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Engineering Analysis

Engineering Analysis. October 23, 2006 Team Moondogs Chris Culver Rahul Kirtikar Elias Krauklis Christopher Sampson Michael Widerquist. Engineering Analysis. Strength of Material Analysis for Critical Components. Critical Components Hydraulic Lines Inner Container Telescoping Arm

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Engineering Analysis

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  1. Engineering Analysis October 23, 2006 Team Moondogs Chris Culver Rahul Kirtikar Elias Krauklis Christopher Sampson Michael Widerquist

  2. Engineering Analysis

  3. Strength of Material Analysis for Critical Components • Critical Components • Hydraulic Lines • Inner Container • Telescoping Arm • Compacting Plate • Spring • Compacting Rod • Hinge • Latch

  4. Materials • Molded Polypropylene • Yield Strength = 1740 – 6240 psi • Flexural Modulus = 79.8 -350 ksi • Tensile Modulus = 72.5 – 1100 ksi • Type 304 Stainless Steel • Modulus of Elasticity = 28,000 ksi • Poisson’s Ratio = 0.29 • Yield Strength = 31.2 ksi • Thus Von mises distortion energy theory will be used

  5. Hydraulic Inputs • Ratio of input to output  Mechanical advantage • Give up output movement for force

  6. Hydraulic Lines

  7. Hydraulic Material Selection • Decision: Use Stainless Steel Type 304 custom built tubing • On all three lines the yield strength is above the von Mises failure criteria even with 2.0 SF

  8. Inner Container/Outer Container • Determined through conceptual inspection that there would be minimal force exerted on the container walls • Since trash is mainly a solid it would not recoil against the compressing plate • Due to the this a lightweight plastic, polypropylene was chosen

  9. Compacting Plate Analysis • Pressure as well as force varies throughout • Force from Telescoping Rod = 612.5 lbf • Reaction Force from Compacting Plate = 572 lbf, Pressure = 2.86 psi • Since the Compacting Plate is connected to the Connecting Rod as well as the Lid, force there remains 572 lbf • Due to lack of pressure on compacting plate polypropylene was chosen Compacting Rod Compacting Plate TRASH Inner Container Telescoping Rod

  10. Spring Analysis • Force necessary to lift 2.5 lb foot pedal • Spring Coefficient k equals 0.52 lbf/in • 25/32" long brass, compression spring with closed ends • k = 7.3 lbs/in

  11. Compacting Rod/Telescoping Arm • Buckling of Compacting Rod as well as Telescoping Arm • Using Type 304 Stainless Steel with Sy=31.2 ksi with max pressure at 182 psi on Compacting Rod and 2 ksi on Telescoping Arm • Deflection on Compacting Rod and Telescoping Arm • Deflection is neglible in both cases (>0.001 in)

  12. Lid Deflection • Maximum bending Stress: 10,000 psi • Only plastic supporting 572 lbf, 87 inch deflection • Add a 14”x14”, 1/8 ” thick steel plate to distribute the load • Max deflection of steel plate: ½ “ • Plastic deflection negligible now

  13. Latch 6082A13 from McMaster-Carr • Rated failure at 363 lbf, well within safety factor limit. • Easy and simple use of operation • Low cost < $5 (McMaster)

  14. Hinge 1582A73 from McMaster-Carr • 12 inch piano hinge used to distribute stress over greater length • Hinge Failure pressure at 31.2 ksi • Analysis yielded max stress of 0.265 ksi, well within limit. • Piano Hinge, Semi-Low Cost < $12 (McMaster)

  15. Fastening of Hinge/Latch • Analysis of stress from bolt and plastic outer container interface yields force between 191 lbs and 686 lbs. • The applied force for the latch and the hinge independently will be 286 lbs (split of reaction force from compacting rod) which is within the range of the hinge/latch bolts. • Consider making plastic thicker, possibly ¼”

  16. Fatigue Failure • Fatigue failure analyzed for Hydraulic System and Telescoping Arm • Alternating stress calculated based on cyclical full load and zero load alternations. • 99.999% reliability factor • Slave cylinder found to be weakest component, calculated to withstand 3.9E6 cycles before failure • Result: Fatigue not considered an issue.

  17. Weight 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

  18. Safety and Stability • Safety Issues • Possible Stability when operating • Stability issue is solved through handles on side of trash can for better control during operation

  19. Performance Analysis and Prediction • Weight = 44 lbs, within tolerable range • All components are well within stress and fatigue levels with a 2.0 SF • Initial Cost of components could be an issue, however mass produced cost would be reduced significantly • For design it is a feasible product

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