PSI - Issue 80

Simone Messina et al. / Procedia Structural Integrity 80 (2026) 232–243 Simone Messina/ Structural Integrity Procedia 00 (2019) 000–000

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3. Static model Fig. 5 shows the first FE model. The initial simulation model has performed a static analysis of the system. The static simulation has aimed at validating the model by analyzing the contact and the torque transmitted between the two meshing gears. Therefore, the two gears, 1 and 2, have been positioned in contact, assuming a rotation of Gear 1 around the negative y-axis, which consequently has induced a positive y-axis rotation for Gear 2. The analysis has focused on the following three key output parameters. The first one has been the contact status; this parameter illustrates how the contact equation has been resolved and how many nodes has been put in contact. Although it provides only a qualitative visualization, it is useful for understanding the influence of Gear 1 on Gear 2. The second main output has been the contact normal stress; this parameter examines the normal stress on the nodes, which has been crucial for understanding how contact generates stress and identifying the regions of highest stress on the gears. The third key result has been the maximum principal stress value, which has been essential for evaluating potential fatigue issues and identifying the location of the highest stress concentration. The analysis has been carried out in MarcMentat. Initially, as shown in Fig. 5, it has been simulated a model consisting of only the discretized geometry of the two meshing gears, which have been pre-positioned in contact. The gears have been connected at their centers using an RBE2 rigid link. Gear 2 has been fully constrained in all six degrees of freedom, while Gear 1 has been constrained in all degrees of freedom except for rotation along its axis. The torque has been applied at the center of the link on Gear 1. In the second model, the discretized shafts have been also included in the model. In this configuration, the connection has been established using four RBE2 links, one per bearing position, and the torque has been applied at the point where the actual input splined shaft connects to Shaft 1. The third model has further enhanced the model by incorporating a bearing mimicked by a link with springs of defined stiffness, which have been connected to the ground. In the final simulation, a modification in the geometry has been introduced to analyze the influence of microgeometry on the behavior of the system. To prevent issues related to an instantaneous torque application, the static model has been set up with a two-step load case. A torque table has been applied to ensure a gradual and linear increase in torque over time.

Fig. 5 The static model considering only the gears.

3.1 Static model results Fig. 6 shows the results of first and last static simulations. The contact areas are accurately identified, and the regions of maximum stress are consistent with experimental evidence reported in standards and literature. However, certain discrepancies in the outputs reveal intrinsic limitations in the modeling assumptions. In particular, the model accounts only discretized gear, while the shaft is represented by a type-2 rigid body element (RBE2), which imposes infinite