A STATIC ANALYSIS OF e-TYPE CLIPS BASED ON INSTALLATION PROCESS OF DT-Ⅲ FASTENING SYSTEMS

The installation state of fastening systems directly affects the fatigue lives of rail clips. Most existing researches on the failure and fatigue lives of e-type clips simulated the installation process of fastening systems based on the simplified loading mode (inserting the rail clip into the jack and then lifting the toe end to move), ignoring those effects on the static behavior of the rail clip, viz., the constraint of the spanner on the middle leg of the rail clip, the gradual lifting of the heel end and back arch for the rail clip, and the friction between the heel end of the rail clip and the base plate of the iron bottom plate. Taking the DT-Ⅲ fastening system as an example, based on the loading mode which is to pull the middle limb of e-type clip in the actual installation process, a fine element model is proposed and the calculation results are compared with those for simplified loading cases. Besides, field and simplified installation experimental verifications are carried out. The results show that: the measured maximum principal strain of field installation case is close to that of a simplified loading case, but the orientation angle differs by about 5° from the latter. In the case of the field installation process, the global maximum position of the maximum principal strain changes significantly with the increased insertion depth of the rail clip. When the rail clip is in an over-installation state, the global maximum position jumps to the place where the middle leg of the rail clip and the jack of the iron base is squeezed, resulting in a step increase. To accurately evaluate and predict the fatigue life of an e-type clip, the fatigue analysis can only be carried out under the actual installation state. A simplified loading condition can be used for approximate simulation when merely analyzing the strength of the clip.