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Seatwork no. 1 -------Strength of Materials----------
The 20 mm diameter bolt fastens two wooden planks together. The nut is tightened until the tensile stress in the bolt is 150 Mpa. Find the smallest safe diameter “d” of the washers, if the working bearing stress for wood is 13 Mpa.
Note: My teacher said that the
“d” = 70.80mm
My solution:
Pb = Ab Sb
P = 150 N/mm2 * ( π/14 * 20 mm2 )
P = 47,123.89 N
47,123.89 N = π/14 (d2) 13
d = 67.94
Question: My “d” is not equal to the “d” of my teacher. Pls help me.
The 20 mm diameter bolt fastens two wooden planks together. The nut is tightened until the tensile stress in the bolt is 150 Mpa. Find the smallest safe diameter “d” of the washers, if the working bearing stress for wood is 13 Mpa.
Note: My teacher said that the
“d” = 70.80mm
My solution:
Pb = Ab Sb
P = 150 N/mm2 * ( π/14 * 20 mm2 )
P = 47,123.89 N
47,123.89 N = π/14 (d2) 13
d = 67.94
Question: My “d” is not equal to the “d” of my teacher. Pls help me.