A designer conceived a simple single support for a lightweight table: a flat she
ID: 1842875 • Letter: A
Question
A designer conceived a simple single support for a lightweight table: a flat sheet of plywood on a central slender cylindrical leg that is fully braced on both ends. The leg must be a solid bar (not hollow) and as light as possible. It must support the table top and whatever is placed upon it without buckling. The length of the legs, 1, is fixed. Use the Ashby figures to solve this problem. State the function, objectives and constraints. 2. What are the two material indices (M_1 and M_2) for this problem? What materials would you suggest? Using a decision matrix, based on at least 4 criteria, what specific material would you select?Explanation / Answer
1. The function is to support the table top. The objectives to be achieved are it should be light weight, stiff, durable, slenderness should be maximum... constraints are cost, weight, must be a solid bar and free from bucklingetc.
2.The two material properties to be considered are stiffness to prevent buckling and low density for light weight. In Ashby's chart these two parametrs are drawn on the co ordinates for different materials and optimal one can be selected.
3. Since the table is light weight very strong materials are not necessary. The materials that can be considered are wood, mild steel rod, thermosetting plastic..use aluminium, composites etc are not suitable since the cost is not reasonable with purpose.
4. You can go for mild steel as the first option since it is stiff, light weight, easily available and of moderate price. Also braced joints can be easily made which is also one of the constraint.l