Problem 4: a) ROTG P co rs ve vou (7 pts) For an industrial application which requires a compressive loading, a helix based coil spring is selected. Spring material is a peened piano wire with a diameter is 0.105-in whereas the spring has an outside diameter of 1.225-in with plain ground ends, and 12 total coils. Note: the set is not removed, and use stress correction factor K wherever necessary. Question 17) Compute the force that is required to compress this spring such that the torsional stress just reaches the yield strength? de Question 19) What should the free length be to ensure that when the spring is compressed solid the torsional stress does not exceed the yield strength, that is, that it is solid-safe? Question 18) Estimate the spring rate. RIGH DIAL Question 20) Is there a possibility that the spring might buckle in service? Assume spring supported between flat parallel surfaces, with fixed end. If buckling is possible, what do you suggest as a simple solution? Question 21) The spring is intended to be flexed between Lmin = 2 in and Lmax = 4 in, with a free length as determined in Question 11). What is the safety factor for this spring at infinite life according to any suitable fatigue-based criteria? da b) Explain your problem-solving approach and solution steps in a paragraph. require (3 pts)