JOINING SEQUENCE OPTIMIZATION IN COMPLIANT VARIATION SIMULATION
Licentiate thesis, 2019
With the recent breakthroughs in the technology, the new digitalization reform, and availability of big data from the manufacturing processes, the concepts of digital twins have grasped the attention of the researchers and the practitioners.
In line with this trend, Söderberg et al. have introduced the geometry assurance digital twin and the concept of the self-compensating individualized assembly line. Steering the assembly process with online real-time optimization, through the digital twin medium is the vision of such a concept.
Joining sequences impact the final geometrical outcome in an assembly considerably. To optimize the sequence for the optimal geometrical outcome is both experimentally and computationally expensive. In the simulation-based approaches, several sequences need to be evaluated together with the finite element method and Monte Carlo simulations.
In this thesis, the simulation-based joining sequence optimization, using compliant variation simulation is studied. Initially, the limitations of the formulations and the applied algorithms in the literature have been addressed. Two evolutionary algorithms have been introduced to compare the computational performances to the genetic algorithm. Secondly, a reduced formulation of the sequence optimization is introduced through the identification of the critical points to lock the geometry, geometry joints. A rule-based method has been proposed to initiate the evolutionary algorithm and thereby to increase the algorithm’s computational efficiency. This approach has been further improved by a contact displacement minimization approach to generate model-dependent rules. Finally, a surrogate-assisted approach has been introduced to parallelize the computation process, saving computation time drastically. The approach also unveiled the potential of the simulation-based geometry joint identification, simultaneous to complete sequence determination.
The results achieved from the presented studies indicate that the simulation-based real-time optimization of the joining sequences is achievable through a parallelized search algorithm, to be implemented in the geometry assurance digital twin concept. The results can help to control the joining sequence in the assembly process, improving the geometrical quality in a cost-effective manner, and saving significant computational time.
Compliant Variation Simulation
Roham Sadeghi Tabar
Chalmers, Industrial and Materials Science, Product Development
Evaluating evolutionary algorithms on spot welding sequence optimization with respect to geometrical variation
Procedia CIRP,; Vol. 75(2018)p. 421-426
Paper in proceeding
A method for identification and sequence optimisation of geometry spot welds in a digital twin context
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science,; Vol. 223(2019)p. 5610-5621
A Novel Rule-Based Method For Individualized Spot Welding Sequence Optimization With Respect to Geometrical Quality
Journal of Manufacturing Science and Engineering, Transactions of the ASME,; Vol. 141(2019)
Tabar R.S., Wärmefjord K., Söderberg R., Lindkvist L., Efficient spot welding sequence optimization in a geometry assurance digital twin
Tabar R.S., Wärmefjord K., Söderberg R., A new surrogate model based method for individualized spot welding sequence optimization with respect to geometrical quality
Smart Assembly 4.0
Swedish Foundation for Strategic Research (SSF) (RIT15-0025), 2016-05-01 -- 2021-06-30.
Production Engineering, Human Work Science and Ergonomics
Areas of Advance
Chalmers University of Technology
Virtual Development Laboratory (VDL), Hörsalsvägen 7A
Opponent: Dr. Alexander Govik, Volvo Car Group, Sweden