Methods Discussion

Static Analysis of Differential under Torque Loading

Background

Results

Acknowledgements

• Armour College of Engineering for funding the Engineering Themes course ENGR 498

• Brazilian Scientific Mobility Program for studying at IIT.

The differential plays a critical role within a machine’s drive train by changing the direction of the power coming from the transmission 90 degrees to allow the axles to be driven. They also allow speed and torque differences between the left and right axles. When a machine is turning, the differential lets the outside wheel move at a faster speed than the inside wheel, allowing for easier turning and less wear on tires or tracks. The gears in the differential also provide speed reduction and torque increases. Many of failures are caused by: Lack of maintenance, exceeding the stress limit of the material and etcetera. Differential structural behavior has been simulated under torque loading to determine whether the differential will sustain the required forces without yielding.

References

1 - “Failure Analysis" Differentials.com. N.p., Jun. 2011. Web. 20 Jun. 2015. 2 – “Part Failure Analysis” winningwithemail.com/content/6490/images/TP0445.PDF. N.p., Apr. 2014. Web. 21 Jun. 2015.3 - Budynas, Richard G., J. Keith. Nisbett, and Joseph Edward. Shigley. Shigley's Mechanical Engineering Design. New York: McGraw-Hill, 2011. 4 - Braess, Dietrich. Finite Elements: Theory, Fast Solvers, and Applications in Solid Mechanics. Cambridge, U.K.: Cambridge UP, 1997.

CAD Model

Analysis(Mesh surfaces in 1st

and 2nd order)

Applying(stresses, torque,

displacement, materials)

Identification(Tolerance to

Damage)

Guilherme Sales, Heitor Bezerra, Matheus Bordignon, Raul Moreira, Dr. Aiman Shibli - Illinois Institute of Technology, Chicago, Illinois 60616 ENGR 498

• Design a CAD model of a differential based on a real one.• Import the CAD file to HyperMesh to create a mesh model in first and second

order.• Understand what will be happening at the Differential.• Choose just the ideal parts that will impact the simulation results.• Analysis of stress, strain and displacement of the Differential under torque

simulation.

• The 1st order mesh presented good results but the 2nd order showed more precise results.

• Was possible to create a different mesh. However, keeping the same size at the teeth, the number of the nodes stayed under 100,000.

• The Heat Treatment is very important to assure better proprieties to material.

• The design is adequate, it can support required forces without yielding.

Figure 5: SAE 8620 Direct Quenched result.

Figure 1: Differential Figure 2: CAD Model Figure 3: Meshed Surfaces Figure 4: 2nd Order Mesh

Figure 6: SAE 4320 Single Quenched and Tempered

Materials Young M. (GPa) Yield S. (MPa) Ultimate S.

(MPa)4320 205 1225 15058620 205 1036 1324

Tf=Final Torque Ti=Initial Torque hp=horsepower gt=gear ratio r=radius σ=stress Ef=Mechanical Efficiency

Steel Force (N) Torque (N.m) Stresses (MPa)SAE 8620 5020 1.7867x103 36.6282SAE 4320 6713 2.3367x103 47.9035

Area= 339.08mm2