DK Ching VD - Material

strength

the capability of a material to resist the forces imposed on it, esp. the ability to sustain a high stress without yielding or rupturing

strength of materials

the study of the relationship between applied external forces and the internal effects produced by these forces in a body

tension

the act of stretching or state of being pulled apart, resulting in the elongation of an elastic body

tensile force

an applied force producing or tending to produce tension in an elastic body

axial force

a tensile or compressive force acting along the longitudinal axis of a structural member and at the centroid of the cross section, producing the axial stress without bending, torsion, or shear

axial stress

the tensile or compressive stress that develops to resist an axial force, assumed to be normal to and uniformly distributed over the area of the cross section; also called "direct stress", "normal stress"

stress

the internal resistance or reaction of an elastic body to external forces applied to it

tensile stress

the axial stress that develops at the cross section of an elastic body to resist the collinear tensile forces tending to elongate it

tensile strain

the elongation of a unit length of material produced by a tensile stress

strain

the deformation of a body under the action of an applied force

Young's modulus

a coefficient of elasticity of a material, expressing the ratio of longitudinal stress to the corresponding longitudinal strain caused by the stress

Poisson's ratio

the ratio of lateral strain to the corresponding longitudinal strain in an elastic body under longitudinal stress

tensile strength

the resistance of a material to longitudinal stress

elongation

a measure of the ductility of a material

reduction of area

a measure of the ductility of a material

compression

the act of shortening or state of being pushed together, resulting in a reduction in size or volume of an elastic body

compressive force

an applied force producing or tending to produce compression in an elastic body

compressive stress

the axial stress that develops at the cross section of an elastic body to resist the collinear compressive forces tending to shorten it

compressive strain

the shortening of a unit length of material produced by a compressive stress

eccentric force

a force applied parallel to the longitudinal axis of a structural member but not to the centroid of the cross section

bulk modulus

a coefficient of elasticity of a material, expressing the ratio between a pressure and the corresponding fractional change in volume produced

compressibility

the reciprocal of bulk modulus

shear

the lateral deformation produced in a body by an external force that causes one part of the body to slide relative to an adjacent part in a direction parallel to their plane of contact

shear force

an applied force producing or tending to produce shear in a body

shearing force

an internal force tangential to the surface on which it acts, developed by a body in response to a shear force

shearing stress

the force per unit area developed along a section of an elastic body to resist a shear force; also called "tangential stress"

shearing strain

the lateral deformation developed in a body in response to shearing stresses

shear modulus

a coefficient of elasticity of a material, expressing the ratio between shearing stress and the corresponding shearing strain produced by the stress; also called "modulus of rigidity", "modulus of torsion"

combined stresses

a set of tensile and compressive stresses resulting from the superposition of axial and bending stresses in the cross section of a structural member

bending

the bowing of an elastic body as an external force is applied transversely to its length

transverse force

a force applied perpendicular to the length of a structural member, producing bending and shear

torque

the moment of a force system that causes or tends to cause rotation or torsion

torsion

the twisting of an elastic body about its longitudinal axis caused by two equal and opposite torques, producing shearing stresses in the body

plastic range

the range of unit stresses for which a material exhibits plastic deformation

strain-hardening range

the range of unit stresses for which a material exhibits increased strength with some loss of ductility

plastic deformation

a permanent change in the dimensions or shape of a body produced by a stress greater than the elastic limit of the material, remaining rigid under stresses of less than a certain intensity; also called "plastic flow"

elastic range

the range of unit stresses for which a material exhibits elastic deformation

deformation

a change in the shape or dimensions of a body or structure resulting from stress

elastic deformation

a temporary change in the dimensions or shape of a body produced by a stress less than the elastic limit of the material

brittleness

the property of a material that causes it to rupture suddenly under stress with little evident deformation

proportional limit

the stress beyond which the ratio of stress to strain for a material no longer remains constant

stiffness

a measure of a material's resistance to deformation when stressed within its elastic range

allowable stress

the maximum unit stress permitted for a material in the design of a structural member, usually a fraction of the material's elastic limit, yield strength, or ultimate strength; also called "working stress"

yield point

the stress beyond which a marked increase in strain occurs in a material without a concurrent increase in stress

ultimate strength

the maximum tensile, compressive, or shearing stress a material can be expected to bear without rupturing or fracturing; also called "ultimate stress"

elastic limit

the maximum stress that can be applied to a material without causing permanent deformation

ductility

the property of a material that enables it to undergo plastic deformation after being stressed beyond the elastic limit and before rupturing

fracture

the breaking of a material resulting from the rupturing of its atomic bonds when stressed beyond its ultimate strength

elasticity

the property of a material that enables it to deform in response to an applied force and to recover its original size and shape upon removal of the force

modulus of elasticity

a coefficient of elasticity of a material, expressing the ratio between a unit stress and the corresponding unit strain caused by the stress, as derived from Hooke's law and represented by the slope of the straight-line portion of the stress-strain diagram; also called "coefficient of elasticity"

Hooke's law

the law stating that the stress on a body is directly proportional to the strain produced, provided the stress does not exceed the elastic limit of the material

yield strength

the stress necessary to produce a specified limiting permanent set in a material, usually 0.2% of its original length when tested in tension; used to determine the limit of usefulness of a material having a poorly defined yield point; also called "proof stress"

permanent set

the inelastic strain remaining in a material after complete release of the stress producing the deformation

toughness

the property of a material that enables it to absorb energy before rupturing, represented by the area under the stress-strain curve derived from a tensile test of the material

dimensional stability

the property of a material that enables it to maintain its original shape and dimensions when subjected to changes in temperature or humidity

kinetic theory of heat

the theory that the temperature of a substance increases with an increase of the average kinetic energy of its particles when heat is absorbed

thermal expansion

an increase in length, area, or volume of a material caused by a rise in temperature

coefficient of expansion

the fractional change in length, area, or volume of a material per unit change in temperature at a given constant pressure; also called "expansivity"

thermal contraction

a decrease in length, area, or volume of a material caused by a drop in temperature

thermal stress

the tensile or compressive stress developed in a material constrained against thermal expansion or contraction

thermal shock

the sudden stress a rapid change in temperature can produce in a material

moisture expansion

an increase in the bulk of a material caused by the absorption of water or water vapor; also called "bulking"

absorption

the taking in or reception of a gas or liquid by molecular or chemical action

adsorption

the adhesion of a thin, condensed layer of gas, liquid, or dissolved substance to the surface of a solid, usually without any physical or chemical change in the material

weatherability

the property of a material that enables it to retain its appearance and integrity when exposed to the effects of sun, wind, moisture, and changes in temperature

accelerated weathering

a process for exposing a material to ultraviolet rays, water sprays, and heating elements in order to simulate the long-term effects of sun, rain, and temperature changes; also called "accelerated aging"

abrasion resistance

the property of material that enables it to resist being worn away by friction when rubbed with another object

abrasion-resistance index

a measure of the abrasion resistance of a material

hardness

the property of a material that enables it to resist deformation by compression, indentation, or penetration

Mohs scale

a scale for measuring the hardness of a mineral

strain-rate effect

the brittle behavior an increased rate of load application can cause in a normally ductile material

temperature effect

the brittle behavior low temperatures can cause in a normally ductile material

stress relaxation

the time-dependent decrease in stress in a constrained material under a constant load

creep

the gradual and permanent deformation of a body produced by a continued application of stress or prolonged exposure to heat

fatigue

the weakening or failure of a material at a stress below the elastic limit when subjected to a repeated series of stresses

fatigue limit

the maximum stress to which a material can be subjected for an indefinite number of cycles without failing

fatigue ratio

the ratio between the fatigue limit and the tensile strength of a material