BME213 Sem 6 Flashcards
What are the factors that affect the mechanical properties of a composite? Explain how each factor affects the mechanical properties.
- Properties of Reinforcement and Matrix:
• Type of fiber (e.g., carbon, glass)
• Type of matrix (e.g., polymer, metal, ceramic)
• These determine strength, stiffness, toughness, and thermal resistance - Fiber Direction / Orientation:
• Aligned fibers → high strength in one direction (anisotropy)
• Random fibers → uniform but lower strength - Volume Fraction of Reinforcement (Vf %):
• Higher Vf → increased strength and stiffness
• Too much → brittleness or poor bonding - Geometry of Reinforcement:
• Shape, size, and length of fibers or particles
• Concentration and distribution in the matrix
• Orientation affects directional properties
What is injection molding in particulate composite fabrication?
A process where heated composite material (polymer + particles) is injected under pressure into a mold cavity, then cooled to form the final shape.
What are the advantages of injection molding for particulate composites?
• Fast and repeatable
• Good for complex shapes
• High volume production
• Good dimensional accuracy
What is compression molding in particulate composite fabrication?
A process where composite material is placed in a heated mold, then compressed under pressure to form the desired shape and cured.
What are the advantages of compression molding?
• Simple and cost-effective
• Good for large, flat, or curved parts
• Suitable for high filler loading
• Low material waste
What is extrusion molding in particulate composite fabrication?
A process where composite material is forced through a die to create long, continuous shapes like rods, tubes, or sheets.
What are the advantages of extrusion molding?
• Continuous production
• Good for uniform cross-sections
• Cost-efficient
• Can be used for thermoplastics and filled materials
Which molding method is best for complex 3D shapes?
Injection molding — ideal for detailed and high-volume parts
What is vacuum bag/autoclaving in fibre composite fabrication?
A process where fibres and resin are laid into a mold, covered with a vacuum bag, and cured under heat and pressure in an autoclave to remove air and compact the laminate
What are the benefits of vacuum bag/autoclaving?
• High fibre volume fraction
• Excellent surface finish
• Reduced porosity
• High-strength aerospace-grade part
What is filament winding in fibre composite fabrication?
A process where continuous fibres soaked in resin are wound around a rotating mandrel in specific patterns, then cured to form hollow structures like pipes or tanks.
What are the benefits of filament winding?
• High strength-to-weight ratio
• Controlled fibre orientation
• Ideal for cylindrical shapes (e.g., pressure vessels)
What is closed mold processing in fibre composites?
A method where resin and fibres are placed into a closed mold, and pressure is applied (e.g., in resin transfer molding or compression molding) to shape and cure the part.
What are the benefits of closed mold processing?
• Smooth surface finish on both sides
• Suitable for medium to high-volume production
• Controlled thickness and resin distribution
