PACE PACE Emerging Market VehicleEmerging Market Vehicle

Suspension Design Suspension Design

University of Cincinnati

Suspension TeamSuspension Team

Undergraduate Students: Adam Quintana Elena Sabatini Michael Martin Nicholas Schira

Graduate Assistant: Ronnie Mathew Faculty Advisor: Dr. Sam Anand

Front SuspensionFront Suspension

• McPherson Strut

Dimensions of the Front SuspensionDimensions of the Front Suspension

Side View

Bottom View

Rear SuspensionRear Suspension

• Watts Linkage

Dimensions of the Rear SuspensionDimensions of the Rear Suspension

Front View

Top ViewSide View

Values of Values of springspring and damper constants and damper constants

• Front spring stiffness of 16 N/mm • Damping coefficient of 30 N-s/mm • Rear spring stiffness of 18.7 N/mm • Damping coefficient of 30 N-s/mm

Suspension Incorporated in Suspension Incorporated in FrameFrame

Static FEM analysis – ANSYS Static FEM analysis – ANSYS WorkbenchWorkbench

Front suspension mesh Max Stress – Steering Force

Rear suspension mesh Max Stress – Force from a bump

Static FEM analysis – ANSYS Static FEM analysis – ANSYS WorkbenchWorkbench

• Loading condition– Braking Torque– Maximum steering force– Forces on suspensions while running over a

bump

• Results – Reduced angle and increased thickness

steering arm on the knuckle .– Reduced thickness of the wishbone arms.– Shortened length of pivot arms of the rear

suspension.

Static FEM analysis – ANSYS Static FEM analysis – ANSYS WorkbenchWorkbench

Convergence TestConvergence Test

• Multiple iterations were performed on the models while increasing the number of elements in the mesh.

• Stresses were all converging – hence model is accurate.

Dynamic analysis – MSC ADAMSDynamic analysis – MSC ADAMS• Input

– Height of bump on the road– Velocity of the vehicle

• Output– Spring and contact forces – values

used for static analysis in ANSYS

Simulation of the vehicle Simulation of the vehicle going over a bump on the going over a bump on the

road.road.

Dynamic analysis – MSC ADAMSDynamic analysis – MSC ADAMS

5 10 15 200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Vehicle Resonant Frequency

Frequency (Hz)

Ya

w, P

ith, a

nd

Ro

ll (D

eg

ree

s)

10cm bump @8km/hr10cm bump @16km/hr10cm bump @32km/hr2.5cm bump @64km/hr2.5cm bump @96km/hr

• Yaw, pitch and roll orientation used to determine the resonant frequency of the vehicle.

• Fast Fourier Transform was performed to obtain the resonant frequency of the vehicle.

Vertical displacement of the wheelVertical displacement of the wheel

• Forces ranging from 2500N to 5000N on the front and rear tires on the drivers side.

0.7 0.8 0.9 1 1.1 1.2

0

5

10

15

20

25

30

time(s)

dis

pla

cem

en

t(m

m)

Front Wheel Displacment

2500N3000N3500N4000N4500N5000N

0.7 0.8 0.9 1 1.1 1.2 1.3

0

5

10

15

20

25

30

35

time(s)

dis

pla

cem

en

t(m

m)

Rear Wheel Displacment

2500N3000N3500N4000N4500N5000N

ResultsResultsFront Suspension• The maximum deflection of 8.22E-04 m was found

during the steering simulation which was seen in the steering arm of the knuckle.

• A strain of 2.75E-03 was determined to be the maximum strain in the bump simulation.

• The highest stress came from the braking condition which was determined to be 4.48E+08 Pa.

• Sufficiency of Model - maximum stress was not higher than the tensile strength of the material

Rear suspension

• Deflection of 5.63E-04 m was determined to be the maximum deformation in the bump simulation.

• The highest strain came from the braking condition which was determined to be 3.02E-03.

• The maximum stress of 6.03E+08 Pa was found during the braking simulation.

Dynamic Analysis

• The resonant frequency of the vehicle is 1.667 Hz. • Verifies stability of vehicle with values of spring

stiffness and damping coefficient for both suspensions.

ResultsResults

Thank You !Thank You !