The challenge

The engineering challenge was to approach the system as a mechatronic assembly, in which the structural response depends both on the overall stiffness of the machine frame and on the way the moving masses are accelerated and decelerated during the operating cycle. On the one hand, it was necessary to characterize the natural modes of the assembly and verify that the characteristic frequencies remained sufficiently far from the main operating excitations, evaluating multiple configurations along the stroke to rule out significant variations as the crossbeam position changed.

On the other hand, the machine had to demonstrate structural stability under the most critical operating conditions, particularly during motion reversals, when process loads and inertial effects act simultaneously. A key aspect was to verify that the supports and sliding interfaces remained in stable contact, avoiding local separations that could trigger nonlinear behavior, increased vibration, and loss of accuracy.

Finally, a realistic dynamic representation of the operating cycle was required in order to estimate the magnitude of head oscillations and the loads at the interfaces, comparing different motion profiles to identify those providing the most favorable machine response.

Our contribution

SmartCAE developed an integrated simulation workflow combining finite element analysis FEA with flexible multibody dynamics to accurately predict the machine’s dynamic behavior under realistic operating conditions.
Starting from the machine geometry and mass distribution, detailed finite element models were created for the primary structural assemblies and their connections, allowing accurate representation of stiffness, load transfer, and joint behavior.
Modal analyses were performed in multiple beam positions to verify that the natural frequencies remained sufficiently separated from the machine’s operating excitations throughout the entire travel range. Static structural assessments were then carried out for representative operating, testing, and idle conditions, including the inertial loads generated during acceleration and deceleration phases.
Critical support and sliding interfaces were modelled using nonlinear contact formulations to verify continuous contact stability and eliminate the risk of local separation that could trigger nonlinear dynamic effects and increased vibration levels.
The study was completed with sensitivity analyses evaluating the influence of uncertain parameters, including contact conditions and process loads, to quantify the robustness of the design. Finally, transient flexible multibody simulations reproduced complete operating cycles using different motion laws, enabling direct comparison of polishing head vibrations and interface loads under each drive strategy.

Benefits for the client

The project delivered a comprehensive digital twin capable of accurately predicting the machine’s behavior under the most demanding operating conditions, significantly reducing the risk of identifying dynamic issues only during commissioning or production.
The multi-configuration modal analysis ensured adequate separation between natural frequencies and operating excitations, improving vibration robustness and maintaining consistent polishing quality across the entire machine stroke.
Verification of nonlinear contact stability at the support and guide interfaces increased confidence in the structural design while supporting informed decisions regarding mass distribution, local stiffness, and machine layout.
Sensitivity analyses identified the parameters with the greatest influence on dynamic stability, enabling the customer to define more robust operating windows and validation procedures.
Finally, the comparison of alternative motion profiles provided practical guidance for optimizing the machine’s control strategy, reducing transient loads during motion reversals, lowering stresses on critical interfaces, shortening commissioning time, and accelerating the overall product development process.