TY - CHAP A1 - Schulz, Carsten A1 - Vogl, Yannick A1 - Geiger, Benjamin A1 - Schaeffer, Thomas T1 - Lumped-Mass-Modellierung von Förderbändern am Beispiel eines Zwei-Walzensystems mit flexiblen Walzen T2 - Dresdner Maschinenelemente Kolloquium - DMK 2024, 14.-15. Mai 2024, Dresden Y1 - 2024 ER - TY - JOUR A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schuderer, Matthias T1 - LuGre or not LuGre JF - Multibody System Dynamics N2 - The LuGre model is widely used in the analysis and control of systems with friction. Recently, it has even been made available in the commercial multibody dynamics simulation software system Adams. However, the LuGre model exhibits well-known drawbacks like too low and force rate-dependent break-away forces, drift problems during sticking periods, and significant differences in non-stationary situations between the pre-defined friction law and the one produced by the LuGre model. In the present literature, these problems are supposed to come from the model dynamics or its nonlinear nature. However, most of these drawbacks are not simple side effects of a dynamic friction model but are caused in the LuGre approach, as shown here, by a too simple and inconsistent model of the bristle dynamics. Standard examples and a more practical application demonstrate that the LuGre model is not a “what you see is what you get” approach. A dynamic friction model with accurate bristle dynamics and consistent friction force is set up here. It provides insight into the physical basis of the LuGre model dynamics. However, it results in a nonlinear and implicit differential equation, whose solution will not be easy because of the ambiguity of the friction characteristics. The standard workaround, a static model based on simple regularized characteristics, produces reliable and generally satisfactory results but definitely cannot maintain a stick. The paper presents a second-order dynamic friction model, which may serve as an alternative. It can maintain a stick and produces realistic and reliable results. KW - Dynamic friction model KW - LuGre model KW - Asymmetric regularization KW - Break-away force KW - Stick-slip KW - Multibody dynamics Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-65653 N1 - Corresponding author: Georg Rill PB - Springer ER - TY - INPR A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schuderer, Matthias T1 - LuGre or not LuGre N2 - The LuGre model is widely used in the analysis and control of systems with friction. Recently, it has even been made available in the commercial multibody dynamics simulation software system Adams. However, the LuGre model exhibits well-known drawbacks like, too low and force rate dependent break-away forces, drift problems during sticking periods, and significant differences in non-stationary situations between the pre-defined friction law and the one produced by the LuGre model. In the present literature, these problems are supposed to come from the model dynamics or its nonlinear nature. However, most of these drawbacks are not simple side effects of a dynamic friction model but are caused in the LuGre approach, as shown here, by a too simple and inconsistent model of the bristle dynamics. Standard examples and a more practical application demonstrate, that the LuGre model is not a “what you see is what you get” approach. A dynamic friction model with accurate bristle dynamics and consistent friction force is set up here. It provides insight into the physical basis of the LuGre model dynamics. However, it results in a nonlinear and implicit differential equation, whose solution will not be easy because of the ambiguity of the friction characteristics. The standard workaround, a static model based on a simple regularized characteristics, produces reliable and generally satisfactory results, but definitely cannot maintain stick. The paper presents a second order dynamic friction model, which may serve as an alternative. It can maintain stick and produces realistic and reliable results. Y1 - 2022 U6 - https://doi.org/10.21203/rs.3.rs-2266522/v1 ER - TY - GEN A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schulz, Carsten A1 - Schaeffer, Thomas T1 - Dynamic Stick-Slip Models based on Continuous and Discontinuous Friction Characteristics T2 - ENOC - European Nonlinear Dynamics Conference, 11th, 2024, Delft N2 - This paper presents the implementation of a recently developed continuous second-order dynamic friction model (FrD2) in the commercial multibody system software Simpack, where it is evaluated against Simpack's discontinuous friction model for stick-slip applications in terms of performance. A method for adapting parameters from the well-known LuGre model to the FrD2 model is introduced. The FrD2 model accurately captures complex friction phenomena, including the Stribeck effect, which is essential for simulating friction-induced vibrations. Tested on a festoon cable system and a belt model, the FrD2 model demonstrates itself as a robust alternative to both the LuGre and Simpack models, especially for applications requiring continuous transitions between static and dynamic friction states, long-term stiction effects, and other complex friction behaviors. KW - Multibody Simulation KW - Simpack KW - FrD2 KW - LuGre KW - Stick-slip Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.5014569 ER - TY - JOUR A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Schratzenstaller, Thomas A1 - Dendorfer, Sebastian A1 - Böhm, Valter T1 - Theoretical considerations on stiffness characteristics of a 3-dimensional tensegrity joint model for the use in dynamic hand orthoses JF - Journal of Medical Robotics Research Y1 - 2025 U6 - https://doi.org/10.1142/S2424905X25400069 PB - World Scientific ER - TY - GEN A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schulz, Carsten T1 - Friction modeling from a practical point of view T2 - MULTIBODY2023: 11th ECCOMAS Thematic Conference on Multibody Dynamics, Tampa, 24th-28th May 2023 Y1 - 2023 ER - TY - JOUR A1 - Vogl, Yannick A1 - Schulz, Carsten A1 - Schaeffer, Thomas A1 - Geiger, Benjamin T1 - Prediction of the wear behavior of a conveyor belt with flexible rollers JF - Multibody System Dynamics N2 - This paper introduces a method to predict wear behavior in conveyor belt systems using a lumped mass modeling approach. While previous research has focused primarily on lateral belt walking, this study shifts attention to belt deformation and its associated wear. Both significantly affect system efficiency and component lifespan. The authors propose using local frictional power as a wear indicator, leveraging its direct relation to frictional work in established wear models. To solely demonstrate the method, the study simulates a conveyor belt with three flexible rollers and a deformable belt modeled through rigid spheres connected by spring-damper elements. The authors visualize frictional power density across the belt width, distinguishing between running and transverse directions. The results demonstrate that the frictional power distribution depends heavily on discretization quality, particularly due to the polygon effect inherent in the lumped mass approach. A convergence analysis reveals the minimum necessary discretization of the belt, ensuring reliable qualitative results. To support the credibility of the work, this study compares theoretical expectations and initial wear observations from a real belt with the results from the shown approach. The plausibility check already shows promising results. The proposed methodology provides an adaptable framework to evaluate wear in belt-like structures. It can be readily adapted to a variety of multibody dynamics applications and integrated into larger MBS models that include the overall drivetrain and engine control. Future work will focus on refining discretization strategies and contact models, as well as validation of the wear model to enable quantitative predictions. Y1 - 2025 U6 - https://doi.org/10.1007/s11044-025-10097-7 SN - 1384-5640 N1 - Die Preprint-Version ist ebenfalls in diesem Repositorium verzeichnet: https://opus4.kobv.de/opus4-oth-regensburg/8194 PB - Springer CY - Cham ER - TY - INPR A1 - Vogl, Yannick A1 - Schulz, Carsten A1 - Schaeffer, Thomas A1 - Geiger, Benjamin T1 - Prediction of the wear behavior of a conveyor belt with flexible rollers N2 - This paper introduces a method to predict wear behavior in conveyor belt systems using a lumped mass modeling approach. While previous research has focused primarily on lateral belt walking, this study shifts attention to belt deformation and its associated wear. Both significantly affect system efficiency and component lifespan. The authors propose using local frictional power as a wear indicator, leveraging its direct relation to frictional work in established wear models. To validate the method, the study simulates a conveyor belt with three flexible rollers and a deformable belt modeled through rigid spheres connected by spring-damper elements. The authors quantify and visualize frictional power density across the belt width, distinguishing between running and transverse directions. The results demonstrate that the frictional power distribution depends heavily on discretization quality, particularly due to the polygon effect inherent in the lumped mass approach. A convergence analysis reveals a minimum discretization of nine sphere rows with 557 spheres per row to achieve reliable qualitative insights. This method enables researchers to evaluate wear distribution in flexible conveyor systems and adapt the approach for broader applications in multibody dynamics. Future work should refine discretization techniques and friction models to enhance quantitative accuracy. Y1 - 2025 U6 - https://doi.org/10.21203/rs.3.rs-6343500/v1 N1 - Der Aufsatz wurde peer-reviewed veröffentlicht und ist ebenfalls in diesem Repositorium verzeichnet unter: https://opus4.kobv.de/opus4-oth-regensburg/8489 PB - Research Square Platform LLC ER -