JOINING SEQUENCE ANALYSIS AND OPTIMIZATION FOR IMPROVED GEOMETRICAL QUALITY
Doctoral thesis, 2021
Joining sequences impact the final geometrical outcome in an assembly considerably. To optimize the sequence for improved geometrical outcome is
both experimentally and computationally expensive. In the simulation-based approaches, based on the finite element method, a large number of sequences need to be evaluated.
In this thesis, the simulation-based joining sequence optimization using non-rigid variation simulation is studied. Initially, the limitation of the applied algorithms in the literature has been addressed. A rule-based optimization approach based on meta-heuristic algorithms and heuristic search methods is introduced to increase the previously applied algorithms' time-efficiency and accuracy. Based on the identified rules and heuristics, a reduced formulation of the sequence optimization is introduced by identifying the critical points for geometrical quality. A subset of the sequence problem is identified and solved in this formulation.
For real-time optimization of the joining sequence problem, time-efficiency needs to be further enhanced by parallel computations. By identifying the sequence-deformation behavior in the assemblies, black-box surrogate models are introduced, enabling parallel evaluations and accurate approximation of the geometrical quality. Based on this finding, a deterministic stepwise search algorithm for rapid identification of the optimal sequence is introduced.
Furthermore, a numerical approach to identify the number, location from a set of alternatives, and sequence of the critical joining points for geometrical quality is introduced. Finally, the cause of the various deformations achieved by joining sequences is identified. A time-efficient non-rigid variation simulation approach for evaluating the geometrical quality with respect to the sequences is proposed.
The results achieved from the studies presented indicate that the simulation-based real-time optimization of the joining sequences is achievable through a parallelized search algorithm and a rapid evaluation of the sequences. The critical joining points for geometrical quality are identified while the sequence is optimized. The results help control the assembly process with respect to the joining operation, improve the geometrical quality, and save significant computational time.
Non-Rigid Variation Simulation
Roham Sadeghi Tabar
Chalmers, Industrial and Materials Science, Product Development
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)
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 new surrogate model–based method for individualized spot welding sequence optimization with respect to geometrical quality
International Journal of Advanced Manufacturing Technology,; Vol. 106(2020)p. 2333-2346
Rapid sequence optimization of spot welds for improved geometrical quality using a novel stepwise algorithm
Engineering Optimization,; Vol. in press(2020)
Critical joint identification for efficient sequencing
Journal of Intelligent Manufacturing,; Vol. 32(2021)p. 769-780
EFFICIENT SPOT WELDING SEQUENCE SIMULATION IN COMPLIANT VARIATION SIMULATION
Journal of Manufacturing Science and Engineering, Transactions of the ASME,; Vol. in press(2021)
Disturbances in the manufacturing and assembly process cause functional and aesthetic problems in the products. Being able to control the disturbances in real-time is the desire of the manufacturing industry to improve quality and reduce waste and costs.
Joining process is one of the crucial elements imposing geometrical inaccuracies to the assemblies. The geometrical outcome of the assemblies are predicted using simulations as the costs and material waste do not allow for physical experimentation.
An assembly often consists of several joined parts. The joining sequences impact the geometrical quality considerably. To simulate all the possible alternatives for joining sequences for finding the optimal answer is computationally heavy and expensive.
In this thesis, methods for identifying the optimal joining sequences time-efficiently and accurately are studied. Initially, a rule-based approach is put forward to increase the efficiency of the previously applied algorithms. The joining sequence-quality behavior is approximated using black-box models, enabling parallel evaluations of the geometrical quality. Based on this finding, a search algorithm for rapid identification of the optimal sequence is presented. Furthermore, a numerical approach to identify the number, location, and sequence of the critical joining points for geometrical quality is introduced. Finally, an efficient simulation approach for evaluating the geometrical quality is proposed.
The results achieved from the studies presented indicate that the simulation-based real-time optimization of the joining sequences is achievable through a parallelized search algorithm and a rapid evaluation of the sequences. The results help control the assembly process, improve the geometrical quality, and save significant computational time.
Smart Assembly 4.0
Swedish Foundation for Strategic Research (SSF), 2016-05-01 -- 2021-06-30.
Manufacturing, Surface and Joining Technology
Areas of Advance
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4905
Chalmers University of Technology
Virtual Development Laboratory (VDL), Hörsalsvägen 7A, and Via Zoom (Password: 713233)
Opponent: Professor Jamie Camelio, University of Georgia, United States