1. T.M.F.T: Thermal Mechanical Fatigue Testing
Sponsored by: Cummins
Group Members
Wale Adewole
Siyé Baker
Heriberto Cortes
Wesley Hawk
Ashley McKnight

2. Outline Project Scope Abstract Background Research Design
Design Analysis
Testing Procedure/Setup
Results
Future Changes
Conclusion
Special Thanks

3. Project Scope
Locate and identify standards for thermal mechanical fatigue failure.
Create a testing rig and a
sample.
Create Testing Procedure
Test aluminum specimens
and accurately identify the necessary
properties that affect thermal fatigue failure.

4. Abstract Final design consist of modifications to an existing machine.
Machine shown is the ATS 1600.
ATS 1600 is equipped with furnace and 50,000 lb load cell.
Computer controlled oven cycles and data acquisition.

5. Research
American Society for Testing and Materials(ASTM) definition of fatigue.
“The process of progressive localized permanent structure change, occurring in a material subjected to fluctuating stresses and strains…which may culminate in cracks or complete fracture after sufficient number of fluctuations.”
Constrained thermal fatigue is the result of a material being restricted from expansion caused by rising temperature.
This constraint places the material under compressive forces with rising temperature and tensile forces during cooling.

6. Initial Design Ideas Idea 1 Idea 2 Idea 3
Electric heating and cooling.
Idea 2
Oil bath heating.
Water cooling.
Mechanical transfer.
Idea 3
Electric heating.
Water cooling of clamps.

7. Fall Design Independent clamps Measurement capabilities
Water cooling over clamps to protect load cell.
Measurement capabilities
Load Cell for force measurements.
Thermal couple for temperature measurements.
Cycle is automated
Load Cell
Aluminum Specimen
Holding Clamps

8. Initial FEM Analysis
Displacement and reaction forces of constrained aluminum sample.

9. Time for a Change
Forces produced by the aluminum expansion exceeded anything that could be built within our budget.
Very large load cell would be needed which would also exceed our budget.
Cooling system would be inadequate.
Heating system would also exceed budget.

10. Final Design Outline ATS background information. Attachment to ATS.
Materials that will be used.
F.E.M. Analysis.
Timing Calculations.

11. ATS-1600
Rigid test frame that contains load cell capable of 50,000 lbs of force.
Load cell has been calibrated to work with testing software.
Contains clamping furnace that will reach temperatures of 1100°C

12. ATS-Sample Holder Threaded attachment to ATS base and load cell.
Macor used for thermal isolation to ensure load cell will not be damaged.
Ability to hold sample centered so that only axial forces will be produced.

13. Materials

14. FEM: Sample
The aluminum sample is exposed entirely to the heat source.
As expected the entire sample reaches 800°F at steady state.

15. FEM: Steel Sleeve
Since the entire sleeve is in the oven, all exposed surfaces where given an applied temperature of 800°F.
At steady state the entire steel sleeve reaches 800 °F

16. FEM: Macor
From the FEA of the steel sleeve, a temperature of 800F was applied to the top of the macor.
The bottom only reaches bout 400 F, roughly half the applied temperature.

17. FEM: Steel Rod
From the FEA of macor, a temperature of 412°F was applied at the contact surface.
A temperature of 69 °F was applied half way on the rod to simulate the water cooling.
All other surface exposed to natural convection with the air at 74 °F

18. Estimated Time Heating through natural convection and radiation.
Approximately 6 min.
Cooling through natural convection and conduction.
Approximately 5.5 min.
10 minute oven heat up time.
Forced convection will be induced to aid in cooling.

19. Procedure Part 1: TestVue32
Log into the computer and open the TestVue32 program.
Complete initial setup(jog pot, load cell, etc..)
Create test program to run experiment.

20. Procedure Part 2: Oven Setup
Flip both power switches.(main & controller)
Set emergency stop temperature.
Use oven controller to create custom heating cycle for test.

21. Procedure Part 3: Equipment Setup-Sample Holder
Steel Sleeve
The sample holder consist of three parts.
Steel Rod, Macor, Steel Sleeve.
All pieces screw together –Steel Rod+Macor+Steel Sleeve.
Macor
Steel Rod

22. Completed Sample Holder
Macor
Steel Sleeve
Steel Rod

23. Procedure Part 3: Equipment Setup-Sample
Screw both sample holders into test rig.
Adjust crosshead height so sample can be placed in.
Place sample in bottom holder and lower crosshead until sample is secure.

24. Procedure Part 3: Equipment Setup
Oven height must be adjusted to enclose the sample.
Loosen hex nut on oven holder.
Adjust so that oven completely closes sample.

25. Procedure Part 3: Equipment Setup-Cooling
Connect main tubes from the source of the water and air.
Place copper on sample holders.(wrap, bend, etc.)
Connect copper tubing to tubes coming from the sources.

26. Results
Pros
Test produced load variation with temperature change.
Load cell successfully isolated from temperature changes.
Cons
Samples bent from thermal expansion loads produced.
Testing cycle not automated.
Cycle length too long.

27. Aluminum 6063 Results

28. Aluminum 6061 Results

29. Temperatures and Times

30. Expenses

31. Future Changes Most Feasible Changes: Encase sample in quartz tube.
Reduce Sample Length.
Clamp sample at ends.
Automation of entire cycle.
Encase sample in quartz tube.
New sample shape.
Heat only small section of sample.
Increase cooling effectiveness.

32. Conclusion Principle material properties that effect thermal fatigue:
Thermal Expansion Coefficient.
Sample Length
Compressive Strength
Testing inconclusive due to:
Euler bending
Cycle Length
Unbroken Sample
Maximum load from thermal expansion
Al-6063: 2,257 lb
Al-6061: 2,278 lb
Euler bending 4,200 lb.
Since actual load was roughly half, the fatigue on the aluminum caused the sample to get weaker as cycles progressed.

33. Special Thanks Sponsor: Cummins Dr. Loungo Bob Walsh
N.H.M.F.L. Machine Shop

34. The End