2D and 3D approach for bolted connections
Backgroud:
Wind turbines include many bolted connections between machinery components. Some of these bolted connections include a bearing, for instance: tower top – main frame and blade – hub connections. Axial loads on the bearing will introduce radial reaction loads which affect the surrounding bolts and flanges.
MECAL developed a 2D approach for the bolted connection which includes:
- a 2D FEM model of bearing, flanges and bolts;
- a spreadsheet which uses the 2D FEM results for the definition of the radial reaction forces in the bearing.
This latter spreadsheet calculation is based on empirical results. The outcome of the spreadsheet is an input for the 2D FEM model. This means that the calculation is iterative (both use the outcome of each other).
The complex geometries of modern turbines ask for a 3D approach, as the 2D model does not include the geometrical and stiffness variations along the circumference of the connection. Therefore a 3D approach was developed, including a non-linear bearing model to calculate the radial reaction forces in the bearings. Downside is increased calculation time, since the 3D models are non-linear and include much more elements and nodes compared to the 2D models.
For axi-symmetric bolt connections and flanges it may not always be necessary to use a 3D approach, so precious modelling and calculation time can be saved. For this, the 2D approach should be updated so iterative calculations can be avoided.
Purpose:
The aim of this project is to compare 2D/3D approaches, in order to generate an engineering approach for 2D models, with realistic results while avoiding iterative calculations.
Outline:
For multiple different geometries (e.g. different bearing types (single/double row), flange or bolt connection geometry) the following steps are to be done:
Build 3D model, verify bearing contact angle (also for different load levels (non-linear behaviour);
- Build 2D model according to old approach
- Compare 2D/3D results;
- Define new 2D approach;
- Verify new 2D approach;
- Reporting in our Good Working Practice documentation.
Preferably you study a bachelor in Mechanical Engineering. Knowledge of finite element method (FEM) and Ansys is preferred. You will work amongst a team of engineers that can benefit from your contribution. Some of these engineers will be involved in this project for assistance and feedback.
Type of project:
Internship, bachelor level.
Coordinator / for more information on the subject:
Ir. Bart Visser, Chief engineer, +31 (50) 3110 996, b.visser@mecal.eu
Product group and location:
Wind Energy, Turbine Development, Enschede or Groningen
To apply for the project:
Mr Dick van Haare, Recruitment, +31 (53) 4821 400, d.vanhaare@mecal.eu