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STRENGTHENING STRUCTURES USING FRP COMPOSITE MATERIALS. DAMIAN I. KACHLAKEV, Ph.D., P.E. California Polytechnic State University San Luis Obispo. WHY COMPOSITES?. ADVANTAGES OVER TRADITIONAL MATERIALS CORROSION RESISTANCE HIGH STRENGTH TO WEIGHT RATIO LOW MAINTENANCE EXTENDED SERVICE LIFE
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STRENGTHENING STRUCTURES USING FRP COMPOSITE MATERIALS DAMIAN I. KACHLAKEV, Ph.D., P.E. California Polytechnic State University San Luis Obispo
WHY COMPOSITES? • ADVANTAGES OVER TRADITIONAL MATERIALS • CORROSION RESISTANCE • HIGH STRENGTH TO WEIGHT RATIO • LOW MAINTENANCE • EXTENDED SERVICE LIFE • DESIGN FLEXIBILITY
COMPOSITES DEFINITION • A combination of two or more materials (reinforcement, resin, filler, etc.), differing in form or composition on a macroscale. The constituents retain their identities, i.e.., they do not dissolve or merge into each other, although they act in concert. Normally, the components can be physically identified and exhibit an interface between each other.
DEFINITION Fiber Reinforced Polymer (FRP) Composites are defined as: “A matrix of polymeric material that is reinforced by fibers or other reinforcing material”
COMPOSITES MARKETS • TRANSPORTATION • CONSTRUCTION • MARINE • CORROSION-RESISTANT • CONSUMER • ELECTRICAL/ELECTRONIC • APPLIANCES/BUSINESS • AIRCRAFT/DEFENSE
U.S. COMPOSITES SHIPMENTS - 1996 MARKET SHARE SEMI-ANNUAL STATISTICAL REPORT - AUGUST 26, 1996 Aircraft/Aerospace 0.7% Transportation 30.6% Construction 20% Other- 3.4% Consumer Products - 6% Marine - 11.6% Electrical/ Electronic - 10% Appliance/Business Equipment - 5.3% Corrosion-Resistant Equipment - 12.4% Includes reinforced thermoset and thermoplastic resin composites, reinforcements and fillers. SOURCE: SPI Composites Institute
Infrastructure Benefits • HIGH STRENGTH/WEIGHT RATIO • ORIENTATED STRENGTH • DESIGN FLEXIBILITY • LIGHTWEIGHT • CORROSION RESISTANCE • LOW MAINTENANCE/LONG-TERM DURABILITY • LARGE PART SIZE POSSIBLE • TAILORED AESTHETIC APPEARANCE • DIMENSIONAL STABILITY • LOW THERMAL CONDUCTIVITY • LOW INSTALLED COSTS
FRP COMPOSITE CONSTITUENTS • RESINS (POLYMERS) • REINFORCEMENTS • FILLERS • ADDITIVES
MATERIALS: RESINS • PRIMARY FUNCTION: “TO TRANSFER STRESS BETWEEN REINFORCING FIBERS AND TO PROTECT THEM FROM MECHANICAL AND ENVIRONMENTAL DAMAGE” • TYPES: • THERMOSET • THERMOPLASTIC
RESINS • THERMOSET • POLYESTER • VINYL ESTER • EPOXY • PHENOLIC • POLYURETHANE
RESINS • THERMOPLASTIC • ACETAL • ACRYRONITRILE BUTADIENE STYRENE (ABS) • NYLON • POLYETHYLENE (PE) • POLYPROPYLENE (PP) • POLYETHYLENE TEREPHTHALATE (PET)
RESINS • THERMOSET ADVANTAGES • THERMAL STABILITY • CHEMICAL RESISTANCE • REDUCED CREEP AND STRESS RELAXATION • LOW VISCOSITY- EXCELLENT FOR FIBER ORIENTATION • COMMON MATERIAL WITH FABRICATORS
RESINS • THERMOPLASTIC ADVANTAGES • ROOM TEMPERATURE MATERIAL STORAGE • RAPID, LOW COST FORMING • REFORMABLE • FORMING PRESSURES AND TEMPERATURES
POLYESTERS • LOW COST • EXTREME PROCESSING VERSATILITY • LONG HISTORY OF PERFORMANCE • MAJOR USES: • Transportation • Construction • Marine
VINYL ESTER • SIMILAR TO POLYESTER • EXCELLENT MECHANICAL & FATIGUE PROPERTIES • EXCELLENT CHEMICAL RESISTANCE • MAJOR USES: • Corrosion Applications - Pipes, Tanks, & Ducts
EPOXY • EXCELLENT MECHANICAL PROPERTIES • GOOD FATIGUE RESISTANCE • LOW SHRINKAGE • GOOD HEAT AND CHEMICAL RESISTANCE • MAJOR USES: • FRP Strengthening Systems • FRP Rebars • FRP Stay-in-Place Forms
PHENOLICS • EXCELLENT FIRE RETARDANCE • LOW SMOKE & TOXICITY EMISSIONS • HIGH STRENGTH AT HIGH TEMPERATURES • MAJOR USES: • Mass Transit - Fire Resistance & High Temperature • Ducting
POLYURETHANE • TOUGH • GOOD IMPACT RESISTANCE • GOOD SURFACE QUALITY • MAJOR USES: • Bumper Beams, Automotive Panels
SUMMARY: POLYMERS • WIDE VARIETY AVAILABLE • SELECTION BASED ON: • PHYSICAL AND MECHANICAL PROPERTIES OF PRODUCT • FABRICATION PROCESS REQUIREMENTS
Physical Properties of Thermosetting Resins Used in Structural Composites
MATERIAL: FIBERREINFORCEMENTS • PRIMARY FUNCTION: “CARRY LOAD ALONG THE LENGTH OF THE FIBER, PROVIDES STRENGTH AND OR STIFFNESS IN ONE DIRECTION” • CAN BE ORIENTED TO PROVIDE PROPERTIES IN DIRECTIONS OF PRIMARY LOADS
REINFORCEMENTS • NATURAL • MAN-MADE • MANY VARIETIES COMMERCIALLY AVAILABLE
MAN-MADE FIBERS • ARAMID • BORON • CARBON/GRAPHITE • GLASS • NYLON • POLYESTER • POLYETHYLENE • POLYPROPYLENE
FIBER PROPERTIESTENSILE STRENGTH x103 psi
FIBER PROPERTIESTENSILE MODULUS 106 psi
FIBER PROPERTIESCTE - Longitudinal x10-6/0C
FIBER PROPERTIESTHERMAL CONDUCTIVITY x10-6/0C BTU-in/hr-ft2 - 0F
FIBER REINFORCEMENT • GLASS (E-GLASS) • MOST COMMON FIBER USED • HIGH STRENGTH • GOOD WATER RESISTANCE • GOOD ELECTRIC INSULATING PROPERTIES • LOW STIFFNESS
GLASS TYPES • E-GLASS • S-GLASS • C-GLASS • ECR-GLASS • AR-GLASS
FIBER REINFORCEMENT • ARAMID (KEVLAR) • SUPERIOR RESISTANCE TO DAMAGE (ENERGY ABSORBER) • GOOD IN TENSION APPLICATIONS (CABLES, TENDONS) • MODERATE STIFFNESS • MORE EXPENSIVE THAN GLASS
FIBER REINFORCEMENT • CARBON • GOOD MODULUS AT HIGH TEMPERATURES • EXCELLENT STIFFNESS • MORE EXPENSIVE THAN GLASS • BRITTLE • LOW ELECTRIC INSULATING PROPERTIES
FIBER ORIENTATION • ANISOTROPIC • UNIDIRECTIONAL • BIAS - TAILORED DIRECTION • 0O - flexural strengthening • 90O - column wraps • + /- 45O - shear strengthening • ANGLE VARIES BY APPLICATION
REINFORCEMENTSSUMMARY • TAILORING MECHANICAL PROPERTIES • TYPE OF FIBER • PERCENTAGE OF FIBER • ORIENTATION OF FIBER
DESIGN VARIABLESFOR COMPOSITES • TYPE OF FIBER • PERCENTAGE OF FIBER or FIBER VOLUME • ORIENTATION OF FIBER • 0o, 90o, +45o, -45o • TYPE OF POLYMER (RESIN) • COST • VOLUME OF PRODUCT - MANUFACTURING METHOD
DESIGN VARIABLESFOR COMPOSITES • PHYSICAL: • tensile strength • compression strength • stiffness • weight, etc. • ENVIRONMENTAL: • Fire • UV • Corrosion Resistance
TAILORING COMPOSITE PROPERTIES • MAJOR FEATURE • PLACE MATERIALS WHERE NEEDED - ORIENTED STRENGTH • LONGITUDINAL • TRANSVERSE • or between • STRENGTH • STIFFNESS • FIRE RETARDANCY
MANUFACTURING PROCESSES • Hand Lay-up/Spray-up • Resin Transfer Molding (RTM) • Compression Molding • Injection Molding • Reinforced Reaction Injection Molding (RRIM) • Pultrusion • Filament Winding • Vacuum Assisted RTM (Va-RTM) • Centrifugal Casting
PROCESS CHARACTERISTICSHand Lay-up/Spray-up • MAX SIZE: Unlimited • PART GEOMETRY: Simple - Complex • PRODUCTION VOLUME: Low - Med • CYCLE TIME: Slow • SURFACE FINISH: Good - Excellent • TOOLING COST: Low • EQUIPMENT COST: Low
PRODUCT CHARACTERISTICSPultrusion • CONSTANT CROSS SECTION • CONTINUOUS LENGTH • HIGH ORIENTED STRENGTHS • COMPLEX PROFILES POSSIBLE • HYBRID REINFORCEMENTS