Operational Stress Analysis of NB Engineering Model Airplane Axles under Static Loading Conditions

Author: Chad Northeast, E.I.T, Design Engineer

Date: January 29, 2004

  1. Introduction
  2. Materials
  3. Load & Restraint Information
  4. Study Property
  5. Stress Results
  6. Deformation Results
  7. Design Check Results
  8. Conclusion
  9. Appendix

1. Introduction

A finite element stress analysis was performed on the airplane axles to determine the amount of deflection and stress in the axles under static loading conditions (ie: model resting on ground). Also to determine the points of maximum stress in order to evaluate and design or manufacturing issues. Shown in the following document are the localized stress concentrations and their associated values, as well a graphical depiction of the deformation that will occur increased by a factor of 90 times.

2. Materials
No. Part Name Material Mass Volume
1 axles [SW]6061 Alloy 0.00637294 lb 0.0653342 in^3

3. Load & Restraint Information
Restraint
Restraint1 <> on 3 Face(s) immovable (no translation).
Description:


Load
Load1 <> on apply force 5.5 lb normal to reference plane Plane1 using uniform distribution
Description:


4. Study Property

Mesh Information
Mesh Type: Solid mesh
Mesher Used: Standard
Automatic Transition: Off
Smooth Surface: On
Jacobian Check: 4 Points
Element Size: 0.040294 in
Tolerance: 0.0020147 in
Quality: High
Number of elements: 10216
Number of nodes: 15805



Solver Information
Quality: High
Solver Type: FFE



5. Stress Results
Name Type Min Location Max Location
Plot1 VON: von Mises stress
0.002596 psi
(7.44583 in,
6.46536 in,
0.000215447 in)
8643.44 psi
(8.102 in,
6.54315 in,
-1.90458e-017 in)


JPEG
VIEW


6. Deformation Results

Plot No. Scale Factor
1 89.154


JPEG
VIEW


7. Design Check Results

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VIEW


8. Conclusion

Under static loading conditions it is assumed that the axle will see a maximum of 5.5 lbs (11lbs max weight/2) uniformly distributed along the wheel hub to axle shaft contact surface. Under this loading a maximum stress of 8643 psi is observed in the root fillet along the axle shaft. With 6061-T6 having a yield strength of approximately 35000 psi this gives the axle a 4:1 factor of safety to yeild (not failure). In other words an upper limit of approximately 22 lbs applied to each axle would be required to yeild (bend) the part. In real world this is not impossible but very unlikely.

The depiction of the deformation of the part is enhanced by 90 times in order to more accurately see what shape the axle will take once deformed. Actually values of deformation for this loading are 0.0015" at the end of the axle shaft.

Other factors will vary the actual results, landing gear and fuselage deformations will effect the loading angles on the shaft, this is outside the scope of this analysis but may be performed in the future.

These axles have the required strength and manufacturing details to easily handle models up to 11 lbs without failure.

Chad Northeast, E.I.T

9. Appendix

Material name: [SW]6061 Alloy
Description:
Material Source: Used SolidWorks material
Material Library Name:
Material Model Type: Linear Elastic Isotropic
Unit system: English (IPS)

Property Name Value
Elastic modulus 1.0009e+007 psi
Poisson's ratio 0.33
Yield strength 8000 psi
Mass density 0.097544 lb/in^3

Note:

COSMOSXpress design analysis results are based on linear static analysis and the material is assumed isotropic. Linear static analysis assumes that: 1) the material behavior is linear complying with Hooke’s law, 2) induced displacements are adequately small to ignore changes in stiffness due to loading, and 3) loads are applied slowly in order to ignore dynamic effects.

Do not base your design decisions solely on the data presented in this report. Use this information in conjunction with experimental data and practical experience. Field testing is mandatory to validate your final design. COSMOSXpress helps you reduce your time-to-market by reducing but not eliminating field tests.