Suspension link trusses

Solid circular beam sections, ø12mm, aluminum. Essentially rigid with respect to other chassis structures.

Rear framework

Hollow circular section beam, aluminum.

Main structure: outer diameter ø40mm, wall thickness 1.8mm.

Stiffeners: outer diameter ø30mm, wall thickness 1.2mm.

Composite monocoque

Thicker backbone: 1.8mm aluminum sheet, 25.4mm aluminum honeycomb 3003, density 5.2 lb/ft^3 (hex-3003-td.pdf), 1.8mm aluminum sheet.

Thinner panels: 1.8mm aluminum sheet, 6.75mm same aluminum honeycomb, 1.8mm aluminum sheet.

Frontal shock absorber support plate: provisionally as thinner panels, to be defined based on shock.

Inertial elements

monocoque_chassis_2019_inertial_elements_alone.mud

inertially_equivalent_cuboid_engine.ods

inertially_equivalent_cuboid_wheel_assemblies.ods

Notes:

The pedagogical model proposed does not include sway/antiroll bars, that are instead a critical element for torsional stiffness loadcases.

In particular, torsional stiffness should be evaluated in both the limiting cases of

• rigid springs, disconnected sway bars;
• disconnected springs, rigid sway bar.

This second loadcase, which is usually neglected, is however relevant for sizing the sway bar support areas on the chassis structure.

• Static test: torsional stiffness;
  • preliminary suspension stroke motion test (original Optistruct tutorial version );
  • rigid spring or rigid anti-roll bar?
• Front, right wheel bump loadcase (inertia relief);
• Frontal crash absorber collapse loadcase (inertia relief); at the element faces belonging to the crash_absorber_bearing_area set (an approx. 155×320 mm area at the front bulkhead), a 25 psi = 0,172 MPa distributed pressure is applied which is due to the honeycomb absorber crushing (see datasheet).
• Dynamic modal response;
• Dynamic harmonic response: vertical harmonic load at the front, right wheel, 1-100 Hz range, sampled at 0.25Hz resolution ((100-1)*4+1 = 397 steps);

RBE3 link kinematics.

sorgente ipe