One of the pretty vibrant trends when it comes to modern architecture is freeform structures, which happen to be one-of-a-kind buildings with unconventional shapes and comprise museums, luxury hotels, stadiums, exhibition pavilions, or even universities.
It is well to be noted that reinforced concrete happens to be the go-to material for such impressive constructions, with their domes, vaults, as well as complex facades. However, fiber-reinforced polymers are also a promising alternative. Although they are more expensive to produce, their maintenance happens to be cheaper as they do not rust and do not require painting. They also happen to be light and sturdy, thereby unleashing new possibilities when it comes to architectural expression; for instance, wider spans sans intermediate supports.
In order to make this happen, the present tools for building design as well as modeling must be reinvented, as they are geared toward traditional materials like reinforced concrete or even steel, for that matter. This is what Associate Professor Alexander Safonov’s scientific team from the Laboratory of Composite Materials and Structures at Skoltech Materials, along with colleagues from the University of Granada, are starting to do within their study reported in Composite Structures.
The lead author of the study, Anastasiia Moskaleva, who is also a Skoltech Materials Ph.D. student, commented that it is indeed tempting to just transfer what one does with reinforced concrete to polymer composites. But this happens to be a mere mechanical reproduction of what they are already used to doing, without due regard for the distinct nature of the new material as well as its potential.
Hence, in this study, they go on to do it properly and thereby go all the way from design to manufacture sans pretending that they are dealing with concrete. It is worth noting that they focus on one specific structure shaped as a curved surface, which they investigate in miniature.
Interestingly, the surface in question is known as a form-found shell structure. It sounds technical; however, it is a kind of shape that comes up in freeform architecture in certain domes as well as vaults. The researchers went on to complete the entire cycle by way of designing the structure, fabricating it as a 30-by-30-centimeter lab model, and finally testing it under some artificial stress in an experiment. They also went on to model the shell’s mechanical properties mathematically.
Within this study, the team stressed the design stage. There happens to be no tried-and-tested technique when it comes to designing composite structures of this kind, and hence the researchers went on to adopt the force density method. It is used for resembling structures that are made of concrete, wood, as well as steel but it has not been applied as yet to composite structures.
Moskaleva states that it is just recently that this method went on to get its formal mathematical description; however, it is rooted within experiments like the ones that were done by Antoni GaudÃ, who used to derive highly efficient forms by ensuring to suspend the models in the air in order to let them sag under their own weight & strength and then invert the shape they assumed. The fact is that he let gravity do the work in a form-follows-force kind of way. She added that they specified that they had required a structure that would rest on the four supports and take its own weight in the maximum way it could, and hence the method led them to this shape.
It is well to be noted that the structure was then manufactured as a small-scale sample by way of using what is called vacuum infusion in the Laboratory of Composite Materials and Structures at Skoltech Materials. This goes on to involve laying sheets of carbon fiber on a rigid framework that helps them get a shape in an airtight pocket, thereby covering the structure with epoxy and leading it to soak the fabric by way of manipulating pressure. After a day within the airtight compartment, the sample went on to solidify and was ready for mechanical tests.
However, first, they ran numerical modeling in order to predict the structure’s mechanical properties, such as how it would behave in the test when it comes to mechanical load, said Moskaleva. All this goes on to give them a reason to believe that the model they chose can very well be used for the same structures in the future due to the fact that it indeed went on to match the experimental observations almost closely. Apparently, in the experiment, one kept loading the structure right from above until the loss of stability.
The study therefore lays a strong foundation when it comes to designing and modeling curved-surface construction components that are made of polymer composites. In the end, they could very well be a part of the freeform architecture toolkit. The shape of a double-curvature shell itself happens to be more efficient for bearing a load as compared to a flat concrete slab, explained the researchers.
However, if one could also go on to tap into the superior properties of polymer composites, the creative possibilities happen to be huge. Between lower maintenance costs as well as outstanding mechanical properties, this can very well be more cost-efficient, not to mention the expressive potential that it would have.
