Marisa BernalNeysa Alicea

Angélica BáezBeatriz Ramos

if you loose any of your limbs?

OutlineDesignPurposeApplicationsEngineering ConsiderationsUniquenessChallengesAreas of OpportunitiesNew Techniques

Prosthetic LegLINER

FEET

SOCKET

KNEE

Socket

PurposeImprove the design of the prosthesis socket,

making it more comfortable for the user, and thus improving the quality of life of people with disabilities.

ApplicationsFor medical purposes, related to athletes

with disabilities.

Engineering ConsiderationsUse impact analysis in our calculationsUse the safest approximations for our design

Proper material selection

Material CharacteristicsLightweight low densityStiff high Elastic Modulus

Minimize

Maximize

Material Characteristics

Material CharacteristicsMaterial Possibilities

WoodTechnical CeramicsCompositesCarbon Fiber Reinforced Plastics (CFRP)

Carbon Fiber Reinforced Plastic (CFRP)Density: 1.8 g/ccModulus of Elasticity: 225 GPa Sut: 3800 Mpa

UniquenessA prosthesis has to be designed to fit the

needs of a specific person.It is customized for each user

ChallengeConsider that the product is a medical deviceConvert our project to shapes that we can

analyze with the concept learned in class

Material Selection

Static Loads Analysis

Static Load AnalysisFor this analysis we used the following

equations and obtained the shown values.

28.115m

KN

I

My

262.4

2

3

m

KN

A

V

EICxC

xCqxx

1

26)( 32

21

3

)(x 2.68 x 10-6m= 2.6 x 10-3mm

Dynamic Load Analysis

Dynamic Load AnalysisImpact Load

Maximum Elongation

M=mass v=velocity at impact L=length E=Elastic Modulus A=area

Dynamic Load AnalysisImpact Load

Maximum stress

E = Elastic Modulus δmax = maximum elongation L = length

Dynamic Load AnalysisWe calculated the values of:

=3195.38KN = = 128.69MPa =

Using stress concentrator factor Kf = 1.5 = 192.95MPa = 192.95MPa

We calculated the fatigue strength: = 0.4 SUT =1520MPa

amplitudePmeanP

meanamplitude

SCamplitude,

SCmean,

'fS'fS

Dynamic Load AnalysisStress concentration factors:

MPaS

S

K

K

K

K

K

f

f

yreliabilit

retermperatu

surface

load

size

5.497

)620.0)(1)(7841.0)(85.0)(792.0(

620.0

1

7841.0

85.0

792.0

Dynamic Load AnalysisUsing Modified Goodman theory to calculate

the safety factor:

28.2

3800

95.192

5.497

95.19211

,,

MPa

MPa

MPa

MPan

UTf S

mvm

S

avm

Component lifeAproximated it to the behavior of aluminum

a=19922.54, b= -0.2815N = 1.3 x 107 cycles

Sm

Sf

5 x 1081.3 x 107

Sm

Areas of OpportunityAssumed values were used since data for our

material was not availableDesign uniqueness.

A different analysis is needed for each person

New KnowledgeReinforce teamwork skillsLoads distribution in prosthetic devicesImpact loads

Any Questions???