Imperial College London

Professor Norbert Hoffmann

Faculty of EngineeringDepartment of Mechanical Engineering

Visiting Professor
 
 
 
//

Contact

 

n.hoffmann

 
 
//

Location

 

557City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Publication Type
Year
to

163 results found

Stender M, Hoffmann N, 2021, bSTAB: an open-source software for computing the basin stability of multi-stable dynamical systems, NONLINEAR DYNAMICS, ISSN: 0924-090X

Journal article

Chabchoub A, Slunyaev A, Hoffmann N, Dias F, Kibler B, Genty G, Dudley JM, Akhmediev Net al., 2021, The Peregrine Breather on the Zero-Background Limit as the Two-Soliton Degenerate Solution: An Experimental Study, Frontiers in Physics, Vol: 9

<jats:p>Solitons are coherent structures that describe the nonlinear evolution of wave localizations in hydrodynamics, optics, plasma and Bose-Einstein condensates. While the Peregrine breather is known to amplify a single localized perturbation of a carrier wave of finite amplitude by a factor of three, there is a counterpart solution on zero background known as the degenerate two-soliton which also leads to high amplitude maxima. In this study, we report several observations of such multi-soliton with doubly-localized peaks in a water wave flume. The data collected in this experiment confirm the distinctive attainment of wave amplification by a factor of two in good agreement with the dynamics of the nonlinear Schrödinger equation solution. Advanced numerical simulations solving the problem of nonlinear free water surface boundary conditions of an ideal fluid quantify the physical limitations of the degenerate two-soliton in hydrodynamics.</jats:p>

Journal article

Klein M, Clauss GF, Hoffmann N, 2021, Introducing envelope soliton solutions for wave-structure investigations, OCEAN ENGINEERING, Vol: 234, ISSN: 0029-8018

Journal article

Neidhardt M, Ohlsen J, Hoffmann N, Schlaefer Aet al., 2021, Parameter Identification for Ultrasound Shear Wave Elastography Simulation, Current Directions in Biomedical Engineering, Vol: 7

Elasticity of soft tissue is a valuable information to physicians in treatment and diagnosis of diseases. The elastic properties of tissue can be estimated with ultrasound (US) shear wave imaging (SWEI). In US-SWEI, a force push is applied inside the tissue and the resulting shear wave is detected by high-frequency imaging. The properties of the wave such as the shear wave velocity can be mapped to tissue elasticity. Commonly, wave features are extracted by tracking the peak of the shear wave, estimating the phase velocity or with machine learning methods. To tune and test these methods, often simulation data is employed since material properties and excitation can be accurately controlled. Subsequent validation on real US-SWEI data is in many cases performed on tissue phantoms such as gelatine. Clearly, validation performance of these procedures is dependent on the accuracy of the simulated tissue phantom and a thorough comparison of simulation and experimental data is needed. In this work, we estimate wave parameters from 400 US-SWEI data sets acquired in various homogeneous gelatine phantoms. We tune a linear material model to these parameters. We report an absolute percentage error for the shear wave velocity between simulation and phantom experiment of <2.5%. We validate our material model on unknown gelatine concentrations and estimate the shear wave velocity with an error <3.4% for in-range concentrations indicating that our material model is in good agreement with US-SWEI measurements.

Journal article

Papangelo A, Putignano C, Hoffmann N, 2021, Critical thresholds for mode-coupling instability in viscoelastic sliding contacts, NONLINEAR DYNAMICS, Vol: 104, Pages: 2995-3011, ISSN: 0924-090X

Journal article

Niedergesass B, Papangelo A, Grolet A, Vizzaccaro A, Fontanela F, Salles L, Sievers AJ, Hoffmann Net al., 2021, Experimental observations of nonlinear vibration localization in a cyclic chain of weakly coupled nonlinear oscillators, JOURNAL OF SOUND AND VIBRATION, Vol: 497, ISSN: 0022-460X

Journal article

Stender M, Adams C, Wedler M, Grebel A, Hoffmann Net al., 2021, Explainable machine learning determines effects on the sound absorption coefficient measured in the impedance tubea), JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, Vol: 149, Pages: 1932-1945, ISSN: 0001-4966

Journal article

Fontanela F, Vizzaccaro A, Auvray J, Niedergesäß B, Grolet A, Salles L, Hoffmann Net al., 2021, Nonlinear vibration localisation in a symmetric system of two coupled beams, Nonlinear Dynamics, Vol: 103, Pages: 3417-3428, ISSN: 0924-090X

We report nonlinear vibration localisation in a system of two symmetric weakly coupled nonlinear oscillators. A two degree-of-freedom model with piecewise linear stiffness shows bifurcations to localised solutions. An experimental investigation employing two weakly coupled beams touching against stoppers for large vibration amplitudes confirms the nonlinear localisation.

Journal article

Stender M, Tiedemann M, Spieler D, Schoepflin D, Hoffmann N, Oberst Set al., 2021, Deep learning for brake squeal: Brake noise detection, characterization and prediction, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 149, ISSN: 0888-3270

Journal article

Nitti A, Stender M, Hoffmann N, Papangelo Aet al., 2021, Spatially localized vibrations in a rotor subjected to flutter, NONLINEAR DYNAMICS, Vol: 103, Pages: 309-325, ISSN: 0924-090X

Journal article

Ohlsen J, Neidhardt M, Schlaefer A, Hoffmann Net al., 2021, Modelling shear wave propagation in soft tissue surrogates using a finite element‐ and finite difference method, PAMM, Vol: 20, ISSN: 1617-7061

Journal article

Stender M, Hoffmann N, Papangelo A, 2020, The Basin Stability of Bi-Stable Friction-Excited Oscillators, LUBRICANTS, Vol: 8

Journal article

Tonazzi D, Passafiume M, Papangelo A, Hoffmann N, Massi Fet al., 2020, Numerical and experimental analysis of the bi-stable state for frictional continuous system, NONLINEAR DYNAMICS, Vol: 102, Pages: 1361-1374, ISSN: 0924-090X

Journal article

Papangelo A, Putignano C, Hoffmann N, 2020, Self-excited vibrations due to viscoelastic interactions, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 144, ISSN: 0888-3270

Journal article

Stender M, Jahn M, Hoffmann N, Wallaschek Jet al., 2020, Hyperchaos co-existing with periodic orbits in a frictional oscillator, JOURNAL OF SOUND AND VIBRATION, Vol: 472, ISSN: 0022-460X

Journal article

Hartmann MCN, Polach FVBU, Ehlers S, Hoffmann N, Onorato M, Klein Met al., 2020, Investigation of Nonlinear Wave-Ice Interaction Using Parameter Study and Numerical Simulation, JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 142, ISSN: 0892-7219

Journal article

Klein M, Dudek M, Clauss GF, Ehlers S, Behrendt J, Hoffmann N, Onorato Met al., 2020, On the Deterministic Prediction of Water Waves, FLUIDS, Vol: 5

Journal article

Jahn M, Stender M, Tatzko S, Hoffmann N, Grolet A, Wallaschek Jet al., 2020, The extended periodic motion concept for fast limit cycle detection of self-excited systems, COMPUTERS & STRUCTURES, Vol: 227, ISSN: 0045-7949

Journal article

Wollmann T, Dannemann M, Langkamp A, Modler N, Gude M, Salles L, Hoffmann N, Filippatos Aet al., 2020, Combined experimental-numerical approach for the 3D vibration analysis of rotating composite compressor blades: An introduction

© CCM 2020 - 18th European Conference on Composite Materials. All rights reserved. As compressor blades are subjected to highly dynamic loads, there is a particular interest in determining their modal properties under operating condition. Furthermore, intensive research is conducted for the development of fibre-reinforced epoxy blades due to the high specific stiffness and strength as well as the high damping of composite materials. Traditional modal analysis techniques are state of the art to determine the vibration behaviour of non-rotating/stationary blades, where some new approaches show the vibration analysis of rotating blades. These approaches for rotating structures have the disadvantage, that either the excitation or the measurement method are influencing the dynamic behaviour of the investigated structure or the method itself cannot be applied for composite materials. Other techniques do not allow a continuous or full-field measurement of the rotating structure. To determine the vibration behaviour of rotating composite compressor blades, a combined experimental-numerical approach is introduced. Therefore, an experimental system for the vibration excitation and a 3-dimensional determination of the vibration behaviour of rotating components are presented. An overview of the main addressed research topics is given.

Conference paper

Stender M, Hoffmann N, 2020, Deep learning for predicting brake squeal, International Conference on Noise and Vibration Engineering (ISMA) / International Conference on Uncertainty in Structural Dynamics (USD), Publisher: KATHOLIEKE UNIV LEUVEN, DEPT WERKTUIGKUNDE, Pages: 3327-3337

Conference paper

Shiroky IB, Papangelo A, Hoffmann N, Gendelman OVet al., 2020, Nucleation and propagation of excitation fronts in self-excited systems, PHYSICA D-NONLINEAR PHENOMENA, Vol: 401, ISSN: 0167-2789

Journal article

Wollmann T, Dannemann M, Langkamp A, Modler N, Gude M, Salles L, Hoffmann N, Filippatos Aet al., 2020, Combined experimental-numerical approach for the 3D vibration analysis of rotating composite compressor blades: An introduction

© CCM 2020 - 18th European Conference on Composite Materials. All rights reserved. As compressor blades are subjected to highly dynamic loads, there is a particular interest in determining their modal properties under operating condition. Furthermore, intensive research is conducted for the development of fibre-reinforced epoxy blades due to the high specific stiffness and strength as well as the high damping of composite materials. Traditional modal analysis techniques are state of the art to determine the vibration behaviour of non-rotating/stationary blades, where some new approaches show the vibration analysis of rotating blades. These approaches for rotating structures have the disadvantage, that either the excitation or the measurement method are influencing the dynamic behaviour of the investigated structure or the method itself cannot be applied for composite materials. Other techniques do not allow a continuous or full-field measurement of the rotating structure. To determine the vibration behaviour of rotating composite compressor blades, a combined experimental-numerical approach is introduced. Therefore, an experimental system for the vibration excitation and a 3-dimensional determination of the vibration behaviour of rotating components are presented. An overview of the main addressed research topics is given.

Conference paper

Wollmann T, Dannemann M, Langkamp A, Modler N, Gude M, Salles L, Hoffmann N, Filippatos Aet al., 2020, Combined experimental-numerical approach for the 3D vibration analysis of rotating composite compressor blades: An introduction

As compressor blades are subjected to highly dynamic loads, there is a particular interest in determining their modal properties under operating condition. Furthermore, intensive research is conducted for the development of fibre-reinforced epoxy blades due to the high specific stiffness and strength as well as the high damping of composite materials. Traditional modal analysis techniques are state of the art to determine the vibration behaviour of non-rotating/stationary blades, where some new approaches show the vibration analysis of rotating blades. These approaches for rotating structures have the disadvantage, that either the excitation or the measurement method are influencing the dynamic behaviour of the investigated structure or the method itself cannot be applied for composite materials. Other techniques do not allow a continuous or full-field measurement of the rotating structure. To determine the vibration behaviour of rotating composite compressor blades, a combined experimental-numerical approach is introduced. Therefore, an experimental system for the vibration excitation and a 3-dimensional determination of the vibration behaviour of rotating components are presented. An overview of the main addressed research topics is given.

Conference paper

Stender M, Di Bartolomeo M, Massi F, Hoffmann Net al., 2019, Revealing transitions in friction-excited vibrations by nonlinear time-series analysis, NONLINEAR DYNAMICS, Vol: 98, Pages: 2613-2630, ISSN: 0924-090X

Journal article

Stender M, Tiedemann M, Hoffmann N, 2019, Energy harvesting below the onset of flutter, JOURNAL OF SOUND AND VIBRATION, Vol: 458, Pages: 17-21, ISSN: 0022-460X

Journal article

Stender M, Oberst S, Tiedemann M, Hoffmann Net al., 2019, Complex machine dynamics: systematic recurrence quantification analysis of disk brake vibration data, NONLINEAR DYNAMICS, Vol: 97, Pages: 2483-2497, ISSN: 0924-090X

Journal article

Gnanasambandham C, Stender M, Hoffmann N, Eberhard Pet al., 2019, Multi-scale dynamics of particle dampers using wavelets: Extracting particle activity metrics from ring down experiments, JOURNAL OF SOUND AND VIBRATION, Vol: 454, Pages: 1-13, ISSN: 0022-460X

Journal article

Stender M, Tiedemann M, Hoffmann L, Hoffmann Net al., 2019, Determining growth rates of instabilities from time-series vibration data: Methods and applications for brake squeal, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 129, Pages: 250-264, ISSN: 0888-3270

Journal article

Chabchoub A, Hoffmann N, Tobisch E, Waseda T, Akhmediev Net al., 2019, Drifting breathers and Fermi-Pasta-Ulam paradox for water waves, WAVE MOTION, Vol: 90, Pages: 168-174, ISSN: 0165-2125

Journal article

Didonna M, Stender M, Papangelo A, Fontanela F, Ciavarella M, Hoffmann Net al., 2019, Reconstruction of Governing Equations from Vibration Measurements for Geometrically Nonlinear Systems, LUBRICANTS, Vol: 7

Journal article

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: respub-action=search.html&id=00623717&limit=30&person=true