Stress and Strain Hooke's Law

8/13/2019 Stress and Strain Hooke's Law

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Lesson: Stressed and StrainedContributed by: Integrated Teaching and Learning Program, College of Engineering, Universityof Colorado at Boulder

Engineering Connection

Engineering analysis or artial designEngineers use their understanding of forces, stress, strain and material roerties to create safe

designs for structures, e!uiment and roducts" #nalysis of strength of materials $yield strength,ultimate tensile strength and fatigue strength% figures into the selection of materials used to create

items such as chairs, aliances, toys, bicycles, medical &oint relacements, roc' climbing roe,

door handles, roof shingles, (ater slides, diving boards, bridges and layground e!uiment, to

name a fe("

Learning Objectives

#fter this lesson, students should be able to: )ecogni*e that engineers use their understanding of forces, stress, strain and material

roerties to create safe designs for structures, e!uiment and roducts

Understand ho( force and area affect stress"

+istinguish bet(een comression and tension"

Understand several roerties of materials

Introduction/Motivation

The handson Stress #naly*er Bench e-hibit at the ITL Laboratory at the

University of Colorado at Boulder demonstrates ho( different structures

handle different stress loads" These hotograhs sho( a lastic bridge structurevie(ed through a olari*ing filter that enables a erson to see, via color

changes, the areas e-eriencing stress" In the hotograh on the right, note the

resulting change in stress on the bridge due to the finger ushing do(n on thestructure"

Stress is a funny (ord because it can mean different things" Stress can be (hat causes your hairto turn gray because you have too much home(or' or deadlines to meet" That.s mental stress"

/hen engineers tal' about stress, they mean ho( much force an ob&ect e-eriences, and ho(

that force is sread over the ob&ect.s area" E-amles of engineering stress are ongoing everyday,

every(here around you, from chairs to cars to bridges to buildings"

Summary

Students are introduced to the concets of stress and strain (ith

e-amles that illustrate the characteristics and imortance of these

forces in our everyday lives" They e-lore the factors that affectstress, (hy engineers need to 'no( about it, and the (ays engineers

describe the strength of materials" In an associated literacy activity,

(hile learning about the stages of grou formation, grou dynamicsand team member roles, students discover ho( collective action can

alleviate ersonal feelings of stress and tension"


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# man named )obert 0oo'e described the concet of stress in 1223, and engineers have been

using it ever since" 4or e-amle, engineers analy*e ho( stress affects the chairs (e sit in so that

the legs are strong enough to not bend or brea'" Stress analysis is imortant to 'ee the (heelson your car and bridges standing u" 5aterials must be strong enough to (ithstand the stress

uon them" If materials are not strong enough, terrible accidents can haen, such as a floor

collasing because too many eole are standing on it6 Understanding stress and the strength ofmaterials is very imortant to 'ee us safe in our daytoday lives6

Stress andstrengthare imortant arameters for engineers to understand" Stress is a measure of

ho( much force an ob&ect e-eriences er unit area, andstrength is a material.s ability to(ithstand stress" /hen the stress e-ceeds the strength of a art, it fails" That is (hat haened in

the 0yatt )egency 0otel in 7ansas City in 1891, (hen too many eole (ere dancing on a

s'y(ay bridge in the hotel atrium and it collased, 'illing 11 eole" Engineers determine

(here the stress (ill be the highest on an ob&ect so that art can be redesigned or reinforced"Engineers also secify the materials that ob&ects and structures are made of, so that airlanes can

fly safely, (heels do not fall off of automobiles, chairs suort the (eight of eole, bridges

suort the loads that travel them, and so on"

Lesson Background & Concepts for Teachers

Stress

Stress is a measurement of force sread over area" ;ne (ay to thin' of stress is to imagine the

different results that haen (hen a erson stands on a tramoline and (hen a erson lays do(non a tramoline" # erson standing on a tramoline concentrates the force of his stress

F> 4orce ?@e(tons or lbsA

A> Crosssectional area ?mor inAThis e!uation mathematically tells us the same conclusion as our thought e-eriment (ith the

tramoline" 4or a constant force $F%, if the area $A% is a small number, the stress $=% $ronounced

sigma% (ill be larger" Similarly, if the area is larger, the stress (ill be smaller"

This mathematical definition is not limited to tramolines" Comuting stress (or's for all sortsof ob&ects e-eriencing all sorts of different forces" /e can comute the stress on ob&ects that are

either being comressed or ulled aart" 4or e-amle, if a roe brea's (hen a certain force is

alied, using a bigger diameter roe (ill reduce the stress because the crosssectional area islarger" #nd, if there is less stress on the roe, it might not brea'6

Compressive and Tensie Stresses


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Comression occurs (hen something is being s!uee*ed together" #s (ith the general discussion

of stress above, compressive stressis created by forces sread over an area" 4or e-amle, as you

sit in a chair, the legs of the chair are e-eriencing comressive stresses because they are beings!uee*ed bet(een you and the floor"

;n the other hand, tensile stressoccurs (hen something is being ulled aart" # roe in a tugo

(ar e-eriences tensile stress" )oes can only resist tensile stresses and not comressivestresses, because they are fle-ible" In other (ords, you cannot ush a roe"

Strain

Strainis a measurement of ho( an ob&ect reacts to stress" Strain is simly a measurement of (hat

the ercentage change in an ob&ect.s shae is (hen a certain stress is alied to it" # good (ay todemonstrate strain is (ith a rubber band" Suose (e have a rubber band that is 133 inches long"

@o(, (e add a tensile stress by hanging a certain amount of (eight from the rubber band, (hich

ma'es it 13D inches long" In this case, the rubber band e-erienced D strain because of the

stress created by the (eight" 5athematically, strain can be comuted by the e!uation:

/here F > strain $ercent%

L> ne( length $mm or in%

Lo> original length $mm or in%

!astic and "astic #eformation

/hen a material is strained, it is said to be deformed" ;nce a material has been deformed and the

stress is relieved, either one of t(o things (ill haen: The material goes bac' to its original

shae or the material stays deformed" If the material is able to go bac' to its original shae, it iscalled elastically deformed$for e-amle, a rubber band%" If the material is strained too much, it

(ill not be able to comletely return to its original shae and is calledplastically deformed$for

e-amle, silly utty%"Let.s use the e-amle of a layground seesa(" # seesa( bar tyically bends less than an inch

(ith t(o children on it, and returns to normal $no bend% (hen the 'ids get off" #n engineer

(ould say that, in this case, the seesa( bar (as elastically deformed" 0o(ever, if (e ut t(overy big adults on each side of the seesa( bar, it may bend it a fe( inches andstay bent$or even

brea'% (hen they leave" In this case, an engineer (ould say that the bar (as lastically deformed

$see illustration%"

The bro'en seesa( in this illustration (as lastically

deformed due to the large stress laced uon it" The seesa(

(ill not be able to return to its original shae"


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Proerties of 5aterials G The Big Three

Engineers use their understanding of forces, stress, strain and material roerties to create safe

designs" /e have already discussed forces, stress and strain, so that leaves material roerties")esearchers measure roerties of materials and ho( they behave under stress" $ied strength,

Sy, is the amount of stress a material can ta'e (ithout lastically $ermanently% deforming" If thestress is greater than the yield stress, the material (ill deform lastically, but not brea'" %timate

tensie strength $UTS%, Sut, is the amount of stress a material can ta'e before brea'ing" The UTSof a material is al(ays greater than or e!ual to the yield strength" The fatigue strength, Se, is the

stress a material can ta'e one million times over and over again, before brea'ing" Believe it or

not, that seesa( bar (ill become tired after 13 years of use and might give out one day if notdesigned roerly" The fatigue strength is al(ays less than or e!ual to the yield strength"

So ho( do engineers use this 'no(ledgeH If you (ere to design a safety roe for roc' climbers

you (ould (ant a roe that (ould e-erience stresses less than the Syand the Sut" This (ay, theroe stretches a little to hel absorb imact, but does not brea'" If you (ere to design layground

e!uiment, you (ould (ant to ma'e sure the stresses in the mon'ey bars (ere belo( Seso that

after a million uses they still (ill not brea'"

ocabuar'/#efinitions

Stress: The amount of force alied over the area of an ob&ect $comuted bydividing force by area%"

Compressive

stress:

Stress that s!uee*es a material together"

Tensile stress: Stress that ulls a material aart"

Strain: The ercent amount of elongation or comression of a material"

Elastic

deformation:

;ccurs (hen a material is strained $deformed%, but returns to its original

shae, li'e a rubber band"Plastic

deformation:

;ccurs (hen a material is strained $deformed% beyond its yield strength and

does not return to its original shae, li'e silly utty"

Yield strength: The ma-imum amount of stress a material can ta'e before it deforms

lastically $ermanently%"

Ultimate tensile

strength:

The ma-imum amount of tensile stress a material can ta'e before brea'ing"

Fatigue strength: The ma-imum amount of stress a material can ta'e one million times (ithout

brea'ing"

(ssociated (ctivities

Brea'ing Beams In this handson activity, student e-lore ho( different designs of

homemade clay beams handle stress and affect beam strength"

Team U6 /hile comleting a team ro&ect and learning about the stages of grou

formation, grou dynamics and team member roles, students discover ho( collective

action can foster a sense of community suort, (hich can alleviate ersonal feelings ofstress and tension"
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Lesson Closure

#s' the students to e-lain (hat engineering stress is and (hy engineers need to 'no( about

stress" #s' the students for different e-amles of designs that e-erience stress $bridges,benches, bicycles"""this can be &ust about anything%" #s' the students if the stress considerations

in these designs are best related to the yield strength, ultimate tensile strength or fatigue strength"

(ssessment

PreLesson #ssessment

iscussion !uestions"Solicit, integrate and summari*e student resonses to the !uestions belo("Encourage (ild ideas and ut ans(ers on the board" See Lesson Bac'ground section for ideas to

suggest if students get stuc'"

/hat do engineers mean (hen they tal' about stressH

0ave you ever e-erienced something brea'ing because of the stress you ut on itH

0o( do engineers decide if something is a good designH

PostIntroduction #ssessment

#oting"#s' a true


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Lesson !)tension (ctivities

0ave the students find an ob&ect in the room $or at home, in the case of a home(or' assignment%

that demonstrates each one of the vocabulary (ords"0ave the students (rite a fictional story about stress and strain that includes all of the vocabulary

(ords"0ave the students research different secific e-amles of (hen engineering failed in terms of

stress and strain" $4or e-amle, structures that collased during earth!ua'es or hurricanes,bridges that (ere affected by high (inds, sace structures that failed due to a lac' of gravity,

etc"% /hat did engineers have to do to fi- each situationH 0ave them create a oster about the

e-amle and include a discussion of the incident in terms if materials, stress and strain"0ave the students research three tyes of bridges" 0o( do these bridges comare and contrast to

each otherH 0o( does each bridge deal (ith comression and tension forcesH

*eferences

Shigley and 5isch'e" 5echanical Engineering +esign" @e( Kor', @K: 5cra(0ill, 331"

Lesson: Stress, Strain and 0oo'e.s La(Contributed by: U Bioengineering )ET Program, School of Engineering, anderbilt University

Summary

This lesson offers an introduction to 0oo'e.s La( as (ell as stressstrainrelationshis" Students (ill first learn the governing e!uations" Then students

(ill (or' through several e-amle roblems first individually, then as a class"

In addition, the lesson includes a t(oart associated activity" In the first art,students e-lore 0oo'e.s la( by e-erimentally determining an un'no(n

sring constant" In the second art, students (ill aly (hat they.ve learned to

create a strain grah deicting a tumor using 5icrosoft E-cel" 4inally, the

lesson includes an attached stressstrain !ui* to assess each student.s 'no(ledgefollo(ing the activities"

Engineering Connection

Engineering analysis or artial design

;ver three hundred years ago, )obert 0oo'e identified a roortionality (hich has remained a

fundamental concet to hysicists and engineers today" Though his la( (as established for thecase of srings alone, it has since been related to all materials of 'no(n surface area" The

relationshi used most readily today is the direct roortionality bet(een stress and strain"Together, civil engineers, mechanical engineers and material scientists, must carefully select

structural materials (hich are able to safely endure everyday stress (hile remaining in the elasticregion of the stressstrain curve, other(ise ermanent deformation (ill ensue" #rchitects (ho

once chose stone for its aesthetic aeal are no( choosing steel for its long term endurance" 4or

biomedical engineers, titanium is the current material of choice for its biocomatibility but mostimortantly, it.s caability to (ithstand the tensile and comressive stress of the body.s (eight" In

the attached roblem set, students e-lore alications of 0oo'e.s La( and stressstrain


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relationshis" In roblem M secifically, students aly these relationshis to the case of body

tissue, li'e a biomedical engineer (ould"

Learning Objectives

#fter this lesson, students should be able to:

1" Understand stress and strain concets and the relationshi bet(een them"

" Understand 0oo'e.s La( and aly it to analy*e srings"

J" Be able to use E-cel to ma'e a simle strain lot"

" )elate stress and strain to the engineering challenge"


In today.s lesson, (e (ill begin to learn about 0oo'e.s la( and then (e (ill learn ho( to alythis roortionality to body tissue" /e (ill learn e-actly (hat the terms stress and strain describe

as (ell as the relationshi bet(een them" #fter going through the lesson.s material, I (ill ass

out a handout (ith samle roblems" I (ould li'e these to be (or'ed to the best of your abilitiesindeendently firstN then (e (ill revie( the roblems as a class" #fter gro(ing familiar (ith

using the ne( e!uations, (e (ill e-lore 0oo'e.s la( in an associated activity $#lying

0oo'e.s La( to Cancer +etection% by e-erimentally determining an un'no(n roortionalityconstant" #fter e-loring 0oo'e.s la(, in the second ortion of the activity, (e (ill begin to

aly (hat (e.ve learned to develo a means of imaging body tissues and (e (ill soon be able

to detect malignant tumors6 Kou (ill ractice grahing reared data to deict cancerous tissue"

#fter (e have mastered this material, (e (ill have a !ui* on stress, strain and 0oo'e.s la("

Please ta'e careful notes and be sure to as' any !uestions you may have about the e-amleroblems (e (ill be (or'ing through"

)eferring bac' to the legacy cycle (hich (e discussed in the revious lesson, today.s lesson (illconstitute the research and revise hase" )efer bac' to your initial thoughts notes and record any

ne( information (hich (ill aly to solving the challenge" Kour goal today is to revie(, revise

and e-and you current 'no(ledge6 @o(, let.s learn ho( to detect cancer"

Lesson Background & Concepts for Teachers

Legacy cycle information:

This lesson falls into the%esearch and %evisehase of the legacy cycle" Students (ill begin to

learn the basic concets re!uired for creating a strain grah to deict cancerous tissue" 4ollo(ingthis lesson, students should revise their initial thoughts and at the conclusion of the associated

activity, students should have the s'ills necessary to &o Public (ith a solution" But before &oing

Public, students (ill comlete the attached handoutOui* Stress, Strain and 0oo'e.s La(as

art of the Test Kour 5ettle hase of the legacy cycle" This !ui* (ill offer formative assessment(hile the ne-t lesson.s &o Publichase (ill offer summative assessment"
http://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/quiz_stress_strain_hookes_law.pdfhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/quiz_stress_strain_hookes_law.pdfhttp://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/van_/activities/van_cancer_activity2/van_cancer_activity2.xmlhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/quiz_stress_strain_hookes_law.pdf


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Lecture Information:

In the late 1233s, )obert 0oo'e stated that The o(er of any sringy body is in the same

roortion (ith the e-tension" Though 0oo'e.s la( has remained valid today, the (ording hasbeen corrected, relacing o(er (ith force" The la( is e-lained by a direct roortionality

bet(een a sring.s comression or e-ansion and the restoring force (hich ensues" Therelationshi is given by +, -k . ) (here )is the distance a sring has been stretch, + is the

restoring force e-erted by the sring and kis the sring constant (hich characteri*es elasticroerties of the sring.s material" This la( is valid (ithin the elastic limit of a linear sring,

(hen acting along a frictionless surface"

E-tending 0oo'e.s e-loration of srings, it becomes aarent that most materials act li'esrings (ith force being directly roortional to dislacement" But as comared to srings, other

materials ossess an area (hich must be accounted for" )elacing force (ith a measure of stress

and dislacement (ith a measure of strain, the follo(ing e-ression may be obtained, 0 , !. 1"/e (ill no( e-lore the measures of stress and strain"

Stress is a measure of average force er unit area, given by 0 , +/( (here average stress, 0,

e!uals force, +, acting over area, (" The SI unit for stress is ascals $Pa% (hich is e!ual to 1@e(ton er s!uare meter" The Psi is an alternative unit (hich e-resses ounds er s!uare inch"

The units of stress are e!ual to the units of ressure (hich is also a measure of force er unit

area"

Stress cannot be measured directly and is therefore inferred from a measure of strain and aconstant 'no(n as Koung.s modulus of elasticity" The relationshi is given by 0 , !. 1, (here 0

reresents stress, 1 reresents strain and ! reresents Koung.s modulus of elasticity" Using this

means of inferring stress, strain is a geometrical measure of deformation and Koung.s modulus isa measure used to characteri*e the stiffness of an elastic material" Strain does not carry a unit but

the units of Koung.s modulus are Pa"

Strain is characteri*ed by the ratio of total deformation or change in length to the initial length"

This relationshi is given by 1 , l/l

3(here strain, 1, is change inl

divided by initial length ,l2"The follo(ing roblems may be (or'ed indeendently and revie(ed as a class, encouraging

students to become more familiar (ith using the e!uations given above" Each student should

receive a coy of the Stress, Strain and 0oo'e.s La( Problem Set $df%"You 'ill need to S()* ALL *)%+, Useful constants that you 'ill need to -no' are in a table

belo', .assume given constants have / Significant Figures .SF0, Please also note the

relationships 'e1ve 2ust discussed given belo',5aterial

1" Steel

Koung.s 5odule: 33-138E$Pa%

" Cast Iron

Koung.s 5odule: 133-138E$Pa%

J" Concrete

Koung.s 5odule: 3"3-138E$Pa%
http://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/stress_strain_hookes_law_problem_set.pdfhttp://www.teachengineering.org/collection/van_/lessons/van_cancer_lesson2/stress_strain_hookes_law_problem_set.pdf


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F=m*a =F/A = l/l0 = E* F= -k * x

1" # JJ3 @ ball is suorted vertically by a 1"83 cm diameter steel cable" #ssuming the

cable has a length of 13"J m, determine the stress and the strain in the cable"" Consider an iron rod (ith a crosssectional area of J"91 cm that has a force of 22,M33 @

alied to it" 4ind the stress in the rod"

J" # concrete ost (ith a D3"9 cm diameter is suorting a comressive load of 9813

@e(tons" +etermine the stress the ost is bearing"

" The concrete ost in the revious roblem has an initial height of 3"DD m" 0o( much

shorter is the ost once the load is alied $in mm%H

D" # construction crane (ith a 1"83 cm diameter cable has a ma-imum functioning stress of1J9 5Pa" 4ind the ma-imum load that the crane can endure"

2" Consider 0oo'e.s La( as a simle roortionality (here 4 is directly roortional to -"Therefore, (e 'no( the force stretching a sring is directly roortional to the distance

the sring stretches" If J @ stretches a sring 1"M cm, ho( much stretch can (e e-ect

to result from a of DJ @H

M" The figure belo( sho(s a column of fatty tissue, determine the strain in each of the three

regions"

ocabuar'/#efinitions

Stress: 1" The hysical ressure, ull, or other force e-erted on a system by another" " #

load, force, or system of forces roducing a strain" J" The ratio of force to area"

Strain: 1" +eformation of a body or structure as a result of an alied force" " Stretch

beyond the roer oint or limit"%adiologist:1" # medical secialist (ho e-amines hotograhs of tissues, organs, bones for use

in the treatment of disease"

(ssociated (ctivities

#ctivity : #lying 0oo'e.s La( to Cancer +etection
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#ttachments

Stress, Strain and 0oo'e.s La( Problem Set $df%

Stress, Strain and 0oo'e.s La( Problem Set Solutions $df%

Oui* Stress, Strain and 0oo'e.s La( $df%

(ssessment

Embedded #ssessment:

The attached roblem set is to be comleted in class and may be used to gauge student

comrehension" The final !uestion of the roblem set and the alication !uestions of #ctivity offer an assessment of the students. understanding of the challenge" These !uestions should be

used as a means of testing (hether the students are alying their ac!uired 'no(ledge to(ard

solving the engineering challenge"

Post Lesson #ssessment:

The attached !ui* (ill offer a formative ostlesson assessment as art of the Test your 5ettle

hase of the legacy cycle"

*eferences

+ictionary"com" Le-ico Publishing rou,LLC" #ccessed +ecember 9, 339" $Source ofvocabulary definitions, (ith some adatation% htt:


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Engineering analysis or artial design

0oo'e.s la( defines the direct roortionality bet(een a sring.s deformation and the restoring

force that results" 5ost commonly, a derivative of 0oo'e.s la( is used in engineeringalicationsGa relationshi that directly relates stress and strain" 4or e-amle, the stressstrain

curve is commonly used by material scientists and engineers (hile selecting materials for

structures" /ithin the linear region, the sloe is defined by the Koung.s modulus of (lasticity"Civil engineers often study the stressstrain curve (hen using strain hardening and other methods

to increase the yield strength of a material" In this activity, articularly in the investigating

!uestions 2 and M, students e-lore the relationshi bet(een 0oo'e.s la( and the stressstraine!uation" In addition, students must aly their understanding of 0oo'e.s la( to create a strain

lot"

Pre)e! 7no(ledge

# basic understanding of the concets of 0oo'e.s la(, stress and strain, as resented in Lesson "

Learning Objectives

#fter this activity, students should be able to:

+escribe (hat is meant by 0oo'e.s la("

#ly 0oo'e.s la( relationshis to analy*ing tissue of a 'no(n surface area"

+eict a cancerous tumor using grahing methods in 5icrosoft E-cel"

5aterials List

Part 1:

Each lab grou needs:

hysics lab stand

meter stic'

sring $(ith hoo's%

endulum clam

slotted mass set

comuter (ith 5icrosoft E-cel $or other sreadsheet alication%

0oo'e.s La( /or'sheet, one er student

Part :
http://www.teachengineering.org/view_lesson.php?url=collection/van_/lessons/van_cancer_lesson2/van_cancer_lesson2.xmlhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdfhttp://www.teachengineering.org/view_lesson.php?url=collection/van_/lessons/van_cancer_lesson2/van_cancer_lesson2.xmlhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdf


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Each grou needs a comuter (ith 5icrosoft E-cel and the enerating a 1+ Strain Plot

0andout" The handout has instructions secifically for E-cel, but if you ad&ust the instructions,

another sreadsheet rogram could be used"


0ave you ever (ondered ho( the value of the gas constant (as measured


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initial thoughts for solving the engineering challenge, students follo( stebyste instructions to

deict a cancerous tissue in a grah generated in 5icrosoft E-cel" Though students (or' in

grous, it is e-ected that they comlete their o(n activity (or'sheets" Students may discuss the!uestions but should ans(er the !uestions individually"

Before the #ctivity

Provide each lab station (ith the necessary materials"

#ssign grous of three for the activity"

5a'e coies of the 0oo'e.s La( /or'sheetand enerating a 1+ Strain Plot 0andout"

/ith the Students

1" Pass out the t(o handouts" Use the 0oo'e.s La( /or'sheet as an instructional guide(hen creating strain lots" Use the enerating a 1+ Strain Plot 0andout as an

instructional guide to the labN each student is resonsible for comleting and submitting

the analysis and alication !uestions by the end of the class eriod"

" 0ave students move into their assigned grous and go to their lab benches"

J" +irect students to follo( the (or'sheet and handout instructions" )emind them that they

may (or' together, but each student is resonsible for comleting and turning in theiro(n ans(ers and solutions"

" /hen students are ready to move on to the strain lot, have them remain in their grousNonly one grah needs to be turned in er grou" )emind them to return to their initial

thoughts notes and add any ne( notes that may hel them solve the challenge"

#ttachments

0oo'e.s La( /or'sheet $doc%

E-amle lab setu"
http://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_generating_plot_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.dochttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_generating_plot_wkst.pdfhttp://www.teachengineering.org/collection/van_/activities/van_cancer_activity2/van_hookes_law_wkst.doc


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0oo'e.s La( /or'sheet $df%

enerating a 1+ Strain Plot 0andout $doc%

enerating a 1+ Strain Plot 0andout $df%

Investigating Ouestions

0o( do 0oo'e.s la( and the stressstrain relationshi relateH /hich variables

corresondH

/hat do (e 'no( about cancerous tissue that allo(s us to use these concets to deict itH

/hat tyes of soft(are (ould be aroriate for our imagingH

Using these methods, (ill our imaging method be ainlessH /ill it be effective and

reliableH 0o( about cost effectiveH

(ssessment

Activity Embedded Assessment: The 0oo'e.s la( alication !uestions and the 1+ strain lotboth function as means of assessment" Students must first develo an understanding of 0oo'e.s

la(" Then they must relate this concet to a tissue (ith 'no(n crosssectional area" This concet

may be used to detect a cancerous tumor (here the tumor.s elastic roerties differ from that ofnormal tissue"

(ctivit' !)tensions

To e-tend the handson asect of e-loring the tissue, consider obtaining ballistic gel $such as

htt:


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+ictionary"com" Le-ico Publishing rou,LLC" #ccessed +ecember 9, 339" $source of

vocabulary definitions, (ith some adatation%

Stress and Strain Hooke's Law

Documents

Transcript of Stress and Strain Hooke's Law