Derived from the greek word "μορφογένεση" ( μορφή (form) + γένεση (genesis) ), morphogenesis generally refers to providing shape to objects.
When these objects are designed to carry loads, then we talk about structural morphogenesis.
During human history, different factors have contributed to the evolution of structural morphogenesis. In the sequel, I briefly present some of those that had a major impact.
Experience & Intuition
Since the early years of humanity, several civilizations developed empirical structural systems to transfer safely loads to the ground. Despite the lack of scientific knowledge and advanced materials, some of these structures cause awe even nowadays and highlight the importance of experience and intuition in creating efficient structural systems.
The Parthenon, built in ancient Athens around 432 BC by Iktinos and Callicrates, is the finest example of ancient Greek architecture. The structure and shape of its columns, being slightly parabolic in order to create a sort of "reverse optical illusion" when seen from a distance, constitute a remarkable achievement of that period.
Hagia Sophia, built in 537 as the patriarchal cathedral of the imperial capital of Constantinople, still creates a strong impression to its visitors mainly thanks to the dimensions of its dome (31,7 meter in diameter and 55,6 meter high from floor level), which collapsed after the earthquake of 558 and was re-built in 563 by Isidore the younger, a nephew of Isidore of Miletus.
The early knowledge on structural mechanics, as well as mechanics of materials, inspired architects to adopt pioneering design methods using physical models to extract optimized shapes.
The hanging-chain models of Gaudi, used in several of his famous creations (Basílica de la Sagrada Família, Colonia Güell Crypt, etc.), have been based on the famous phrase of the English scientist Robert Hooke, back in 1675:
“As hangs the flexible line, so but inverted will stand the rigid arch.”
which provided valuable insight in how one should design efficiently using materials that work under compression (e.g. stone).
Similar techniques have been used by other famous architects in their trial to design optimally for new materials and structural systems, such as the hanging models of Frei Otto used for his gridshells and his experiments with soap films to extract organic shapes.
The significant advance in technology during the 20th century has provided engineers and architects with the means to realize designs that were not possible before.
Novel structural materials (reinforced concrete, high-strength concrete, fiber-reinforced concrete, structural steel, composite materials, etc.) have paved the way for efficient use of mater and lightweight structures.
Besides materials, structural technology has also had a strong contribution in exceeding previous limitations. For example:
Pre-stress systems allowed to span long distances and design "invisible" structural systems.
3D-trusses are another typical example where efficient structural systems boosted MorphoGenesis.
Post-tensioned membranes have become particularly common, especially for outdoor spaces.
Moreover, the significant advance in computational techniques allowed to study complicated structural systems that was not able to analyze by hand and understand their structural behavior without resulting in costly physical experiments.
Designs extracted using computational tools and/or algorithms.
Common: automated generation of forms.
- mechanical simulation or just geometry
- algorithmic/iterative or not
During the last two decades, there has been an explosure around the use of Compter-Aided Design (CAD) and Computer-Aided Engineering (CAE) by designers, architects and engineers. Initially, such tools have been used to re-create in digital format and analyze an existing conception, probably sketched before by hand. However, the burst in computational power in the recent years made feasible to use algorithmic approaches for automated generation of forms in realistic times.
When computational tools are used for form-finding, we refer to Computational MorphoGenesis.
We can distinguish (at least) two distinct categories of this type:
CAD-based MorphoGenesis: when the automated generation of forms is purely based on some geometric kernel (e.g. Beijing National Stadium "Bird's Nest").
CAE-based MorphoGenesis: when mechanical analysis is somehow implicated in the form-finding process.
CAE-based Computational MorphoGenesis
This branch of Computational MorphoGenesis has attracted significant interest during the last years, both in academia and industry.
Although different names have been used in literature, they are commonly refered to as Topology Optimization methods and combine tools of Mechanics, Applied Mathematics and/or Artificial Intelligence (AI).
They are based on optimization algorithms, where the form evolves iteratively based on structural efficiency criteria.
Several software editors have incorporated related techniques in their products, helping large audiences to familiarize with such cutting-edge techniques in a seamless way. Today, they find a wide area of application in the everyday design cycle of several industries, while novel applications are being presented in other sectors. In the sequel, I present some of these applications.
Engineers were the first to adopt Topology Optimization in their everyday design process. In several idustries (automotive, aeronautic, aerospace, etc.) the structural form is dictated by specific mechanical and geometric criteria,. Therefore, it is possible to formulate a rigorous optimization problem and search for an optimized shape via Computational MorphoGeneis techniques.
Moreover, the progress in Additive Manufacturing techniques made possible to realize geometrically intricate shapes and thus increase the industrial interest and feasibility of topologically optimized shapes.
There is a variety of software today available for engineers, based on CPU or even GPU (e.g. Discovery Live by ANSYS). Their use in frameworks where experience and intuition is limited (e.g. structural dynamics) has proven the interest of Computational MorphoGenesis as a valuable design tool.
Architectural design is seldom amenable to the formulation of some rigorous optimization problem. Most of the times, strong manufacturing constraints and budget limitations suggest a typological design process, where the structural system is chosen among well-known examples. In addition, aesthetical considerations play a principal role and can rarely be described via mathematical formulas.
However, applications of Computational MorphoGenesis in architectural design have appeared, motivated by different reasons:
In exceptional structures, where budget limitations are not dominant, one can argue that a certain sense of aesthetics derives from rendering visible the flow of forces via topology optimization. The entrance of Qatar National Convention Centre, designed by Arata Isozaki and Mutsuro Sasaki, is probably the most famous example in this direction.
In unique structures with complicated geometry such as skyscrappers, using Computational MorphoGenesis allows to extract pioneering structural systems, speed-up convergence between architects and engineers and thus enter faster into competitions. SOM (Skidmore Owings & Merrill) is the most well-known company employing a variety of optimization techniques.
Large-scale topology optimization has been recently employed (Baandrup et al.) to explore novel structural systems in order to overcome existing design limitations in bridge engineering and save material.
We tend to regard furniture as simple objects, not as structures bearing loads. We focus merely on their functional part in our everyday life, while the manufacturing cost usually dominates the design of the structural part, which tends to be significantly oversized.
In reality, a great part of furniture are structures (load-bearing objects) and therefore the complexity of their design could be equivalent to that of mechanical parts or architectural buildings.
My personal point of view is that Computational MorphoGenesis could be used for the structural part of furniture, contributing to their aesthetical appeal in our everyday life.
Inspired by a phrase of the nobelist greek poet Odysseus Elytis:
"You'll come to learn a great deal if you study the insignificant in depth."
I have decided to further explore this direction. (Read more...)