Description

As hand sanitizers are being installed in every entrance of the shopping center, you are tasked to design a mechanical foot pedal to actuate the sanitizers when needed.  The schematic drawing is shown in Figure 1.  The use of this foot pedal will eliminate contact for a person on the sanitizer, thus reducing contact transmission.

Please use the data corresponding to your surnames for this assignment. The loads and major dimensions are provided in Table 1. You, as a designer, are free to choose the other geometric parameters freely considering that design requirements for safety factors and reliability of usage are satisfied. The foot pedal is mounted on the ground.

Parametrized geometric data which will constitute your design choices are given in the Figure.   (You are free to assume any other data if deem necessary.)

1)      By doing a literature survey to choose the type of material to be used in the design of the connecting pins, Ø1, Ø2 and Ø3 and also the foot pedal.  Material selection can be based on ASTM, ANSI or any other standards as available for selection of the material for the pins and pedal.                                        [15 pts.]

2)      The pedal is expected to withstand a force of F (N) without yielding. Size your design to provide a reasonable Factor of Safety for static yielding.          [25 pts.]

(You should find the stresses at the most critical location with respect to the coordinate system shown. Then find the Principle Stresses, Maximum Shear

Stress, von Mises Stress and the planes on which Principle Stresses and Maximum Shear Stress are acting. Show these planes by drawing a schematic at the critical location. Use a suitable static failure criteria.)

3)      The actuation load consists of the depressing the pedal and spring foce applied when the applied force is released. So for fatigue life calculations, the foot pedal can be considered to be subjected to a sinusoidal force with Fmax =F and Fmin =−F . Resize your design so that you can provide a reasonable factor of safety for infinite life in fatigue. (By doing a literature survey, try to find the actual S-N diagram of the material you have chosen.)                                                [20 pts.]

4)      If the bracket is subjected to a sinusoidal force function with Fmax = 2F and

           Fmin =0 what will be the safety factor for infinite life in fatigue?                   [20 pts.]

5)      Considering that the data retrieved from literature or provided by the manufacturer may not be reliable, you decided to test the specimen in the laboratory yourself. Find the relevant standards for obtaining the relevant material data for your design, provide a brief description of the specimens and procedures in your report.                                                                                             [15 pts.]

6)      Summary of the design and conclusion.                                                      [5 marks]

The report is maximum 10 pages and should contain the formulas used, calculations, all relevant graphs and charts. Description and presentation of any assumptions made and pertinent knowledge of mechanics of materials must be shown in the report. A summary table in a specified format for geometric dimensions, loads, stresses, stress concentration factors, stress intensity factors, and safety factors. Please ensure that you satisfy the required factors of safety by iterating your design.

An Excel Sheet is provided with this brief, please fill it with required data and submit it as an appendix (not included in the page count) to your report.