The curved shapes of hand-made figurines are widespread in the Bethlehem’s tourism industry. What is intriguing about all these crafts is the precision of the forms given the basic tools used for their fabrication. An established hierarchy and apprentice curriculum maintains the artisans’ skills to a certain standard. Becoming an olive-wood master carver is, among other skills, being able to reproduce a complex-geometry shaped figurine while only looking at it.
Olive wood artisan – Credits: AAU ANASTAS
The process of fabrication of olive-wood objects in Bethlehem calls high-tech mass customization into question. Mass imperfections is a project that experiments the potential of artisanal fabrication for the construction of large-scale structures.
The project experiments the ability of craftsmanship of stepping back into the forefront of the fabrication processes. Mass imperfections challenges high tech fabrication processes by monitoring and anticipating imperfections of highly skilled artisans.
The structure’s global shape is a 3m high arch made out of olive-wood pieces that are 1cm thick. The structure is made out of 552 mutually supported olive wood pieces that are small with respect to the entire structure. Each olive-wood panel has six vertices, three of which are supported by three neighboring panels while the remaining three support three other neighboring panels. In that sense, the structure is reciprocal; each panel plays an equivalent structural and topological role in the overall stability of the structure.
The global shape of the structure has been determined according to a process of design at the opposite end of the planning spectrum, from the bottom up. After several experimentations of faithfulness of an artisanal fabrication to a designed complex-shaped geometry, the level of imperfections has determined the family of possible panels and consequently potential global forms. The understanding and monitoring of imperfections helped merge into the deep understanding of local know-hows, and capacities of widening or subverting the initial end result to new uses.
Plan and elevation
Olive wood has the particularity of being issued of branches thus avoiding the uprooting of the entire tree. The collected wood is of relatively small dimensions initially soaked with oil and water. Before it is ready for use, the wood is dried in hangars protected from exterior climatic conditions for several years. Once the wood is dry, it usually has a volumetric mass varying between 800 kg/m3 and 990 kg/m3. For the purpose of this project physical tests were held on dry olive wood in order to input our Finite Element Analysis (FEA) with the correct material properties:
The first concern of the structural analysis was to ensure the stresses in the panels were not exceeding the yield strength of the material, while our second concern involved the global buckling of the arch given its slenderness. The panels were defined as shell elements while their connections were free to rotate along the axis of connection.
The following diagrams show the values of axial stress in the structure and the displacement values. Although the thickness of panels is 1cm, their curved shape and the interlocking arrangement of the structure’s modules gives a 2cm structural thickness.
|Modulus of Rupture (MPa)||120|
|Compressive strength (MPa)||90|
|Tensile strength (MPa)||77|
Utilization structural diagram and displacement structural diagram
The fabrication of each panel has followed a long and slow process involving hybrid procedures of hand and machine controlled fabrication techniques. While a template panel was realized, the copy machine was the first step in duplicating panels, in batches of 12. The hand-powered movement of the 12-head copy machine monitors the movement of the artisan as a reference for the production of a batch of 12 pieces. As such each batch is an exact approximation of the original piece.
Errors are embedded in the process of fabrication of the mass imperfections pavilion. Although it stands for the ability of low-tech to produce complex structures, it experiments a proposal of novel ways to blend the human and the machine.
Mass imperfections is an olive-wood structure created for Dubai Design week 2016 — Abwab which opened on the 24th of October 2016.
Author: Yousef Anastas
Yousef Anastas is an architect and structural engineer.
He holds a Master’s in Architecture from l’Ecole d’architecture de la Ville et des Territories (2011), and a structural engineering Master’s degree from l’Ecole Nationale des Ponts et Chaussées (2014). He is currently a PhD candidate at Geometrie Structure Architecture (GSA) research lab in Paris, working on the resistance optimization of stone vaults through advanced stereotomy. In 2014, he conducted a research at the Form-Finding lab of Princeton University on biomimetic building skins. In 2014, he was awarded the 40 under 40 award for young European architects. He is currently leading AAU Anastas’ research department, SCALES – a research laboratory that is consistently enhanced by linking scales that are otherwise opposed.