P14006 Bath Tub Lift Amos Baptiste Jeremy Czeczulin Andrew Hughes Richard Prilenski
Introductions Name Major/Role Amos Baptiste Industrial & Systems Engineer/Team Leader Jeremy Czeczulin Mechanical Engineer/R&D Andrew Hughes Mechanical Engineer/CAD Designer Richard Prilenski Mechanical Engineer/FEA & CAD Designer
Agenda • Review Problem Statement • Stakeholders • Final Prototype • Bill of Materials • Components Ordered • Components Machined • Stress Analysis • Budget • Problem Tracking • Review/Recommendation • Questions
Problem Statement Description: • Bathtub lift – A device that provides assistance to an individual with physical disabilities, including limited balance, coordination, or mobility Objective: • Improve the current design of Theresa Loce’s bathtub lift since the current device does not meet her needs • Develop a powered lift that is sturdy, comfortable, easy to use/clean, makes minimal noise, and takes into account physical limitations of user • Produce a product that the user maintains autonomy and privacy
Stakeholder(s) • Primary Customer : Theresa Loce • Contact: 585-647-2329 • Secondary Customer (s) : Wheel chair users/handicap public & Elizabeth DeBartalo, Hospitals (RGH), Nursing Homes, suppliers/vendors, individuals recovering from knee surgeries, Linak, Klein Steel, SpringField Marine Company, McMaster Carr, and SeaSuckers. • Contact: eademe@rit.edu • Faculty Guide : Art North • Contact: ajnddm@rit.edu • Sponsor (financial support): RIT
Final Prototype
Final Prototype
Bill of Materials ID Part/Component Weight (lb.) Material 1 Actuator 5.8 2 Control Box 1 3 Control Box Remote 0.7 4 Battery 6.2 5 Slider 5.5 6 Seat 7.2 Low density polyethylene 8 Slider Mount Screws 0.2 Stainless Steel 9 Charger with Cable 1.5 10 Suction Cup (4) 6.8 Stainless Steel and Plastic 12 Top Base 30 304 Stainless Steel 13 Bottom Base 35 304 Stainless Steel 14 Carriages 0.28 Steel 15 Rails (4) 3.75 Anodized Aluminum 16 Scissors Legs (4) 21.6 304 Stainless Steel 17 Actuator Clevis 1.43 304 Stainless Steel 19 Misc. Hardware 0.184 Stainless Steel 20 Dowel 1.3 304 Stainless Steel 21 Bellow 0.5 Polyurethane 22 Adapter 1.3 304 Stainless Steel 23 Clevis (8) 7.576 304 Stainless Steel Total Weight 137.82 Weight of Device 122.92
Components Ordered • Light Duty Seat Slide with Stainless Steel Swivel Commodore Seat (LLPE)
Components Ordered McMaster Carr Rails and Carriages SeaSucker Suction Cups Linak Actuator with a Bellow
Linak Actuator System
Machined Components Drawing and outcome of the scissor legs machined.
Machined Components Dowel and actuator adapter.
Machined Components Drawing and outcome of the base plate machined.
Machined Components Drawing and outcome of the top plate machined.
Machined Components Drawing and outcome of the clevis machined.
Budget Component Cost Amount Left Material Vendor Turn Table $ 86.44 $ 1,948.20 Electrical Linear Acutator $ 193.95 $1,754 Linak Rechargeable Battery $ 63.96 $1,690 Linak Electric Control Box $ 107.51 $1,583 Linak Battery Charger $ 157.37 $1,425 Linak Remote Handset $ 84.05 $1,341 Linak Control Box Mounting $ 9.76 $1,332 Linak Charger Bracket $ 11.59 $1,320 Linak Main Cable $ 15.77 $1,304 Linak 4 1/2" SeaSucker $ 191.96 $1,112 SeaSucker Light Duty Seat Slide with Stainless Steel Swivel $ 98.76 $1,014 Stainless Steel Springfield Marine Company Seat $ 74.00 $940 Low Density Polyethylene Springfield Marine Company Ziploc Space Bag $ 13.39 $926 Walmart Home Depot Demo Purchase #1 $ 67.66 $858 PVC Pipes Home Depot Home Depot Demo Purchase #2 $ 43.78 $815 Home Depot Shipping for Swivel and Seat $ 25.00 $790 Springfield Marine Company Turn Table Returned $ (69.15) $859 3/8" 304 SS 15"X31" $ 134.00 $ 724.84 304 Stainless Steel Klein Steel 3/8" 304 SS 15"X24" $ 111.00 $ 613.84 304 Stainless Steel Klein Steel 3/8" 304 SS Plate 7"X22" $ 108.00 $ 505.84 304 Stainless Steel Klein Steel 1.5" 304 SS Plate 1.5" X 3" $ 44.00 $ 461.84 304 Stainless Steel Klein Steel 0.5" 304 SS Round 17" $ 12.24 $ 449.60 304 Stainless Steel Klein Steel PBC Linear Rollers Rail and Carriages $ 311.84 $ 137.76 Stainless Steel PBC Clevis (4) $ 172.00 $ (34.24) Cast Iron Cylinder Repair Componenets Bellow $ 67.13 $ (101.37) Polyurethane McMaster Carr 0.75" 304 SS Round 17" $ 27.00 $ (128.37) Stainless Steel Klein Steel McMaster Carr Rails and Carriages $ 288.92 $ (417.29) Steeland Anodized aluminum McMaster Carr Misc. part (Nylon Bushings, Washers) $ 10.74 $ (428.03) Stainless Steel McMaster Carr Total Spent $ 2,462.67
Bottom Plate Stress Analysis • The four yellow arrows are the acting forces on the base plate and each is 100 pounds which adds up to a total of 400 pounds of force. • The type of steel that was used was 304 stainless steel where its yield stress values are 36 ksi. • The maximum stress concentrations occurred at the welded spots on the four ends of the base plate where it was 4.564 ksi which is significantly below the 36 ksi limit.
Bottom Plate Displacement • The fixed constraint positions occurred by the bottom of the 4 suction cups at each end of the base plate. The displacement occurred in the middle of the base plate where it underwent a natural bending motion. • The maximum deflection was noted at 0.007” which is very low for 304 stainless steel. The maximum acceptable limit would be 0.035”.
Bottom Plate Safety Factor • The safety factor values along the base plate which ranged from 2.55 all the way to 15. Probes were taken to better portray the safety factor values in various locations on the base plate where stress concentrations were the highest. • For this project the original accepted safety factor values were to be at least 2. The lowest which was 2.55 and in order for the base plate to fail, the total acting forces would have to exceed 1,020 pounds which highly acceptable.
Rod/Adapter Stress Analysis The total load value was 350 pounds. The maximum stress that occurred was 12 ksi which is significantly lower than the 36 ksi limit.
Rod/Adapter Displacement The maximum displacement values were roughly 0.005” which successfully passes the deflection test for 304 stainless steel. (The maximum displacement limit is usually 0.035”).
Rod/Adapter Safety Factor The safety factor values that are along the rod supporting the load. The stress concentrations occurred close to the pin ends by the clevises and also by the rod adapter piece. The lowest safety factor value was 2.51 which is satisfactory. The desired safety factor range for this project is 2-4.
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