Final report
Dates and location
7 June — 9 June 2017, KTH Royal Institute of Technology, Stockholm, Sweden
Chairperson
Sören Östlund
Co-chairperson
Umberto Perego, Ron Peerlings
Conference fees
- Early Registration Fee: 320.00 €
- Late Registration Fee: 370.00 €
What other funding was obtained?
3 minor sponsors. In total €3000.
What were the participants offered?
Printed Abstract booklet. Note materials. Welcome reception with drinks and snacks. Colloquium dinner. Lunches including coffee all three days. Morning and afternoon tea/coffee with cakes and cookies all three days.
Applicants (members)
- Lars Beex
- Emanuela Bosco
- Pierre Dumont
- Per Isaksson
- Jarmo Kouko
- Artem Kulachenko
- Sören Östlund
- Ron Peerlings
- Umberto Perego
- Catalin Picu
- Matti Ristinmaa
- Denny Tjahjanto
Applicants (non members)
- Marcus Alexandersson
- Johan Alfthan
- Christophe Barbier
- Per Bergström
- Gabriella Bolzon
- Eric Borgqvist
- August Brandberg
- Ern Clevers
- Douglas Coffin
- Thomas Dintelmann
- Victoria Gorazdova
- Anton Hagman
- Marek Hauptmann
- Lars Hildén
- Ulrich Hirn
- Shakawath Hossain
- Markus Kakkonen
- Gustav Kettil
- Jussi Lahti
- Yujun Li
- ELIAS LIARTE
- Mikael Magnusson
- Petri Mäkelä
- Rami Mansour
- Florian MARTOIA
- Kurosh (Hamid Reza) Motamedian
- Abolhasan Nazarinezhad Giashi
- Mikael Nygårds
- Laurent ORGEAS
- Marcus Pfeiffer
- Mika Pihlajamäki
- Elias Retulainen
- Kristofer Robertsson
- Priyam Samantray
- Sohan Sarangi
- Samuel Schabel
- Heinz-Joachim Schaffrath
- Robert Schennach
- Jaan-Willem Simon
- Daniel Söderberg
- Prashanth Srinivasa
- Christoph Steiner
- Johan Tryding
- Tetsu Uesaka
- Manfred Ulz
- Georg Urstöger
- Marcel van der Woude
- Thijs van Stiphout
- Mathias von Essen
Scientific report
Wood-fibre network-based materials and structures, e.g. paper and paperboard, have a long tradition in society as carriers of information and as packaging material. However, recent concerns regarding environment and sustainability, as well as increased industrial demands of efficiency, have created a demand for a deeper understanding of the mechanics of such materials, reaching a level considerably beyond current industrial practice. This also includes the use of wood-fibre network-based materials in non-traditional applications.
The objective EUROMECH Colloquium 592 was to share and discuss recent advances in experimental characterisation and modelling of the deformation and damage mechanisms of wood fibre network based materials and structures in manufacturing, converting and end-use at all relevant length scales.
There were altogether 61 participants and about 37 presentations including one key-note lecture given by Daniel Söderberg (KTH, Stockholm), see the list of participants and the full programme included in the PROGRAMME folder. Extended abstracts of all presentations are included in the Book of ABSTRACTS. There were also numerous occasions for discussions frequently used by the participants and illustrated by the hard work of session chairmen to get the participants gathered in the lecture hall after all breaks. Here, the relatively large number of participants from research institutes and industry should be acknowledged.
The presentations covered a wide range of topics related to the grand challenges in the field, such as paper-moisture interaction during converting and end-use, paper-fluid interaction during papermaking and printing, and the multiscale and stochastic nature of paper damage.
Recurring issues addressed in the talks and discussed were:
• The true bonded contact area in fibre-fibre joints
The mechanical properties of the fibre-fibre joint play an important role for the strength and stiffness properties of fibre network materials, and detailed understanding of the physics, chemistry and mechanics of the fibre-fibre joint is far from complete. A key concept here is to understand the area in real contact between two fibres and the chemical bonds acting between the surfaces. At the colloquium, contributions addressing these issues were presented in the form of X-ray microtomography analyses of the joint and analysis of the dominating bonding mechanisms at different length scales.
• Modelling of the fibre-fibre joint
The mechanical properties of fibre-fibre joints, both from physical and modelling points of view, were also heavily discussed and here issues related to combined loading of the fibre-fibre joint and to how to capture the physics of the fibre-fibre joint in modelling at different scales were addressed. The mechanics of fibre-fibre joints under combined modes of loading and aspects related to network modelling were addressed by several groups, and issues related to the important problem of dimensional stability, such as hygroexpansion, were also heavily discussed. An important issue in this context is not only to capture the continuum behaviour, but also local variations in properties and to include parameters that make it possible for material producers and end-users to benefit from the results.
• Statistical effects
The mechanisms that control stiffness and strength of fibre-based materials originate from the structure at the microscale, where the fibre mechanical properties, fibre morphology and orientation, the number of interfibre contacts, bonding properties and disordered nature of the fibre network play crucial roles. Therefore, statistical effects play an important role in understanding the mechanical properties of these materials. Important issues addressed at the colloquium are the applicability of weakest links concepts and Weibull theory. This was discussed by several groups. Statistical effects is a relatively novel research area for the community, where major advancements are needed and expected in the near future. This is also related to the homogenization of materials at different length scales in multiscale modelling.
• Moisture effects
Understanding and modelling the influence of moisture on the mechanical properties of paper materials is one of the grand challenges in the mechanics of paperboard. This topic was addresses by several speakers at different structural levels, including continuum based mixture theory, build-up of stiffness and strength during drying and modelling of hygroexpansion. Here, it should be noted that the inclusion of moisture and also temperature effects in 3D continuum models still is a relatively unexplored research area, although some recent advancements were presented at the colloquium.
• Capturing micro- and mesomechanical phenomena in continuum models
The mechanisms that control stiffness and strength of fibre-based materials originate from the structure at the microscale, where the fibre mechanical properties, fibre morphology and orientation, the number of interfibre contacts, bonding properties and disordered nature of the fibre network play crucial roles. Therefore, it is natural to tackle the questions related to the mechanics of the fibre network structures at the length scale where the essential components can be taken into consideration. At the same time, bringing the information from the microscale upwards to the product scale at the appropriate climate conditions is the only way to make the scientific findings both relevant and applicable. Failure is often initiated at the scale of a few fibres, whereas quality parameters, in general, are defined in a continuum mechanics setting that results in essentially size-independent properties.
Issues related to these aspects were frequently addressed in many of the talks. It can be concluded that the advancements of both continuum and network models have made major steps in the last years, but there are still many important issues that are unresolved, particularly regarding the coupling between different length scales. In continuum models, issues brought-up at the colloquium include, for example, damage in the form of e.g. delamination and deformation and damage in load cases characterized by significant contributions from in-plane compression. In network modelling, issues related to both characterization of the network structure and modelling of fibre-fibre joints were addressed. In network modelling, the important issues of multi-axial loading, particularly in the case of substantial compression and shear, are still in the very early stages.
• Parameter identification in multi-scale models
While being touched upon in many talks, this is still an unresolved area. Particularly important is to define reliable and robust parameters that capture the underlying deformation and damage mechanisms, while still allowing measuring them in an industrial setting where statistical effects also play an important role.
From this list, it is clear that there are many critical questions far from being solved and the community has agreed to plan for a new meeting in about 5 years. Many participants have expressed their strong appreciation for the colloquium; we would like to quote one of the participants “Frankly, this EUROMECH conference was one of the most enjoyable meetings I experienced. Engaged, dynamic, and interesting!” This is what we wanted to achieve and we believe we did. The colloquium has also strengthened the ties between the paper mechanics and material mechanics communities and this was also one of the objectives.
Finally, we would like to thank EUROMECH for the financial and, not the least, organisational support.
Number of participants from each country
| Country | Participants |
|---|---|
| Sweden | 26 |
| Germany | 9 |
| Netherlands | 6 |
| Austria | 5 |
| Finland | 5 |
| France | 3 |
| Italy | 2 |
| United States | 2 |
| Luxembourg | 1 |
| Russia | 1 |
| Spain | 1 |
| Total | 61 |