# Dmat1

version from 2016-09-18 04:08

## properties of materials (terms)

Stiffness is higher and Flexibility lower for this propertyModulus of Elasticity
resistance to breakage or permanent distortionStrength
ability to be formed into a duct or tube, drawn into a wire, or hammered thin without breakingductility
amount that material expands on heating and contracts on coolingThermal Expansion
What types of bonds play an important role in a material when a) high modulus of elasticity (stiff material)  b) high strength  & c) low thermal expansion?Primary Bonds (metals and ceramics)
What types of bonds play an important role in a material when 1. a) low modulus of elasticity (flexible material) b) low strength  & c) high thermal expansionPrimary and Secondary Bonds (polymers)
What is the formula for modulus of elasticity?Elasticity = Stress/strain (Young's Modulus of Elasticity)

## definitions

determined by dividing the force by the area.Stress
yielding without breaking (oppositie of brittlness)Permanent (plastic) deformation
material is subjected to a force which tends to stretch it (opp compression)Tension
compressive force applied to materialCompression
relates to the force required to bend or otherwise permanently deform itYield strength
force required to break a materialFracture strength
The discontinuity in the lattice caused by this extra plane.. what allows metals to be deformed (plastically) without breaking.Dislocation
fracture with little or no permanent deformationBrittleness
amount that a material expands upon heating and contracts upon cooling.Thermal expansion
amount a material elongates under a given stress. Epsilon. designated as a fraction of the original length.Strain
any irregularity (sharp angles, etc) which acts as stress concentration points. stress around a stress raiser can be many times higher than the average stress in the bodyStress raiser
describes whether a material is flexible or stiffModulus of Elasticity

## properties of specific materials table (ceramics, metals, or polymers)

which of the three materials (ceramics, metals, or polymers) has a low Modulus of Elasticity (is flexible)Polymers
which of the three materials (ceramics, metals, or polymers) has a low strengthPolymers
which of the three materials (ceramics, metals, or polymers) has high ductilityMetals
which of the three materials (ceramics, metals, or polymers) has a high thermal expansionPolymers
which of the three materials (ceramics, metals, or polymers) has behavior determined by major importance in both primary and secondary bonds?Polymers
which of the three materials (ceramics, metals, or polymers) has primary bonds that have major importance to their behavior (and secondary bonds only affect behavior in a minor sense)Metals and Ceramics
which of the three materials (ceramics, metals, or polymers) can deform without breaking?Metals
The ability of ______ to YIELD WITHOUT FRACTURING is understandable in light of the concept of dislocations in the structureMetals
which of the three materials (ceramics, metals, or polymers) is fundamentally different from the other two?Polymers
The low strengths and elastic moduli of _____ can be understood in light of the concept of strong bonds within chains and weak bonds between chainsPolymers

## theoretical vs actual strengths

which is lower... theoretical strength or actual strength?Actual strength (100 times lower than theoretical strength)
define: strength based on strengths of inter-atomic bonds (calculation)Theoretical strength
The discrepency between theoretical and actual strengths is best explained by the phenomenon called ____ ____ (ex notch in a potato chip bag)Stress Concentration