A helical compression spring made from hard drawn wire needs to be designed to fit inside a 50mm cylindrical cavity and there must be enough space inside the coils for a 20mm cylindrical guide rod.
The spring must provide a pre load of 300N and 600N (maximum load) when compressed a further 25mm. The spring will be used in static conditions only and for this preliminary design the Bergstrasser factor can be approximated as 1.
Design the helical compression spring for minimum mass.
• Identify the design variables, geometric, strength constraints and the cost function which expresses the total mass of the spring.
• In point form, describe the optimisation procedure.
• Show the answer graphically and list the optimum diameters and number of coils.