Automated and interactive evaluation of welding producibility in an multidisciplinary design optimization environment for aircraft components

The automation capabilities and virtual tools within engineering disciplines, such as structural mechanics and aerodynamics, enable efficient Multidisciplinary Design Optimization (MDO) approaches to evaluate and optimize the performance of a large number of design variants during early design stages of aircraft components. However, for components that are designed to be welded, in which multiple functional requirements are satisfied by one single welded structure, the automation and simulation capabilities to evaluate welding-producibility and predict welding quality (geometrical deformation, weld bead geometrical quality, cracks, pores, etc) are limited. Besides the complexity of simulating all phenomena within the welding process, one of the main problems in welded integrated components is the existing coupling between welding quality metrics and product geometry. Welding quality can vary for every new product geometrical variant. Thus, there is a need of analyzing rapidly and virtually the interaction and sensitivity coefficients between design parameters and welding quality to predict welding producibility. This paper presents as a result an automated and interactive welding-producibility evaluation approach. This approach incorporates a data-based of welding-producibility criteria, as well as welding simulation and metamodel methods, which enable an interactive and automated evaluation of welding quality of a large number of product variants. The approach has been tested in an industrial use-case involving a multidisciplinary design process of aircraft components. The results from analyzing the welding-producibility of a set of design variants have been plotted together with the analysis results from other engineering disciplines resulting in an interactive tool built with parallel coordinate graphs. The approach proposed allows the generation and reuse of welding producibility information to perform analyses within a big spectrum of the design space in a rapid and interactive fashion, thus supporting designers on dealing with changes and taking fact-based decisions during the multidisciplinary design process

A Virtual Design of Experiments Method to Evaluate the Effect of Design and Welding Parameters on Weld Quality in Aerospace Applications

During multidisciplinary design of welded aircraft components, designs are principallyoptimized upon component performance, employing well-established modelling and simulationtechniques. On the contrary, because of the complexity of modelling welding process phenomena,much of the welding experimentation relies on physical testing, which means\ua0 welding producibility aspects are considered after the design has already been established. In\ua0 addition, welding optimization research mainly focuses on welding process parameters, overlooking the potential impact of product design. As a consequence, redesign loops and welding rework increases product cost. To solve these problems, in this article, a novel method that combines the benefits of design of experiments (DOE) techniques with welding simulation is presented. The aim of the virtual design of experiments method is to model and optimize the effect of design and welding parameters interactions early in the design process. The method is explained through a case study, in which weld bead penetration and distortionare quality responses to optimize. First, a small number of physical welds are conducted to develop and tune the welding simulation. From this activity, a new combined heat source model is presented.Thereafter, the DOE technique optimal design is employed to design an experimental matrix that enables the conjointly incorporation of design and welding parameters. Welding simulations are then run and a response function is obtained. With virtual experiments, a large number of design and welding parameter combinations can be tested in a short time. In conclusion, the creation of a meta-model allows for performing welding producibility optimization and robustness analyses during early design phases of aircraft component

Managing Geometrical Variation through Optimization and Visualization

All manufacturing processes are afflicted by variation that causes deviations in critical dimensions in the final product. Geometrical variation results in form and size deviation in individual parts. Assembly variation comes from defects in assembly equipment, and influence how parts are mounted together. To secure and control the effects of variation, an efficient geometry assurance process is required. In this thesis, the research challenge was to develop methods and tools that increased the efficiency in managing geometrical variation in the virtual geometry assurance process. To fulfil this challenge, focus was set on optimization techniques and algorithm development. The research project was divided into three main areas: 1) Locating scheme optimization, 2) Tolerance allocation and 3) Visualization of variation.The focus in the first area was set on locating scheme optimization. The way parts in an assembly are located in relation to each other or to fixtures is critical for how geometrical variation will propagate and cause variation in critical product dimensions. The result from this part was a demonstrator that utilizes optimization to find the locator positions that maximise robustness in critical dimensions. The second area of the research investigated how tolerances on individual dimensions can be set automatically to fulfil tolerance requirements on critical product dimensions. Traditionally, tolerances are set based on engineering knowledge and earlier experiences from design projects. Here, demonstrators were developed for different tolerance allocation optimization strategies, based on either cost or geometric properties. Finally, in the third area of this research, the centre of interest was visualization of variation. Here, a new method was developed to calculate an envelope enclosing a total volume based on simulation or measurement data. The contribution of this research is enhanced knowledge of how to virtually manage geometrical variation within product development. It has also contributed to an increased understanding of research connected to the virtual geometry assurance process. In addition, contributions have been made in the area of demonstrator development for locating scheme optimization, tolerance allocation and visualization of variation. Finally, the results have been spread within both academia and industry

Managing Geometrical Variation through Optimization and Visualization

All manufacturing processes are afflicted by variation that causes deviations in critical dimensions in the final product. Geometrical variation results in form and size deviation in individual parts. Assembly variation comes from defects in assembly equipment, and influence how parts are mounted together. To secure and control the effects of variation, an efficient geometry assurance process is required. In this thesis, the research challenge was to develop methods and tools that increased the efficiency in managing geometrical variation in the virtual geometry assurance process. To fulfil this challenge, focus was set on optimization techniques and algorithm development. The research project was divided into three main areas: 1) Locating scheme optimization, 2) Tolerance allocation and 3) Visualization of variation.The focus in the first area was set on locating scheme optimization. The way parts in an assembly are located in relation to each other or to fixtures is critical for how geometrical variation will propagate and cause variation in critical product dimensions. The result from this part was a demonstrator that utilizes optimization to find the locator positions that maximise robustness in critical dimensions. The second area of the research investigated how tolerances on individual dimensions can be set automatically to fulfil tolerance requirements on critical product dimensions. Traditionally, tolerances are set based on engineering knowledge and earlier experiences from design projects. Here, demonstrators were developed for different tolerance allocation optimization strategies, based on either cost or geometric properties. Finally, in the third area of this research, the centre of interest was visualization of variation. Here, a new method was developed to calculate an envelope enclosing a total volume based on simulation or measurement data. The contribution of this research is enhanced knowledge of how to virtually manage geometrical variation within product development. It has also contributed to an increased understanding of research connected to the virtual geometry assurance process. In addition, contributions have been made in the area of demonstrator development for locating scheme optimization, tolerance allocation and visualization of variation. Finally, the results have been spread within both academia and industry

Managing Geometrical Variation in Complex Assemblies through Visualization and Tolerance Allocation

To stay competitive in the market today, manufacturing companies have to shorten their time to market. This implies that time also has to be saved during the product development phase. This thesis will mainly focus on how to be more efficient in the detail design phase through different design activities. These activities are related to methods and tools regarding how to manage geometrical variation when digital CAD models are available. Controlling the variation in a digitalized environment can save time and resources by decreasing the need for test series and avoiding quality problems during production start/ramp-up. The research in the thesis discusses and suggests methods regarding how to manage variation in the detail design phase. The research project presented in this thesis is divided into two parts: 1) decomposition of requirements and 2) visualization of variation.The first part investigates how geometry requirements or functional requirements can be decomposed into design parameters. One example of a requirement could be the allowed variation between a door and a fender of a car. This allowed variation shall be decomposed into design parameters. In this case those parameters are tolerances on dimensions of parts and locators in the assembly that affect the variation in critical dimensions. This can be done automatically, which implies an optimization problem with the constraints on an allowed variation in the critical dimension. The decomposition can be done in a number of different ways and is discussed in this thesis.The second part of this research focus on visualization of variation. The research behind this thesis has concentrated on methods for visualization of the total volume a part or assembly creates when affected by variation or motion. This total volume is called motion envelope. A part of the result has been implemented in an industrial product development process. The results were used to calculate and visualize the total volume an engine creates when being affected by motion. The main advantage was time savings when the motion envelope is used as design support. This was due to fewer loops of controlling the packaging. Now it is possible to look for conflicts within the whole engine compartment. Earlier this was made between different parts or even between individual points. The envelope also decreases the risk of finding conflicts too late in the product development process, which might imply in late and costly tool changes

Managing Geometrical Variation in Complex Assemblies through Visualization and Tolerance Allocation

To stay competitive in the market today, manufacturing companies have to shorten their time to market. This implies that time also has to be saved during the product development phase. This thesis will mainly focus on how to be more efficient in the detail design phase through different design activities. These activities are related to methods and tools regarding how to manage geometrical variation when digital CAD models are available. Controlling the variation in a digitalized environment can save time and resources by decreasing the need for test series and avoiding quality problems during production start/ramp-up. The research in the thesis discusses and suggests methods regarding how to manage variation in the detail design phase. The research project presented in this thesis is divided into two parts: 1) decomposition of requirements and 2) visualization of variation.The first part investigates how geometry requirements or functional requirements can be decomposed into design parameters. One example of a requirement could be the allowed variation between a door and a fender of a car. This allowed variation shall be decomposed into design parameters. In this case those parameters are tolerances on dimensions of parts and locators in the assembly that affect the variation in critical dimensions. This can be done automatically, which implies an optimization problem with the constraints on an allowed variation in the critical dimension. The decomposition can be done in a number of different ways and is discussed in this thesis.The second part of this research focus on visualization of variation. The research behind this thesis has concentrated on methods for visualization of the total volume a part or assembly creates when affected by variation or motion. This total volume is called motion envelope. A part of the result has been implemented in an industrial product development process. The results were used to calculate and visualize the total volume an engine creates when being affected by motion. The main advantage was time savings when the motion envelope is used as design support. This was due to fewer loops of controlling the packaging. Now it is possible to look for conflicts within the whole engine compartment. Earlier this was made between different parts or even between individual points. The envelope also decreases the risk of finding conflicts too late in the product development process, which might imply in late and costly tool changes

Top-Down Decomposition of Multi-Product Requirements onto Locator Tolerances

The tolerance allocation problem consists of choosing tolerances on dimensions of a complex assembly so that they combine into an ‘optimal state’ while fulfilling certain requirements on an allowed variation. This optimal state often coincides with the minimum manufacturing cost of the product. Sometimes it is balanced with an artificial cost that the deviation from target induces on the quality of the product.This paper suggests a multiobjective formulation of the tolerance allocation problem to automatically decompose requirements for an allowed variation on a set of critical product dimensions. This formulation is demonstrated using a rear lamp on a car with multiple requirements on allowed variation. In this case only the tolerances on locators that locates the lamp on the body are considered. The paper also reviews a selection of work that has been made on solving tolerance allocation problems

Top-Down Decomposition of Multi-Product Requirements onto Locator Tolerances

The tolerance allocation problem consists of choosing tolerances on dimensions of a complex assembly so that they combine into an ‘optimal state’ while fulfilling certain requirements on an allowed variation. This optimal state often coincides with the minimum manufacturing cost of the product. Sometimes it is balanced with an artificial cost that the deviation from target induces on the quality of the product.This paper suggests a multiobjective formulation of the tolerance allocation problem to automatically decompose requirements for an allowed variation on a set of critical product dimensions. This formulation is demonstrated using a rear lamp on a car with multiple requirements on allowed variation. In this case only the tolerances on locators that locates the lamp on the body are considered. The paper also reviews a selection of work that has been made on solving tolerance allocation problems

An Efficient Solution to the Discrete Least-Cost Tolerance Allocation Problem with General Loss Functions

The tolerance allocation problem consists of choosing tolerances on dimensions of a complex assembly so that they combine into an optimal state while retaining certain requirements. This optimal state often coincides with the minimum manufacturing cost of the product. Sometimes it is balanced with an artificial cost that the deviation from target induces on the quality of the product.This paper analyses and suggests a solution to the discrete allocation problem. It also extends the problem to include treating general loss functions. General loss in this paper means an arbitrary polynomial function of a certain degree. We also briefly review the current work that has been made on solving the tolerance allocation problem