Material Flashcards
The attractive force by which atoms, ions, or groups of atoms are bound together in a molecule or crystaline structure.
Bond, Chemical Bond
A chemical bond characteristic of salts and ceramic materials, formed by the complete transfer of one or more electrons from one kind of ion to another.
Ionic Bond or Electrovalent Bond
A positively charged ion created by electron loss, which is attracted to the cathode in electrolysis.
Positive Ion, Cation
An electrically charged aton or group of atoms formed by the loss or gain of one or more electrons.
Ion
A negatively charged ion created by electron gain, which is attracted to the anode in electrolysis.
Negative Ion or Anion
A measure of the capacity of an atom or group to combine with other atoms or groups, equal to the number of chemical bonds the atom or group can form.
Valence
An electron located in the outer shell of an atom that can be transferred or shared in forming a chemical bond with another atom.
Valence electron
That which occupies space, can be perceived by the senses, and constitutes the substance of physical body.
Matter
Any of up to seven spherical surfaces containing the orbits of electrons of approximately equal energy about the nucleus of an atom.
Shell
A fundamental particle of matter having a negative charge.
Electron
A fundamental particle having no charge.
Neutron
A positively charged particle that is a fundamental constituent of all atomic nuclei.
Proton
Matter having unique qualities by which it may categorized.
Material
The smallest unit of an element that can exist either alone or in combination, consisting of a nucleus of neutrons and protons surrounded by one or more electrons bound to the nucleus by electrical attraction.
Atom
The number of protons in the nucleus of an atom of a given element, which equals the number of electrons normally surrounding the nucleus.
Atomic Number or Proton Number
One of a class of substances that cannot be separated into simper substances by chemical means, composed of atoms having an identical number of protons in each nucleus.
Element
The average weight of an atom of an element based on 1/12 the weight of the carbon-12 atom.
Atomic Weight
A chemical bond formed by the sharing of pairs of electrons between two atoms.
Covalent Bond
An electrostatic bond between an electronegative atom and a hydrogen atom already lined to another electronegative atom by a covalent bond.
Hydrogen Bond
The smallest particle of a substance that displays all of the characteristic physical and chemical properties of the substance, consisting of one or more like atoms in an element, or two or more different atoms in a compound.
Molecule
The stable configuration of an element in which the outer shells of its atoms or ions are filled with the maximum number of electron pairs. nature moves atoms and ions toward this configuration by capturing, surrendering or sharing electrons with neighboring atoms or ions in an effort to achieve a relatively inert state of low energy.
Inert Gas Configuration
Any of the chemically inert gaseous elements: helium, neon, argon, krypton, xenon, and radon.
Noble Gas, inert Gas
The average weight of a molecule of an element or compound calculated as the sum of the atomic weights of the molecule’s constituent atoms.
Molecular Weight or Formula Weight
The molecular weight of a substance expressed in grams; gram molecule.
Mole or Mol
To reduce to a denser form, as a gas or vapor to a liquid or solid state,
Condense
The heat liberated by a unit mass of gas at its boilding point as it condenses to a liquid.
Heat of condensation
The quantity of heat required to convert a unit mass of liquid at its boilindg point into vapor at the same temperature, equal to the heat of condensation.
Heat of Vaporization
Matter distinguished from the solid or gaseous states by a characteristic readiness to flow, little or no tendency to disperse, and relatively high incompressibility.
Liquid
To change or convert from a liquid or solid into a vapor
Evaporate
To change or convert from a liquid or gas into a solid.
Solidify
A substance, such as gas or liquid, that is capable of flowing, yields easily to pressure and conforms to the shape of its container.
Fluid
Matter having neither independent shape nor volume, possessing perfect molecular mobility and the tendency to expand indefinitely.
Gas
Matter having relative firmness, coherence of particles, or persistence of form.
Solid
The heat liberated by a unit mass of liquid at its freezing point as it solidifies.
Heat of Solidification
The quantity of heat required to convert a unit mass of a solid at its melting point into a liquid at the same temperature, equal to the heat of solidification.
heat of fusion
A tabular arrangement of the chemical elements in related groups, formerly in the order of their atomic weights and now according to their atomic numbers.
Periodic table
A chemical bond characteric of metals, produced by the sharing of valence electrons which move freely through the lattice of a usually stable crystalline strucutre.
Metallic Bond
A regular pattern of isolated points in space showing the location of atoms, ions, or molecules in a crystalline solid.
Lattice
A solid having a regularly repeating internal structure of atoms, ions, or molecules and enclosed by symmetrically arranged plane surfaces.
Crystal
Not crystalline in structure.
Amorphous
An essential or distinctive attribute or quality belonging specifically in the constitution of, or found in, the behavior of a thing.
Property
Any of the physical properties of a material that exhibit a response to applied forces.
Mechanical Property
The capability of a material to resist the forces mposed on it, esp the ability to sustain a high stress without yielding or rupturing.
Strength
The study of the relationship between applied external forces and the internal effects produced by these forces in a body.
Strength of materials
Exhibiting the same physical properties along all axes.
Isotropic
Having different physical properties along different aes, such as those of wood and other fibrous materials.
Anisotropic
The act of stretching or state of being pulled apart, resulting in the elongation of an elastic body.
Tension
An applied force producing or tending to produce tension in an elastic body.
Tensile Force
A tensile or compressive force acting along the longitudinal axis of a structural member and at the centroid of the cross section, producing axial stress without bending, torsion or shear.
Axial force, axial load
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.
Axial Stress, Direct Stress, Normal Stress
The act of shortening or state of being pushed together, resulting in a reduction in size or volume of an elastic body.
Compression
An applied force producing or tending to produce compression in an elastic body.
Compressive Force
A force applied parallel to the longitudinal axis of a structural member but not to the centroid of the cross section, producing bending and an uneven distribution of stresses in the section.
Eccentric Force, Eccentric Load
The axial stress that develops at the cross section of an elastic body to resist the collinear compressive forces tending to shorten it.
Compressive Stress
The shortening of a unit length of material produced by a compressive stress.
Compressive Strain
The internal resistance or reaction of an elastic body to external forces applied to it, equal to the ratio of force to area and expressed in units of force per unit of cross-sectional area.
Stree, Unit 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 Stress
The elongation of a unit length of material produced by a tensile stress.
Tensile Strain
The deformation of a body under the action of an applied force. Strain is a dimensionless quantity, equal to the ratio of the change in size or shape to the original size or shape of a stressed element.
Strain
A coefficient of elasticity of a material, expressing the ratio of longitudinal stress to the corresponding longitudinal strain caused by the stress.
Young’s Modulus
The ratio of lateral strain to the corresponding longitudianl strain in an elastic body under longitudinal stress.
Poisson’s Ratio
A test for determining the behavior of a material under axial tension, in which a specimen is gripped at both ends and pulled apart until rupture occurs, the most common test for structural materials.
Tensile Test
The resistance of a material to longitudinal stress, measured by the minimum amount of longitudinal stress required to rupture the material.
Tensile Strength
A measure of the ductility of a material, expressed as the percentage increase in length of a test specimen after failure in a tensile test.
Elongation
A measure of the ductility of a material, expressed as the percentage decrease in cross-sectional area of a test specimen after rupturing in a tensile test.
Reduction of area
A test for determining the behavior of a material under axial compression, in which a specimen is crushed until fracture or disintegration occurs. The compression test is used for brittle materials since their low tensile strength is difficult to measure accurately.
Compression Test
An instrument for measuring minute deformations in a test specimen caused by tension, compression, bending, or twisting.
Strain Gauge or Extensometer
A coefficient of elasticity of a material, expressing the ratio between a pressure and the corresponding fractional change in volume produced.
Bulk Modulus
The reciprocal of bulk modulus, equal to the ratio of the fractional change in volume to the pressure applied to a substance.
Compressibility
An internal force tangential to the surface on which it acts, developed by a body in response to a shear force. For equilibrium of a rectangular element subject to shear, shearing in a vertical plane necessarily involves shearing in a horizontal plane, and vice verse.
Shearing force
The force per unit area developed along a section of an elastic body to resist a shear force.
Shearing Stress, Shear Stress, Tangential Stress
The lateral deformation developed in a body in response to shearing stresses, defined as the tangent of the skew angle of the deformation. Since this skew angle is always very small, shearing strain is a pure number very nearly equal to the skew angle in radians.
Shearing Strain or Shear Strin
A coefficient of elasticity of a material, expressing the ratio between shearing stress and the corresponding shearing strain produced by the stress.
Shear modulus, Modulus of rigidity, modulus of torsion
An applied force producing or tending to produce shear in a body.
Shear Force
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
A set of tensile and compressive stresses resulting from the superposition of axial and bending stresses in the cross section of a structural member, acting in the same direction and equal at any point to their algebraic sum.
Combined Stresses
The bowing of an elastic body as an external force is applied transversely to its length. Bending is the structural mechanism that enables a load to be channeled in a direction perpendicular to its application.
Bending
A force applied perpendicular to the length of a structural member, producing bending and shear.
Transverse Force
An increase in stress that develops at discontinuities or flaws in a material. Stress concentration in brittle materials develop cracks that propagate until failure. In ductile materials, stress concentrations develop local deformations that serve to redistribute and relieve the stresses.
Stress Concentration
The moment of a force system that causes or tends to cause rotation or torsion.
Torque
The twisting of an elastic body about its longitudinal axis caused by two equal and opposite torques, producing shearing stresses in the body.
Torsion
A graphic representation of the relationship between unit stress values and the corresponding unit strains for a specific material.
Stress-Strain diagram
The range of unit stresses for which a material exhibits elastic deformation.
Elastic Range
A change in the shape or dimensions of a body or structure resulting from stress.
Deformation
A temporary change in the dimensions or shape of a body produced by a stress less than the elastic limit of the materia.
Elastic Deformation
The range of unit stresses for which a material exhibits plastic deformation.
Plastic Range
The range of unit stresses for which a material exhibits increased strength with some loss of ductility.
Strain-Hardening Range
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. The molecular bonds in a material that exhibits plastic behavior reform after being stressed beyond the elastic limit. The material thus retains a measure of reserve strength.
Plastic Deformation or Plastic Flow
The stress beyond which a marked increase in strain occurs in a material without a concurrent increase in stress. Many materials do not have clearly defined yield points. For these materials, a theoretical yield strength is calculated from the stress-strain curve.
Yield Point
The maximum tensile, compressive or shearing stress a material can be expected to bear without rupturing or fracturing.
Ultimate Strength, Ultimate Stress
The breaking of a material resulting from the rupturing of its atomic bonds when stressed beyond its ultimate strength.
Fracture
The property of a material that causes it to rupture suddenly under stress with little evident deformation. Since material that has this characteric lact the plastic behavior of ductile materials, they cam give no advance warning of impending failure.
Brittleness
The stress beyond which the ratio of stress to strain for a material no longer remains constant.
Proportional Limit
A measure of a material’s resistance to deformation when stressed within its elastic range.
Stiffness
The maximum stress that can be applied to a material without causing permanent deformation.
Elastic Limit
The property of a material that enables it to undergo plastic deformation after being stressed beyond the elastic limit and before rupturing. It is a desirable property of a structural material since plastic behavior is an indicator of reserve strength and can serve as a visual warning of impending failure.
Ductility
The maximum unit stress permitted for a material in the design of a strucutral member, usually a fraction of the material’s elastic limit, yield strength, or ultimate strength. The allowable stresses for various materials are specified by building codes, engineering societies, and trade associations, based on specifications and methods of testing established by the American Society for Testing and materials.
Allowable Stress, Allowable Unit Stress, Working Stress
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.
Elasticity
A coefficient of elasticity of a material, expressing the ratio betwen 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.
Modulus of Elasticity, Coefficient of elasticity, elastic modulus.
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.
Hooke’s Law
The stress necessary to produce a specified limiting permanent set in a material, usually 0.2% of its original length when tested in tension. Yield strength is used to determine the limit of usefulness of a material having a pooly defined yield point.
Yield Strength, Proof Stress
The inelastic strain remaining in a material after complete release of the stress producing the deformation.
PErmanent Set
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. Ductile materials are tougher than the brittle materials.
Toughness
An increase in the bulk of a material caused by the absorption of water or water vapor.
Moisture Expansion, Bulking
The taking in or reception of a gas or liquid by molecular or chemical action.
Absorption
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.
Adsorption
The fractional change in length, area, or volume of a material per unit change in temperature at a given constant pressure.
Coefficient of Expansion, expansivity
The property of a material that enables it to maintain its origina shape and dimensions when subjected to changes in temperature or humidity.
Dimensional Stability
The theory that the temperature of a substance increases with an increase of the average kinetic energy of its particles when heat is absorbed.
Kinetic Theory of Heat
An increase in length, area, volume of a material caused by a rise in temperature.
Thermal Expansion
A decrease in length, area, volume of a material caused by a drop in temperature.
Thermal Contraction
The tensile or compressive stress developed in a material constrained against thermal expansion or contraction.
Thermal Stress
The sudden stress a rapid change in temperature can produce in a material.
Thermal Shock
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.
Weatherability
A device for determining the weather resistance of a material by subjecting a test specimen to accelerated weathering.
Weatherometer
Extensometer
Weatherometer
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.
Accelerated Weathering, Accelerated aging
The property of a material that enables it to resist being worn away by friction when rubbed with another object.
Abrasion Resistance
Abrasion resistance is a measure of toughness rather than hardness and is a necessary quality of flooring materials and surface finishes.
A measure of the abrasion resistance of a material, commonly expressed as the depth of penetration or material loss after testing with a weighted abrasive wheel for a specified number of cycles.
Abrasion-resistance index
The property of a material that enables it to resist deformation by compression, indentation, or penetration.
Hardness
A scale for measuring the hardness of a mineral. Its degrees, in increasing hardness, are:
1 - Talc
2 - Gypsum
3 - Calcite
4 - Fluorite
5 - Apatite
6 - Feidspar
7 - Quartz
8 - Topaz
9 - Sapphire
10 - Diamond
Mohs Scale
A measure of the hardness of a material, determined by pressing a standard steel ball into a test piece using a standard force and dividing the load by the area of indentation. The hight the number, the harder the material.
Brinell NUmber
A measure of the hardness of a material, determined by indenting a test piece with a conoidal diamond indenter, or with a standard steel ball, under two sucessive loads and measuring the net increase in depth of the impressions; the higher the number, the harder the material.
Rockwell Number
A measure of the hardness of a material, determined by indenting a test piece with the point of a diamond using a known force and dividing the load by the surface area of indentation, the higher the number, the harder the material.
Vickers Number
The weakening or failure of a material at a stress below the elastic limit when subjected to a repeated series of stresses.
Fatigue
The maximum stress to which a material can be subjected for an indefinite number of cycles without failing.
Fatigue Limit
THe ratio between the fatigue limit and the tensile strength of a material.
Fatigue Ratio, Endurance Ratio
The brittle behavior an increased rate of load application can cause in a normally ductile material.
Strain-rate effect
The brittle behavior low temperatures can cause in a normally ductile material.
Temperature Effect
The time-dependent decrease in stress in a constrained material under a constant load.
Stress relaxation
The gradual and permanent deformation of a body produced by a continued application of stress or prolonged exposure to heat. Creep deflection in a concrete structure continues over time and can be significantly greater than the initial elastic deflection.
Creep
