TY - JOUR AB - In applications of piezoelectric actuators and sensors, the dependability and particularly the reliability throughout their lifetime are vital to manufacturers and end-users and are enabled through condition-monitoring approaches. Existing approaches often utilize impedance measurements over a range of frequencies or velocity measurements and require additional equipment or sensors, such as a laser Doppler vibrometer. Furthermore, the non-negligible effects of varying operating conditions are often unconsidered. To minimize the need for additional sensors while maintaining the dependability of piezoelectric bending actuators irrespective of varying operating conditions, an online diagnostics approach is proposed. To this end, time- and frequency-domain features are extracted from monitored current signals to reflect hairline crack development in bending actuators. For validation of applicability, the presented analysis method was evaluated on piezoelectric bending actuators subjected to accelerated lifetime tests at varying voltage amplitudes and under external damping conditions. In the presence of a crack and due to a diminished stiffness, the resonance frequency decreases and the root-mean-square amplitude of the current signal simultaneously abruptly drops during the lifetime tests. Furthermore, the piezoelectric crack surfaces clapping is reflected in higher harmonics of the current signal. Thus, time-domain features and harmonics of the current signals are sufficient to diagnose hairline cracks in the actuators. AU - Aimiyekagbon, Osarenren Kennedy AU - Bender, Amelie AU - Hemsel, Tobias AU - Sextro, Walter ID - 51518 IS - 3 JF - Electronics KW - piezoelectric transducer KW - self-sensing KW - fault detection KW - diagnostics KW - hairline crack KW - condition monitoring SN - 2079-9292 TI - Diagnostics of Piezoelectric Bending Actuators Subjected to Varying Operating Conditions VL - 13 ER - TY - CONF AB - Modelling of dynamic systems plays an important role in many engineering disciplines. Two different approaches are physical modelling and data‐driven modelling, both of which have their respective advantages and disadvantages. By combining these two approaches, hybrid models can be created in which the respective disadvantages are mitigated, with discrepancy models being a particular subclass. Here, the basic system behaviour is described physically, that is, in the form of differential equations. Inaccuracies resulting from insufficient modelling or numerics lead to a discrepancy between the measurements and the model, which can be compensated by a data‐driven error correction term. Since discrepancy methods still require a large amount of measurement data, this paper investigates the extent to which a single discrepancy model can be trained for a physical model with additional parameter dependencies without the need for retraining. As an example, a damped electromagnetic oscillating circuit is used. The physical model is realised by a differential equation describing the electric current, considering only inductance and capacitance; dissipation due to resistance is neglected. This creates a discrepancy between measurement and model, which is corrected by a data‐driven model. In the experiments, the inductance and the capacity are varied. It is found that the same data‐driven model can only be used if additional parametric dependencies in the data‐driven term are considered as well. AU - Wohlleben, Meike Claudia AU - Muth, Lars AU - Peitz, Sebastian AU - Sextro, Walter ID - 46813 KW - Electrical and Electronic Engineering KW - Atomic and Molecular Physics KW - and Optics SN - 1617-7061 T2 - Proceedings in Applied Mathematics and Mechanics TI - Transferability of a discrepancy model for the dynamics of electromagnetic oscillating circuits ER - TY - CONF AB - This paper presents a comprehensive study on diagnosing a spacecraft propulsion system utilizing data provided by the Prognostics and Health Management (PHM) society, specifically obtained as part of the Asia-Pacific PHM conference’s data challenge 2023. The objective of the challenge is to identify and diagnose known faults as well as unknown anomalies in the spacecraft’s propulsion system, which is critical for ensuring the spacecraft’s proper functionality and safety. To address this challenge, the proposed method follows a systematic approach of feature extraction, feature selection, and model development. The models employed in this study are kMeans clustering and decision trees combined to ensembles, enriched with expert knowledge. With the method presented, our team was capable of reaching high accuracy in identifying anomalies as well as diagnosing faults, resulting in attaining the seventh place with a score of 93.08 %. AU - Aimiyekagbon, Osarenren Kennedy AU - Löwen, Alexander AU - Bender, Amelie AU - Muth, Lars AU - Sextro, Walter ID - 47116 IS - 1 KW - PHM KW - Fault Diagnostics KW - Multiple Fault Modes KW - Expert-Informed Diagnostics KW - Anomaly Detection T2 - Proceedings of the Asia Pacific Conference of the PHM Society 2023 TI - Expert-Informed Hierarchical Diagnostics of Multiple Fault Modes of a Spacecraft Propulsion System VL - 4 ER - TY - GEN AU - Scheidemann, Claus AU - Hemsel, Tobias AU - Friesen, Olga AU - Claes, Leander AU - Sextro, Walter ID - 51117 TI - Influence of Temperature and Pre-Stress on the Piezoelectric Material Behavior of Ring-Shaped Ceramics ER - TY - GEN AU - Scheidemann, Claus AU - Hemsel, Tobias AU - Friesen, Olga AU - Claes, Leander AU - Sextro, Walter ID - 51118 TI - Influence of Temperature and Pre-Stress on the Piezoelectric Material Behavior of Ring-Shaped Ceramics ER - TY - GEN AU - Scheidemann, Claus AU - Hagedorn, Oliver Ernst Caspar AU - Hemsel, Tobias AU - Sextro, Walter ID - 51119 TI - Experimental Investigation of Bond Formation and Wire Deformation in the Ultrasonic Wire Bonding Process ER - TY - CHAP AU - Schütte, Jan AU - Sextro, Walter ID - 51338 T2 - 20. VDI-Fachtagung Reifen - Fahrwerk - Fahrbahn TI - Einfluss der Radhubkinematik auf den Reifenverschleiß VL - 2425 ER - TY - CONF AB - Tire and road wear are a major source of emissions of nonexhaust particulate matter (PM) and make up the largest share of microplastics in the environment. To reduce tire wear through numerical optimization of a vehicle's suspension system, fast simulations of the representative usage of a vehicle are needed. Therefore, this contribution evaluates if instead of a full simulation of a representative test drive, only specific driving maneuvers resulting from a clustering of the driving data can be used to predict tire wear. As a measure for tire wear, the friction work between tire and road is calculated. It is shown that enough clusters result in negligible deviations between the total friction work of the full simulation and the cluster simulations as well as between the distributions of the friction work over the tire width. The calculation time can be reduced to about 1% of the full simulation. AU - Muth, Lars AU - Noll, Christian AU - Sextro, Walter ED - Orlova, Anna ED - Cole, David ID - 29934 KW - Tire Wear KW - Vehicle Dynamics KW - Clustering KW - Virtual Test SN - 978-3-031-07304-5 T2 - Advances in Dynamics of Vehicles on Roads and Tracks II - Proceedings of the 27th Symposium of the International Association of Vehicle System Dynamics, IAVSD 2021 TI - Generation of a Reduced, Representative, Virtual Test Drive for Fast Evaluation of Tire Wear by Clustering of Driving Data ER - TY - CHAP AU - Wohlleben, Meike Claudia AU - Bender, Amelie AU - Peitz, Sebastian AU - Sextro, Walter ID - 29727 SN - 0302-9743 T2 - Machine Learning, Optimization, and Data Science TI - Development of a Hybrid Modeling Methodology for Oscillating Systems with Friction ER - TY - CONF AB - To achieve optimum bond results at ultrasonic bonding thick copper wire on sensitive components is quite challenging. Bearing in mind that high normal force and ultrasonic power are needed for bond quality but as well increase stress and finally failure risk of the substrate, methods should be found to achieve high bond quality even at lower bond parameters. Therefore, bond experiments with different bond tool grove geometries have been conducted for copper and aluminum wire on direct copper bonded (DCB) substrates to investigate the impact of geometric parameters on bond formation and bond quality. The wire material depending impact of geometry changes on the bond formation and deformation was quantified. Additionally, a bonding parameter design of experiments (DOE) has been conducted for the reference and the most promising groove geometry. Higher shear values were achieved at reduced vertical tool displacement for most bonding parameter combinations, compared to the reference tool. This behavior allows for reducing ultrasonic power to obtain equal shear values; consequently, mechanical stresses in the interface decrease. This could potentially reduce the risk of chip damage and thus yield loss. AU - Hagedorn, Oliver Ernst Caspar AU - Broll, Marian AU - Kirsch, Olaf AU - Hemsel, Tobias AU - Sextro, Walter ID - 30371 SN - ISBN 978-3-8007-5757-2 T2 - CIPS 2022 - 12th International Conference on Integrated Power Electronics Systems TI - Experimental Investigation of the Influence of different Bond Tool Grooves on the Bond Quality for Ultrasonic Thick Wire Bonding ER - TY - GEN AU - Aimiyekagbon, Osarenren Kennedy AU - Bender, Amelie AU - Sextro, Walter ID - 47159 IS - 425 SN - 0268-8050 T2 - Condition Monitor TI - On the applicability of time series features as health indicators for technical systems operating under varying conditions ER - TY - CONF AB - ue to the constantly growing energy demand of power electronics and the need to reduce the size of electronic components like power modules for e-mobility, new challenges arise for ultrasonic wire bonding: the electrical connection must endure higher thermal and mechanical stress while the connecting partners become more sensitive or require more energy to get bonded. Past investigations have shown already that multi-dimensional ultrasonic bonding and welding yield the same or even better bond quality while reducing the load on the components. This contribution is intended to show whether multidi-mensional thick wire bonding is a promising concept to over-come the new challenges. The focus is on experimental investi-gations of different bond tool trajectories in ultrasonic wire bonding of aluminum and copper wire on DCB's and chips. The bond quality is analyzed by shear tests, microsections and, in the case of aluminum bonding, by a new machine learning method for an objective automated evaluation of the sheared area. AU - Scheidemann, Claus AU - Kirsch, Olaf AU - Hemsel, Tobias AU - Sextro, Walter ID - 34104 T2 - 2022 IEEE 9th Electronics System-Integration Technology Conference (ESTC) TI - Experimental Investigation of Multidimensional Ultrasonic Heavy Wire Bonding ER - TY - GEN AB - Die Erfindung betrifft ein Gerät mit wenigstens einem elastisch verformbaren Bauteil als Strukturteil und/oder Lagerteil, auf das im Betriebsverlauf von wechselnden Betriebszuständen abhängige, unterschiedliche Verformungskräfte einwirken, die zu einem die Bauteilnutzungsdauer begrenzenden Bauteilverschleiß führen, und mit einer Einrichtung zur Bestimmung der Bauteilnutzungsdauer und einer verschleißbedingten Bauteil-Restnutzungsdauer. Erfindungsgemäß wird ein sich zeitversetzt wiederholender, jeweils gleicher Betriebszustand vorbestimmt, dem eine jeweils gleiche, periodisch wirkende Verformungskraft zugeordnet ist, durch die das elastisch verformbare Bauteilmaterial periodisch verformt wird, wobei durch Walkarbeit ein Energieeintrag mit einem messbaren Temperaturanstieg im Vergleich zu einer Umgebungstemperatur erfolgt und wobei der jeweilige Temperaturanstieg als Kenngröße im Verlauf einer Bauteilnutzungsdauer entsprechend einer abnehmenden Bauteilsteifigkeit größer wird. Ein solcher vorbestimmter Betriebszustand wird jeweils von einer Messund Auswerteeinheit erkannt und ein Messvorgang durch ein Startsignal selbsttätig gestartet, wobei mit wenigstens einem bauteilzugeordneten Temperatursensor, der aktuelle Temperaturanstieg im Vergleich zur Umgebungstemperatur als Kenngröße für eine aktuelle Bauteilsteifigkeit gemessen und jeweils in einer Messkurve gespeichert und verglichen wird. AU - Reinke, Kai AU - Bender, Amelie AU - Meyer, Tobias AU - Sextro, Walter AU - Kimotho, James Kuria ID - 9980 TI - Patent DE 10 2017 000 926 B4: Gerät mit wenigstens einem elastisch verformbaren Bauteil, insbesondere einem Gummi-Metall-Lager und mit einer Einrichtung zur Feststellung des Beginns einer verschleißbedingten Bauteil-Restnutzungsdauer, sowie Verfahren zur Bestimmung der Bauteil-Restnutzungsdauer. ER - TY - GEN AU - Scheidemann, Claus AU - Hemsel, Tobias AU - Sextro, Walter ID - 52045 TI - Modellbasierte Ermittlung optimaler Prozessparameter für neuartige Ultraschallbondverbindungen ER - TY - CONF AB - Aufgrund der Fortschritte der Digitalisierung finden Systeme zur Zustandsüberwachung vermehrt Einsatz in der Industrie, um durch eine zustandsbasierte oder eine prädiktive Instandhaltung Vorteile, wie eine verbesserte Zuverlässigkeit und geringere Kosten zu erzielen. Dabei beruhen Zustandsüberwachungssysteme auf den folgenden Bausteinen: Sensorik, Datenvorverarbeitung, Merkmalsextraktion und -auswahl, Diagnose bzw. Prognose sowie einer Entscheidungsfindung basierend auf den Ergebnissen. Jeder dieser Bausteine erfordert individuelle Einstellungen, um ein geeignetes Zustandsüberwachungssystem für die jeweilige Anwendung zu entwickeln. Eine offene Fragestellung im Bereich der Zustandsüberwachung ergibt sich aufgrund der Unsicherheit der Zukunft, die sich in den zukünftigen Betriebs- und Umgebungsbedingungen zeigt. Diese Unsicherheit gilt es in allen Bausteinen zu berücksichtigen. Dieser Beitrag konzentriert sich auf den Baustein Merkmalsextraktion und -selektion, mit dem Ziel anhand geeigneter Merkmale eine Prognose der nutzbaren Restlebensdauer mit hoher Genauigkeit realisieren zu können. Daher werden geeignete Merkmale aus dem Zeitbereich und daraus abgeleitete Zustandsindikatoren für die Restlebensdauerprognose von technischen Systemen vorgestellt. Dabei sind Zustandsindikatoren Kenngrößen zur Beobachtung des Zustands der kritischen Systemkomponenten. Anhand dreier Anwendungsbeispiele wird ihre Eignung evaluiert. Dabei werden Daten aus Lebensdauerversuchen unter instationären Betriebs- und Umgebungsbedingungen ausgewertet. Die auftretenden Unsicherheiten der Zukunft werden somit berücksichtigt. Die Beispielsysteme beruhen auf Gummi-Metall-Elementen und Wälzlagern. Aus den generierten Ergebnissen lässt sich schließen, dass die Zustandsindikatoren aus der betrachteten Zeitreihen-Toolbox auch unter unbekannten Betriebs- und Umgebungsbedingungen robust sind. AU - Aimiyekagbon, Osarenren Kennedy AU - Bender, Amelie AU - Sextro, Walter ID - 27652 KW - run-to-failure KW - rubber-metal element KW - bearing prognostics KW - non-stationary operating conditions KW - varying operating conditions KW - feature extraction KW - feature selection SN - 0083-5560 T2 - VDI-Berichte 2391 TI - Extraktion und Selektion geeigneter Merkmale für die Restlebensdauerprognose von technischen Systemen trotz aleatorischen Unsicherheiten ER - TY - JOUR AB - Ultrasonic wire bonding is a solid-state joining process, used in the electronics industry to form electrical connections, e.g. to connect electrical terminals within semiconductor modules. Many process parameters affect the bond strength, such like the bond normal force, ultrasonic power, wire material and bonding frequency. Today, process design, development, and optimization is most likely based on the knowledge of process engineers and is mainly performed by experimental testing. In this contribution, a newly developed simulation tool is presented, to reduce time and costs and efficiently determine optimized process parameter. Based on a co-simulation of MATLAB and ANSYS, the different physical phenomena of the wire bonding process are considered using finite element simulation for the complex plastic deformation of the wire and reduced order models for the transient dynamics of the transducer, wire, substrate and bond formation. The model parameters such as the coefficients of friction between bond tool and wire and between wire and substrate were determined for aluminium and copper wire in experiments with a test rig specially developed for the requirements of heavy wire bonding. To reduce simulation time, for the finite element simulation a restart analysis and high performance computing is utilized. Detailed analysis of the bond formation showed, that the normal pressure distribution in the contact between wire and substrate has high impact on bond formation and distribution of welded areas in the contact area. AU - Schemmel, Reinhard AU - Krieger, Viktor AU - Hemsel, Tobias AU - Sextro, Walter ID - 21436 JF - Microelectronics Reliability KW - Ultrasonic heavy wire bonding KW - Co-simulation KW - ANSYS KW - MATLAB KW - Process optimization KW - Friction coefficient KW - Copper-copper KW - Aluminium-copper SN - 0026-2714 TI - Co-simulation of MATLAB and ANSYS for ultrasonic wire bonding process optimization VL - 119 ER - TY - CONF AB - Predictive Maintenance as a desirable maintenance strategy in industrial applications relies on suitable condition monitoring solutions to reduce costs and risks of the monitored technical systems. In general, those solutions utilize model-based or data-driven methods to diagnose the current state or predict future states of monitored technical systems. However, both methods have their advantages and drawbacks. Combining both methods can improve uncertainty consideration and accuracy. Different combination approaches of those hybrid methods exist to exploit synergy effects. The choice of an appropriate approach depends on different requirements and the goal behind the selection of a hybrid approach. In this work, the hybrid approach for estimating remaining useful lifetime takes potential uncertainties into account. Therefore, a data-driven estimation of new measurements is integrated within a model-based method. To consider uncertainties within the system, a differentiation between different system behavior is realized throughout diverse states of degradation. The developed hybrid prediction approach bases on a particle filtering method combined with a machine learning method, to estimate the remaining useful lifetime of technical systems. Particle filtering as a Monte Carlo simulation technique is suitable to map and propagate uncertainties. Moreover, it is a state-of-the-art model-based method for predicting remaining useful lifetime of technical systems. To integrate uncertainties a multi-model particle filtering approach is employed. In general, resampling as a part of the particle filtering approach has the potential to lead to an accurate prediction. However, in the case where no future measurements are available, it may increase the uncertainty of the prediction. By estimating new measurements, those uncertainties are reduced within the data-driven part of the approach. Hence, both parts of the hybrid approach strive to account for and reduce uncertainties. Rubber-metal-elements are employed as a use-case to evaluate the developed approach. Rubber-metal-elements, which are used to isolate vibrations in various systems, such as railways, trucks and wind turbines, show various uncertainties in their behavior and their degradation. Those uncertainties are caused by diverse inner and outer factors, such as manufacturing influences and operating conditions. By expert knowledge the influences are described, analyzed and if possible reduced. However, the remaining uncertainties are considered within the hybrid prediction method. Relative temperature is the selected measurand to describe the element’s degradation. In lifetime tests, it is measured as the difference between the element’s temperature and the ambient temperature. Thereby, the influence of the ambient temperature on the element’s temperature is taken into account. Those elements show three typical states of degradation that are identified within the temperature measurements. Depending on the particular state of degradation a new measurement is estimated within the hybrid approach to reduce potential uncertainties. Finally, the performance of the developed hybrid method is compared to a model-based method for estimating the remaining useful lifetime of the same elements. Suitable performance indices are implemented to underline the differences between the results. AU - Bender, Amelie AU - Sextro, Walter ED - Do, Phuc ED - King, Steve ED - Fink, Olga ID - 22724 IS - 1 KW - Hybrid prediction method KW - Multi-model particle filtering KW - Uncertainty quantification KW - RUL estimation T2 - Proceedings of the European Conference of the PHM Society 2021 TI - Hybrid Prediction Method for Remaining Useful Lifetime Estimation Considering Uncertainties VL - 6 ER - TY - CONF AB - Several methods, including order analysis, wavelet analysis and empirical mode decomposition have been proposed and successfully employed for the health state estimation of technical systems operating under varying conditions. However, where information such as the speed of rotating machinery, component specifications or other domain-specific information is unavailable, such methods are often infeasible. Thus, this paper investigates the application of classical time-domain features, features from the medical field and novel features from the highly comparative time-series analysis (HCTSA) package, for the health state estimation of rotating machinery operating under varying conditions. Furthermore, several feature selection methods are investigated to identify features as viable health indicators for the diagnostics and prognostics of technical systems. As a case study, the presented methods are evaluated on real-world and experimentally acquired vibration data of bearings operating under varying speed. The results show that the selected features can successfully be employed as health indicators for technical systems operating under varying conditions. AU - Aimiyekagbon, Osarenren Kennedy AU - Bender, Amelie AU - Sextro, Walter ID - 22507 KW - Wind turbine diagnostics KW - bearing diagnostics KW - non-stationary operating conditions KW - varying operating conditions KW - feature extraction KW - feature selection KW - fault detection KW - failure detection T2 - Proceedings of the Seventeenth International Conference on Condition Monitoring and Asset Management (CM 2021) TI - On the applicability of time series features as health indicators for technical systems operating under varying conditions ER - TY - CONF AB - In the industry 4.0 era, there is a growing need to transform unstructured data acquired by a multitude of sources into information and subsequently into knowledge to improve the quality of manufactured products, to boost production, for predictive maintenance, etc. Data-driven approaches, such as machine learning techniques, are typically employed to model the underlying relationship from data. However, an increase in model accuracy with state-of-the-art methods, such as deep convolutional neural networks, results in less interpretability and transparency. Due to the ease of implementation, interpretation and transparency to both domain experts and non-experts, a rule-based method is proposed in this paper, for prognostics and health management (PHM) and specifically for diagnostics. The proposed method utilizes the most relevant sensor signals acquired via feature extraction and selection techniques and expert knowledge. As a case study, the presented method is evaluated on data from a real-world quality control set-up provided by the European prognostics and health management society (PHME) at the conference’s 2021 data challenge. With the proposed method, our team took the third place, capable of successfully diagnosing different fault modes, irrespective of varying conditions. AU - Aimiyekagbon, Osarenren Kennedy AU - Muth, Lars AU - Wohlleben, Meike Claudia AU - Bender, Amelie AU - Sextro, Walter ED - Do, Phuc ED - King, Steve ED - Fink, Olga ID - 27111 IS - 1 KW - PHME 2021 KW - Feature Selection Classification KW - Feature Selection Clustering KW - Interpretable Model KW - Transparent Model KW - Industry 4.0 KW - Real-World Diagnostics KW - Quality Control KW - Predictive Maintenance T2 - Proceedings of the European Conference of the PHM Society 2021 TI - Rule-based Diagnostics of a Production Line VL - 6 ER - TY - JOUR AB - To analyze the influence of suspension kinematics on tire wear, detailed simulation models are required. In this study, a non-linear, flexible multibody model of a rear axle system is built up in the simulation software MSC Adams/View. The physical model comprises the suspension kinematics, compliance, and dynamics as well as the non-linear behavior of the tire using the FTire model. FTire is chosen because it has a separate tire tread model to compute the contact pressure and friction force distribution in the tire contact patch. To build up the simulation model, a large amount of data is needed. Bushings, spring, and damper characteristics are modeled based on measurements. For the structural components (e.g., control arms), reverse engineering techniques are used. The components are 3D-scanned, reworked, and included as a modal reduced finite element (FE)-model using component mode synthesis by Craig–Bampton. Finally, the suspension model is validated by comparing the simulated kinematic and compliance characteristics to experimental results. To investigate the interaction of suspension kinematics and tire wear, straight line driving events, such as acceleration, driving with constant velocity, and deceleration, are simulated with different setups of wheel suspension kinematics. The influence of the setups on the resulting friction work between tire and road is examined, and an exemplarily calculation of tire wear based on a validated FTire tire model is carried out. The results demonstrate, on the one hand, that the chosen concept of elasto-kinematic axle leads to a relatively good match with experimental results and, on the other hand, that there are significant possibilities to reduce tire wear by adjusting the suspension kinematics. AU - Schütte, Jan AU - Sextro, Walter ID - 27508 JF - Vehicles SN - 2624-8921 TI - Tire Wear Reduction Based on an Extended Multibody Rear Axle Model ER -