Engineering Engineering AnalysisAnalysis

October 23, 2006October 23, 2006Team MoondogsTeam MoondogsChris Culver Chris Culver Rahul KirtikarRahul KirtikarElias KrauklisElias KrauklisChristopher SampsonChristopher SampsonMichael WiderquistMichael Widerquist

Engineering AnalysisEngineering Analysis

Strength of Material Strength of Material Analysis for Critical Analysis for Critical

ComponentsComponents Critical ComponentsCritical Components

Hydraulic LinesHydraulic Lines Inner ContainerInner Container Telescoping ArmTelescoping Arm Compacting Plate Compacting Plate SpringSpring Compacting RodCompacting Rod HingeHinge LatchLatch

MaterialsMaterials Molded PolypropyleneMolded Polypropylene

Yield Strength = 1740 – 6240 psiYield Strength = 1740 – 6240 psi Flexural Modulus = 79.8 -350 ksiFlexural Modulus = 79.8 -350 ksi Tensile Modulus = 72.5 – 1100 ksiTensile Modulus = 72.5 – 1100 ksi

Type 304 Stainless SteelType 304 Stainless Steel Modulus of Elasticity = 28,000 ksiModulus of Elasticity = 28,000 ksi Poisson’s Ratio = 0.29Poisson’s Ratio = 0.29 Yield Strength = 31.2 ksiYield Strength = 31.2 ksi

Thus Von mises distortion energy theory Thus Von mises distortion energy theory will be usedwill be used

Hydraulic InputsHydraulic Inputs

Ratio of input to output Ratio of input to output Mechanical advantageMechanical advantage

Give up output movement for forceGive up output movement for force

Ratio of Input : Output 3Master Area (in^2) Slave Area (in^2)

3.14 9.62Input Force (lbf) Output Force (lbf)

200.00 612.50Input Pedal Distance (in) Output Movement (in)

5.00 1.63

Hydraulic LinesHydraulic Linespsi

inlbf

AFP 6.63

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ir P

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Master Slave Brake LineTangential stress 882 924 879 psiRadial stress -64 -64 -64 psiAxial stress 409 430 408 psiVon Mises 1638 1711 1632 psi

Hydraulic Material Hydraulic Material SelectionSelection

Decision: Use Stainless Steel Type 304 custom Decision: Use Stainless Steel Type 304 custom built tubingbuilt tubing

On all three lines the yield strength is above On all three lines the yield strength is above the von Mises failure criteria even with 2.0 SFthe von Mises failure criteria even with 2.0 SF

Master Slave Brake LineVon Mises 1638 1711 1632 psiSteel Strength 1903 1816 1909 psiInner radius 1 1.75 0.2325 inOuter Radius 1.08 1.875 0.25 in

Inner Container/Outer Inner Container/Outer ContainerContainer

Determined through Determined through conceptual inspection conceptual inspection that there would be that there would be minimal force minimal force exerted on the exerted on the container wallscontainer walls

Since trash is mainly Since trash is mainly a solid it would not a solid it would not recoil against the recoil against the compressing platecompressing plate

Due to the this a Due to the this a lightweight plastic, lightweight plastic, polypropylene was polypropylene was chosenchosen

Compacting Plate Compacting Plate AnalysisAnalysis

Pressure as well as Pressure as well as force varies throughoutforce varies throughout

Force from Telescoping Force from Telescoping Rod = 612.5 lbfRod = 612.5 lbf

Reaction Force from Reaction Force from Compacting Plate = Compacting Plate = 572 lbf, Pressure = 572 lbf, Pressure = 2.86 psi2.86 psi

Since the Compacting Since the Compacting Plate is connected to Plate is connected to the Connecting Rod as the Connecting Rod as well as the Lid, force well as the Lid, force there remains 572 lbfthere remains 572 lbf

Due to lack of pressure Due to lack of pressure on compacting plate on compacting plate polypropylene was polypropylene was chosenchosen

TRASH

Telescoping Rod

Inner Container

Compacting Plate

Compacting Rod

Spring AnalysisSpring Analysis Force necessary to Force necessary to

lift 2.5 lb foot pedallift 2.5 lb foot pedal Spring Coefficient Spring Coefficient

kk equals 0.52 lbf/in equals 0.52 lbf/in 25/32" long brass, 25/32" long brass,

compression spring compression spring with closed endswith closed ends

k = k = 7.3 lbs/in7.3 lbs/in

Compacting Compacting Rod/Telescoping ArmRod/Telescoping Arm

Buckling of Compacting Rod as well as Buckling of Compacting Rod as well as Telescoping ArmTelescoping Arm Using Type 304 Stainless Steel with Sy=31.2 Using Type 304 Stainless Steel with Sy=31.2

ksi with max pressure at 182 psi on ksi with max pressure at 182 psi on Compacting Rod and 2 ksi on Telescoping ArmCompacting Rod and 2 ksi on Telescoping Arm

Deflection on Compacting Rod and Deflection on Compacting Rod and Telescoping ArmTelescoping Arm

Deflection is neglible in both cases (>0.001 in)Deflection is neglible in both cases (>0.001 in)

LEA

F

LEA

F

LEA

F

LEA

F

Lid DeflectionLid Deflection

Maximum bending Stress: 10,000 psiMaximum bending Stress: 10,000 psi Only plastic supporting 572 lbf, 87 inch deflectionOnly plastic supporting 572 lbf, 87 inch deflection Add a 14”x14”, 1/8 ” thick steel plate to distribute Add a 14”x14”, 1/8 ” thick steel plate to distribute

the loadthe load Max deflection of steel plate: ½ “Max deflection of steel plate: ½ “ Plastic deflection negligible nowPlastic deflection negligible now

IEL

LLLp

MAX 39

22

23

22

IMc

MAX

Latch 6082A13 from Latch 6082A13 from McMaster-CarrMcMaster-Carr

Rated failure at Rated failure at 363 lbf, well within 363 lbf, well within safety factor limit.safety factor limit.

Easy and simple Easy and simple use of operationuse of operation

Low cost < $5 Low cost < $5 (McMaster)(McMaster)

Hinge 1582A73 from Hinge 1582A73 from McMaster-CarrMcMaster-Carr

12 inch piano hinge used to distribute stress over greater 12 inch piano hinge used to distribute stress over greater lengthlength

Hinge Failure pressure at 31.2 ksiHinge Failure pressure at 31.2 ksi Analysis yielded max stress of 0.265 ksi, well within limit.Analysis yielded max stress of 0.265 ksi, well within limit. Piano Hinge, Semi-Low Cost < $12 (McMaster)Piano Hinge, Semi-Low Cost < $12 (McMaster)

Fastening of Hinge/LatchFastening of Hinge/Latch Analysis of stress from bolt and plastic Analysis of stress from bolt and plastic

outer container interface yields force outer container interface yields force between 191 lbs and 686 lbs.between 191 lbs and 686 lbs.

The applied force for the latch and the The applied force for the latch and the hinge independently will be 286 lbs (split hinge independently will be 286 lbs (split of reaction force from compacting rod) of reaction force from compacting rod) which is within the range of the which is within the range of the hinge/latch bolts.hinge/latch bolts.

Consider making plastic thicker, possibly Consider making plastic thicker, possibly ¼”¼”

Fatigue FailureFatigue Failure Fatigue failure analyzed for Hydraulic Fatigue failure analyzed for Hydraulic

System and Telescoping ArmSystem and Telescoping Arm Alternating stress calculated based on Alternating stress calculated based on

cyclical full load and zero load cyclical full load and zero load alternations.alternations.

99.999% reliability factor99.999% reliability factor Slave cylinder found to be weakest Slave cylinder found to be weakest

component, calculated to withstand component, calculated to withstand 3.9E6 cycles before failure3.9E6 cycles before failure

Result: Fatigue not considered an issue.Result: Fatigue not considered an issue.

Weight DistributionWeight Distribution• Densities

•4140 Carbon Steel = 0.283 lbm/in^3•304 Stainless Steel = 0.283 lbm/in^3• Polypropylene Molded = 0.0325 lbm/in^3• Brake Fluid = 0.0385 lbm/in^3

Material Value UnitsFoot Pedal Assembly Molded Polypropylene 2.7 lbmOuter Container Molded Polypropylene 22.1 lbmInner Container Molded Polypropylene 5.6 lbmLid Molded Polypropylene 6.3 lbmPlates and rod 4140 Carbon Steel 3.5 lbmHydraulic System Type 304 Stainless Steel 5.0 lbmTotal 45.2 lbm

Safety and StabilitySafety and Stability Safety IssuesSafety Issues

Possible Stability when operatingPossible Stability when operating Stability issue is solved through handles Stability issue is solved through handles

on side of trash can for better control on side of trash can for better control during operationduring operation

Performance Analysis and Performance Analysis and PredictionPrediction

Weight = 44 lbs, within tolerable Weight = 44 lbs, within tolerable rangerange

All components are well within stress All components are well within stress and fatigue levels with a 2.0 SFand fatigue levels with a 2.0 SF

Initial Cost of components could be an Initial Cost of components could be an issue, however mass produced cost issue, however mass produced cost would be reduced significantlywould be reduced significantly

For design it is a feasible productFor design it is a feasible product