Composite Materials and Strain Quiz
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Questions and Answers

What is the unit of strain?

  • Newton
  • Megapascal (MPa)
  • It has no units (correct)
  • Joule

    • A metal that experiences little or no plastic deformation upon fracture is termed ductile.

    False

    What is the strain offset when a straight line is constructed parallel to the elastic portion of the stress-strain curve?

    0.002

    The phase of the composite that is continuous and surrounds the other phase is known as the ______.

    <p>matrix</p> Signup and view all the answers

    Match the following characteristics with the composite matrices:

    <p>Epoxy = Better bonding characteristics with fiber Polyester = Lower cost Vinylester = Moderate properties Polypropylene = Good flexibility</p> Signup and view all the answers

    Which of the following matrices has the best bonding characteristics with the fiber?

    <p>Epoxy</p> Signup and view all the answers

    Carbon fiber can be identified by its white color.

    <p>False</p> Signup and view all the answers

    What is the purpose of adding a catalyst or hardener to the composite?

    <p>Starts the cross-linking process and sets the composite</p> Signup and view all the answers

    Resultant stress is a combination of which types of stress?

    <p>Shear stress and normal stress</p> Signup and view all the answers

    The stress that acts along the length of the fuselage is known as tensile stress.

    <p>False</p> Signup and view all the answers

    Which stress is used to predict failure in brittle materials?

    <p>Ultimate stress</p> Signup and view all the answers

    In plane stress problems, the thickness of the material is assumed to be ____.

    <p>zero</p> Signup and view all the answers

    If the number of unknowns is less than the number of equations, then the problem is considered?

    <p>Statically determinate</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Ultimate stress = Used for predicting failure in brittle materials Longitudinal stress = Acts along the length of a structure Von Mises stress criterion = Applicable to ductile materials Plane strain = The strain is in one plane</p> Signup and view all the answers

    In plane strain problems, the strain is zero.

    <p>False</p> Signup and view all the answers

    In principal stresses, the shear stress is assumed to be?

    <p>Zero</p> Signup and view all the answers

    In iso-strain condition, what is true about the strain of the matrix and fiber?

    <p>Matrix and fiber strains are the same</p> Signup and view all the answers

    Concrete is an example of a fiber-reinforced composite.

    <p>False</p> Signup and view all the answers

    What type of composite has the best impact resistance characteristics?

    <p>Aramid fiber reinforced composites</p> Signup and view all the answers

    The dispersed phase in composites refers to the particles and __________.

    <p>fibers</p> Signup and view all the answers

    What is the typical particle size for dispersion-strengthened composites?

    <p>0.01 μm -- 0.1 μm</p> Signup and view all the answers

    Match the following composite characteristics with their descriptions:

    <p>Iso-stress = Stress is uniform across the composite Iso-strain = Strain is uniform across the composite Dispersed phase = Fibers and particles in composites Thin-walled structure = Common assumption for fuselage design</p> Signup and view all the answers

    The critical length of the fiber is independent of fiber diameter.

    <p>False</p> Signup and view all the answers

    In a uni-directional laminate, how are the fibers arranged?

    <p>Either 0 degrees or 90 degrees</p> Signup and view all the answers

    The internal shear forces in a material are typically __________ to the plane.

    <p>parallel</p> Signup and view all the answers

    Which of the following properties is NOT a defined material main property?

    <p>Conductive</p> Signup and view all the answers

    Ductility refers to the ability of a metal to extend without losing strength.

    <p>True</p> Signup and view all the answers

    What type of material has less resistance to fracture?

    <p>Concrete</p> Signup and view all the answers

    The primary property that describes the ability of a material to recover energy after deformation is called __________.

    <p>Resilience</p> Signup and view all the answers

    Match the following material types with their characteristics:

    <p>Metals = Good conductors of electricity Polymers = Less stiff compared to others Ceramics = High durability under compression Composites = Combines properties of multiple materials</p> Signup and view all the answers

    What is the measure of the degree of plastic deformation sustained at fracture?

    <p>Ductility</p> Signup and view all the answers

    The units of yield strength are typically expressed in Pascals or Megapascals.

    <p>True</p> Signup and view all the answers

    If the applied strength is significantly lower than the yield strength, describe the state of the material.

    <p>Elastic</p> Signup and view all the answers

    A material that is brittle can lose its strength when cooled to very low __________.

    <p>temperatures</p> Signup and view all the answers

    Which one of the following materials is known to be stiffer and stronger than the others?

    <p>Carbon fiber reinforced</p> Signup and view all the answers

    Which structure has a lower packing factor?

    <p>Body-Centered Cubic</p> Signup and view all the answers

    A homogeneous portion of a system is known as a microstructure.

    <p>False</p> Signup and view all the answers

    What is the primary result of a fast cooling rate on material strength?

    <p>Makes the material stronger</p> Signup and view all the answers

    Piezoelectric ceramics are classified under ______ materials.

    <p>smart</p> Signup and view all the answers

    What is the carbon content in low-carbon steel?

    <p>Less than 0.3%</p> Signup and view all the answers

    Free energy is a function of internal energy.

    <p>True</p> Signup and view all the answers

    What type of deformation occurs after the yield point?

    <p>Plastic</p> Signup and view all the answers

    Edge dislocation is a type of?

    <p>Linear defect</p> Signup and view all the answers

    The study that relates deformation to an applied load or force is known as thermal properties.

    <p>False</p> Signup and view all the answers

    What is the property related to changes in temperature or temperature gradients across a material?

    <p>Thermal properties</p> Signup and view all the answers

    When the solution is not capable of dissolving any more solute, it is known as the ______.

    <p>solubility limit</p> Signup and view all the answers

    Which element has a higher percentage in stainless steel?

    <p>Iron</p> Signup and view all the answers

    Match the following properties with their definitions:

    <p>Toughness = Resistance to fracture Ductility = Ability to deform under tensile stress Hardness = Resistance to localized plastic deformation Resilience = Ability to absorb energy and deform elastically</p> Signup and view all the answers

    The smaller the grain size, the weaker the material will be.

    <p>False</p> Signup and view all the answers

    A system is at equilibrium if its free energy is at?

    <p>Minimum</p> Signup and view all the answers

    Study Notes

    Material Properties and Definitions

    • Material Main Property (not defined): Conductive
    • Ductility: The ability of a metal to extend without losing strength or breaking.
    • Fracture Resistance: Concrete has the lowest resistance to fracture among the provided materials (Metals, Polymers, Ceramics, and Concrete).
    • Advanced Materials: Nanomaterials, Biomaterials, and Smart materials are included. Micromaterials are not
    • Stiffness: Polymers are less stiff than Metals, Ceramics, or Composites.
    • Electrical Conductivity: Metals are better conductors than the other listed materials.

    Composite Materials

    • Stiffest and Strongest Composite: Carbon fiber reinforced composites are stiffer and stronger than glass fiber reinforced, aramid fiber reinforced, or ceramic matrix composites.
    • Crack Propagation Prevention: Heat treatment, stress relieving, and material substitution are methods to prevent crack propagation. Rounding hatch corners is not.
    • Brittle Ductile Transition: Cooled to very low temperatures can cause ductile metal alloys to become brittle
    • Design Factor: If applied strength is 100 MPa and yield strength is 200 MPa, the design factor is 2.

    Stress and Strain

    • Tensile Strength: The average tensile strength for the provided samples (200 MPa, 210 MPa, 220 MPa) is 210 MPa.
    • Elastic Deformation: Deformation before the yield point is elastic.
    • Strain Removal: If loading is removed before the yield strength, strain becomes zero
    • Maximum Stress: The maximum stress experienced by a structure/material is the yield strength.
    • Stress Formula: Stress = Force/Area.
    • Stress Unit: The unit of stress is Megapascal (MPa).
    • Unit of Strain: Strain has no units.
    • Strain Offset: Strain offset is 0.002 when a straight line is parallel to the elastic portion of the stress-strain curve.
    • Modulus of Elasticity: E = stress/strain
    • Brittle Materials: A brittle material experiences very little or no plastic deformation before fracture.

    Other Material Properties

    • Ductility: The degree of plastic deformation sustained at fracture is called ductility.

    • Hooke's Law: Hooke's law can be implemented before the yield point.

    • Composite Material Properties: Composite material properties are generally anisotropic.

    • Matrix Material Bonding: Epoxy matrices have better bonding characteristics with fibers than other available matrices.

    • Composite Phase: The continuous phase surrounding other phases is called the matrix phase.

    • Cross-Ply Composite Fiber Direction: The fibers in cross-ply composite laminates are oriented at 0 degrees and 90 degrees.

    • Strain condition in composite: In iso-strain condition, the strain of the matrix and fiber are equal.

    • Concrete Composite: Concrete is a particle-reinforced composite material.

    • Dispersed Phase: Fibers and particles in composites are described as the dispersed phase.

    • Impact Resistance Aramid fiber reinforced composites have the best impact resistance.

    • Critical Fiber Length: The critical length of fiber depends on the fiber diameter.

    • Iso-Strain Condition: In an iso-strain condition, the strain of the matrix and fiber are equal.

    • Fuselage Structure: A fuselage is typically modeled as a thin-walled structure.

    • Internal Shear Forces: Internal shear forces are parallel to the plane.

    • Resultant Stress: Combination of shear and normal stresses.

    • Fuselage Stress: The longitudinal (axial) stress acts along the length of the fuselage.

    • Brittle Materials Failure: Use ultimate stress to predict failure in brittle materials.

    • Plane Stress Assumption: In plane stress problems, the thickness is assumed as negligible.

    • Degrees Of Freedom: If the number of unknowns is less than the number of equations, it's statically determinate.

    • Material Properties on a macro/micro scale Microstructure corresponds to structural elements visible via microscopy.

    • Equilibrium State: A system is in equilibrium when its free energy is at a minimum.

    • Saturation Point: The solubility limit defines when a solution can't absorb any more solute.

    • Isotropy: If a material has the same properties in all directions, it is isotropic.

    • Rolling effect on ductility: Rolling reduces ductility.

    • Small grain size effect: Smaller grain size leads to stronger materials.

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    Material Science Quiz PDF

    Description

    Test your knowledge on composite materials and strain concepts in this comprehensive quiz. Explore topics such as stress-strain curves, bonding characteristics, and the nature of ductile materials. Perfect for students studying materials science and engineering.

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