Periodic Reporting for period 2 - THREAD (Joint Training on Numerical Modelling of Highly Flexible Structures for Industrial Applications)
Reporting period: 2021-10-01 to 2024-03-31
Virtual prototyping is a cornerstone in modern industrial product development cycles, as it is used to accelerate the design process, reduce the cost associated with real prototypes and improve the final product’s performances. The European Training Network THREAD addressed the numerical modelling of slender and highly flexible structures like yarns, cables, hoses or ropes that are essential parts of high-performance engineering systems. The complex response of such structures in real operational conditions is far beyond the capabilities of current modelling tools that are at the core of modern product development.
The mechanical response of highly flexible structures in application areas such as mechanical and aerospace engineering, biomedical engineering, offshore engineering, civil engineering and textile engineering is dominated by very complex phenomena that occur at different spatial and temporal scales. Full-scale 3D models of multimaterial rods based on a detailed representation of their internal structure would be incompatible with the requirements of a system-level analysis because of their high complexity and computational cost. Classical 1D rod models led to lower-dimensional problems but were hardly able to reproduce experimental results because of their inability to account for local nonlinear phenomena in the cross-section and of their extreme sensitivity to numerical disturbances.
THREAD was a unique network of universities, research organisations and industry from Austria, Belgium, Croatia, France, Germany, Norway, Slovenia and Spain that brought together mechanical engineers and mathematicians around major challenges in industrial applications and simulation software development. It established an innovative modelling chain starting from detailed 3D models and experimental measurements to build validated 1D rod models which were then brought to a system-level simulation thanks to the development of next-generation algorithms with outstanding numerical properties.
THREAD addressed the pressing need for a new generation of young scientists capable of solving fundamental problems related to highly flexible structures and transferring results to applications. The 14 Early Stage Researchers (ESRs) benefitted from cooperation with 12 industrial partner organisations who implemented a comprehensive programme of research secondments and contributed their experience.
The mechanical response of highly flexible structures in application areas such as mechanical and aerospace engineering, biomedical engineering, offshore engineering, civil engineering and textile engineering is dominated by very complex phenomena that occur at different spatial and temporal scales. Full-scale 3D models of multimaterial rods based on a detailed representation of their internal structure would be incompatible with the requirements of a system-level analysis because of their high complexity and computational cost. Classical 1D rod models led to lower-dimensional problems but were hardly able to reproduce experimental results because of their inability to account for local nonlinear phenomena in the cross-section and of their extreme sensitivity to numerical disturbances.
THREAD was a unique network of universities, research organisations and industry from Austria, Belgium, Croatia, France, Germany, Norway, Slovenia and Spain that brought together mechanical engineers and mathematicians around major challenges in industrial applications and simulation software development. It established an innovative modelling chain starting from detailed 3D models and experimental measurements to build validated 1D rod models which were then brought to a system-level simulation thanks to the development of next-generation algorithms with outstanding numerical properties.
THREAD addressed the pressing need for a new generation of young scientists capable of solving fundamental problems related to highly flexible structures and transferring results to applications. The 14 Early Stage Researchers (ESRs) benefitted from cooperation with 12 industrial partner organisations who implemented a comprehensive programme of research secondments and contributed their experience.
The team of highly qualified and motivated PhD students with 5 female and 9 male ESRs from three continents represented well the interdisciplinary character of the ETN with backgrounds in the fields of mechanical engineering, computational sciences and mathematics. THREAD’s training programme aimed at scientific skills in Cosserat rod models, their numerical treatment and practical application, transferable skills including high level experience in dissemination and communication as well as interdisciplinary and inter-sectoral experience. The local training in supervised individual research projects and local PhD programmes was accompanied by a comprehensive network-wide training programme with 14 network-wide training events, 6 industrial workshops and more than 40 secondments to academic and non-academic partners.
The ESRs focussed on the three research-related work packages on advanced constitutive laws, on interactions of 1D structures in a 3D world and on geometric numerical integration methods. They started with a literature review, defined test cases for validation of new computational models and considered industrial use cases in tight interaction with the non-academic partners. The inter-sectoral three-month secondments of all 14 ESRs provided deep insights into how modelling and simulation are utilised in virtual product development processes to address industrial challenges.
The physical phenomena in the deformation of electric cables, spiral strands, wire ropes and hollow endoscopes have been studied by test-rig experiments and by numerical simulations with newly developed methods and open-source software components in specially tailored simulation tools. This experimental work has provided the basis for designing novel constitutive laws which can deal with, e.g. variable axial forces, composite cross sections, hysteretic operators or data driven models. The analysis of contact and friction phenomena inside spiral strands and cable harnesses, in braiding processes and in ropeway systems has been addressed by improved modelling and simulation techniques that are implemented in the open-source software packages Odin and Exudyn and in the proprietary software Multifil for exploitation in industrial projects. Research on geometric integration methods with focus on adaptivity, robustness and adaptivity has shown their feasibility in the industrial context. Reduced order models with nonlinear normal modes were investigated as key technologies for further gains in efficiency.
THREAD has already been presented in as many as 26 high-quality research papers in reputable scientific journals from mathematics and engineering (14 more papers currently under review). The submission of up to 12 PhD theses is expected before the end of year 2024 including 5 theses that have already been successfully defended or are under review.
The ESRs contributed to a series of THREAD mini-symposia and special sessions at leading international conferences in this field such as WCCM 2020, ECMI 2021, NUMDIFF-16, ECCOMAS Congress 2022, ICIAM 2023 and the ECCOMAS Conferences on Multibody Dynamics (2021, 2023). The THREAD network has initiated a new series of biannual ECCOMAS Thematic Conferences on Highly Flexible Slender Structures (Rijeka 2023, Kaiserslautern 2025).
The ESRs focussed on the three research-related work packages on advanced constitutive laws, on interactions of 1D structures in a 3D world and on geometric numerical integration methods. They started with a literature review, defined test cases for validation of new computational models and considered industrial use cases in tight interaction with the non-academic partners. The inter-sectoral three-month secondments of all 14 ESRs provided deep insights into how modelling and simulation are utilised in virtual product development processes to address industrial challenges.
The physical phenomena in the deformation of electric cables, spiral strands, wire ropes and hollow endoscopes have been studied by test-rig experiments and by numerical simulations with newly developed methods and open-source software components in specially tailored simulation tools. This experimental work has provided the basis for designing novel constitutive laws which can deal with, e.g. variable axial forces, composite cross sections, hysteretic operators or data driven models. The analysis of contact and friction phenomena inside spiral strands and cable harnesses, in braiding processes and in ropeway systems has been addressed by improved modelling and simulation techniques that are implemented in the open-source software packages Odin and Exudyn and in the proprietary software Multifil for exploitation in industrial projects. Research on geometric integration methods with focus on adaptivity, robustness and adaptivity has shown their feasibility in the industrial context. Reduced order models with nonlinear normal modes were investigated as key technologies for further gains in efficiency.
THREAD has already been presented in as many as 26 high-quality research papers in reputable scientific journals from mathematics and engineering (14 more papers currently under review). The submission of up to 12 PhD theses is expected before the end of year 2024 including 5 theses that have already been successfully defended or are under review.
The ESRs contributed to a series of THREAD mini-symposia and special sessions at leading international conferences in this field such as WCCM 2020, ECMI 2021, NUMDIFF-16, ECCOMAS Congress 2022, ICIAM 2023 and the ECCOMAS Conferences on Multibody Dynamics (2021, 2023). The THREAD network has initiated a new series of biannual ECCOMAS Thematic Conferences on Highly Flexible Slender Structures (Rijeka 2023, Kaiserslautern 2025).
The interdisciplinary and inter-sectoral cooperation in THREAD has put the challenges from industrial applications in virtual product development into the focus of cutting-edge research on modelling and simulation of highly flexible structures.
A unique network-wide training programme has been implemented combining in a holistic approach advanced concepts in experimental and theoretical structural mechanics, non-smooth dynamics, computational geometry, discretisation methods and geometric numerical integration to enable the next generation of virtual prototyping and to boost the career development of the ESRs. THREAD established a firm backbone of different players that brought local research and training activities to this common objective and opened new perspectives for structuring European doctoral training in the long term.
The mobility of ESRs was strongly supported by the comprehensive secondment programme including mandatory three-month secondments to industrial partner organisations. The international cooperation in THREAD contributed actively to the European Research Area and put strong emphasis on scientific excellence in terms of open-access publications in peer-reviewed high impact journals, dissemination at leading international conferences and dissemination to industry.
The results of 14 individual ESR projects have shown significant progress beyond the state of the art in application-specific constitutive models for highly flexible structures and contributed to significant gains of robustness and efficiency in computational methods and software tools for industrial use. In that way, the project advanced the innovation capacity and the competitiveness of European industries related to the topics of THREAD.
A unique network-wide training programme has been implemented combining in a holistic approach advanced concepts in experimental and theoretical structural mechanics, non-smooth dynamics, computational geometry, discretisation methods and geometric numerical integration to enable the next generation of virtual prototyping and to boost the career development of the ESRs. THREAD established a firm backbone of different players that brought local research and training activities to this common objective and opened new perspectives for structuring European doctoral training in the long term.
The mobility of ESRs was strongly supported by the comprehensive secondment programme including mandatory three-month secondments to industrial partner organisations. The international cooperation in THREAD contributed actively to the European Research Area and put strong emphasis on scientific excellence in terms of open-access publications in peer-reviewed high impact journals, dissemination at leading international conferences and dissemination to industry.
The results of 14 individual ESR projects have shown significant progress beyond the state of the art in application-specific constitutive models for highly flexible structures and contributed to significant gains of robustness and efficiency in computational methods and software tools for industrial use. In that way, the project advanced the innovation capacity and the competitiveness of European industries related to the topics of THREAD.