Hybrid teaching and learning environment in the context of virtual product development. - In: Engineering for a changing world, (2023), 4.2.052, S. 1-8
Product development means identifying the needs of different stakeholders, developing a product for them to the point where it is ready for production and use, and documenting it. To manage the complexity of product development, it is becoming increasingly digitalised. As virtual product development is a key area of industry, teaching in this area is an important component of a practice-oriented engineering curriculum. Engineering education constantly requires new teaching and learning formats. The trend is towards a systematic combination of digital teaching materials for self-organised individual and cooperative self-study on the one hand, and in-depth forms of classroom teaching tailored to the needs of students on the other - in short: hybrid forms of teaching and learning. Within the framework of an eTeach impulse project for a hybrid teaching and learning environment for virtual product development, important results have been developed, implemented and evaluated to achieve this goal.
https://doi.org/10.22032/dbt.58902
Systematization of existing uncertainties in the context of product development in the automotive supply industry. - In: Engineering for a changing world, (2023), 4.2.044, S. 1-18
Along the development process of technical products, challenges arise repeatedly, which result from uncertainties, i.e., conscious, or unconscious gaps in knowledge or definitions. The causes often lie in the fact that empirical values represent the basis for many decisions, from the specification of tasks to the required organizational and control structures to the models and calculation tools used. Based on this knowledge, it is essential to continuously identify, evaluate and, if necessary, reduce the degree of uncertainty during the development of innovative products. This is intended to avoid potentially negative influences on the strategic goals of the magic triangle of project management (costs, time, and quality). This is exactly where the investigations started, using the example of an automotive supplier company. Completed projects are the starting point. A first focus is on the analysis of the effects of unclearly defined requirements and ambiguities in verification, validation, and end customer use. A second focus is the systematization, classification up to the provision of project-specific tools, which should facilitate the reduction of uncertainties already in early project phases.
https://doi.org/10.22032/dbt.59012
Analysis of potential errors in technical products by combining knowledge graphs with MBSE approach. - In: Engineering for a changing world, (2023), 4.2.032, S. 1-15
Technical products are developed to meet the demands of stakeholders. Therefore, the product's functions and associated properties are important. Various influencing factors e.g., external disturbances can have an impact on the input flows of the products or its characteristics and thus on the functions. If this leads to deviations between the required and as-is functions, these deviations are called errors. It is therefore important to analyze errors in product development and implement measures to increase the robustness of the product. Model-Based Systems Engineering (MBSE) supports the development of complex systems. However, MBSE alone has limited ability to identify in-depth errors. This requires knowledge of possible errors from previous products in specific contexts. For this purpose, the method proposed in this paper facilitates identifying errors in the concept phase by combining MBSE approaches with reusable knowledge (i.e., knowledge graph). The approach is presented using an application example for a mobile robot.
https://doi.org/10.22032/dbt.58898
Systematic use of model-based solution patterns using the example of a load cell. - In: Engineering for a changing world, (2023), 4.2.029, S. 1-17
Complex mechatronic products are usually decomposed into several sub-systems for their development. These sub-systems are developed in parallel or even independently based on their specifications and use cases. The application of model-based solution patterns is an effective way to comprehensively and efficiently describe the available knowledge about the sub-systems. This contribution proposes an approach to support the selection and application of model-based solution patterns. The approach, based on a metamodel for solution patterns using SysML, describes the process for selecting solution patterns and aligning requirements and constraints with the as-is properties of the sub-systems. Additionally, the approach supports the design of solution patterns taking into account special knowledge from the development of the sub-systems as well as the usage of the solution patterns in different systems and contexts. As an example, an application scenario of a specific load cell within a measurement system is explained.
https://doi.org/10.22032/dbt.58904
Relaxation behavior of (cylindrical) helical compression springs. - In: Engineering for a changing world, (2023), 4.1.091, S. 1-13
This paper deals with the relaxation behavior of helical compression springs made out of different types of spring steel wire. The starting point of the examinations marks the creep and relaxation behavior of similar preprocessed wires prior to the cold forming under torsional stress. In this context the main influencing factors regarding creep deformations and relaxation losses are discussed and the particular findings contrasted, which allows for transfer factors to be deducted. The mathematical models forming the evaluation basis of the experimental data are based upon the NORTON-BAILEY creep law and utilized to determine creep specific characteristics and identify material constants. Doing so enables the deviation of calculating instructions to estimate the relaxation losses of helical compression springs based on numerous influencing factors. Applying those calculation methods facilitates the deduction of relaxation figures as well as recommendations regarding the manufacturing process in order to achieve springs with favorable relaxation behavior.
https://doi.org/10.22032/dbt.58890
Behaviour of FRP-sandwich structures for lightweight composite springs in static and cyclic torsional load cases. - In: Engineering for a changing world, (2023), 4.1.064, S. 1-13
Fiber-reinforced polymers (FRP) are established as high-tech materials for special purposes such as racing cars, planes or bicycles. Nowadays, they are increasingly used for functional parts and machine elements. For lightweight optimization, FRP sandwich structures can be used, which also appear to be suitable for spring applications. But material data availability is often limited for UD-specimen or specific load cases, which makes it difficult to use FRPs for technical springs. In order to reduce this gap and to facilitate the development of new applications, this paper deals with the basic static and cyclic behavior of FRP sandwich strips under torsional load. Therefore, manufacturing methods have been developed, to produce FRP strip specimens with GFRP and CFRP shells containing various core materials. An analytical model was used to describe the static behavior, which shows decent agreement with test results. Initial studies on fatigue characteristics of these strips were carried out as well as tests on associated volute springs. The results contribute to composite lightweight spring design and could extend the range of applications for composite springs in the future.
https://doi.org/10.22032/dbt.58893
FEM simulation of wire drawing. - In: Engineering for a changing world, (2023), 4.1.022, S. 1-12
The paper deals with the finite element simulation of wire drawing processes with focus on unalloyed carbon steels. Based on the development of suitable material models as a basis for the simulation model, the forming processes are analyzed over several drawing stages for different drawing regimes. The simulation model is validated by comparing the simulation results with measured values. For the description of the forming behavior, the damage developments of the wire during the multi-stage forming are specifically analyzed. Subsequently, forming limits are derived by correlating the calculated damage with mechanical parameters of the wires. The validation of the damage models used is made possible by an FE parameter study, within which a targeted variation of the drawing die geometry takes place at a specific drawing stage. The paper is concluded by the verification of the results obtained theoretically by practical tests on a wire drawing machine using critical drawing die geometries.
https://doi.org/10.22032/dbt.58892
Threshold based reduction of EMS stimulation artifacts in the electromyogram when stimulation intensity increases. - In: Engineering for a changing world, (2023), 3.2.144, S. 1-10
To investigate muscular strain, it is possible to record an electromyogram (EMG) during electromyostimulation (EMS). However, stimulation artifacts make it difficult to examine evoked compound muscle action potentials (M-waves). The aim of this work was to algorithmically remove stimulation artifacts from the EMG signal when the stimulation intensity increases. For this purpose, EMG signals were recorded on four subjects who underwent a 30-second EMS of the right M. triceps surae. Afterwards we conducted offline signal processing to reduce stimulation artifacts. We implemented a two-stage threshold algorithm, adapted from O'Keeffe et al. (2001), to remove signal segments passing the thresholds in a defined sequence. Here, the thresholds in the first iteration are two constants, while the algorithm uses linearly or exponentially increasing thresholds in the second iteration. After empirically adjusting the threshold parameters, the stimulation artifacts were successfully reduced. This allows further investigations of the M-waves with respect to muscular fatigue.
https://doi.org/10.22032/dbt.59139
Control for non-linear compliant actuation of an upper arm exoskeleton. - In: Engineering for a changing world, (2023), 3.2.088, S. 1-15
Musculoskeletal diseases of the back and upper extremities are one of the main causes of sick leave in Europe. Exoskeletons are one possible approach to preventive measures. The Biomechatronics Group at Technische Universität Ilmenau is developing an antagonistically actuated exoskeleton with non-linear compliance to support flexion and extension of the elbow in repetitive tasks like in assembly. Here, we present a control strategy to achieve joint stiffness control while benefitting from the advantages of non-linear compliant actuation. We use a decentralized control approach, combining two PID controllers to control joint position and string force and thus, joint stiffness, in the antagonistically acting drive. We show limitations and benefits of this approach through simulation and measurement.
https://doi.org/10.22032/dbt.58877
Concept for the measurement of vital parameters during the use of an infrared cabin to investigate physiological effects and to individualize the sauna session. - In: Engineering for a changing world, (2023), 3.2.050, S. 1-20
Infrared sauna bathing has positive effects on body and mind. Quantifying these effects helps to make sauna use more efficient and safer and to increase the user-observed wellness effects. Currently, there are no practical solutions for a comprehensive and user-friendly monitoring of the physical impact of sauna bathing. This paper focuses on the concept development to investigate which measurement setups are suitable to record and evaluate changes in vital parameters. Based on prioritized vital parameters and requirements a pre-selection of devices in form of wearables is made, which is going to be examined in detail for their suitability. An investigation with ten test persons is planned, in which the wearables’ measurement accuracy and the user acceptance outside and inside the infrared cabin are quantified. The result is a concept for the test procedure and the evaluation of the wearables in order to integrate a suitable device into the overall system.
https://doi.org/10.22032/dbt.58880