The analyses that can be carried our in IGD are arranged in two main groups:
- TCA & FEM analyses: Tooth Contact Analysis and Finite Element Modeling
- GEO-Comp analyses: Comparison of gear geometries
Tooth Contact Analysis (TCA) involves: (i) the determination of the contact pattern and the contact path on the gear tooth surfaces, (ii) the determination of the function of unloaded transmission errors, and (iii) the determination of the function of backlash. These results are obtained considering the following user data:
- The selected pinion and wheel geometries
- The positioning errors of pinion and wheel in the gear set
- The number of pairs of contacting teeth: One or Three
- The number of contact positions along one or two cycles of meshing
- The virtual marking compound thickness for an estimation of the size of the bearing contact under light load
- The direction of pinion rotation: counterclockwise or clockwise
A general-purpose algorithm for tooth contact analysis is applied for computerized simulation of gear meshing and contact pattern estimation. It is based on a numerical method that takes into account the positional study of the tooth surfaces, which are discretized by means of a grid definition, and minimization of the distances until contact is achieved.
Examples of results that can be obtained from our TCA are shown below for a spiral bevel gear set, a planetary gear set, and a spline coupling. Application of TCA in a planetary gear set requires the determination of the contact patterns between the sun gear and each planet gear, and between each planet gear and the ring gear. A spline coupling requires just one contact position since all pairs of teeth can be simultaneously in contact.
IGD allows the preprocessing of the finite element model of the gear set for the investigation of its mechanical behavior. Different types of finite element models are supported in IGD. Those FE models can be exported to Abaqus or Ansys for further analysis. The main features of the finite element models that can be generated in IGD are as follows:
- The user has a complete control on the number of elements to be considered on the tooth surfaces, under the tooth surfaces, and inside the rim. The nodes located on the tooth surfaces are points generated from the virtual gear generator or from the free-form design tool
- The finite element models are all set for the FE analysis at a chosen contact position or for the FE analysis along one or two cycles of meshing. The finite element models consider the direction of rotation of the pinion (counterclockwise or clockwise), and one, three, five or seven pairs of contacting teeth
- The fillet surfaces can be considered as contacting surfaces for detection of interferences
- The load is directly applied to the pinion by means of the transmitted torque while the rotation of the gear (wheel) is blocked. No assumptions of load distribution are required
- The torsional deformations of gear tooth surfaces can be considered in the finite element models
- Shaft deflections can be considered by adding the shafts to the finite element models. IGD incorporates a design tool for shafts that allows the definition of the dimensions (length and diameter) for each section of the shaft, the location of the gears, and the location of the bearings
GEO-Comp analyses allow the comparison of gear geometries through the determination of the distances between the corresponding gear tooth surfaces. The geometry comparison analysis requires selection of the geometries to be compared and the reference side (left or right) for comparison. One of the geometries is considered as primary geometry whereas the other one is considered as secondary geometry. The tooth surfaces of the selected geometries are brought into contact at the reference side for comparison (left or right). The results of the comparison are the distances between the primary and the secondary gear tooth surfaces, measured in the normal direction to the primary gear tooth surfaces. The results of comparison are illustrated on the primary tooth surface. GEO-Comp analyses allow independent comparison at left and right sides, or combined comparisons where results on both sides will be simultaneously shown.
