We all know Euler buckling of a beam under axial thrust, but can buckling occur in an elastic structure in which all elements are subject to tensile dead loading?
We provide a positive answer to this question, see http://www.youtube.com/user/RoyalSociety#p/u/0/EKngs1vvcJU
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.ing.unitn.it/
Have you ever seen a structure subject to flutter instability?
Can flutter instability be connected to dry friction?
We provide positive answers to the above questions, watch the video at
http://www.ing.unitn.it/~bigoni/flutter.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.ing.unitn.it/
See our YouTube channel and Facebook Page
Can a single-degree-of-freedom elastic structure have two buckling loads?
We provide a positive answer to this question, see http://www.ing.unitn.it/~bigoni/multiple_bifurcations.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.unitn.it/
Please, give a look to my research activity at: http://www.ing.unitn.it/~bigoni/
If you are strongly motivated to work with a very active group (http://ssmg.unitn.it) in Solid Mechanics, we have a post-doc position for 2 years available not before October 2012.
The position is on a EU grant (http://intercer2.unitn.it/) and is addressed to constitutive/numerical/theoretical modelling of ceramics.
For details on the application see:
http://ec.europa.eu/euraxess/index.cfm/jobs/jobDetails/33796111
Davide Bigoni
The Journal Club Theme of February 2012 "Elastic Instabilities for Form and Function" (http://imechanica.org/node/11812), coordinated by Doug Holmes (http://www2.esm.vt.edu/~dpholmes/), has provided an excellent review of elastic instability as related to pattern formation in soft materials.
The October 2012's Journal Club is on a closely related subject, namely, "instabilities of structures". This is a mature research field, but still strongly vital. In particular, we would like to draw the attention on recent results on how to exploit the post-critial behaviour of an elastic structure to obtain flexible mechanisms with special behaviours: (i.) a spherical shell shrinking towards its center; (ii.) a one-degree-of-freedom elastic structure buckling in tension and compression and providing a constant force ("neutral") post-critical behaviour; (iii.) dynamical instabilities explain wrapping of a liquid drop by an elastic strip.
(i.) A spherical shell shrinking towards its center
A spherical shell patterned with a regular array of circular engraves is shown to buckle, when subject to external pressure, in a sort of torsional-mode, giving rise to a shrink of the shell toward its center (Shima et al. 2012), Fig. 1.
This folding mechanism is induced by a mechanical instability in an elastic structure and therefore is fully reversible.
Fig. 1 Sequence of progressively deformed shapes of the buckliball (from Shima et al. 2012)
A video on the buckliball can be found at: http://www.youtube.com/watch?v=pKdWa8aIqno
(ii.) A one-degree-of-freedom elastic structure buckling in tension and compression and providing a constant force ("neutral") post-critical behaviour
Zaccaria et al. (2011) have shown that elastic structures (in which each element is governed by the Euler's elastica) can be designed to buckle under purely tensile dead loading and that the shape of the buckled elastica in tension corresponds to the shape of a water meniscus in a capillary channel (Fig. 2).
Fig. 2 Analogy between an elastic rod buckled under tensile force (left) and a water meniscus in a capillary channel (right, superimposed to the solution of the elastica, marked in red): the deflection of the rod and the surface of the liquid have the same shape (from Zaccaria et al. 2011)
These concepts have been developed by Bigoni et al. (2012) to show that the profile of the constraint where an end of an elastic structure has to slide can be designed to obtain buckling in tension or compression, and two buckling loads for a one-degree-of-freedom structure. Moreover, the profile can be designed to obtain a "neutral" postcritical response, in which the displacement increases at constant load (Fig. 3).
Fig. 3 A one-degrees-of-freedom elastic structure with two (one tensile and one compressive) buckling loads and neutral postcritical behaviour. Right: experimental set-up. Left: theoretical predictions versus experimental results (from Bigoni et al. 2012)
A video on multiple bifurcations and neutral postcritical response can be found at: http://www.youtube.com/watch?feature=player_embedded&v=plQqUGFYegw
(iii.) Dynamical instabilities explain wrapping of a liquid drop by an elastic strip
Experiments by Antkowiak et al. (2011) show that a liquid drop can be wrapped by an elastic thin film by a drop impact on millimetric and centimetric scales (Fig. 4). This capillary phenomenon, is competing with the weight of the elastic film and can be explained (Rivetti and Neukirch, 2012; Hure and Audoly, 2012) in terms of elastic instability.
Fig. 4 Instant capillary origami, obtained with a water droplet impacting a thin triangular polymer sheet with thickness (from Antkowiak et al. 2011).
A video on the wrapping of liquid drops can be found at: http://www.youtube.com/watch?v=-FewxlkYOME
In the previously-quoted works, the theoretical predictions are substantiated with experiments and a close agreement is shown, so that we may think that it will be possible in the future to realize flexible structures with designed pre- and post- critical behaviours. Results presented in (i.) and (iii.) can find applications in the industrial process of encapsulation, while results presented in (ii.) can be employed to design of shock-absobers for tensile forces.
References
A. Antkowiak, B. Audoly, C. Josserand, S. Neukirch, and M. Rivetti (2011) "Instant fabrication and selection of folded structures using drop impact". PNAS 26, 108, 10400–10404.
D. Bigoni, D. Misseroni, G. Noselli and D. Zaccaria (2012) Effects of the constraint’s curvature on structural instability: tensile buckling and multiple bifurcations. Proc. R. Soc. A, 468, 2191-2209.
J. Hure, B. Audoly (2012) Capillary buckling of a thin film adhering to a sphere. J. Mech. Phys. Solids, DOI: http://dx.doi.org/10.1016/j.jmps.2012.09.016.
M. Rivetti and S. Neukirch (2012) "Instabilities in a drop-strip system: a simplified model." Proc. R. Soc. A doi:10.1098/rspa.2011.0589
J. Shima, C. Perdigoub, E.R. Chen, K. Bertoldi, and P.M. Reis (2012) "Buckling-induced encapsulation of structured elastic shells under pressure", PNAS 109, 16, pp. 5978-5983.
D. Zaccaria, D. Bigoni, G. Noselli and D. Misseroni (2011) Structures buckling under tensile dead load. Proc. R. Soc. A, 467, 1686-1700.
Within the IAPP research poject INTERCER2 (http://intercer2.unitn.it/) coordinated by me, the Institute of Mathematics and Physics at Aberystwyth University (Research unit coordinator: Prof. Gennady Mishuris) is seeking to appoint a research lecturer in mathematical modelling. The successful candidate will have had research experience in the respective areas of Applied Mathematics and possess a PhD having less then 10 years experience. This is a two year fixed term post.
Research objectives:
The appointee will participate in FP7 IAPP project INTERCER2 and collaborate with partners in this project as well as with colleagues from other two IMAPS FP7 IAPP projects: HYDROFRAC and PARM-2. In particular, the successful candidate will work with problems in areas including, but not limited to
- Mathematical modelling of multiphysics phenomena in composite materials
- Average properties of various elastic and piezoelectric composites;
- Crack problems in composite material (piezeoceramics);
- Waves, fracture and damage propagation in inhomogeneous structures
For more details, please refer to
http://ec.europa.eu/euraxess/index.cfm/jobs/jobDetails/33829112
Webpage: http://events.unitn.it/en/cermodel2013
Deadline for 1 page-abstract submission: February 15, 2013
The aim of the congress is to gather together international experts in the
field of ceramic science and material modelling with representatives from
research institutes and industry in order to enhance the communication
between experimental materials research and computational work, to improve
efficiency in several steps of the processing procedures and to predict
the potential of new advanced materials under specific application
conditions and for specific functionalities.
A special issue of Journal of European Ceramic Society is planned as the
outcome of the CERMODEL2013 congress.
Invited Speakers:
• Paul Bowen, École Polytechnique Fédérale de Lausanne, Switzerland
• Vicente Cantavella Soler, Institute of Ceramic Tecnology (ITC), Spain
• Norman Fleck, University of Cambridge, United Kingdom
• Tomasz Hueckel, Duke University, Usa
• Robert McMeeking, University of California Santa Barbara, Usa
• Cristiano Nicolella, University of Pisa, Italy
• Alexandru Stancu, Alexandru Ioan Cuza University, Romania
Scientific Committee:
• Paul Bowen, École Polytechnique Fédérale de Lausanne, Switzerland
• Vicente Cantavella Soler, Institute of Ceramic Tecnology (ITC), Spain
• Francesco Dal Corso, University of Trento, Italy
• Michele Dondi, ISTEC-CNR, Italy
• Norman Fleck, University of Cambridge, United Kingdom
• Alessandro Gajo, University of Trento, Italy
• Massimiliano Gei, University of Trento, Italy
• Marc Geers, Eindhoven University of Technology, Netherlands
• Stefano Guicciardi, ISTEC-CNR, Italy
• Tomasz Hueckel, Duke University, Usa
• Robert McMeeking, University of California Santa Barbara, Usa
• Cristiano Nicolella, University of Pisa, Italy
• Andrea Piccolroaz, University of Trento, Italy
• Nicola Pugno, University of Trento, Italy
• Alexandru Stancu, Alexandru Ioan Cuza University, Romania
Congress Chairs:
• Alida Bellosi, ISTEC-CNR, Italy
• Davide Bigoni, University of Trento, Italy
• Paolo Zannini, University of Modena and Reggio Emilia, President of the Italian Ceramic Society, Italy
More detailed information about deadlines, invited speakers, committees, registration, support grant for young researchers are available at
http://events.unitn.it/en/cermodel2013
Please, give a look to my research activity at http://www.ing.unitn.it/~bigoni and to my group at http://ssmg.unitn.it
If you are strongly motivated to work with a very active group in Solid Mechanics, we have a PhD position (3 years) available from January 2014, but the deadline for application is September 15, 2013!
The position is on a EU grant and is addressed to numerical/theoretical modelling of ceramics.
For details on the application see the attachement.
Davide Bigoni
Do Eshelby forces exist in elastic structures?
We provide a positive answer to this question, see http://www.ing.unitn.it/~bigoni/eshelbylikeforce.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.unitn.it/
If you're having trouble playing videos on YouTube,
click here to watch it.
Can buckling and instability of a structure be affected by Eshelby forces?
We provide a positive answer to this question, see http://www.ing.unitn.it/~bigoni/blade.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.unitn.it/
If you're having trouble playing videos on YouTube,
click here to watch it.
Lecturers:
Basile Audoly - Université Pierre et Marie Curie and CNRS, Paris, France
Katia Bertoldi - University of Harvard, Cambridge, MA, USA
Davide Bigoni - Università di Trento, Italy
Alain Goriely - University of Oxford, UK
Sébastien Neukirch - Université Pierre et Marie Curie and CNRS, Paris, France
Sergio Pellegrino - California Institute of Technology, Pasadena, CA, USA
see the attachment for details on the course and the registration
We all know Euler buckling of a beam under axial thrust, but can buckling occur in an elastic structure in which all elements are subject to tensile dead loading?
We provide a positive answer to this question, see http://www.youtube.com/user/RoyalSociety#p/u/0/EKngs1vvcJU
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.ing.unitn.it/
Have you ever seen a structure subject to flutter instability?
Can flutter instability be connected to dry friction?
We provide positive answers to the above questions, watch the video at
http://www.ing.unitn.it/~bigoni/flutter.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.ing.unitn.it/
See our YouTube channel and Facebook Page
Can a single-degree-of-freedom elastic structure have two buckling loads?
We provide a positive answer to this question, see http://www.ing.unitn.it/~bigoni/multiple_bifurcations.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.unitn.it/
Please, give a look to my research activity at: http://www.ing.unitn.it/~bigoni/
If you are strongly motivated to work with a very active group (http://ssmg.unitn.it) in Solid Mechanics, we have a post-doc position for 2 years available not before October 2012.
The position is on a EU grant (http://intercer2.unitn.it/) and is addressed to constitutive/numerical/theoretical modelling of ceramics.
For details on the application see:
http://ec.europa.eu/euraxess/index.cfm/jobs/jobDetails/33796111
Davide Bigoni
The Journal Club Theme of February 2012 "Elastic Instabilities for Form and Function" (node/11812), coordinated by Doug Holmes (http://www2.esm.vt.edu/~dpholmes/), has provided an excellent review of elastic instability as related to pattern formation in soft materials.
The October 2012's Journal Club is on a closely related subject, namely, "instabilities of structures". This is a mature research field, but still strongly vital. In particular, we would like to draw the attention on recent results on how to exploit the post-critial behaviour of an elastic structure to obtain flexible mechanisms with special behaviours: (i.) a spherical shell shrinking towards its center; (ii.) a one-degree-of-freedom elastic structure buckling in tension and compression and providing a constant force ("neutral") post-critical behaviour; (iii.) dynamical instabilities explain wrapping of a liquid drop by an elastic strip.
(i.) A spherical shell shrinking towards its center
A spherical shell patterned with a regular array of circular engraves is shown to buckle, when subject to external pressure, in a sort of torsional-mode, giving rise to a shrink of the shell toward its center (Shima et al. 2012), Fig. 1.
This folding mechanism is induced by a mechanical instability in an elastic structure and therefore is fully reversible.
Fig. 1 Sequence of progressively deformed shapes of the buckliball (from Shima et al. 2012)
A video on the buckliball can be found at: http://www.youtube.com/watch?v=pKdWa8aIqno
(ii.) A one-degree-of-freedom elastic structure buckling in tension and compression and providing a constant force ("neutral") post-critical behaviour
Zaccaria et al. (2011) have shown that elastic structures (in which each element is governed by the Euler's elastica) can be designed to buckle under purely tensile dead loading and that the shape of the buckled elastica in tension corresponds to the shape of a water meniscus in a capillary channel (Fig. 2).
Fig. 2 Analogy between an elastic rod buckled under tensile force (left) and a water meniscus in a capillary channel (right, superimposed to the solution of the elastica, marked in red): the deflection of the rod and the surface of the liquid have the same shape (from Zaccaria et al. 2011)
These concepts have been developed by Bigoni et al. (2012) to show that the profile of the constraint where an end of an elastic structure has to slide can be designed to obtain buckling in tension or compression, and two buckling loads for a one-degree-of-freedom structure. Moreover, the profile can be designed to obtain a "neutral" postcritical response, in which the displacement increases at constant load (Fig. 3).
Fig. 3 A one-degrees-of-freedom elastic structure with two (one tensile and one compressive) buckling loads and neutral postcritical behaviour. Right: experimental set-up. Left: theoretical predictions versus experimental results (from Bigoni et al. 2012)
A video on multiple bifurcations and neutral postcritical response can be found at: http://www.youtube.com/watch?feature=player_embedded&v=plQqUGFYegw
(iii.) Dynamical instabilities explain wrapping of a liquid drop by an elastic strip
Experiments by Antkowiak et al. (2011) show that a liquid drop can be wrapped by an elastic thin film by a drop impact on millimetric and centimetric scales (Fig. 4). This capillary phenomenon, is competing with the weight of the elastic film and can be explained (Rivetti and Neukirch, 2012; Hure and Audoly, 2012) in terms of elastic instability.
Fig. 4 Instant capillary origami, obtained with a water droplet impacting a thin triangular polymer sheet with thickness (from Antkowiak et al. 2011).
A video on the wrapping of liquid drops can be found at: http://www.youtube.com/watch?v=-FewxlkYOME
In the previously-quoted works, the theoretical predictions are substantiated with experiments and a close agreement is shown, so that we may think that it will be possible in the future to realize flexible structures with designed pre- and post- critical behaviours. Results presented in (i.) and (iii.) can find applications in the industrial process of encapsulation, while results presented in (ii.) can be employed to design of shock-absobers for tensile forces.
References
A. Antkowiak, B. Audoly, C. Josserand, S. Neukirch, and M. Rivetti (2011) "Instant fabrication and selection of folded structures using drop impact". PNAS 26, 108, 10400–10404.
D. Bigoni, D. Misseroni, G. Noselli and D. Zaccaria (2012) Effects of the constraint’s curvature on structural instability: tensile buckling and multiple bifurcations. Proc. R. Soc. A, 468, 2191-2209.
J. Hure, B. Audoly (2012) Capillary buckling of a thin film adhering to a sphere. J. Mech. Phys. Solids, DOI: http://dx.doi.org/10.1016/j.jmps.2012.09.016.
M. Rivetti and S. Neukirch (2012) "Instabilities in a drop-strip system: a simplified model." Proc. R. Soc. A doi:10.1098/rspa.2011.0589
J. Shima, C. Perdigoub, E.R. Chen, K. Bertoldi, and P.M. Reis (2012) "Buckling-induced encapsulation of structured elastic shells under pressure", PNAS 109, 16, pp. 5978-5983.
D. Zaccaria, D. Bigoni, G. Noselli and D. Misseroni (2011) Structures buckling under tensile dead load. Proc. R. Soc. A, 467, 1686-1700.
Within the IAPP research poject INTERCER2 (http://intercer2.unitn.it/) coordinated by me, the Institute of Mathematics and Physics at Aberystwyth University (Research unit coordinator: Prof. Gennady Mishuris) is seeking to appoint a research lecturer in mathematical modelling. The successful candidate will have had research experience in the respective areas of Applied Mathematics and possess a PhD having less then 10 years experience. This is a two year fixed term post.
Research objectives:
The appointee will participate in FP7 IAPP project INTERCER2 and collaborate with partners in this project as well as with colleagues from other two IMAPS FP7 IAPP projects: HYDROFRAC and PARM-2. In particular, the successful candidate will work with problems in areas including, but not limited to
- Mathematical modelling of multiphysics phenomena in composite materials
- Average properties of various elastic and piezoelectric composites;
- Crack problems in composite material (piezeoceramics);
- Waves, fracture and damage propagation in inhomogeneous structures
For more details, please refer to
http://ec.europa.eu/euraxess/index.cfm/jobs/jobDetails/33829112
Webpage: http://events.unitn.it/en/cermodel2013
Deadline for 1 page-abstract submission: February 15, 2013
The aim of the congress is to gather together international experts in the
field of ceramic science and material modelling with representatives from
research institutes and industry in order to enhance the communication
between experimental materials research and computational work, to improve
efficiency in several steps of the processing procedures and to predict
the potential of new advanced materials under specific application
conditions and for specific functionalities.
A special issue of Journal of European Ceramic Society is planned as the
outcome of the CERMODEL2013 congress.
Invited Speakers:
• Paul Bowen, École Polytechnique Fédérale de Lausanne, Switzerland
• Vicente Cantavella Soler, Institute of Ceramic Tecnology (ITC), Spain
• Norman Fleck, University of Cambridge, United Kingdom
• Tomasz Hueckel, Duke University, Usa
• Robert McMeeking, University of California Santa Barbara, Usa
• Cristiano Nicolella, University of Pisa, Italy
• Alexandru Stancu, Alexandru Ioan Cuza University, Romania
Scientific Committee:
• Paul Bowen, École Polytechnique Fédérale de Lausanne, Switzerland
• Vicente Cantavella Soler, Institute of Ceramic Tecnology (ITC), Spain
• Francesco Dal Corso, University of Trento, Italy
• Michele Dondi, ISTEC-CNR, Italy
• Norman Fleck, University of Cambridge, United Kingdom
• Alessandro Gajo, University of Trento, Italy
• Massimiliano Gei, University of Trento, Italy
• Marc Geers, Eindhoven University of Technology, Netherlands
• Stefano Guicciardi, ISTEC-CNR, Italy
• Tomasz Hueckel, Duke University, Usa
• Robert McMeeking, University of California Santa Barbara, Usa
• Cristiano Nicolella, University of Pisa, Italy
• Andrea Piccolroaz, University of Trento, Italy
• Nicola Pugno, University of Trento, Italy
• Alexandru Stancu, Alexandru Ioan Cuza University, Romania
Congress Chairs:
• Alida Bellosi, ISTEC-CNR, Italy
• Davide Bigoni, University of Trento, Italy
• Paolo Zannini, University of Modena and Reggio Emilia, President of the Italian Ceramic Society, Italy
More detailed information about deadlines, invited speakers, committees, registration, support grant for young researchers are available at
http://events.unitn.it/en/cermodel2013
Please, give a look to my research activity at http://www.ing.unitn.it/~bigoni and to my group at http://ssmg.unitn.it
If you are strongly motivated to work with a very active group in Solid Mechanics, we have a PhD position (3 years) available from January 2014, but the deadline for application is September 15, 2013!
The position is on a EU grant and is addressed to numerical/theoretical modelling of ceramics.
For details on the application see the attachement.
Davide Bigoni
| Attachment | Size |
|---|---|
 UNITN_PhD_fellow.pdf | 74.26 KB |
Do Eshelby forces exist in elastic structures?
We provide a positive answer to this question, see http://www.ing.unitn.it/~bigoni/eshelbylikeforce.html
More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.unitn.it/
If you're having trouble playing videos on YouTube,
click here to watch it.
| Attachment | Size |
|---|---|
| eshelbylikeforcesMoM2013.pdf | 2.01 MB |