Using the CATIA DMU motion simulation module to analyze the motion characteristics of the six-link h1

Abstract:

The CATIA DMU motion simulation module is a valuable tool for simulating the motion of mechanical systems and analyzing their kinematic characteristics. In this study, the module is applied to simulate the motion of a six-link hinge mechanism and analyze its kinematic characteristics. The six-link hinge mechanism is widely used in large bus side luggage compartment doors due to its high structural strength, compact size, and wide opening angle.

The basic structure of the six-link hinge mechanism consists of support AB, rod AC, rod CD, rod EF, rod BE, and support DF connected by seven rotating pairs. The motion of the mechanism is complex, making it difficult to visualize using a two-dimensional CAD drawing alone. The CATIA DMU kinematics module provides a more intuitive analysis tool for simulating the motion, drawing motion trajectories, and measuring motion parameters such as speed and acceleration.

By simulating the motion process, the analysis allows for a more accurate understanding of the motion of the side hatch and prevents interference. To perform the motion simulation, a three-dimensional digital model of the six-link hinge mechanism is created. Each link is modeled as an independent component, and they are assembled to form the complete mechanism.

The rotating pairs are added to the mechanism using the CATIA DMU kinematics module, and the motion characteristics of the rods are observed. The gas spring connected to rod AC provides the driving force for the mechanism. The motion status of the support DF, to which the door lock is attached, is analyzed and its trajectory is drawn during the simulation.

The simulation analysis focuses on the motion of the support DF from 0 to 120 degrees, which represents the opening angle of the side hatch. The trajectory of the support DF reveals that the mechanism produces a combination of translational and flipping motions, with the amplitude of the translational motion being greater at the beginning and gradually decreasing over time.

To gain a deeper understanding of the kinematic characteristics of the six-link hinge mechanism, the mechanism can be simplified by decomposing its motion into the motions of two quadrilaterals, aboc and odfe. The quadrilateral aboc generates the translational motion, while the quadrilateral odfe contributes to the rotational motion.

After analyzing the kinematic characteristics of the six-link hinge mechanism, the next step is to verify the conclusions by assembling the hinge into the vehicle environment. In this case, the movement of the side door is checked to ensure that there is no interference with other parts of the vehicle. The motion of the hinge is observed at the upper corner of the door, and the trajectory of the H point is drawn.

From the trajectory of the H point, it is confirmed that the door motion aligns with the analysis conclusions. However, there is interference between the H point and the sealing strip when the door is not fully opened. Therefore, improvements to the hinge are necessary.

To improve the hinge, the trajectory of the support DF in the flipping stage is analyzed. It is found that the trajectory resembles a section of an arc moon, with the center of the circle on the upper side. By adjusting the lengths of the rods ac, bo, and CO, while keeping the bearings AB and DF unchanged, the translational and rotational components of the hinge can be matched more reasonably, resulting in a gentler curvature of the motion trajectory.

The improved hinge is then simulated and its motion trajectory is examined. The improved hinge demonstrates a better match between translational and rotational components, resulting in a smoother motion trajectory. The gap between the H point and the rolled skin of the side wall is reduced to 17mm when the door is fully opened, meeting the requirements.

In conclusion, the CATIA DMU module is an effective tool for analyzing the motion characteristics of mechanical systems. The motion simulation and analysis of the six-link hinge mechanism provided valuable insights into its kinematic characteristics. The conclusions were verified through the assembly of the hinge into the vehicle environment. The improvements made to the hinge based on the analysis findings resulted in a smoother motion trajectory and eliminated interference.