MA2001: Mechanics of Materials Report, NTU, Singapore You are analysing the components design and possible failure mechanisms on the connecting pins A and B of a mini-stepper exercise equipment

You are analysing the components design and possible failure mechanisms on the connecting pins A and B of a mini-stepper exercise equipment. The mini-stepper is used by persons of varying body weight with varying speed and duration of exercise.

The dominant force acting on the equipment would be the weight of the person stepping on the pedals as shown on Figure 3. Different users may exert their bodyweight at different points on the stepper e.g. at points P, Q, or R.

Please use the data corresponding to your student number as provided in Table 1. (You may make any other reasonable assumptions or estimates as relevant)

Question 3 

The mini-stepper is expected to support the mass of the user F (kgf) without yielding. Choose the type of material to be used for the connecting pins and size your design to provide a reasonable Factor of Safety for static yielding. An idealized forces model to facilitate your analysis would be recommended. You should relate the stresses at the connecting pins due to the dominant load. Recall that some loads can contribute to different kind of loadings. Use a suitable static failure criterion.

Question 4

If a fatigue failure life of 5×105 cycles is desired, size your design and determine an appropriate Factor of Safety. Cyclic loads are present, and clearly identify the approximations, references, tools, charts, etc. you are using to obtain certain parameters.

Question 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.