Optimal design of a photovaltaic station using Markov and energy price modelling. - In: Engineering for a changing world, (2023), 4.2.083, S. 1-14
This paper addresses the optimization of photovoltaic (PV) systems to increase their efficiency. The study introduces a new pricing model that considers the current price of PV inverters. In addition, Markov modeling is used in a new optimization framework to determine the optimal configuration, considering the number of PV modules and inverters, operational constraints, and failure events of PV inverters up to 100 kW. A case study with six real PV inverters confirms the effectiveness of the proposed framework. It calculates the average daily hours of rated power generation considering geographic location, temperature, and solar irradiance using real data from a real PV system. The study identifies both local and global optimal solutions for PV inverters (15 kW to 100 kW), while minimizing the effective levelized cost of energy. The results of the study have important implications for future assessments of PV module failures and repairs.
https://doi.org/10.22032/dbt.58910
Building agile product design competences in student projects. - In: Engineering for a changing world, (2023), 4.2.066, S. 1-11
The increasing complexity of technical solutions caused by constantly changing requirements and competitive situations, has led to the introduction of agile development processes in various domains in order to be able to react faster and more efficient to changes. This paper explores the integration of agile aspects into engineering education to prepare students for the corporate world. Two approaches, a single-stage and a two-stage approach, were implemented and evaluated in student projects at Technische Hochschule Ulm and Technische Universität Ilmenau. The findings reveal that both approaches effectively enhance students' competencies in agile product development. The observations highlight the value of iterative sprints, design thinking, peer learning, focused work, stakeholder involvement and the application of digital tools. Students exhibited increased confidence, independence, and creativity in their development projects. The integration of agile approaches in teaching methodologies proves beneficial in addressing the challenges posed by complex technical solutions and evolving requirements.
https://doi.org/10.22032/dbt.58911
Methodical procedure for a surrogate model based fatigue calculation to support the design process of eBike drive units. - In: Engineering for a changing world, (2023), 4.2.053, S. 1-19
In this paper, a method is developed to consider multiaxial load spectra and their variation in a computationally efficient local fatigue calculation procedure. This method is based on an FE data-based surrogate model and is intended to support the simulation-based product design process. To demonstrate their application and necessity, a case study on the design of eBike drive units is presented. For this purpose, the general requirements for the design of eBike drive units as well as the fundamentals of multiaxial fatigue analysis and surrogate modeling are outlined. In addition, a validation process of the surrogate model and its use for fatigue calculation is presented and discussed.
https://doi.org/10.22032/dbt.58909
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