PSI - Issue 42

Taško Maneski et al. / Procedia Structural Integrity 42 (2022) 1503–1511 T. Maneski at al/ Structural Integrity Procedia 00 (2019) 000 – 000

1508

6

Figure 8. Plastic profile deformations and unwelded joints visible along the I-girder

FEM analysis showed that the dynamic behavior of the support structure was unfavorable, considering it was designed to hold painting and lacquering robots that constantly move in all directions. Given the gross failures in the maintenance of the support structure, it was expected that the parameters of measured dynamic behavior could be slightly worse than the calculated values. Therefore, careful measurements were made that could be compared with numerical values from FEM analysis and values prescribed by appropriate standards. 4. Measured dynamic behavior of the robotic system As part of the experimental analysis, displacement and acceleration at the locations of the existing robots were measured. To confirm the validity of the results, parameters were measured twice. Firstly, acceleration was measured, and in a second investigation, both displacement and acceleration were measured. The measurement and acquisition system of the Laboratory for Stress and Deformation Measurement of the Faculty of Mechanical Engineering, University of Belgrade, was used. A schematic repr esentation of the layout of all six robots in Magneti Marelli’s paint shop in Kragujevac is presented in Figure 9. All robots were located in one horizontal plane, each supported on the underside of the support structure by a carrier. The adopted directions for measuring displacement and acceleration are marked with different colors, which are also used in the results (below). Figure 10 (robots 2 and 3) shows that the greatest concern was the behavior of the structure in the horizontal plane, in both directions. Figure 11 shows the acceleration measured for the robot 2 carrier in the coordinate axis directions in the time domain. The diagrams show the acceleration in the vertical direction was negligible, but the acceleration in both horizontal directions was approximately ±4 m/s 2 .

Robot 2

R4

Horizontal longitudinal direction − x -axis

R3

Robot contr oler

R2

R1

R5

Horizontal transverse direction – z -axis

Robot 3

Vertica l direction y -axis

Figure 9. Locations of robots on the support structure and measurement directions Figure 10. Acceleration, measured in the frequency domain, of robot carriers 2 and 3 The acceleration at the top of the housing was approximately ±1.5 m/s 2 , while the accelerations measured on the column below the robot 2 carrier in all directions were up to a maximum of ±0.5 m/s 2 .