Wood is quite unique in comparison with most building materials used today given that its material cosmetic is because naturally grown biological structure (ill. 18). Thus, the material makeup and structure of wood is significantly different than that of most industrially produced, isotropic materials. Upon close exam, wood can be described as an anisotropic natural fibers composite. As opposed to isotropy, which constitutes equivalent properties in all directions of a materials, anisotropy concerns the property of being directionally dependent. For instance, one can see this in the manner that timber can bend easily in the tangential axis (ill. 19) which is the route perpendicular to its grain path. When examining real wood from any given viewpoint, you can identify materials characteristics and behaviours specific compared to that angle, relative to the material's main grain orientation. In other words, should one look at the material properties of real wood at an viewpoint 45 levels to the primary grain orientation, one will quickly realize properties extremely unique of those obtained from an viewpoint 90 degrees to the main grain orientation.
The directionally centered property of solid wood is because the horizontal or vertical orientation of the individual cells and the preparations of growth levels in a tree. [1] Throughout architectural record, this natural heterogeneity of hardwood as well as its intricate materials characteristics have often been characterized as deficiencies by architects, designers and members of the timber industry. [2] This can be traced to the fact that a lot of designs and construction methodologies used today require the use of materials bearing nominal variants in their properties and behaviours in order to satisfy the need for isotropic set ups.
In distinction, this thesis views wood's sophisticated material makeup and its own capacities as significant advantages alternatively than deficiencies. Furthermore, it aspires to understand these interesting characteristics of lumber and employ them through an informed design process.
In addition to these complex material properties, real wood also reveals many beneficial characteristics including variety, weight, durability, appearance, workability, cost and availability. Another factor which makes wood an extremely appealing material today concerns its overall ecological advantages. In light of environmentally friendly challenges that the built environment is facing today, it is becoming increasingly identified that hardly any building materials can rival wood's environmental benefits. Real wood is a natural, renewable materials that holds an extremely low level of embodied energy. It really is known for its ability to lessen skin tightening and emissions by keeping CO2 and also by substituting for materials with a higher carbon content[3]. In this manner, the use of lumber actually produces a positive carbon footprint. [4] Solid wood is also an extremely energy conserving building material in its creation. For example, real wood requires 50 times less energy in its developing than steel to ensure a given structural stiffness all together. [5]
Unlike many natural resources, forests consist of a renewable source of information. With careful forest management, you can ensure that forests flourish and continue to provide the benefits to which we have become accustomed. Foresters can analyze an 'allowable cut' of trees per year for any given forest area that will secure a stable harvest. Tree farming is just one more way of sustainably gratifying today's demand for solid wood. Programs at Oak Ridge National Laboratory have built a variety of super trees that can increase at rapid rates of speed in order to create a large amount of bio mass in a single given acre. These made trees and shrubs are being farmed at tree farms including the Boardman Tree Plantation LLC, and are redefining modern forestry (ill. 20). The Boardman Tree Plantation plantations are positioned in eastern Oregon, USA, where dry desert land has been transformed into a thirty thousand acre farm. This plantation currently has seventy million trees and is capable of producing half a million trees yearly to satisfy requirements. The plantation harvests five acres of trees every day to be able to keep this continuous circuit. [6]
As a result of wood's naturally-grown origin, its unique material composition accounts for almost all of its properties and characteristics. [7] The aim of the thesis is to explore some of the potential ways of utilizing the materials properties and specific materials characteristics of hardwood in the look field. To carry out so, the heterogeneous framework of solid wood must first be grasped in more detail.
Wood can be defined as a low-density, mobile, composite material and as such, does not readily fall into an individual class of material, but instead overlaps a number of classes. In terms of its high power performance and affordability, timber remains the world's most successful dietary fiber composite. In the microscopic scale, one can describe hardwood as a natural fibers composite. [8] (Ill. 21)
Wood skin cells are comprised of layers, upon which cellulose microfibrils function like fibers inlayed in a matrix of lignin and hemicelluloses, reinforcing the assemblage as a whole. For this reason make-up at the microscopic level, real wood shares lots of properties with materials like: fabricated composites, strengthened plastics, fiberglass, and carbon fiber. Similar to solid wood, these materials are characterized with relatively low tightness in blend with relatively high structural capacity. In other words, wood is made up of innate elastic properties especially well-suited for development methods that seek to hire elasticity in reaching complex lightweight buildings from primarily planar elements.
What follows is supposed as a brief overview of the material composition of hardwood. Understanding the anatomical areas of wood is vital to the research and investigations that have been conducted.
In compare to building materials that are specifically made and manufactured to suit the needs of the architect or an engineer, hardwood is a result of the biological tissues functions that take place in a tree. Although there exists a wide variety of species of trees on the planet, all trees and shrubs, despite their variety, share certain characteristics. Trees are vascular and perennial this means they can handle adding yearly expansion to previously expanded wood. The growth process of a tree occurs in the cambium, a slim coating of living cells between the bark of the tree and the interior stem structure. (Ill. 22) Cambial cells have thin surfaces and separate themselves lengthwise to increase into two new cells. Following the cell section, one of both cells enlarges to become another cambial mother cell as the other either matures into a bark cell or forms towards the inside of the cambium to become a new solid wood cell.
When the primary wood skin cells reach maturity and become their mature size, a second wall is constructed from long string hemicellulose and cellulose substances. The long chains of cellulose molecules are oriented in a way parallel to the long axis of the cells and strengthened by lignin (ill. 23). Lignin is an integral area of the wood's cellulous composition since it provides support for the cells. Additionally it is the material that gives rigidity to crops. [9] The syndication and orientation of the skin cells combined with the material structure of the cell surfaces determine most of the causing characteristics and properties of hardwood. [10]
Trees are characterized into two types: softwoods and hardwoods (ill. 24). The terms 'softwood' and 'wood' do not symbolize softness or hardness of wood. The two terminologies are related to the botany of the species and to how a tree develops. The differences between your two types of real wood is seen in the cellular framework of the materials. Within the relatively simple mobile framework of softwood, nine tenths of the hardwood volume involves one cell type called "tracheid", while the remainder contain ray tissues. Tracheids are fiber-like cells and also have a length-to-width ratio of 100:1, and therefore they are about a hundred times much longer than they may be vast. The tracheid skin cells are assemble parallel to the stem axis positioned in the radial layers of the tree and are in charge of the transportation of normal water and nutrients throughout the tree.
In compare, a much increased variety of cell types and set up configurations are present in hardwoods. In addition to tracheids, hardwoods also contain vessels, rays and fiber content cells. Vessel elements in hardwood have a big diameter and slim walls, including no end-to-end wall space. As a result, they are set up within an end-to-end creation that is parallel to the stem axis of the tree, building continuous channels that take sap through the tree. Unlike vessels, fiber content cells are much smaller in diameter and have thicker cell surfaces and possess shut tapered ends (ill. 25). In both softwood and hardwood, the structure, syndication and orientation of skin cells are the deciding factors of the anisotropic, structural, and hygroscopic characteristics of lumber. [11]
The anisotropic and hygroscopic characteristics of real wood caused by its internal cellular structure have typically been regarded as difficult in the techniques of structures and structural executive, especially when compared to more homogeneous, secure, industrially produced isotropic materials like metallic, plastic or glass. In design strategies within architecture, engineering and timber market sectors, knowledge of wood's material structure and characteristics has typically been used to counterbalance its intricate materials behaviours. [12] For instance, the development of engineered industrial hardwood products (ex: MDF, or cross-laminated-timber) emerged as a response to the heterogeneous composition of lumber. These timber products are capable of producing a material that is much more homogenous and which provides isotropic material characteristics.
Unfortunately, the design opportunities that might be made possible using the innate heterogeneous characteristics of solid wood are too often overlooked in today's construction projects. In fact, particularly in THE UNITED STATES, the construction material of timber is often no more referred to as such. Instead, timber is known as a dimensional building factor, such as a '2x4'. The aim of this research is to propose an alternative solution method of design which views wood's intricate material structure and related behaviours as useful rather than difficult. Such an integrated design strategy can perhaps contribute towards a renewed understanding for the behavioral capacities of real wood and the wealthy design opportunities that may be realized thanks to the natural anatomy of the material.
Three-ply plywood and veneer are unmistakably industrially-produced materials. However, unlike other industrially-produced materials such as material, glass, clear plastic, MDF or particle plank, three-ply plywood and veneer are anisotropic materials. This implies that the properties and behaviours of these materials range significantly with regards to the fiber route. For instance, veneer and plywood encounter considerable variations in stiffness depending on grain course. The compressive durability of lumber differs significantly depending on grain direction, as do most of its other mechanical and materials properties. The following section details the manufacturing process of veneer and plywood to be able to better understand the materials exploration that will be presented in Section 3.
Plywood may appear to be always a relatively new industrially-produced timber product, however its principle is in fact very old and can be tracked back to more than 5, 000 years. Prior to the expression "plywood" was invented in the 1920s, the procedure was known as veneering. Among the earliest traces of plywood was within the tomb of Ruler Tutankhamun, an Egyptian Pharaoh who ruled around the year 1334 BC. The discovered pieces of plywood were remains of coffins manufactured from six levels of lumber, each 4mm thick and held alongside one another by glue and real wood pegs. [13] The plywood remains were fabricated using the same important techniques as today. Like modern plywood, the grains of the layers where arranged perpendicularly with each part for strength[14] (ill. 26). Out of this period onwards, veneering techniques became ever more widespread across the world. Thanks to the introduction of tools and technology over time, veneer thicknesses were reduced and new adhesives (ex: glue made from bone, sinew and cartilage) were used to bond the layers together with temperature. [15]
Although plywood is made much just as today, modernized adhesion techniques and tools found in its production have advanced significantly, rendering it one of the most affordable and easily-produced building materials. Both hardwoods and softwoods are used in the production of plywood. The typical sequence of procedure mixed up in creation of plywood is as follows:
There exists an extended standing discourse about sheet materials in structures, partly because they are so ubiquitous in conventional construction. Broadening the knowledge of these materials is valuable to the architectural profession, as it allows someone to discover new potentials concerning materials which are already familiar. Being a sheet materials, plywood thus offers many advantages as a topic of research and experimentation. Like other sheet materials, it can aid the creation of complex geometry using at first planar elements. Three-ply plywood is the materials of choice for this thesis because of its ability to offer high amounts of flexibility in one direction, without diminishing its strength. Three-ply plywood, as previously described, is made up of odd tiers, two of which are oriented in a single direction, while the center layer is placed perpendicularly to the external layers. Thus, due to the predominant fiber course present in the two outer levels, three-ply plywood has a natural tendency to flex perpendicularly to this grain direction. The main of the assemblage, normally known as the guts layer, provides durability to the assemblage by offering amount of resistance to the predominant fibers direction. As a result, the plywood assemblage is less likely to break or snap when being bent since it is strengthened by one interior sheet comprising fibers running perpendicular to the outside layers.
Knowledge of the production process for plywood is important for this research since it provides an release to lamination techniques that may be further utilized in the materials investigations and implementations that will follow. The process detailed above elaborates on the task mixed up in mass-produced creation of smooth plywood sheets found in the building industry. However, the process of lamination do not need to strictly connect with planar floors, but also to the development of three-dimensional varieties.
[1] J. M. Dinwoodie, Timber: Its Mother nature and Behaviour (London: E&FN Spon, 2000).
[2] T. Herzog, Holzbau Atlas (Basel: Birkhuser, 2003).
[3] A. Alcorn, Embodied Energy Coefficients of Building Materials (Wellington: Centre for Building Performance Research, 1996), 92.
[4] Joseph Kolb, Systems in Timber Executive: Loadbearing Constructions and Component Layers (Basel: Birkhcustomer, 2008), 19.
[5] J. E Gordon, Structure (Cambridge: Da Capo Press, 2003).
[6] "A Source That Lasts Forever, " previous revised July 23, 2014, http://www. greenwoodresources. com/
[7] Barnett and Jeronimidis, Wood Quality and its own Biological Basis (Oxford: Blackwell CRC Press, 2003).
[8] "Amalgamated Materials - Natural Woods. " Previous customized July 23, 2014, http://www. technologystudent. com/joints/composit1. html.
"Composite materials, sometimes known as composites, are materials composed of two or more component parts. These component parts may have different physical or chemical substance properties so when carefully inspected, they look as independent parts, bonded alongside one another, forming a amalgamated material.
[9] R. Bruce Hoadley, Understanding Real wood: A Craftsman's Guide to Solid wood Technology (Newtown, Conn. : Taunton Press, 2000).
[10] R. Wagenfјhr, Anatomie des Holzes : Strukturanalytik, Identifizierung, Nomenklatur, Mikrotechnologie (Leinfelden-Echterdingen: DRW-Verlag, 1999).
[11] R. Wagenfјhr, Anatomie des Holzes : Strukturanalytik, Identifizierung, Nomenklatur, Mikrotechnologie (Leinfelden-Echterdingen: DRW-Verlag, 1999).
[12] T. Herzog, Holzbau Atlas. (Basel: Birkhend user, 2003).
[13] Lucas A. and Harris, Old Egyptian Materials and Market sectors (Dover Publications; 4th edition, 2011), 451.
[14] H. Taylor John, Death and the Afterlife in Ancient Egypt (Chicago: U of Chicago, 2001), 218.
[15] L. Patrick Robert and Minford J. Dean, Treatise on Adhesion and Adhesives (CRC Press, 1991), 3.
