Week 1 Spur Gear Challenge

Objective 1: Structural Analysis of Spur Gear using 3 different materials

Case 1 Spur Gear-Cast Steel

Static Structural Analysis is carried for Spur Gear. The material used is Cast Steel and analysis is carried out in Ansys Workbench. The gear is imported and shown in figure below.

Nos. of Teeth in each Gear is 13 for both Driver and Driven Gears.

Material properties:

Density: 7820 Kg/m3

Young’s Modulus: 2.03E+11 Pa

Poisson’s Ratio: 0.3

Tensile Yield Strength: 3.49E+08 Pa

Tensile Ultimate Strength: 5.05E+08 Pa

Mesh:

Mesh Size: 0.5mm, Nodes 98564, Elements 19712

Mesh Matrix: Most of the elements are of high quality in the range of 0.8 to 1. This is an acceptable mesh. The elements of lowest quality are very low.
Mesh Quality- Mesh Matrix

Case 2 Spur Gear - Cast Bronze

The same gear is now considered in Cast Bronze material.

Material Properties

Density: 8810 Kg/m3

Young’s Modulus: 8E+10 Pa

Poisson’s Ratio: 0.345

Tensile Yield Strength: 1.44E+08 Pa

Tensile Ultimate Strength: 2.67 E+08 Pa

Mesh Metrix: Most of elements are of high quality in the range of 0.7 to 1. This is acceptable mesh.

Case 3: Spur Gear – Ductile Cast Iron

The same gear is now considered in Ductile cast Iron material.

Material Properties

Density: 7100 Kg/m3

Young’s Modulus: 170 GPa

Tensile Yield Strength: 276 MPa

Tensile Ultimate Strength: 414 MPa

Mesh Matrix: Most of the elements are of high quality in the range of 0.8 to 1. This is an acceptable mesh. The elements of lowest quality are very low.

Results

1. Stress

Equivalent Stress-Cast Steel

Equivalent Stress-Cast Bronze

Equivalent Stress- Ductile Cast Iron

2. Stress Intensity

Stress Intensity-Cast Steel

Stress Intensity-Cast Bronze

Stress Intensity-Ductile Cast Iron

3. Total Deformation

Total Deformation-Cast Steel

Total- Deformation-Cast Bronze

Total Deformation-Ductile Cast Iron

Objective 2

Comparisons of Results of the 3 different material:

Features	Cast Steel	Cast Bronze	Ductile Cast Iron
Equivalent Stress MPa	452	436.62	460.06
Stress Intensity MPa	511.06	490.93	521.184
Total Deformation mm	30	30	30
Yield Strength MPa	349	144	276

The Yield Strength in all cases is being exceeded. Cast Bronze has the lowest Equivalent Stress, lowest Stress Intensity (Stress Intensity=(Max. Principal Stress-Minimum Principal Stress) or 2 x Shear Stress). Considering Fracture MechanicsHence recommended but with decreased loading condition).