Specifications

CT Corsair Final Report May 2, 2014

Figure 45: ANSYS FEA Results of Lower Scissor Arm Loading

Figure 46: Quarter-Scale Model of Lower

Scissor Arm

Figure 47: Scale Model Arm Fixture

As can be seen, the two end bearing holes are being pulled in tension while the bottom two

bearing holes are used to fix the arm in place. It can be noted that a mesh convergence analysis

was completed for this arm, just as one was completed for the lower scissor arm earlier in the

report. A high mesh density was chosen after reviewing the mesh convergence analysis. After the

simulation of the loading was complete, we were left with an arm that would look as follows in

Figure45.

The highest concentration of stress is at the

sides of the bearing holes, which was expected.

There is also little to no deformation in any part

of the arm besides at the ends. The final results

of the analysis report that the arm fails at the

bearing holes at about 5,000 lbs in shear as a

tensile load is applied. The shearing would

occur at the highest stress concentration points,

which are at the sides of the bearing holes rather

than at the top or the holes

8.5.4 Tensile Test Validation

To verify the accuracy of the analysis, the team manufactured

a quarter-scaled scissor arm, analyzed it in ANSYS, and

performed a physical tensile test on it to see if the results

matched. The quarter-scale arm was inexpensive, and would

served a huge purpose in this multi-year capstone project, as

it verified that the finite element analyses. This arm is shown

in Figure 46.

After the arm was modeled into ANSYS, identical results

were found for the full-scale scissor arm, except the failure

loadings were scaled differently as the arm was much

smaller. We found after FEA, the quarter-scale arm would

fail/yield around a 600 lb. maximum applied force, or 17,000

psi. The arm was expected not to fail at the very tip of the

bearing hole either, yet at the sides of the bearing hole; most

likely just one side, and not both at the same time due to

imperfect manufacturing.

The quarter-scale arm tensile test required that the arm be

fixed slightly differently than what was modeled in the

analysis, but the results were expected to be accurate. The

fixture that was used to hold and load the arm is shown in Figure 47. Instead of having the

bottom bearing holes fixed by the "springs", one end of the arm was fixed while loadings were

applied to the other.