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Traditionally, the geometric quality of assembled products has been evaluated by deviation from nominal values. However, the increased use mixed materials in especially automotive industry, in combination with an increased use of non-rigid simulation, open up for other evaluation criteria to complement the traditionally used deviation. The stiffness of a part or subassembly will, in combination with its deviation from nominal, give rise to different amounts of energy needed to join it to other parts. In this paper, the energy needed for joining is suggested as an evaluation criterion, complementary to geometric deviation, to judge the severity of the deviation. [ABSTRACT FROM AUTHOR]

Digital twins have gained a lot of interest in recent years. This paper presents a survey among researchers and engineers with expertise in variation management confirming the interest of digital twins in this area. The survey shows, however, a gap between future research interest in academia and industry, identifying a larger need in industry. This indicates that there are some barriers in the industry to overcome before the benefits of a digital twin for variation management and geometry assurance can be fully capitalized on in an industrial context. To identify those barriers and challenges, an extensive interview study with engineers from eight different companies in the manufacturing sectors was accomplished. The analysis identifies industrial challenges in the areas of system-level, simulation working process, management issues, and education. One of the main challenges is to keep the 3D models fully updated, including keeping track of changes during the product development process and also feedback changes during full production to the development engineers. This is a part of what is called the digital thread, which is also addressed in this paper. [ABSTRACT FROM AUTHOR]

Abstract Spot welding is the prevalent joining process in the automotive industry. The spot welding sequence has a notable effect on the geometrical variation of the final assembly. Finding the optimal weld sequence for geometrical quality is a fast growing and NP-complete problem. Using exhaustive search for this purpose can be a time-consuming task. In this paper, genetic, particle swarm and ant colony optimization algorithms are applied to three industrial reference cases. The performance of these algorithms for finding the optimal sequence with respect to geometrical variation is compared considering the number of function evaluations. [ABSTRACT FROM AUTHOR]

Variability is unavoidable in the realization of products. While design must specify ideal geometry, it shall also describe limits of variability (tolerances) that must be met in order to maintain proper product function. Although tolerancing is a mature field, new manufacturing processes and design methodologies are creating new avenues of research, and modelling standards must also evolve to support these processes. In addition, the study of uncertainty has produced widely-accepted methods of quantifying variability, and modern tolerancing tools should support these methods. The challenges introduced by new processes and design methodologies continue to make tolerancing research a fertile and productive area. [ABSTRACT FROM AUTHOR]

In aerospace engine industry, large casted components are, because of sustainability considerations, being replaced by smaller parts that are welded together. This reduces weight because some parts can be made of lighter material. It also opens up for use of platforms. The division of a large component into smaller parts is called form division. The form division affects the geometrical robustness in the weld splitlines between the parts and thereby the weldability. By optimizing the robustness in weld splitlines, conditions for welding can be improved. A greedy algorithm for weld splitline division is described and exemplified on aerospace case studies. [ABSTRACT FROM AUTHOR]

Weight reduction requirements in aerospace and automotive industry lead to an increased use of composite materials. However, composite parts cannot be bent like sheet metal parts. Hence, only low forces can be applied to close gaps between parts, caused by geometrical variation in parts and assembly fixtures. Shimming is therefore used to compensate for bad fitting, with increase cost as a consequence. This paper investigates how variation in assembly fixtures and parts give rise to variation in gaps and thereby also to variation in stress. Monte Carlo simulations are used to find the distribution of stress, which supports shimming strategies. [ABSTRACT FROM AUTHOR]

Fixturing strategies during the different stages of manufacturing of a part strongly affect the final geometrical outcome on both part level and assembly level. Different manufacturing setups, processes and operations allow for, and put requirements on, the fixturing strategy. In this article, different fixturing strategies during cutting of stamped sheet metal parts are discussed and evaluated with respect to minimized variation in critical features. The strategies are discussed from a theoretical point of view. Geometrical decoupling philosophies are used to minimize the number of variation sources during cutting. The strategies are also illustrated using an industrial case study consisting of laser cutting of a stamped sheet metal part. Some general guidelines, based on the results, for fixturing during sequences of operations are formulated. In this article, fixturing during laser cutting followed by fixturing during assembly are in focus, but the strategies should be generalizable to other sequences of manufacturing operations as well. [ABSTRACT FROM PUBLISHER]

This article presents how to do stability analysis, variation simulation and tolerance envelopes for deformable cables and hoses. In this way, the well-established methods for analyzing and minimizing the propagation of geometric variation are extended from rigid and sheet metal assemblies to large deformations of slender parts. This extension is highly motivated, not at least, by the increased amount of cables and hoses in electrified and hybrid solutions in the automotive industry. To secure the geometric correctness of the analysis, we use a nonlinear rod approach in the implementation of a simulation model of flexible cables that accounts for large deformations and supports a wide range of common cable clip types, cable joints and branches. A selection of measures and visualizations that reflect the spatial effects of geometric variation in deformable cables is incorporated in established variation analysis techniques. In particular, the concept of tolerance envelopes for rigid parts has been extended to also handle system of slender parts such as cables and hoses. This article extends previous research on robust design and variation simulation to cables subject to large deformations and has been successfully applied on two typical industrial cases: a wiring harness attached with various types of clips to a static surrounding and a cooler hose subjected to a high-frequency sampled engine motion. [ABSTRACT FROM AUTHOR]

Abstract: The body of a car is typically joined by thousands of spot welds. The spot welds guarantee the strength of the car, but their positions also affect the geometrical quality of subassemblies and the final product. In practice, the positions of the weld points often deviate from nominal position. By analyzing industrial scanning data, deviations of spot weld positions are found to be of magnitudes up to 19mm. In this paper, the influence of variation in position of spot welds is investigated with respect to geometrical quality, by simulating and analyzing the geometrical variation of an A-pillar assembly. [Copyright &y& Elsevier]