Flexible Structures Final

Tufting

Sewing (stitching) of surface yarns onto a primary backing

Tufted Carpet Structure

Surface yarns (nylon, polyester, cotton), primary backing (usually woven or split film polypropylene yarns), coating (latex), and secondary backing (either spun jute or fibrillated polypropylene yarns).

Needle Gauge

Number of needles per unit width

Stitches per minute

the rate of reciprocal up and down motions by the needle bar (it is also equal to the speed of the needle bar in revolutions per minute, rpm)

Stitches per inch

spacing of the needle bar stitches along the machine (or vertical) direction of the fabric

Pile height

the distance of the loops below the primary fabric

Tufting elements for loop pile

Various Surface Elements

By using different types of loopers, knives and yarn feed control, the following effects can occur:

• Level loops

• Multi Level Loops

• Level cut loops

• Multi Level cut and uncut loops

• Level cut and uncut loops

Tufting Elements for cut pile

How to build a backing

Twist Level

Stitch rate/gauge

Optimum Latex application

Saxony Carpet

• Cut-pile carpet

• Highly twisted yarn

• Evenly sheared

• Medium length pile yarns

Plush Carpet

• Cut-pile carpet

• Pile yarns are slightly twisted, dense and very evenly sheared

• Has the look of a solid, flat velvet surface

Shag Carpet

• Loosely tufted carpet construction

• Cut pile of 1-5 inches

• Greater than normal spacing between tufts

Markets for Carpet

• Homes (consumer)

• Business institutions

• Indoor

• Outdoor

Factors for Carpet Selection

• Location and traffic pattern

• Frequency and kind of cleaning

• Flammability

• Nature of the environment

• Static control

Typical Carpet Styles

Primary Backing

• Jute (8-10 oz/sy)

• Split film woven polypropylene (3-4 oz)

• Polypropylene film sheet

• Cotton duck

The secondary backing is added to provide…

• Increased thickness (resilience, hand, insulation)

• Dimensional stability

• Improvement in locking tufts

• Resistance to fraying

• Skid resistance

The secondary backing fabric must…

• Be dimensionally stable

• Stick to the adhesive which binds it to the carpet

• Resist environmental degradation

Tufted Fabric Control

• Secondary Backing (type, composition construction)

• Primary backing (type, composition construction)

• Surface fiber (material, characteristics i.e: type, length, denier)

• Yarn

• Fabric

• Coloration

• Finish (shearing, brushing, final inspection)

Braiding

Simplest form of fabric formation: diagonal intersection of yarns

Braiding Industrial Applications

• Electrical wires and cables

• Harnesses

• Hoses and belts

• Surgical sutures

• Composite reinforcements

• Reinforcement structure of sporting goods

Braiding Manufacturing

• Geometry directly related to the machine that forms the fabric

• 2D Brading

  • Circular Braiding (Maypole and rotary)

• 3D Braiding

Common 2D Braiding Patterns

Braiding Fabric Parameters

Triaxial Braid

Schematic of Maypole Braiding

Size of Braid is governed by…

• The number of carriers

  • Tubular braids: even number of carriers

  • Flat braids: odd number of carriers

• Diameter of the yarns

• Number of yarn ends per carrier

• Number of yarns per unit length

Narrow Fabrics

• Less than 12 inches (30 cm) in width

• Woven selvage

• Examples are Ribbons, Tapes, and Webbings

Narrow Fabrics Manufacturing

• Several sets of warp yarns may be beamed to make several narrow fabrics, side-by-side on the same loom

• A full width thermoplastic fabric can be cut into strips; edges are sealed, forming ribbons

• Elastic webbing or tape is made by using bare or wrapped rubber warp yarn

• Heavy webbings are made with stuffer warps

• Single warp beam or multiple beams

• Warp yarn can be taken from the creel directly

• Needle inserts a loop of filling yarn into the shed at a high speed

Essential Fiber Properties for Architecture and Construction

• Synthetic Fibers

  • Good strength

  • Hydrophobicity

  • Rot and fungi resistant

  • UV resistant

  • Temperature resistant

  • Biological resistance

  • Weather resistant

Advantages of Fibers in Construction

• Weight

  • 1/30th of the conventional weight of bricks and steel

• Large, obstruction-free spans

• Shorter erection time of the fabric envelope

• Mechanical damage due to wear is restricted to a small area by the fabric structure

• Damage can be easily repaired

• Resistance to Earthquakes

• Freedom to design various shapes and appearances

Film Membrane Structure

• Transparent polymers in sheet form without coating or lamination

  • Clear vinyl, polyester or polyethylene

  • Less expensive and durable

Mesh Membrane Structure

• Porous fabrics that are lightly coated with vinyl

• Knitted meshes

  • High density polyethylene, polypropylene or acrylic yarns

• Used as shelters from wind and sun

• Not as much rain protection

Fabric Structures

• The most widely used membrane structures

• Coated or laminated to improve strength and environmental resistance

Coated Fabrics

• “Envelope” of large building constructions

  • Airports, stadiums, sports halls

Schematic of a Laminate

Typical requirements for fabrics in construction

• Resistance to deformation and extension under tension

• Waterproof

• Impermeable to air and wind

• Resistant to abrasion and mechanical damage

• Resistance to sunlight and acid rain

Base Fibers

• Made of synthetic fibers

• Carrier layer

• Provides the necessary strength to the structure

  • High tenacity polyester

  • Fiberglass

  • Nylon

• Continuous filament yarns

  • Inherent strength

  • Elongation resistance

• Low yarn twist to carry higher tensile loads

• Hydrophobic materials

Base Fabrics Manufacturing

• Woven (plain, low-harness twill)

  • Warp tension not to exceed 9 N/tex during weaving

  • Rapier, projectile, air-jet and water-jet

  • Width up to 5m

• Knit (warp-knit)

• Nonwoven stitch bonded

• Heat-setting usually not required

Coating and Laminating

• Provides waterproofness

• Protects base fabric from sunlight and weathering degradation

Polyester Fabrics

• Usually coated or laminated with PVC films

• Precontraint process used to improve dimensional stability

Fiberglass Fabrics

• Usually coated with PTFE for durability

• PTFE coated fiberglass is the only material that meets the US model building codes definition of non-combustible materials

Coated vs. Laminated

Aging of Fabrics

• Weather effects and Residual strength

Application of Coated Fabrics in Building Structures

• Membrane structures

  • Tents

  • Clear-span structures

  • Air structures

  • Tensile structures

Most widely used structures

• PVC coated polyester

• PTFE coated woven fiberglass

• Silicone coated fiberglass

Tents

• Probably the first constructions

• Used by nomadic people, traders, military, explorers and campers

• New tents for building construction, businesses, exhibits, leisure and recreation

• Typical materials for tent walls include polyesters, nylon and vinyls

Pole Tents

• Fabric is draped or hung

• Mass produced

Tension tent

• Fall between tents and tensile structures

• Provides clear span

• Does not require ropes or cords

• Mass produced

Clear-Span Structures

• Provides clear space beneath the fabric

• Free of poles and other supporting elements

• Fabric is pulled taut through channels in the frame’s ribs

• More permanent than tents and less permanent than air or tensile structures

• Can accommodate doors, flooring, insulation and HVAC

• PVC coated polyester

Tension Structures

• Metal bars, tensioning cables, wooden or metal frameworks

• Fabric carries most of the load

• Curvilinear structures

• Fabric is highly tensioned

Schematic of Tension Structures

Basic building block shapes

• Hyperbolic paraboloid

• Hyperboloid

• Fabric is double curved

• Curvatures opposing each other from a single intersecting point

• Crossed arc appears parabolic in cross section and as an “X” from above

Air Structures

• Air Supported System

  • Air pressure inside the envelope

    • Provides tensioning

    • Maintains required configuration and stability

  • Main components

    • Envelope (fabric)

    • Inflation system (fans)

    • Anchorage systems (cables and foundation)

    • Doors and access equipment

  • Pressure 0.3% above the ambient pressure

  • PVC coated polyester is the most used

Pressurized air-supported structure

History of Air Pressurized Structures

• Collapse of some large-scale stadium domes in the early 80s

• Well-built air structures are stable and strong

• Modular buildings

• Can be designed for nearly any shape

• Surfaces are curved

Air Inflated Ribs (Air Beams)

• Pressurized air-inflated support tubes

• Wide diameter (42 inches)

  • Low pressure (4-10 psi)

• Narrow diameter (4-18 inches)

  • High pressure (30-100 psi)

• Mostly for lightweight, easy to transport military structures

• Polyester and nylon

Safety tarpaulins for cold weather construction

• Waterproof. flame retardant tarpaulins

• Cold weather construction

• Usually polyester fabrics (6-8 ounces)

Designing with Coated Fabrics

• Three types of stresses

  • Stresses due to applied load tension in the fabric

  • Weight of suspended fabric

  • Stresses induced by natural forces die to wind, rain and snow

Textiles as Roofing Materials

• Single-ply and multi-ply materials

• Traditional built-up roofing (BUR)

  • Alternating plies of felts, fabrics and mats are bonded together with asphalt or coal tar

• Single ply roofing

  • Introduced in the 1960s in the US

  • Used mostly in commercial applications
    

Single Ply Roofing

• Made of single layer, watertight, weatherable membrane

• Sealed at the seams and edges

• Three types of membranes

  • Elastomers and thermosets (rubber)

  • Thermoplastics

  • Modified bitumens

Elastomer Membranes

• EDPM (ethylene propylene diene monomer): most commonly used single ply elastomer

• Neoprene (chloroprene rubber)

• Chlorosulfonated polyethylene (CSPE)

• Chlorinated polyethylene (CPE)

• Polyisobutylene (PIB)

Properties Required in Roof Materials

• Toughness, non-wicking, delamination resistance, chemical resistance, UV resistance, flame resistance and fungus resistance

Textiles for Acoustic and Heat Insulation

• Two types of noises and buildings

  • Airborne noise

  • Impact noise

• Three acoustical properties

  • To improve audibility

  • Preserve the natural quality of sound

  • Prevent the transmission of undesired sound

Reverberation Time

• Time it takes a sound to die away in a budling

• Absorbent materials to reduce the time

  • Carpet

  • Textile wall coverings

  • Curtains

Factors affecting sound absorption

• Cut pile is better than a loop pile

• In cut pile construction, pile height and density increase absorption

• In loop pile, pile height is more important than density

• Acoustic performance is independent of the pile fiber type

Filtration

• Process of separation (separation of one material from another)

• Purpose is to improve the purity of the filtered material and recover solid particles

Why textiles are suitable?

• Complicated structure

• Considerable thickness

• 3D network of fibers

• Small pockets of void volume

• “tortuous” path around textile fibers

• High filtration efficiency (25%-99.9%)

• Reasonable filter life before plugging

• Woven and nonwoven fabrics

Principles of Filtration

• Main objective of the filter medium:

  • Maximize the possibility of collision

  • Subsequent retention of the suspended particles in the fluid

  • Minimize the energy lost

Fabric Structure

• Porosity: air volume/total volume

• The amount and distribution of air space influences the efficiency of filtration

• Air permeability: capacity of a porous medium to transmit fluids

• As the porosity increases, the pressure drop decreases

• Pressure drop should be minimized

Process of Separation

• Particle filtration

• Microfiltration

• Ultrafiltration

• Nanofiltration

• Reverse osmosis (hyperfiltration)

Filtration Equipment

• Filters for Dry Filtration

• Filters for Liquid Filtration

• Drum, disk, plate, frame, belt, vessel, ...filters

Liquid Filter Bags

• petroleum derivatives

• chemicals

• cutting oil

• cleaning fluid

• paints

• pharmaceuticals

• food processing

• beverages

• cosmetics

• semiconductors

Rotary Drum Filters

• For slurry filtration

• Large drum (20 ft in diameter, 20 ft long)

• Vacuum type (rotary drum vacuum filters)

  • Drum rotates continuously and slowly

  • Lower part is dipped in the slurry

  • Vacuum is applied inside the drum to suck the fluid leaving a layer of solid on the outside of the fabric

  • As the drum rotates, solid is lifted and separated by the fabric by knife

Belt Filter

• Suction tray supports a rotating filter cloth

• Continuous cycle of vacuum stroke/return stroke

Bag Filters

• Used for dust removal in industrial atmosphere

• Dust can be captured on the internal or external surface of the bag

• Large numbers of woven or nonwoven fabric tubes or bags used

• Suction created by a fan pulls the dusty air through the bags, collecting the dust on the fabric surface

• Filtration efficiency: 99.9% for fine dust collection

• Collected dust must be removed from the fabric surface periodically for efficient filtration

• Dust is collected in a container below the bags and removed periodically

Textiles in Dry Filtration

• mining, chemical, iron and steel industry

• cement, lime, clay, kaolin and ceramic works

• utilities

• feed, grain and food industry

• woodworking and furniture industry

• paper related industry

• textile plants

Polyester in Filtration

• Advantages

  • Strength

  • Relatively high temperature resistance

  • low cost

• Disadvantages

  • Low resistance to alkalis, acids and steams

Nonwoven Fabrics in Filtration

• Filtration of gases

• Needle punched fabrics

  • Good dimensional stability

  • Excellent particle retention

  • Freedom from plugging

Geosynthetics

• Geo refers to earth

• Synthetics is manmade materials

• Manufacturing: Polymer and Fiber Engineering

• Application: Civil Engineering

  • Heavy construction

  • Building construction

  • Hydrogeology

  • Environmental engineering

  • Soil, rock and ground related activities

Geosynthetic Functions

• Separation of soils

• Reinforcing poor soils

• Soil filtration

• Water drainage

• Leak proof barrier for preventing liquid movement

Advantages of Geosynthetics

• Performance (no deterioration of material or excessive leakage)

• Economics (lower initial costs and long life)

Geotextiles

• Largest group of geosynthetics

• Traditional textile structures

• Tremendous growth last 40 years

• Biodegradation is not a problem

• Flexible, porous fabric structures

• Woven, nonwoven, warp knit

• 80 specific applications for geotextiles

Geogrids

• Small but rapidly growing segment of geosynthetics

• not textile-like structures

• plastics formed into a very open, gridlike configuration with large apertures

• at least 25 application areas

• two functions (reinforcement and seperation)

Geonets

• Manufactured by continuous extrusion of polymeric ribs at acute angles to one another

• large apertures in a netlike configuration

• function: drainage (to convey fluids)

Geomembranes

• Second largest group of geosynthetics

• Impervious thin sheets of rubber or plastic materials

• Used for linings and covers of liquid or solid storage facilities

• Primary function: liquid or solid barrier

• At least 30 individual applications

Geocomposites

• Combination of the other geostructures

• Major functions include separation, reinforcement, filtration, drainage, and moisture barrier

Geosynthetic Clay Liners (GCL)

• Newest member of the family

• Rolls of thin layers of clay sandwiched between two geotextiles or bonded to a geomembrane

• Needle punched, stitched or adhesive bonded

• Used as primary or secondary liners or beneath a geomembrane

Geo-others

• Threaded soil masses

• Polymeric anchors

• Encapsulated soil cells

• Any of the five major functions of geosynthetics

Designing with Geotextiles

• Design by cost and availability

• Design by specification

  • Using standard tables

• Designed by function

  • Factor of safety (FS)

Design by Function

• FS = Allowable property/required property

• Allowable property (value based on a lab test that models the actual situation)

• Required property (value based on design method that models the actual situation)

Geotextile Properties and Test Methods

• Physical Properties

• Mechanical Properties

• Hydraulic Properties

• Endurance Properties

• Degradation Properties

Application areas of medical textiles

• Protective medical apparel

• Implants

• Blood filters

• Surgical dressings

Biomaterials

• Materials used in contact with tissue, blood, cells, protein and any other living substance