Exam 1 3400
The stress values in engineering stress-strain curves are calculated using the which area of the specimen.
Initial cross-sectional area
An _________ is an atom that has lost or gained an electron Neutron Proton Ion Micron
Ion
_________ is a physical blend of two or more substances.
MIXTURE
Which one is a SI unit for strength?
MPa
________ properties are characteristics of a substance related to its durability and ability to withstand applied forces. Mathematical Chemical Mechanical Biological Physical
Mechanical
Which of the following is NOT a mechanical property? Fatigue Strength Toughness Hardness Tensile Strength Melting Point
Melting Point
SI units of Stress is
N/m 2
What makes elements different from each other? Number of elements Number of protons Electron spins Number of atoms
Number of protons
________ properties are attributes of a substance that can be measured without altering or destroying it. Mechanical Chemical Physical Biological Mathematical
Physical
___________ is the most industrially important strengthening mechanism in metals. Metal forging Quench hardening Plumbing Welding
Quench Hardening
What is an atom? The smallest part of a substance An element Neutrons A form of energy
The smallest part of a substance
Which one is a physical property? Corrosion Friction All of them Hardness Toughness Thermal Expansion Strength Composition
Thermal Expansion
Aluminum expands twice as much as steel, this is called ____________. Thermal conductivity Thermal expansion Use Temperature Thermal heat
Thermal expansion
Which one is NOT one of the basic type of stresses? Tensile stress Toughness stress Shear stress Compressive stress Torsional stress Bending stress
Toughness stress
What is Poisson's ratio ?
Transverse strain (diameter direction) / longitudinal strain (length direction)
An atom is the smallest part of a substance that retains the properties of that substance. True False
True
Before the ultimate tensile stress is reached, the rate of work hardening in the material increases faster than the reduction in cross-sectional area.
True
Bending stress deflects a member.
True
Both ionic and covalent bonds involve strong bonds between neighboring atoms. True False
True
Ceramics are electric insulators
True
Corrosion is the degradation of a material by reaction with its environment.
True
Creep is used to rate the resistance of a material to plastic deformation under sustained load.
True
Crystalline ceramics with strong bonds tend to be brittle.
True
Dislocations can be caused by the atomic mismatch effects of adding alloy elements.
True
Dislocations can be produced by crystal mismatch in solidification.
True
Ductility is also reported as percent elongation or percent reduction in area
True
General shape of the curve is the area under the curve provides a relative indication of material toughness.
True
If the atoms of the alloying element are significantly larger than the atoms of the host metal, these large atoms can impede the motion of dislocations and thus strengthen the metal. True False
True
In a stress strain curve, the midpoint of the curve is called yield strength.
True
In the tensile test, the sample can continue to elongate until the permanent plastic deformation occurs.
True
Inert gases can be used for providing protective atmospheres
True
Iron, nickel, cobalt have ferromagnetism.
True
Many metals can tolerate plastic deformation before failing.
True
Metal usually can be deformed plastically.
True
Metal usually can be strengthened. True False
True
Modulus of elasticity E= stress/strain = σ/ε.
True
Modulus of elasticity is used to measure the stiffness of materials
True
Most engineering literature uses the engineering stress- strain technique.
True
Protons, neutrons, and electrons have mass.
True
Shear stresses are proportionally related to the shear strains through an elastic constant called the shear modulus.
True
Strength is a materials ability to accommodate stress
True
The fatigue strength or endurance limit of a material is obtained by repeatedly loading a specimen at given stress levels until it fails.
True
The outer electron shell of atoms will be complete when it contains eight electrons.
True
The point at which the deformation of the material transitions from elastic deformation to plastic deformation is referred to as Yield point.
True
Thermal Expansion becomes important when dissimilar materials will be fastened and heated
True
True stress-strain curves are more difficult to measure and calculate because of the changing of the cross-sectional area.
True
When a bar is pulled axially in the elastic regions, the ratio of the two strains, lateral : axial, is called Poisson's Ratio.
True
When a material is plastically deformed, the material becomes stronger and harder.
True
When metals are deformed by dislocation motion, the more barriers the dislocations meet, the stronger the metal. True or False
True
Wood is a composite of cellulose fibers held together with a glue.
True
_________ is more difficult to measure and calculate because the cross-sectional area of the specimen must be accounted for as it necks down.
True stress-strain curve
At what point, the rate of cross-sectional area reduction occurs faster than the work hardening rate. Ultimate tensile stress Break Yield stress Creep Pulling stress
Ultimate tensile stress
In a stress-strain curve, the end point of Elastic region is called
Yield Strength
What property describes the weight or mass of materials
gravimeter
Which material below is the best for electric insulators? saline water alloys polymers metals
polymers
Which one is a mechanical property of gold? Its unique color Does not corrode in water or air Soft and malleable Does not tarnish (oxidize)
soft and malleable
In true stress-strain testing, an equation may be used to approximate the shape of the plastic region of the stress-strain curve What does the " n" represent?
strain hardening exponent
Modulus of elasticity = ------ /------
stress/strain
Which of the following is not a chemical property Solubility Composition Corrosive nature Specific gravity
Specific Gravity
__________ is the amount of heat energy required to raise one unit mass of material with one degree. Thermal conductivity Use temperature Thermal expansion Specific heat
Specific heat
Which one is a mechanical property? Composition All of them Specific Heat Strength Density Color Atomic Structure
Strength
In true stress-strain testing, an equation may be used to approximate the shape of the plastic region of the stress-strain curve What does the " K" represent?
Strength coefficient
Metals are inorganic materials. True False
TRUE
Resilience is a prosperity defines a material's ability to absorb elastic energy.
TRUE
The formula for calculating the Percent of Elongation is (Final length - initial length) / Final length (Initial length - final length) / Initial length (Final length - initial length) / Initial length (Initial length - final length) / Final length
(Final length - initial length) / Initial length
What poission's ratio does most of engineering materials have? 7 14 0.01 0.3
.3
The periodic table is A categorization of elements by chemical characteristics A glossary of elements A table of atoms A table for earth substances
A categorization of elements by chemical characteristics
In true stress-strain curves, the stress is calculated using which area of specimen?
Actual
Metals can be strengthened by ________ . All of them Mechanical working strengthening Precipitation hardening Quench hardening Solid solution strengthening
All
Which of the following is a property of strong bonds, such as ionic bonding or covalent bonding, in ceramics? Chemical inertness High hardness Electron insulation
All
NDT can be used in _____ ? sheet Castings All of them Weldments Strip Extrusions
All of them
Which of the following is a physical property? Hardness Microstructure Color Composition
Color
An alloy is ________. molecules composed of two elements Composed of two or more elements Composed of two electrons Composed of two or more atoms
Composed of two or more elements
Which one is a chemical property? Toughness Reflectance Composition All of them Strength Thermal Expansion
Composition
Alloy is ______ . None of the answer is correct Nonmetal Mixture Compound
Compound
Which of the following is a mixture? Fe Proton Carbon Concrete
Concrete
Which of the following is NOT a thermal property. Specific heat Thermal expansion Elastic modulus Thermal conductivity
Elastic modulus
What determines the rate at which current flows through a per unit cross section and per unit length. Ampere rate Inductance Electricity resistivity Potential resistivity
Electricity resistivity
What is the formula to calculate stress?
F/A
A value of "0" in strain hardening exponent means that a material is a perfectly elastic solid.
False
An atom is the smallest part of a compound that retains the properties of that compound T or F
False
As the tester continues to pull the sample, the material continues to work harder and gets stronger; at the same time the cross-sectional area of the sample begins to rapidly increase.
False
Creep is used to rate the resistance of a material to elastic deformation under sustained load.
False
Elastic Modulus, Modulus of Elasticity, and Young's Modulus are all dissimilar properties of the material.
False
Fourier's law are usually used for calculating Thermal Expansion.
False
Glasses and plastics often have a crystalline structure.
False
Inorganic materials are usually derived from living things.
False
Modulus of Elasticity and Modulus of Elasticity in Shear are the same property.
False
Modulus of elasticity is the measure of a material's toughness.
False
Necking begins before the ultimate strength point.
False
Petroleum products, crude oil, plants, and animals are inorganic materials.
False
Precipitation hardening is used to strengthen many ferrous metals.
False
Strength is defined by hardness
False
Stress concentration factors cannot be applied to loadings such as tension, bending, and torsion.
False
Tensile limit is the point at which the deformation of the material transitions from elastic deformation to plastic deformation
False
The units of strain is psi.
False
Toughness is the ability of a material to release energy before fracturing.
False
Yield strength is typically measured in ft/sec
False
Percentage of Elongation and Bend Radius falls under the property of _____ ? Strength Formability Durability Toughness Rigidity
Formability
The usual purpose of dye penetrant inspection is to _____ ? Find internal voids Measure density Assess surface wetting Assess surface texture Measure porosity Identify surface cracks
Identify surface cracks