Visualizing the Effects of Geometrical Variation on Perceived Quality in Early Phases

In a perfect world, geometrical variation in a manufacturing process would not exist. Every component produced in a series would have the exact same dimensions and, when observed by a trained eye, look exactly identical. However, the world is not perfect and neither are manufacturing processes. When developing new products, this fact must be considered since a product, in most cases, consists of several components that are assembled together. The geometrical variation may impact the function of the product, the ability to assemble the product and the aesthetics of the product. Geometrical variation may thereby affect the customer’s perception of the overall quality of the product. That is the reason why the visual appearance of the relationships between components, also defined as split-lines, in many cases is of exceptional importance in the automotive industry. Perceived quality of split-lines is one of several aspects of perceived quality, which is an overall quality as perceived through the human senses.This thesis is concerned with methods for simulating and evaluating perceived quality in early phases of the product development process. Early simulation and evaluation of perceived quality can minimize the number of corrections in late phases, increase quality and save both time and money. The potential for savings is of substantial importance as projects in the automotive industry are conducted with consistently decreasing budgets and tighter time plans.The thesis elaborates on methods for performing non-rigid variation simulation in early phases when data maturity is low. These are placed in a proposed framework for managing and supporting evaluation of perceived quality in general during the development process based on the maturity of the data available. Some activities in the framework are widely used in the automotive industry while others are based on recent research in the area. The thesis reports on several case studies that highlight different aspects in the framework. It shows how mesh morphing can be used to predict component variation and component stiffness in very early phases by using historical inspection data and design solutions as input. This facilitates a way of visualizing the effects of geometrical variation on perceived quality in very early phases by utilizing reference data linked from previous projects.Another study was performed to investigate the applicability of non-FEA-based deformation methods for simulation and visualization of effects of geometrical variation on perceived quality. Results showed that many of the involved engineers and managers endorsed the alternative of taking decisions based on simulated results from the method. They also emphasized the advantage of having the possibility to visualize expected scenarios early on in the development phase. Based on results from this study, a follow-up study was performed to show how the method could be applied in industry.Also included in this thesis is a study showing that evaluators perceive rigid and non-rigid visualizations differently. This further supports the need of non-rigid simulations and visualizations for correct judgments of the virtual models. Unfortunately, most non-rigid simulation models are more time demanding to build, compared to rigid ones, and may consequently not be applied in all cases. Therefore, a study has been conducted to investigate in which vehicle areas non-rigid variation simulations are recommended.These results are expected to support and improve the work with perceived quality in the industrial development process, and they expand the body of scientific knowledge in the research field

Towards Efficient Evaluation of Impacts of Geometrical Variation on Perceived Quality in Early Phases

In a perfect world, manufacturing would lead to components without geometrical variation. This would mean that every component produced in a series would have the exact same dimensions and, when observed by a trained eye, look exactly identical. However, the world is not perfect and neither are manufacturing processes. When developing new products, this fact must be considered since a product, in most cases, consists of several components that are assembled together. The geometrical component variation may impact the function of the product, the ability to assemble the product and the aesthetics of the product. Geometrical variation may thereby affect the customer’s perception of the overall quality of the product. That is the reason why the appearance of the relationships between visible components, also defined as split-lines, in many cases is of exceptional importance in the automotive industry. This overall quality as perceived through the human senses is here referred to as Perceived Quality (PQ).This thesis is concerned with methods for simulating and evaluating PQ in early phases of the product development process. Early simulation and evaluation of PQ will minimize the number of corrections in late phases, saving both time and money. The potential for savings is of substantial importance as projects in the automotive industry are conducted with ever decreasing budgets and with ever tighter schedules. However, in these early phases, the maturity of the data (i.e. geometrical models) used for simulation activities is low, which has earlier restricted the possibly to perform certain types of simulations.The thesis includes a proposed method for how to perform non-rigid variation simulation in early phases when data maturity is low. It solves the issue of data immaturity by introducing so-called reference data linked to previous projects. Further, a framework is presented for managing and supporting evaluation of PQ during the development process based on the maturity of the data available. Some activities in the framework have been widely used in the automotive industry and some are based on recent research within the area. An interview study is reported that investigated on what vehicle areas, non-rigid variation simulation was to be recommended before rigid variation simulation, in order to further support the work with PQ. A number of critical areas were identified along with a number of factors important when performing non-rigid variation in early phases. Further the need for non-rigid variation simulation was addressed by the respondents. Finally, a user-study directed towards the visualization activity when evaluating PQ has been performed. Here, the ability to identify geometrical deviations on rendered images was investigated. The results showed that there is a significance difference in how certain relevant deviations (here meaning deviations normal to the surface extent) on non-rigid components are perceived, compared to how the corresponding deviations are perceived when performing rigid simulation

Towards Efficient Evaluation of Impacts of Geometrical Variation on Perceived Quality in Early Phases

In a perfect world, manufacturing would lead to components without geometrical variation. This would mean that every component produced in a series would have the exact same dimensions and, when observed by a trained eye, look exactly identical. However, the world is not perfect and neither are manufacturing processes. When developing new products, this fact must be considered since a product, in most cases, consists of several components that are assembled together. The geometrical component variation may impact the function of the product, the ability to assemble the product and the aesthetics of the product. Geometrical variation may thereby affect the customer’s perception of the overall quality of the product. That is the reason why the appearance of the relationships between visible components, also defined as split-lines, in many cases is of exceptional importance in the automotive industry. This overall quality as perceived through the human senses is here referred to as Perceived Quality (PQ).This thesis is concerned with methods for simulating and evaluating PQ in early phases of the product development process. Early simulation and evaluation of PQ will minimize the number of corrections in late phases, saving both time and money. The potential for savings is of substantial importance as projects in the automotive industry are conducted with ever decreasing budgets and with ever tighter schedules. However, in these early phases, the maturity of the data (i.e. geometrical models) used for simulation activities is low, which has earlier restricted the possibly to perform certain types of simulations.The thesis includes a proposed method for how to perform non-rigid variation simulation in early phases when data maturity is low. It solves the issue of data immaturity by introducing so-called reference data linked to previous projects. Further, a framework is presented for managing and supporting evaluation of PQ during the development process based on the maturity of the data available. Some activities in the framework have been widely used in the automotive industry and some are based on recent research within the area. An interview study is reported that investigated on what vehicle areas, non-rigid variation simulation was to be recommended before rigid variation simulation, in order to further support the work with PQ. A number of critical areas were identified along with a number of factors important when performing non-rigid variation in early phases. Further the need for non-rigid variation simulation was addressed by the respondents. Finally, a user-study directed towards the visualization activity when evaluating PQ has been performed. Here, the ability to identify geometrical deviations on rendered images was investigated. The results showed that there is a significance difference in how certain relevant deviations (here meaning deviations normal to the surface extent) on non-rigid components are perceived, compared to how the corresponding deviations are perceived when performing rigid simulation

Identifying Critical Areas for Styling Data Based Simulation to Evaluate Perceived Quality Related to Non-Rigidity

When handling mass-produced parts in the automotive industry it is of great importance to take into consideration the geometrical variation that will occur as a result of the manufacturing process used. By using a Computer Aided Tolerancing (CAT) software, effects of geometrical variation are simulated to support robust design. As an additional step, simulated results may be evaluated in a high-end visualization tool to judge a predicted outcome of the final Perceived Quality (PQ). PQ is an overall quality impression perceived by the product user. However, when a new styling concept is evaluated the data used for analysis and visualization will be less mature in terms of component design. Design parameters such as material selection, material thickness, locating scheme, design and position of reinforcements and flanges are rarely defined here. These parameters influence the deformation behavior of a component which is critical for the outcome of the variation simulation. Previously presented methods for variation simulation of non-rigid parts are FEA-based, a method that are strongly dependent on these design parameters for a reliable result. A method of how to handle these uncertainties by using information from earlier design solutions, preferably based on the same platform, and applying them to current styling has earlier been suggested by the authors. In this paper, the result from a descriptive study carried out at a Swedish automobile manufacturer is presented. The objective of the study was to identify areas where PQ is most frequently evaluated with non-rigidity in components as a contributing factor. This will on one hand indicate where non-rigid variation simulation is most critical for a more reliable prediction of the final PQ. On the other hand, it will support the further development of the above mentioned method, as diverse approaches may be necessary for different areas on the vehicle

Non-FEA-Based Method as Means for Knowledge Based Assessment of Perceived Quality

Fit and finish of vehicle split-lines is one important contributor to the final Perceived Quality (PQ) of the product. To achieve high PQ of split-lines, effects of geometrical variation has to be considered. In early phases of the development chain the geometry models used for simulation and visualization have low level of detail. This limits the possibility to perform certain simulations that rely on a more complete detailed design. Consequently, alternative methods have to be considered to predict and simulate possible outcome in early phases concerning PQ issues. This paper proposes how an existing non-FEA-based deformation method can support virtual assessment of the PQ of split-lines in early phases. The method is based on mesh morphing and has been implemented in a CAT-tool (Computer-Aided Tolerancing). Its strength lies in the simplicity of generating deformed shapes. The paper specifically focuses on how available knowledge regarding issues from previous projects can be used as input to the method, to predict part deviation and part behavior. The paper further presents industrial examples where the method has been applied. The results show that the proposed technique can be used as a complement to other simulation tools in early phases, where low level of detail on geometries limits the possibility to perform FEA (Finite Element Analysis) based simulations

Identifying Critical Areas for Styling Data Based Simulation to Evaluate Perceived Quality Related to Non-Rigidity

When handling mass-produced parts in the automotive industry it is of great importance to take into consideration the geometrical variation that will occur as a result of the manufacturing process used. By using a Computer Aided Tolerancing (CAT) software, effects of geometrical variation are simulated to support robust design. As an additional step, simulated results may be evaluated in a high-end visualization tool to judge a predicted outcome of the final Perceived Quality (PQ). PQ is an overall quality impression perceived by the product user. However, when a new styling concept is evaluated the data used for analysis and visualization will be less mature in terms of component design. Design parameters such as material selection, material thickness, locating scheme, design and position of reinforcements and flanges are rarely defined here. These parameters influence the deformation behavior of a component which is critical for the outcome of the variation simulation. Previously presented methods for variation simulation of non-rigid parts are FEA-based, a method that are strongly dependent on these design parameters for a reliable result. A method of how to handle these uncertainties by using information from earlier design solutions, preferably based on the same platform, and applying them to current styling has earlier been suggested by the authors.In this paper, the result from a descriptive study carried out at a Swedish automobile manufacturer is presented. The objective of the study was to identify areas where PQ is most frequently evaluated with non-rigidity in components as a contributing factor. This will on one hand indicate where non-rigid variation simulation is most critical for a more reliable prediction of the final PQ. On the other hand, it will support the further development of the above mentioned method, as diverse approaches may be necessary for different areas on the vehicle

Towards Non-FEA-Based Deformation Methods for Evaluating Perceived Quality of Split-Lines

In the automotive industry, the evaluation of Perceived Quality of split-lines is strongly dependent on simulation and visualisation activities to analyse consequences of geometrical variation. A truthful representation of the part behaviour is therefore essential. Moreover, variation simulation of non-rigid parts is today performed by finite element analysis (FEA). FEA-based methods demand meshed models that correspond to the final engineering design to calculate the correct stiffness matrix. However, geometrical models in early phases have significantly lower level of detail. Approximate methods are therefore considered as options to better deal with this restriction. In this paper, an approximate non-FEA-based simulation method, based on a mesh morphing approach, has been the subject of a case study to evaluate its acceptance and applicability. It involved a focus group and individual interviews with engineers and project managers from two companies within the automotive industry. The study shows that providing the possibility to perform visualisation activities in the early phases is highly sought after, both on an engineering level and on a management level. Furthermore, a number of application scenarios for this type of approximate method were proposed. The study also identified strengths and risks of visualising the effects of geometrical variation in this way

Non-FEA-Based Method as Means for Knowledge Based Assessment of Perceived Quality

Fit and finish of vehicle split-lines is one important contributor to the final Perceived Quality (PQ) of the product. To achieve high PQ of split-lines, effects of geometrical variation has to be considered.In early phases of the development chain the geometry models used for simulation and visualization have low level of detail. This limits the possibility to perform certain simulations that rely on a more complete detailed design. Consequently, alternative methods have to be considered to predict and simulate possible outcome in early phases concerning PQ issues.This paper proposes how an existing non-FEA-based deformation method can support virtual assessment of the PQ of split-lines in early phases. The method is based on mesh morphing and has been implemented in a CAT-tool (Computer-Aided Tolerancing). Its strength lies in the simplicity of generating deformed shapes. The paper specifically focuses on how available knowledge regarding issues from previous projects can be used as input to the method, to predict part deviation and part behavior. The paper further presents industrial examples where the method has been applied. The results show that the proposed technique can be used as a complement to other simulation tools in early phases, where low level of detail on geometries limits the possibility to perform FEA (Finite Element Analysis) based simulations

Using Morphing Techniques in Early Variation Analysis

Today, in order to be competitive in a fierce global car market, higher demands are placed on the Perceived Quality (PQ) of the products. The end customer's visual impression of fit and finish are one of several factors influencing the overall PQ. When assessing the PQ of split-lines, the assumed geometric variation of the ingoing parts is an important prerequisite for trustworthy visualization and for correct judgments. To facilitate early decision making in conceptual phases, new demands are set on virtual tools and methods to support the engineers. In this study, a method for early evaluation of the impact of geometrical variation on PQ of split-lines is proposed. Starting from an exterior styling model, mesh morphing techniques have been used to distort the exterior model according to measurement data acquired in running production. Morphing techniques have also been used to adopt previous structural design solutions onto the new styling, in order to make an early assumption of the assembly stiffness. The used method is described and adopted in an industrial case. The study shows that the presented technique can be used to create continuous and correlated datasets. Non-rigid part behavior can be included in early PQ evaluations, even if final CAD/FEA engineering design models do not yet exist