Applied Mechanics and Materials Vol. 807

Abstract: Scaling methods allow the estimation of the impact of changes in individual parameters on system performance. In the technical context, physical similarity is the focus. This paper demonstrates the extension of scaling methods to include uncertainty scaling. The advantages of using scaling uncertainty for the development of scaled products and the contribution of extended scaling methods to the analysis and assessment of uncertainty are illustrated. Uncertainty scaling based on dimensional analysis and complete similarity is derived. The potential of this method is demonstrated using a load carrying structure - a buckling beam.

Abstract: The authors propose a method to assess the clarity of a design on working principle level. To do so, the Contact and Channel Model is used in an adapted form to differentiate elemental interfaces based on their geometry and function. This classification is used to derive a generic catalogue of elemental interfaces. A product can be represented through a combination of these interfaces and working structures in between. The design clarity can then be assessed through generic information stored in the catalogue. The authors propose a procedure model to implement this method and show exemplarily its applicability. Additionally, main design parameters that strongly affect a product’s behavior can be identified with help of the generic catalogue for every elemental interface. Finally, further steps regarding variability in design parameters are discussed.

Abstract: Uncertainty in the properties of semi-finished parts can cause fluctuations in the product properties, especially if they have a strong effect on the process and cannot be compensated by process adjustments. Incremental forming processes have the potential to react to changing conditions by adapting the tool movement during the process. This paper analyzes the feasibility of controlling material flow in an orbital forming process in order to selectively fill those geometric elements which were specified with narrow tolerances by the designer. The effect of different process parameters on the mushroom effect and the degree of mold filling are analyzed by FEM simulations and experiments. In order to realize online monitoring and control, an estimation model is introduced, which maps signals from sensors and the process control to the geometric target values.

Abstract: The market pressure and the products of competitors are decreasing the duration of product life cycles. Besides that, special customer requirements and rising product complexity result in an increase of the effort and the costs of the development process. In order to minimize the effort of the development process as well as to handle the uncertainties which come along with the planning and selection of manufacturing systems a data-based configuration tool was developed for the use in the field of sheet metal forming. Based on the product data of existing press systems, the tool is able to predict the fundamental configuration of a newly developed press system. The utilization and functionality of the tool is illustrated on two exemplary press systems.

Abstract: To provide high quality in production and assembly processes need to be controlled. This paper analyzes the effect and necessity of online monitoring and closed-loop control of pin insertion. In this investigation pin insertion is an assembly process wherein metallic pins are pressed into polymer structures. The investigations described in this paper are made at the Robert Bosch GmbH and according to their requirements towards production standards, quality and traceability.

Abstract: In production processes uncertainty has a great impact on the product quality as well as production costs. In automotive industry the reaming of valve guides in a cylinder head of a combustion engine is a quality determining process. Due to the force fitting of the valve guides into the cylinder head the final reaming process has to deal with increased uncertainty. On the other hand, the finished hole is closely tolerated. To ensure the process reliability the admissible tolerance must be strictly met even in case of uncertainty. This paper presents a possibility to achieve process reliability by a modified process chain with an additional pilot reaming tool. Thereby, the effect of different cutting edge preparation is also analyzed. Further, the influence of the pilot reamer geometry on the final hole quality is investigated.

Abstract: The bore quality is influenced by machine’s accuracy, work piece and tool errors as well as handling errors. This uncertainty has a huge impact on the quality of the finished bore. During reaming, the majority of tool deflection arises during the unsteady process phase. The entry phase is regarded as the biggest influencing factor for the reamer’s deflection with increasing bore depth. This paper examines the influence of various entry strategies on the bore quality during the reaming process.

Abstract: Ti-6Al-4V is the most common used titanium alloy in aerospace. Parts are therefore often machined from wrought material with high buy-to-fly ratios. Additive manufacturing, however, allows to build parts rapidly and directly from computer-aided design information, offering better material utilisation and lead time reduction. Despite the high potential for aerospace applications, the reliability of the mechanical properties is still at an early stage. This work should give a first overview by determining and comparing DMLS, EBM and DMD Ti-6Al-4V material. Each process is compared based on standardised post treatments, specimen geometries and test methods.It can be seen that the chemistry, the microstructure, and the defect formation differs between the processes, which leads to a scatter in the experimentally determined static tensile, axial fatigue, and crack growth properties.

Abstract: This article extends the Uncertainty Mode and Effects Analysis (UMEA) to human effects and uses ontologies to connect human driven uncertainty data to the corresponding parts in an aircraft CAD-Assembly. Still, human behaviour is one of the major sources of uncertainty in the product usage phase. Hence, using uncertainty data of human behaviour for product design becomes increasingly important, especially for the control of uncertainty in load carrying systems. In this context, the exchange of semantically enriched uncertainty data between different domains and domain specific applications guarantees the consistency of the data prevents misinterpretation and enables the reuse of existing data for future design decisions.

Abstract: In uncertainty calculation, the inability of interval parameters to take into account mutual dependency is a major shortcoming. When parameters with a geometric perspective are involved, the construction of a model using intervals at discrete locations not only increases the problem dimensionality unnecessarily, but it also assumes no dependency whatsoever, including unrealistic parameter combinations leading to results that probably overestimate the true uncertainty. The concept of modelling uncertainty with a geometric aspect using interval fields eliminates this problem by defining basis functions and expressing the uncertain process as a weighted sum of these functions. The definition of the functions enables the model to take into account geometrically dependent parameters, whereas the coefficients in a non-interactive interval format represent the uncertainty. This paper introduces a new type of interval field specifically tailored for geometrically oriented uncertain parameters, based on a maximum gradient condition to model the dependency. This field definition is then applied to a model of a clamped plate with uncertain clamping stiffness with the purpose of identifying the effects of spatial variability and mean value separately.