Hello Ivón! Bilingual report from the research project Support Vasa part III: Dreams can come true

 

Guest blogger Ivón Hassel is from Argentina, formed at the University of Kyoto, Associate Professor at the Division of Applied Mechanics of Uppsala University, specialized in timber construction and researcher in the Support Vasa project. Here, Ivón reports in her native language and English on her experimental work on the joints of Vasa: 

Dreams can come true

Discover the World!, that was my dream since I was a little child!, and I had no idea that I was going to actually do it!. I use airplanes to go from one place to the other, fast and safe enough, unlike during the 17th century when travelling involved saying goodbye from family and friends, leaving everything behind to an uncertain return. I feel actually very lucky for two reasons, being able to use airplanes instead of Ships (I get easily seasick), and the fact that Ships actually sank, leaving loads of knowledge for us to gain from their remains.

From the north of Argentina, passing through Germany and Israel, I ended up in the most traditional city of Japan, Kyoto. There I spent almost a decade studying, and it became my home. It was while in Japan that I first heard of the Vasa Ship. Just before coming to Sweden for the first time many years ago, a French friend told me: “the only thing you should not miss in Sweden is a visit to the Vasa Museum”. I did not understood why all the fuzz until I entered the museum for the first time and saw her!, she was amazing!

Now I found myself in Sweden again (not that I was lost :P), working at the Division of Applied Mechanics of Uppsala University as an Associate Professor, and as a member of a remarkable group of researchers (I am referring to them! :P)…life is full of surprises and opportunities!.

Los sueños pueden hacerse realidad

Descubrir el Mundo!, fue mi sueño desde que era una niña!, y en ese entonces no tenía idea de que lo iba a cumplir!. Uso aviones para ir de un lugar a otro, lo suficientemente rápido y seguro, no como ocurría durante el siglo 17, que antes de emprender un viaje, la gente se despedía de familiares y amigos, ya preparados para dejar todo detrás de sí, y pensar sólo en un retorno incierto. Yo me siento realmente afortunada por dos motivos, poder viajar en aviones en vez de barcos (ya que me mareo muy fácilmente), y por el hecho de que los barcos de antaño se hundía, dejando montañas de conocimientos por ser descubiertos.

Desde el norte de la Argentina, pasando por Alemania e Israel, terminé en la ciudad más tradicional de Japón, Kioto. Allá pasé casi una década estudiando, y se convirtió en mi hogar. Y fue durante mi estadía en Japón que escuché por primera vez mencionar al barco Vasa. Justo antes de mi primer viaje a Suecia, ya hace muchos años, un amigo francés me sugirió: “lo único que no tenés que dejar de visitar en Suecia es el Museo de Vasa!”. No entendí el porqué de tanto alboroto hasta el momento de entrar al museo y encontrarme con tremenda hermosura!, simplemente impresionante!.

Ahora me encuentro en Suecia nuevamente (no es que esté perdida :P), donde trabajo en le división de mecánica aplicada de la universidad de Upsala como profesora asociada, y miembro de un extraordinario grupo de investigadores (me refiero a ellos! :P)…la vida está llena de sorpresas y oportunidades!.

The most interesting project…and a challenge of “massive” magnitude

The goal of the project that I am working on was set very clearly: “Find a way to preserve the Vasa Ship for the coming generations!”. This means finding out how the Ship is deforming in order to being able to design a better support structure for the Ship. Although it is a very ambitious goal, we are a very stubborn and tenacious group of people, and loooove challenges.

My colleagues Ingela Bjurhager, Alexey Vorobyev, and Nico van Dijk have already reached a profound knowledge regarding the properties of the material constituting the Ship. Now, the time has come to zoom out and look at the “research object” at a different scale…

What is the first thing one notice about the Ship?  Well… the second…as the first one is her size!. The answer is, her structure, which is a puzzle of many massive pieces of wood put together and working as a whole. From now on I am going to refer to the pieces of wood as “structural members”, and the point at which each of the structural members meet, as “joint”. There are joints throughout the structure of the Ship, and each one of them is a weak point in the structure. Through the joints the loads are transferred from one structural element to the other, and displacement between them is generated. This adds up to the deformation of the ship due to the time-dependent-material deformation, under investigation by my colleagues.

If we want to know how the joints are influencing the overall as well as local deformation of the Ship, the best way (to my opinion) is to perform actual tests on the joints. This means, apply a force and measure the displacement that occurs in different strategic parts of the joint. Due to the difficulties of performing this type of tests directly on the Vasa ship, we decided to do it on a replica of a joint.

El Proyecto más interesante…y un desafío de magnitud “masiva”

El objetivo del proyecto en el cual estoy trabajando es muy claro: “Encontrar la manera de preservar el barco Vasa para las siguientes generaciones!”. Esto significa que tenemos que determinar cómo se está deformando la estructura, para luego poder diseñar una nueva estructura que lo soporte sin dañar. A pesar de que es un objetivo muy ambicioso, nosotros somos un grupo de personas tenaces y ambiciosas, y amaaamos los desafíos.

Mis colegas Ingela Bjurhager, Alexey Vorobyev, y Nico van Dijk ya han adquirido conocimientos profundos acerca de las propiedades mecánicas del material que constituye el barco. Ahora ha llegado el momento de mirar al problema desde una nueva perspectiva y a una escala diferente…

¿Qué es lo primero que uno nota al ver al Vasa? Bueno, lo segundo …ya que lo primero es en realidad su tamaño!. La respuesta es, su estructura, que es un rompecabezas compuesto de un montón de piezas de masivas madera, colocadas de manera que trabajan en conjunto. De ahora en más me voy a referir a estas piezas masivas de madera como “miembros estructurales”, y al punto de encuentro de los diferentes miembros estructurales lo llamaremos “unión”. Existen muchísimas uniones en el barco, y cada una de ellas constituye un punto débil en la estructura. Es a través de las uniones que es posible transmitir los esfuerzos de un elemento estructural a otro, y debido a ello se producen también desplazamientos. A esto hay que sumarle la deformación del material en función del tiempo, tema del que se ocupan de investigar mis colegas.

Si queremos saber cómo afectan las uniones a la deformación total y local del barco, la mejor manera (según mi opinión) es ensayar las uniones directamente. Esto quiere decir, aplicar cargas y medir los desplazamientos que ocurren en lugares estratégicos de las uniones. Por motivos obvios, esto no es posible de hacer directamente en el barco, por lo cual decidimos ensayar una réplica representativa de las uniones del Vasa.

On our way to fulfill the goals

I walked a long path since last year until finally reaching what felt for a long time as a dream: testing the Replica!

Replica of a representative Vasa joint ready to be tested. Réplica de una union representative del Vasa lista para ser ensayada.

Along the way many fantastic people walked with me, sharing their expertise and helping me jump over different obstacles. Fred Hocker, and Anders Ahlgren helped me become acquainted with the Ship’s structure, in order to design the joint to be tested. The best team of carpenters manufactured it, and I must say…I never thought I could have so much fun at work!. Monika Ask, Ove Olssen, Håkan Altrock, Åsa Egerquist and Robert Jonsson made every one of our meetings a memory to keep. The design of the steel testing frame (structure to support the Replica and hold the testing equipment) was designed with the help of hard-working and inquisitive minds, Florian Bommier and Alexey Vorobyev, and the help of Reza Afshar for the computer drawings and modeling. Many nights we stayed at the office with Florian sharing noodles, but very happy doing our job!

Finally the assembly of the Replica in the testing facility of KTH to use their special reinforced floor became a reality!

Different systems were used to measure the displacements on the joint when load was applied. Diferentes sistemas utilizados para la medición de desplazamientos al aplicar cargas.

Two full weeks of applying forces, measuring displacements in different parts of the joint, resulted in an extensive amount of data.

The next step is processing the pool of data, and validating a detailed computer model of the joint. Right after, the material properties of the Vasa-Oak will be included into the verified computer model. Only at this point we are going to have the computer model of the Vasa joint, and we will be ready to quantify the effect of the Vasa joints on the deformation of the Ship.

There is a lot of work for us to do still, so I better go back to it!...I say bye for now until my next post!!!

De camino a alcanzar nuestras metas

Recorrí un largo camino desde el año pasado hasta finalmente alcanzar lo que por largo tiempo parecía sólo un sueño: ensayar la Réplica!

He caminado junto a mucha gente realmente fantástica a lo largo del camino, quienes han compartido conmigo su pericia y me han ayudado a superar diferentes obstáculos. Fred Hocker y Anders Ahlgren me ayudaron a familiarizarme con la estructura del barco, y poder así diseñar la unión a ser ensayada. El mejor equipo de carpinteros la construyeron, y debo decir que nunca hubiera pensado que uno podría divertirse tanto en el trabajo!. Monika Ask, Ove Olssen, Håkan Altrock, Åsa Egerquist y Robert Jonsson hicieron memorables cada uno de nuestros encuentros. El diseño de la estructura de acero (soporte de la Réplica y del equipamiento para aplicar las cargas) fue diseñado con la ayuda de personas trabajadoras y de mentes inquisitivas, Florian Bommier y Alexey Vorovyev, y la ayuda de Reza Afshar en los dibujos y modelo por computadora. Muchas noches pasamos en la oficina con Florian compartiendo fideos, pero muy felices haciendo nuestro trabajo!

Finalmente el montaje de la Réplica en el centro de ensayos del KTH se convirtió en una realidad!

Dos semanas completes dedicadas solamente a aplicar cargas, y medir desplazamientos en diferentes partes de la unión, resultaron en un extensivo volumen de información.

a) Test and test setup, b) detailed computer model of the joint and c) replica of a representative Vasa joint. a) Ensayo y montaje del mismo, b) detallado modelo por computadora de una unión and c) réplica de una unión representativa del Vasa.

Dos semanas completes dedicadas solamente a aplicar cargas, y medir desplazamientos en diferentes partes de la unión, resultaron en un extensivo volumen de información.

El siguiente paso es procesar los datos, y validar el modelo de la unión creado en computadora. Luego de esto, las propiedades del material que constituye el barco Vasa (Vasa-roble) se incluirán en el modelo por computadora. Y sólo luego de finalizar esto, se tendrá finalmente un modelo por computadora de una unión del Vasa, y estaremos listos para cuantificar el efecto de las diferentes uniones en la deformación del barco.

Hay mucho trabajo por hacer todavía, así que mejor que vuelvo a mis obligaciones!...Por ahora digo chau hasta el siguiente mensaje!!!

 

From left to right: Reza, Florian, Ivón and Alexey. De izquierda a derecha: Reza, Florian, Ivón and Alexey.

Kartläggning

Mapping! The time has come. As the data stands, I have two binders full of measured drawings and a folder full of high-resolution photographs of the tools, plus pages and pages of notes. These things all deal with the objects as individual things. Now it's time to plug them into the bigger picture and pull the chapter together. Mapping is a really important visualization tool to help us see the relationships between the objects more clearly on a variety of levels. 

Right now, the locations in which each object was found exists only as a set of numbers and letters on the individual find records. The eventual goal is to place all of our objects into a 3-D model of the ship so that we can virtually reconstruct what the archaeologists encountered, but all at once and free of mud and water. Pretty exciting possibilities and a hundred years worth of dissertations right there. But in the meantime, we're approaching mapping in a slightly more analog way. 

I will take these profiles, traced directly from excavation photographs where we have them and from drawings where we don't, and start plotting them on the plans we have for each of the decks. It will be a visual database made up of multiple layers so that we have the possibility to see different relationhips - for example, the distribution of all the tools that also have bomärke carved into them, alongside tools with decorative marks aside from or in addition to bomärke. Or, all the measuring tools at once. Or all the cutting tools. Or, the knives and awls - things generally thought to be personal equipment, things carried by people in pockets or personal containers - alongside all the human remains. It will help us to visualize how things were distributed at the time Vasa sank, which will contribute to our understanding of what exactly was going on onboard when Vasa set sail on her first and last voyage. 

Bygningsvernkongressen 2014

I've just returned from an inspiring trip to Norway for the Bygningsvernkongressen 2014 * at the Norsk Folk Museum in Oslo. It was three days of workshop practicums, lectures, and discussions attended by more than 350 cultural historians, conservators, academics, builders/makers, scientists, teachers, practictioners, etc. I was there as a representative of Vasamuseet to present my study of the ship's carpenter's tool chest alongside PhD candidate Roald Renmaelmo of Göteborgs Universitet's Institutionen för Kulturvård, who has recently built a replica of the carpenter's bench that was found aboard Vasa (more about that project to follow).  

 

The conference took place around the campus of the Folk Museum and the Norsk Maritimt Museum over the course of three glorious crisp early autumn days. I followed a track that was mostly sailing/maritime archaeology/museum focused, but there were practical workshops on everything from blacksmithing to sod-roof(ing?) and window glazing. The lectures and discussions covered an impressive range of cultural heritage topics, from painting conservation and pigment theory to dendrochronology. In addition to the smaller workshops and panels, each day there was one large gathering of all pariticpants in an outdoor amphitheater on the museum grounds (see above and below). These all-school meetings were somewhat improvised, and thematically arranged around the performative aspects of craft - i.e. how mesmerizing it is to watch other people do hard work.

We're all familiar with the phenomenon - five people standing around watching while one person does all the work - we've probably all even participated in similar scenes ourselves. On the surface, it's humorous! Jokes about the relative affinities for work among different careers/nationalities/age groups/whatever ! abound. But let's reconsider. It makes sense that people are drawn to watching other people work at a high level of specialization. Watching someone work with a specific tool or material or methodology that they have spent thousands of hours practicing is an incredible thing. It almost doesn't matter what the content is, or what is being produced, only that the object (say, a shingle, or a plank, or a piece of blown glass) is an artifact that represents an immense investment of time in learning to master that particular craft. It's the same reason we are enthralled by watching live musicians or dancers perform; it is a pure form of engagement, the closest we can get to something we have not mastered ourselves. To watch someone work at something in person, not translated through photographs or words or a screen, is an increasingly rare privilege in the digital age. Translation is an art form in it's own right, and I don't mean to demean it here - but it always involves some loss or, more accurately, evolution; a step of removal from the original. But the singular connection that occurs between craftsperson and viewer in person is impossible to replicate through any other media.  

The idea of work being performance, and performance as a mechanism for teaching and preserving craft, was revisited consistently over the three days of the conference. There was also an undeniably playful element to it all, with the opening ceremony involving the quasi-magical surprise reveal of a sign painted inside a log that was sawn in front of us on stage, and the amplification and broadcasting of the sounds of planes and saws with the help of wireless mics (see above and above). These were all noises that the whole audience (with a strong majority of carpenters and woodworkers) were familiar with - but by putting a microphone on the plane itself, and broadcasting the ensuing familiar sound, a single element in the normal workshop environment is picked out. Our attention is drawn to something that is has become "invisible" to us because it is so familiar. In contrast, here, with this amplification, it was as if the organizers were grabbing us all by the jaw and turning our heads gently to the side - "shh. Listen." No one had to stand up on stage and ask everyone to quiet down before the talking could begin. Instead, the assembly of 350 people simply rolled to a full hushed stop naturally, captivated by the sound of the pit-saw working through the log up on stage.

 

Translation in the literal sense was also an important theme for me over the course of the three-day conference. The whole thing was in Norwegian!** Which, incidentally, I do not speak. I understand a little with my limited grasp of Swedish, but I am still very much an observer when it comes to events like this. My entire experience of the conference necessarily passed through a language filter ("barrier" is not quite accurate; "semi-permeable membrane" is more applicable in this case, I think). I found it limiting in some ways, naturally. I'm sure I was seen wandering around more than once looking slightly bemused, detached, attempting to infer through the movement patterns of those around me those key single sentences regarding logistics - buses! times! building names! meeting points! - that seem often to come at the end of long theoretical talks and are so easily missed by the far-from-fluent.  

But, this distance was also liberating in that I could take in the broad swathe of what was going on around me without getting tangled up in the details. Not being able to understand everything all the time frees one to watch, to listen to the sounds and the crowd instead of to the specific words, to observe how those around you are engaging with one another and the local environment as well as what is being presented to them. It was illuminating and diverting to watch how a whole group of 21st century makers connected with the space around them: with the one and two and three hundred year old buildings scattered around the grounds, with their cameras, with their phones, and with one another. Watching what they focused on, and how. 

The incorporation of the modern alongside the investigation of the historical or the traditional was another important theme. I loved that around the museum and within the context of the conference, there was no pretense - no one was trying to fool anyone into thinking it was 1900 or 1750 or 1600. We are modern thinkers and builders investigating traditional processes, but also acknowledging as conservators and people interested in preservation that those practices continue to evolve. Great stuff.

 

Here is Roald's Vasa carpenter's bench replica! He's done a great job of both documenting and presenting the building process as well as the bench as a funtioning object, so I'll let his blog speak for itself: http://hyvelbenk.wordpress.com/

 

Stay tuned for a future post about how the bench itself fits in with my research into the ship's carpenter's tools. There are some surprises in store - !

   

On the last day of the conference I had the privilege of visiting the off-center storage site for the museum for a lecture and discussion about arranging storage spaces so that they function, practically as storage (their primary purpose for being, right?) but can also be useful to researchers and interested folks at large. 

This beautiful piece caught my eye - who knows, perhaps this particular carpenter was born around the same time as Vasa...

In summary, it was a fantastic few days. Looking forward to continuing the conversations that began there. But now, back to Stockholm! Schools back in session, the high summer season is over. Time to get back to the office and to storage, and time to get writing again! & also hopefully to shorter, more regular blog posts... 

* roughly: Heritage Conservation Conference, 2014

** with the obvious exception of my own paper, and possibly a few others? But none that I attended

Hello Nico! Bilingual report from the research project Support Vasa part II: Vasa's body language

Guest blogger Nico van Dijk from Delft, The Netherlands, postdoctoral researcher specialized in mechanics at Uppsala University and in the Support Vasa project. Here, Nico reports in his native language and English on his work on simulations of the Vasa that will aid in the design of a new support structure for the ship:

Vasa’s lichaamstaal

Ontmoeting met de Vasa

Iets meer dan twee jaar geleden wist ik niets van het oorlogsschip Vasa. Ik wist überhaupt niet zoveel van Zweden, hoewel Nederland, waar ik vandaan kom, helemaal niet zo ver weg ligt. Het is bijzonder dat iets kleins (of iets groots) je leven zo kan veranderen.

Na mijn promotie aan de TU Delft in Nederland was ik op zoek naar een mogelijkheid mijn academische loopbaan voort te zetten in een ander land. Na wat rondkijken vond ik een vacature bij de universiteit van Uppsala bij de Toegepaste Mechanica groep: Postdoctoral position for structural optimization of the support structure of the Vasa.

Ik werd uitgenodigd om bij de Vasa in Stockholm een kijkje te nemen. In mei 2012 stapte ik voor het eerst door de deuren van het Vasa museum. Hoewel ik al wel foto’s gezien had, was ik overdonderd door de ontzettende grootte van het schip. Het voelde alsof ik terug in de tijd keek.

Anders Ahlgren en Fred Hocker namen ons mee op een rondleiding door het museum en zelfs aan boord van het schip. We keken hoe het schip in elkaar zat en onderzochten, natuurlijk, de draagconstructie waar ik me in mijn onderzoek mee bezig zou gaan houden. Tijdens het bezoek aan het museum werd het voor me duidelijk dat het niet zomaar een academisch onderzoek zou zijn. Nee, een grote verantwoordelijkheid rustte op de schouders van zowel het onderzoeksteam als het personeel van het museum: het behouden van de Vasa voor de komende 1000 jaar. 

Vasa’s body language

Meeting the Vasa

A little over two years ago, I knew nothing of the Vasa. In fact, my knowledge of Sweden was very limited even though my home country The Netherlands is not very far away. It is amazing how small things (or big things) can change our lives.

After my PhD studies at Delft University of Technology in The Netherlands, I was looking for an opportunity to continue my academic career in another country. After some searching I found a vacancy at Uppsala University in the Applied Mechanics group: Postdoctoral position for structural optimization of the support structure of the Vasa.

I was invited to take a look at the Vasa ship in Stockholm. In May 2012 I first stepped through the doors of the Vasa museum. Even though I did see some pictures before that, I was amazed by the sheer size of the ship. It felt like looking back into the distant past.

Anders Ahlgren and Fred Hocker took us on a tour through the museum and even on board the ship. We looked at the construction of the ship and, of course, at the support structure that would be the subject of my research. During this visit to the museum it dawned on me that this was not going to be just another academic study. No, a large responsibility rested upon the shoulders of both the research team as well as the personnel at the museum: to preserve the Vasa for 1000 years to come.

 

De Vasa beweegt. The Vasa is moving.

De Vasa beweegt

De Vasa ligt al sinds 1988 ogenschijnlijk roerloos in het huidige Vasa museum. Elk jaar verplaatsen echter verschillende delen van het schip zich ten opzichte van elkaar. Bij het museum realiseren ze zich goed dat het schip beweegt en houden ze haar voortdurend in de gaten door middel van regelmatige metingen aan een groot aantal locaties op de romp. Deze metingen geven ons een idee hoe het schip zich aan het bewegen en deformeren is. We proberen de lichaamstaal van de Vasa te lezen.

De verzameling ribben met gelijke tussenruimten die de huidige draagconstructie vormen zijn verre van ideaal. Ze ondersteunen het schip niet waar dat het meest nodig is en kunnen zelfs de oorzaak zijn van sommige plaatselijke vervormingen in de romp van het schip. De ingenieurs bij het museum zijn voortdurend bezig de wiggen tussen de metalen ribben en de romp van het schip te controleren en te verstellen om deze plaatselijke vervormingen te minimaliseren. Het project “Support Vasa” is tot stand gekomen om deze vervormingen in het schip te onderzoeken en een verbeterde draagconstructie te ontwerpen.

The Vasa is moving

The Vasa ship has been residing in the current Vasa museum seemingly motionless since 1988. However, every year different parts of the ship are displaced a couple of millimeters. At the museum they are well aware that the ship is moving and constantly busy to keep an eye on her by means of regular measurements of a large number of points on the hull. These measurements give us an idea of how the ship is moving and deforming. We try to read the body language of the Vasa.

The set of equally spaced ribs that is now the support structure is far from ideal. It does not support the ship where it is most needed and may even cause some local deformations of the hull of the ship. Engineers at the museum are constantly checking and adjusting the wedges between the metal ribs and the hull of the ship to minimize these local deformations. The project “Support Vasa” was started to investigate the deformations of the Vasa and to design an improved support structure.

Verstelbare wiggen ondersteunen de Vasa. Adjustable wedges support the Vasa.

Vasa-eikenhout imiteren

Het is natuurlijk erg belangrijk om in de gaten te houden wat de Vasa ons op dit moment vertelt met haar bewegingen, maar we zouden ook graag willen weten wat er met haar gaat gebeuren in de toekomst. In deze moderne tijd proberen ingenieurs het gedrag van constructies zoals de Vasa te voorspellen met behulp van computermodellen. Deze modellen zijn natuurlijk pas nauwkeurig wanneer de daadwerkelijke eigenschappen van het materiaal worden gebruikt als input. Een simpel voorbeeld: Als we willen weten hoeveel een veer uitrekt als we er een gewicht aan hangen, dan moeten we de stijfheid en lengte van de veer weten en hoeveel gewicht we eraan hangen.

Op dezelfde manier moeten we de eigenschappen weten van het eikenhout dat gebruikt is om de Vasa te bouwen. Jammer genoeg is Vasa-eikenhout een erg complex materiaal; het heeft verschillende eigenschappen in verschillende richtingen (probeer maar eens hout in de verkeerde richting te spijten), op verschillende plekken (probeer maar eens hout te hakken bij een knot) en deze eigenschappen hangen af van de tijd, de temperatuur en vochtgehalte (hout snijden wordt makkelijker als je het nat maakt). Maar het is nog lastiger, want Vasa-eikenhout is niet ‘normaal’ hout, maar archeologisch (oud), doordrenkt (voorheen lag het onder water) and geïmpregneerd (behandeld om scheuren te voorkomen tijdens het drogen) wat allemaal invloed heeft op de eigenschappen.

Het eikenhout van de Vasa is een zo ingewikkeld materiaal dat de beste manier om alle eigenschappen te verkrijgen waarschijnlijk is om het te imiteren - er een computermodel van te maken. We weten veel over hoe Vasa-eikenhout eruit ziet tot in de microscopisch kleine details. Door van deze kennis  gebruik te maken zijn wij op dit moment bezig de (gemiddelde) eigenschappen van Vasa-eikenhout te reproduceren met verschillende modellen van de microstructuur.

Deze eigenschappen kunnen dan gebruikt worden om te voorspellen wat er gaat gebeuren met de Vasa en een draagconstructie te ontwerpen die precies voldoet aan haar behoeftes. Ons team van onderzoekers is hard aan het werk om te begrijpen wat de Vasa ons wil vertellen en zo te zorgen dat de volgende generaties ook de kans krijgen om terug te kijken in ons verre verleden.

We simuleren eikenhout van de Vasa. We simulate Vasa oak.

Imitating Vasa oak

Of course it is extremely important to keep track of what the Vasa is telling us with her movements right now, but we would also like to know what will happen to her in the future. In this modern age, engineers try to predict the behavior of structures such as the Vasa ship by creating computer models. Of course these models are only accurate when accurate properties of the material are used as input. A simple example: If we want to know how much a spring extends when we hang a weight from it, we need to know the stiffness and length of the spring and how much weight we hang from it.

In the same way, we need to know the properties of the oak wood that has been used to build the Vasa ship. Unfortunately, Vasa oak is a very complex material; it has different properties in different directions (try splitting wood in the wrong direction), in different places (try cutting wood where there is a knot) and depending on time, temperature and moisture (carving wood becomes easier when you make it wet). But it is even more difficult, since Vasa oak is not ‘normal’ wood, but archaeological (old), waterlogged (previously submersed in water) and impregnated (treated to avoid cracking during drying) which all affect its properties.

Vasa oak is so complex that probably the best way to obtain all necessary properties is to imitate it - to create a computer model. We know a lot about what Vasa oak looks like down to the microscopic scale. Using this knowledge, we are currently working on reproducing the (average) properties of Vasa oak with different models of its microstructure.  

These properties can then be used to predict what will happen to the Vasa ship and to design a support structure that is tailored specifically to her needs. Our team of researchers is hard at work to understand what the Vasa wants to tell us and ensure that the coming generations also have an opportunity to look back into our distant past.