Fabric structures are architecturally innovative forms of constructed fiber

Fiber

Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....

s that provide end users a variety of aesthetic free-form building designs. Custom-made fabric

Fabric

A fabric is a textile material, short for "textile fabric".Fabric may also refer to:*Fabric , the spatial and geometric configuration of elements within a rock*Fabric , a nightclub in London, England...

 structures are engineered

Engineering

Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...

 and fabricated to meet worldwide structural, flame retardant

Flame retardant

Flame retardants are chemicals used in thermoplastics, thermosets, textiles and coatings that inhibit or resist the spread of fire. These can be separated into several different classes of chemicals:...

, weather-resistant, and natural force requirements.

A fabric structure's material selection, proper design, engineering, fabrication

Manufacturing

Manufacturing is the use of machines, tools and labor to produce goods for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale...

, and installation are integral components to ensuring a sound

Soundness

In mathematical logic, a logical system has the soundness property if and only if its inference rules prove only formulas that are valid with respect to its semantics. In most cases, this comes down to its rules having the property of preserving truth, but this is not the case in general. The word...

 structure.

Fabric Structure basics

Membrane Materials
Most fabric structures are composed of actual fabric

Textile

A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...

 rather than mesh

Mesh

Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to web or net in that it has many attached or woven strands.-Types of mesh:...

es or films

Artificial membrane

An artificial membrane, or synthetic membrane, is a synthetically created membrane which is usually intended for separation purposes in laboratory or in industry. Synthetic membranes have been successfully used for small and large-scale industrial processes since the middle of twentieth century. A...

. Typically, the fabric is coated and laminated with synthetic materials

Synthetic fiber

Synthetic fibers are the result of extensive research by scientists to improve on naturally occurring animal and plant fibers. In general, synthetic fibers are created by forcing, usually through extrusion, fiber forming materials through holes into the air, forming a thread...

 for increased strength

Strength of materials

In materials science, the strength of a material is its ability to withstand an applied stress without failure. The applied stress may be tensile, compressive, or shear. Strength of materials is a subject which deals with loads, deformations and the forces acting on a material. A load applied to a...

, durability, and environmental resistance

Sustainability

Sustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of well being, which has environmental, economic, and social dimensions, and encompasses the concept of union, an interdependent relationship and mutual responsible position with all living and non...

. Among the most widely used materials are polyesters laminated or coated with polyvinyl chloride

Polyvinyl chloride

Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...

 (PVC), and woven fiberglass

Fiberglass

Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

 coated with polytetrafluoroethylene

Polytetrafluoroethylene

Polytetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. PTFE is most well known by the DuPont brand name Teflon....

 (PTFE).

Cotton canvas
The traditional fabric for fabric structures in light cotton twil, light canvas, or heavy proofed canvas.

Polyesters
Strength, durability, cost, and stretch make polyester material the most widely used in fabric structures. Polyesters that are laminated or coated with PVC

PVC

Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter, a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...

 films are usually the least expensive option for longer-term fabrications.

Laminates generally consist of vinyl films over woven or knitted polyester meshes (called scrims or substrates), while vinyl-coated polyesters usually have a high-count, high-tensile base fabric coated with a bondable substance that provides extra strength. Our WSSL'S fabric supplier, Ferrari, places the polyester fabric under tension both before and during the coating process. This results in a weave that has increased dimensional stability and is known commercially as Precontraint.

Vinyl-laminated polyesters
A laminated fabric usually is composed of a reinforcing polyester scrim pressed between two layers of unsupported PVC film. For most fabric structure uses, however, it refers to two or more layers of fabric or film joined by heat, pressure, and an adhesive

Adhesive

An adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...

 to form a single ply.

With an open-weave or mesh polyester scrim, the exterior vinyl films bond to themselves through the openings in the fabric. Heavier fabric scrims, however, are too tightly woven to allow the same bonding. In this case, an adhesive is used to bond the exterior films to the base fabric.

A good chemical bond

Chemical bond

A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

 is critical to both prevention of delamination and development of seam strengths. The seam is created when vinyl-coated fabrics are welded together. The adhesive enables the seam to meet shear forces and load requirements for a structure at all temperatures. The adhesive prevents wicking of moisture into the scrim’s fibers, which also prevents fungal growth or freezing that could affect the exterior coating's adhesion to the scrim. Adhesives are water-based to comply with EPA regulations.

Open-weave scrims generally make the fabric more economical, although this can also depend on the number and type of features that you require in the vinyl. Almost any color, UV resistance Vinyl coated polyester, and colorfastness may be incorporated into the vinyl. However, the more features added, the higher the cost of the fabric.

Vinyl-coated polyester
Vinyl-coated polyester is the most frequently used material for flexible fabric structures. It is made up of a polyester scrim, a bonding or adhesive agent, and exterior PVC coatings. The scrim supports the coating (which is initially applied in liquid form) and provides the tensile strength, elongation, tear strength, and dimensional stability of the resulting fabric. Vinyl-coated polyester is manufactured in large panels by heat-sealing an over-lap seam with either a radio-frequency welder or a hot-air sealer. A proper seam will be able to carry the load requirements for the structure. The seam area should be stronger than the original coated fabric when testing for tensile strength.

The base fabric's tensile strength is determined by the size (denier) and strength (tenacity) of the yarns and the number of yarns per linear inch or meter. The larger the yarn and the more yarns per inch, the greater the finished product's tensile strength.

The adhesive agent acts as a chemical bond between the polyester fibers and the exterior coating and also prevents wicking. Wicking is the term used to describe the action of fibers absorbing water, which could result in freeze-thaw damage in the fabric.

The PVC coating liquid (vinyl Organisol or Plastisol) contains chemicals to achieve the desired properties of color, water and mildew resistance, and flame retardancy. Fabric can also be manufactured that contains high levels of light transmission or can be made completely opaque. After the coating has been applied to the scrim, the fabric is put through a heating chamber that dries the liquid coating. PVC coatings are available in a range of colors, although non-standard colors can be pricey. Colors may be subject to minimum order runs that allow the coating machine to clear out traces of any previous color.

Fiberglass
Woven fiberglass coated with PTFE (Teflon or silicone) is also a widely used base material. Glass fibers are drawn into continuous filaments, which are then bundled into yarns. The yarns are woven to form a substrate. The fiberglass carries a high ultimate tensile strength, behaves elastically, and does not suffer from significant stress relaxation or creep. The PTFE coating is chemically inert, can withstand temperatures from 100°F upwards to 450°F+. It is also immune to radiation and can be cleaned with water.

Because of its energy efficiency, high melting temperature and lack of creep, fiberglass-based fabrics have been the material of choice for stadium domes and other permanent structures, particularly in the United States. However, when properly constructed, polyester structures may be equally durable.

Olefin / polyolefin
A number of polymers consisting mainly of polyethylene, polypropylene or combinations of the two are available for fabric structures.

PVDF woven
PVDF woven fabric are available for fabric structures.

ePTFE woven
ePTFE woven fabric are available for fabric structures.

Blackout Fabric
Blackout material, also known as blockout material, is an opaque fabric. Blackout fabric consists of a laminate that sandwiches an opaque layer between two white exterior layers. Heating and lighting of a structure may be controlled because the fabric does not allow light to permeate the top or walls. The opaque quality also prevents stains, dirt, repairs, or slightly mismatched panels on the structure's exterior from being noticed from the inside.

Topcoatings
Most fabrics used for fabric structures have some form of topcoating applied to the exterior or coating to make cleaning easier. Topcoating provides a hard surface on the outside of the material, forming a barrier that aids in preventing dirt from sticking to the material, while allowing the fabric to be cleaned with water. As the material ages, the topcoating will eventually erode, exposing the fabric to dirt and making it more difficult to clean. The thicker the topcoating, the longer it will last. However, coatings that are too thick will embrittle and crack when folded.

There are several commonly used topcoatings:

• PVF film lamination is made up of polyvinyl fluoride
  Polyvinyl fluoride
  Polyvinyl fluoride or –n– is a polymer material mainly used in flammability-lowering coating of airplane interiors and photovoltaic module backsheets. It is also used in raincoats and metal sheeting...
  
   (commercially known as Tedlar). It consists of a film layer laminated to the PVC fabric during the manufacturing process. The result is a thicker fabric that can resist weather and chemical agents better than competing fabrics. Its self-cleaning ability repels such things as acid rain, graffiti, and bird droppings. Because of these characteristics it can often be found in use in industrialized areas, desert regions, and coastal zones. The thicker coating has a slow erosion rate, resulting in a life expectancy of approximately 25 years depending upon environmental conditions. This topcoating is flexible, which creates a strong and consistent bond to the PVC. PVF coated fabrics may be manufactured in a variety of colors, but are also subject to minimum manufacture runs. PVF coating also makes the fabric non-weldable. Seams are not overlapped, but instead are butted with an extra welded seam, then applied to the underside of the fabric that does not have a topcoating.
• Acrylic topcoating is the most economical and widely available topcoating used. Its spray-on application provides a glossy finish and a resistance to UV degradation. Because the coating is thin, the material is both easy to fabricate and is reparable by high frequency or hot air welding. Depending on environmental conditions, an acrylic topcoating will give the fabric a life span of 10 years or more. Acrylic topcoats are ideal for fabric structures, and can be found on products used as tradeshow pavilions, temporary concert halls, and portable warehouses.
• PVDF topcoating is composed of a mix of fluorine, carbon, and hydrogen. The combination of the fluorine and carbon provides superior resistance to UV degradation and chemical damage than that of the acrylic topcoat. PVDF coated fabrics also maintain color longer than do those coated with acrylic. PVDF fabrics resist algae and fungi, and also have self-cleaning properties that make them easy to maintain. These coated fabrics are flexible, resist cracking, are easily handled, and generally have a life span of 15 to 20 years depending upon environmental conditions. PVDF is chemically grafted to the PVC and polymers used, which reduces the color choices. Because white is the only standard color, other color choices are limited and must be specially manufactured. Because of the chemical properties of the coating, it must be abraded off to expose the PVC before welding. This, too, increases fabrication costs. On site repairs are also difficult, as the membrane must be manually abraded before repair.
• PVDF/PVC topcoating is essentially a dilution of the PVDF topcoat that makes the finished fabric less expensive to manufacture. The finished fabric may be welded without having to abrade the material, which reduces costs. However, because the PVDF is diluted, longevity and the ability to withstand environmental factors are reduced. This results in a general life expectancy of 10 to 15 years. These materials are also available in colors, but are subject to limited manufacturing runs.

Fabric properties
When discussing fabric properties for use on a structure, there are several terms that are commonly used:

• Tensile strength
  Tensile strength
  Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...
  
   is a basic indicator of relative strength. It is fundamental for architectural fabrics that function primarily in tension.
• Tear Strength is important in that if a fabric ruptures in place, it generally will do so by tearing. This can occur when a local stress concentration or local damage results in the failure of one yarn, which thereby increases the stress on remaining yarns.
• Adhesion
  Adhesion
  Adhesion is any attraction process between dissimilar molecular species that can potentially bring them in close contact. By contrast, cohesion takes place between similar molecules....
  
  strength is a measure of the strength of the bond between the base material and coating or film laminate that protects it. It is useful for evaluating the strength of welded joints for connecting strips of fabric into fabricated assembly.
• Flame retardancy does not have the same meaning as flameproofing. Fabric that contains a flame-retardant coating can withstand even a very hot point source. However, it can still burn if a large ignition source is present.

Structural properties

When deciding on a fabric it is imperative to keep certain fabric properties in mind. These include stress versus strain (unit load versus unit elongation), expected service life, the mechanisms of joining the material together (welding, gluing, etc.), and the fabric’s behavior in or around fire.

Stress versus strain data should be obtained in both uniaxial and biaxial forms. This information characterizes the fabric in terms of stiffness, elasticity, and plasticity. This is essential information when determining the material's response under load in a load-carrying application. Shear strength, shear strain, and Poisson's ratios, though difficult to obtain, are fundamental when analyzing a fabric as a structural material.

Cost Savings to Fabric Buildings
The benefits of fabric buildings are many - No lighting is required as fabric is translucent, which makes it an energy efficient solution. Mobility: You can move them, either on wheels or relocate them completely. Savings: They cost about half of what a traditional structure costs.

Fabric properties When discussing fabric properties for use on a structure, there are several terms that are commonly used:

Tensile strength is a basic indicator of relative strength. It is fundamental for architectural fabrics that function primarily in tension.
Tear Strength is important in that if a fabric ruptures in place, it generally will do so by tearing. This can occur when a local stress concentration or local damage results in the failure of one yarn, which thereby increases the stress on remaining yarns.

Adhesion strength is a measure of the strength of the bond between the base material and coating or film laminate that protects it. It is useful for evaluating the strength of welded joints for connecting strips of fabric into fabricated assembly.
Flame retardancy does not have the same meaning as flameproofing. Fabric that contains a flame-retardant coating can withstand even a very hot point source. However, it can still burn if a large ignition source is present.

Of course, other properties must be factored in when determining a material’s suitability for a structure. To fully understand a fabric's value and usefulness, consider the following:

• Shading coefficients
• General solar, optical, and thermal performance data
• Acoustical data
• Dimensional stability
• Colorfastness
• Cleanability
• Seam strength and stability
• General handling ability things like:including abrasion resistance, foldability, etc.