چكيده به لاتين
The highest amount of reported failures in railway tracks are due to turnout problems. The main causes of these breakdowns are: high wheel-rail contact forces, creep in the switch blade due to changes in the rail profile, and inconsistency in the rail profile during wheel passage over wing rail and crossing nose causing collision forces. Also plastic deformation in new turnouts has a significant influence on its lifetime.
In this thesis, a new model for crossing nose fatigue life prediction is presented using FE approach. Firstly, a dynamic model containing a complete turnout (switch and crossing panels) is simulated. For a closer look at crossing, the results of the forces generated by the dynamic model are transmitted to a more detailed static model at specific sections, because of the criticality of this point in track. Then the stress and strain results are extracted to perform the fatigue analysis on the crossing nose. Regarding the importance of fatigue and the necessity of investigating the effect of different variables on fatigue life, a parametric study is conducted considering variables such as velocity, wagon weight, friction coefficient, turnout type and curve radius.
The results are presented in three sections: The results of the dynamic model in which analysis was performed on the long track containing the turnout. These results include axial and lateral contact forces. The second part is the results of the static model and it consist of stress and strain tensors, which are performed on different sections of the crossing. The results of this models have produced fatigue analysis inputs. The results indicate that the fatigue life predicted in UIC60 crossings are less than U33 and more curve radius influence is investigated. Also, there are less contact forces in UIC60 crossings than U33.
