Advanced Structural Analysis using ANSYS Workbench-Spur Gears

Introduction

The purpose of this ansys analysis is to compare the equivalent stress, total deformation and stress intensity of spur gears made from three materials namely

Case 1: Cast Iron

Case 2: Cast Steel

Case 3 : Cast Bronze

Results

The results for each case is as follows

Case 1: Cast Iron

Equivalent Stress

Total Deformation

Stress Intensity

Case 2: Cast Steel

Equivalent Stress

Total Deformation

Stress Intensity

Case 3:Cast Bronze

Equivalent Stress

Total Deformation

Stress Intensity

Result Interpretation

Equivalent Stress:

As seen from above cast bronze is the material under the maximum amount of stress. The stress on cast iron exceeds its tensile yield strength,hence it would not be a good choice for the material.Cast steel has the maximum tensile yield strength,hence it would be the safe choice for the gear.

Total deformation

All the gears face similiar levels of totall deformation maxing out at 30mm.

Stress Intensity

The stress intensity factor is used in fracture mechanics to predict the stress state ("stress intensity") near the tip of a crack caused by a remote load or residual stresses.It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion for brittle materials, and is a critical technique in the discipline of damage tolerance. The concept can also be applied to materials that exhibit small-scale yielding at a crack tip.

All three exhibit maximum stress intensity at similar point as shown in figure. Cast iron teeth is more likely to fracture the easiest due to its brittle nature and low impact resistance. The least likely to fracture is cast bronze due to its high ductility. The cconventional choice would be cast steel due to its high strength and availablity.