Cruzado, Uchegui, and Gomez have written an interesting paper numerically analyzing fretting wear occurring in bundles of steel wires. Some of the keys aspects of this study are that the modeling was three-dimensional and that the effects of different finite element modeling parameters on simulation accuracy and speed were investigated. The modeling was carried out on the crossed cylinder geometry which is simple enough geometry to be easily meshed, for parameters to be analyzed, and for results to be interpreted.
The Abaqus finite element program was used for this study along with the UMESHMOTION subroutine. The authors cited the work by other scientists in England and France as the inspiration and building blocks for their study. Those analyses were also carried out with Abaqus.
A partitional meshing strategy was used for the two cylinders and its results can be seen in the picture below. The cubic shape of the elements is better for uniform numerical analysis than the tetrahedral elements. Three-dimensional eight node linear brick element were used in the study. Partitional meshing is a relatively simple way of having a highly organized mesh and refining it along in three dimensions although it is different from the strategies which I have seen used in two dimensional studies.
For the crossed cylinder geometry it was important to model wear on both surfaces not only the upper or lower body. However, the contact was solved using a master-slave algorithm. This makes it difficult to determine the pressure and slip on the master surface. The pressures and slips need to be interpolated onto the opposing surface. Cruzado et al. tried three strategies for interpolating between the surfaces:
- Bivariate interpolation
- Triangle-based linear interpolation
- Nearest interpolation
The effect of mesh size was investigated. Mesh refinement was not found to have a large effect on the surface dimensions of the wear scar, but it did affect the wear depth. A coarse mesh led to a trapezoidal profile for the wear scar. The authors decided that the optimal size was 3% to 4% of the final wear scar width.
The authors also studied the number of steps needed to carry out each cycle and found that a specific value was optimal. The value in and of itself is not critical because it will probably vary with different simulation loadings and geometries. If fewer than the critical number of increments was used convergence problems appeared. The cycle jump or number of real life cycles each computational fretting cycle represented was also found to be extremely important. The authors gave their solutions which would be a good starting point for anyone carrying out similar studies.
- Cruzado, A., Urchegui, M., Gomez, X., 2012, “Finite element modeling and experimental validation of fretting wear in thin steel wires,” Wear, Vol. 289, pp. 26-38.
