%0 Thesis %1 mitruka2021implementation %A Vinod Kumar Mitruka, Tarun Kumar Mitruka %D 2021 %I Masterarbeit. Betreuer: Tobias Willmann und Dr. Ulrich Mandel (Hilti AG, Kaufering). Institut für Baustatik und Baudynamik, Universität Stuttgart %K ibb %T Implementation of a Hyperelastic and a Non-linear Viscoelastic Material Model for Elastomers in LS-DYNA %X Hammering tools uses damping elements of various geometries and hardness levels not only to reduce the reaction forces and vibrations, but also to protect the structural parts from failure. This makes damping elements a key component during the design phase of any tool. Since many design quantities initially rely on the results obtained via simulations for optimization and improvement purposes, it makes it essential to have an appropriate material model which could capture the behaviour of the damping elements accurately. Damping elements are made up of elastomeric compounds showcasing highly non-linear behaviour especially when subjected to very high strains and strain rates when mounted in a tool. This aim of this work is to study various phenomena regarding the rubber material behaviour and develop a user-defined material model in LS-DYNA which provides error-free stress updates at a given strain level for elastomers. The fundamental concepts of hyperelastic and viscoelastic constitutive theories are emphasized in the beginning as these theories are more suitable to model elastomeric behaviour. Material parameter identification procedure is also highlighted for both hyperelastic and linear viscoleastic material models. An Ogden-based linear viscoelastic model is programmed which is extended with strain-level based non-linearity included in the material model and later validated with the experimental results obtained with a gas-gun test fixture and O-ring specimens. Discussions regarding energy dissipation is focussed towards the end as it plays a crucial role in understanding the behaviour of the damping element.

@mastersthesis{mitruka2021implementation, abstract = {Hammering tools uses damping elements of various geometries and hardness levels not only to reduce the reaction forces and vibrations, but also to protect the structural parts from failure. This makes damping elements a key component during the design phase of any tool. Since many design quantities initially rely on the results obtained via simulations for optimization and improvement purposes, it makes it essential to have an appropriate material model which could capture the behaviour of the damping elements accurately. Damping elements are made up of elastomeric compounds showcasing highly non-linear behaviour especially when subjected to very high strains and strain rates when mounted in a tool. This aim of this work is to study various phenomena regarding the rubber material behaviour and develop a user-defined material model in LS-DYNA which provides error-free stress updates at a given strain level for elastomers. The fundamental concepts of hyperelastic and viscoelastic constitutive theories are emphasized in the beginning as these theories are more suitable to model elastomeric behaviour. Material parameter identification procedure is also highlighted for both hyperelastic and linear viscoleastic material models. An Ogden-based linear viscoelastic model is programmed which is extended with strain-level based non-linearity included in the material model and later validated with the experimental results obtained with a gas-gun test fixture and O-ring specimens. Discussions regarding energy dissipation is focussed towards the end as it plays a crucial role in understanding the behaviour of the damping element. }, added-at = {2021-10-15T11:30:41.000+0200}, author = {Vinod Kumar Mitruka, Tarun Kumar Mitruka}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2efc6a63682e9cf5503255472b6d75092/ibb-publication}, interhash = {07cb7df84d10ea1328b75bde46f6948a}, intrahash = {efc6a63682e9cf5503255472b6d75092}, keywords = {ibb}, publisher = {Masterarbeit. Betreuer: Tobias Willmann und Dr. Ulrich Mandel (Hilti AG, Kaufering). Institut für Baustatik und Baudynamik, Universität Stuttgart}, timestamp = {2022-08-17T14:40:09.000+0200}, title = {Implementation of a Hyperelastic and a Non-linear Viscoelastic Material Model for Elastomers in LS-DYNA}, year = 2021 }