum height H of a bump upon
which one wheel of one axle rests,
with all other wheels on level ground.
Accelerating
Maximum performance in longitudinal acceleration of a motor vehicle
is determined by one of two limits– engine power or traction limits on
the drive wheel.
- At low speeds tire traction may be the limiting factor.
- At high speeds engine power may account for the limits.
Basic Requirements
Purpose of structure
1. To maintain the shape of the vehicle
2. To support the various loads applied to vehicle.
Design criteria (aim)
1. To achieve sufficient levels of
strength and stiffness with
a minimum mass.
2. To achieve acceptable
crash performance.
Stiffness
1. Bending stiffness, KB
- Stiffness has an important influences on vehicle handling and
vibrational behaviors and function of vehicle part such as doors.
The two stiffness definitions are
Relates the symmetrical vertical deflection of the point near the
center of the wheelbase to multiples static loads on the vehicle.
2. Torsional stiffness, KT
Relates the angular deflection to an applied pure torque about the
longitudinal axis of the vehicle.
- Torsion case usually difficult to design for, so that the torsional
stiffness is often used as a benchmark of vehicle structure.
Definition
SSS is a plane structural element that can be considered as rigid
only in its own plane (i.e. flexible to out-of-plane load).