Mechanics of Materials Overview
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Questions and Answers

What is the branch of mechanics that studies the internal effects of stress and strain in a solid body?

Mechanics of materials

What does stress describe in materials?

The intensity of the internal force acting on a specific plane.

What are the two types of external loads a body can be subjected to?

  • Neither A nor B
  • Body forces
  • Both A and B (correct)
  • Surface forces

    • Surface forces are developed when one body exerts a force on another without physical contact.

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

    What equation is used to maintain equilibrium in a body?

    <p>Balances the forces and moments.</p> Signup and view all the answers

    Which of the following is a type of resultant loading?

    <p>All of the above</p> Signup and view all the answers

    What is compressive stress?

    <p>Stress occurring on members that are axially loaded in compression.</p> Signup and view all the answers

    What is Hooke's Law?

    <p>States that strain of a material is proportional to the applied stress within the elastic limit.</p> Signup and view all the answers

    What is the elastic limit of a material?

    <p>Both B and C</p> Signup and view all the answers

    Ductile materials exhibit small tensile strains up to the point of rupture.

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

    What is the maximum stress point in the stress-strain diagram called?

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

    What is the term for the work done on a unit volume of material, gradually increased from O to R?

    <p>Modulus of Toughness</p> Signup and view all the answers

    Study Notes

    Mechanics of Materials

    • Studies the internal effects of stress and strain in a solid body when subjected to an external load.
    • Stress is associated with the strength of the material.
    • Strain is a measure of deformation.

    Historical Context

    • Galileo conducted experiments in the 17th century to study the effects of load on rods and beams.
    • Experimental methods for testing materials improved during the 18th century.
    • Theoretical studies were undertaken by individuals like Saint-Venant, Poisson, Lame, and Navier.

    Equilibrium of a Deformable Body

    • A body can experience surface forces or body forces.
    • Surface forces result from direct contact between bodies.
    • Body forces are exerted without physical contact.

    Support Reactions

    • Reactions are surface forces that develop at supports or points of contact.
    • There are various types of connections: cable, roller, smooth support, pin, and fixed support.

    Equations of Equilibrium

    • These equations balance forces to prevent translation, and balance moments to prevent rotation.
    • Equilibrium requires both a balance of forces and a balance of moments.

    Internal Resultant Loadings

    • Statics is used to determine the resultant loadings within a body.
    • There are four types of resultant loadings:
      • Normal Force (N)
      • Shear Force (V)
      • Torque (T)
      • Bending Moment (M)

    Normal Force

    • Perpendicular to the area.
    • Occurs when external loads tend to push or pull on two segments of a body.

    Shear Force

    • Lies in the plane of the area.
    • Develops when external loads cause two segments to slide over each other.

    Torque

    • Develops when external loads twist.

    Bending Moment

    • Caused by external loads that tend to bend.

    Stress

    • Describes the intensity of the internal force on a specific plane passing through a point.
    • Formerly expressed in psi, now commonly in N/mm² or MPA
    • ksi/psi is commonly used in the English System.

    Normal Stress

    • Occurs in members that are axially loaded.
    • An axial force can be either tension or compression and is applied at the centroid of the cross-section.
    • There are two types of normal stress:
      • Compressive Stress
      • Tensile Stress

    Shear Stress

    • Forces are parallel to the area resisting the force.
    • Also known as tangential stress.

    Bearing Stress

    • Contact pressure between separate bodies.
    • Internal stress caused by compressive forces.

    Thin-Walled Vessel

    • A tank or pipe carrying fluid or gas under pressure experiences tensile forces that resist bursting.
    • These forces develop across both longitudinal and transverse sections.
    • There are three types of stress in a thin-walled vessel:
      • Tangential Stress (Circumferential Stress)
      • Longitudinal Stress
      • Spherical Stress

    Strain

    • Also known as unit deformation.
    • The ratio of change in length caused by the applied force.

    Stress-Strain Diagram

    • A graphical representation of the behavior of a material under stress.
    • Metallic engineering materials can be classified as ductile or brittle.
    • Ductile materials experience a large tensile strain up to the point of rupture.
    • Brittle materials experience a small strain up to the point of rupture.

    Proportional Limit (Hooke's Law)

    • Hooke's law states that stress and strain are proportional for small deformations.
    • It states that the strain of a material is proportional to the applied stress within the elastic limit of that material.
    • F = -kx

    Elastic Limit

    • The limit beyond which the material will no longer return to its original shape when the load is removed.

    Elastic Range

    • The region in the stress-strain diagram from O to E.

    Plastic Range

    • The region in the stress-strain diagram from E to R.

    Yield Point

    - The point where the material exhibits significant elongation or yielding without an increase in load.

    Ultimate Strength

    • The maximum ordinate in the stress-strain diagram.

    Rupture Strength

    • The strength of the material at rupture.
    • Also known as breaking strength.

    Modulus of Resilience

    • The work done on a unit volume of material, gradually increased from O to P.
    • The resilience of a material is its ability to absorb energy without creating permanent distortion.

    Modulus of Toughness

    • The work done on a unit volume of material, gradually increased from O to R.
    • The toughness of a material is its ability to absorb energy without breaking.

    Hooke's Law Disadvantages

    • It ceases to apply past the elastic limit.
    • It is accurate only for solid bodies.
    • It is not a universal principle.

    Hooke's Law FAQs

    • Applies to any elastic object of arbitrary complexity.
    • Is linear, meaning the restoring force is proportional to displacement.

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    Related Documents

    Mechanics of Materials PDF

    Description

    Explore the fundamental concepts of Mechanics of Materials, focusing on the internal effects of stress and strain in solid bodies under external loads. Learn about the historical developments, equilibrium of deformable bodies, and support reactions critical to understanding material behavior. This quiz will test your knowledge on key principles and historical context in this field.

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