Spur Gear Set - Stress Evaluation

Semih Tinmaz

4 Jan, 2025 11:10 PM

Spur gears have their teeth cut parallel to the axis of the shaft on which the gears are mounted, transmitting power between the parallel shafts. To maintain a constant angular velocity ratio, two meshing gears must satisfy a fundamental law of gearing: the shape of the teeth must be such that the common normal at the point of contact between two teeth must always pass through a fixed point on the line of centers. The contact point is called the pitch point.

The goal is to assess the maximum stress during the transmission of the torque. By engineering judgement, the maximum stress occurs either at a contact point or at the root of a tooth due to
the bending of the tooth.

Since there is no restriction of deformation in the depth direction, i.e.,the gears are free to expand (or contract) in the depth direction, so it is modeled as a plane stress problem.

1. Step 1: Overview

   

   

   
   

   • Spur gears have their teeth cut parallel to the axis of the shaft on which the gears are mounted, transmitting power between the parallel shafts. To maintain a constant angular velocity ratio, two meshing gears must satisfy a fundamental law of gearing: the shape of the teeth must be such that the common normal at the point of contact between two teeth must always pass through a fixed point on the line of centers. The contact point is called the pitch point.

   
   

   • The goal is to assess the maximum stress during the transmission of the torque. By engineering judgement, the maximum stress occurs either at a contact point or at the root of a tooth due to the bending of the tooth.

   
   

   • Since there is no restriction of deformation in the depth direction, i.e.,the gears are free to expand (or contract) in the depth direction, so it is modeled as a plane stress problem.

   
   

2. Step 2: Engineering Data (Material Model)

   • The selected material for this tutorial is "Structural Steel" which is the default material in ANSYS Workbench.

   
   

3. Step 3: Geometry (Design Modeler)

   • The Spur Gear Set which has been created on DesignModeler could be seen below:

   
   

   

4. Step 4: Meshing Operations

   • Firstly, the default mesh operations with the default element size have been implemented:

   
   

   

   
   

   • The "Edge Sizing" with 0.254mm element size has been used for contact surfaces:

   
   

   

   
   

   

   
   

   

5. Step 5: Contacts (Frictional Contact)

   • "Frictional Contact" with 0.2 Friction Coefficient has been used for "Spur Gear Set" interactions as seen below:

   
   

   

   
   

   

6. Step 6: Boundary Conditions

   • The Boundary Conditions have been implemented as below figure:

   
   

   

   
   

   

   
   

   

   
   

   

7. Step 7: Results

   • Equivalent von-Mises Stress (Spur-Gear Set):

   
   

   

   
   

   

   
   

   • Equivalent von-Mises Stress (Main-Shaft):

   
   

   

   
   

   • Equivalent von-Mises Stress (Lay-Shaft):