Calculating Bolt Length and Stiffness for Steel Plates

a) What is a suitable length for the bolt, rounded up to the nearest 5 mm?

a) 50 mm

b) What is the bolt stiffness?

b) 808.24 MN/m

Answer:

a) 50 mm

b) 808.24 MN/m

Given two steel plates of 15 mm thickness each clamped together with an M14 x 2 hexagonal head bolt, a nut, and one 14R metric plain washer under the nut, we need to determine the suitable length for the bolt and the bolt stiffness.

Calculating the Bolt Length:

To find the suitable length of the bolt, we need to consider the grip length and the height of the nut. The grip length is calculated by adding the plate thickness and washer thickness, which results in 33.5 mm. Adding the height of the nut (12.8 mm) gives a total length of 46.3 mm. Rounding up to the nearest 5 mm, the suitable bolt length is 50 mm.

Calculating the Bolt Stiffness:

The bolt stiffness is determined using the formula: [tex]\\frac{A_d A_t E}{A_d l_t + A_t l_d}[/tex]. By calculating the respective areas and lengths of the threaded and unthreaded portions, the bolt stiffness is found to be 808.24 MN/m.