University:
Michigan State University
Course:
ERG 100 | Introduction to Engineering Design
Academic year:

2021
Views:

142

Pages:

1
Author:

Alma Stephenson

PROBLEM 1.7 Each of the four vertical links has an 8 × 36-mm uniform rectangular cross section and each of the four pins has a 16-mm diameter. Determine the maximum value of the average normal stress in the links connecting (a) points B and D, (b) points C and E. SOLUTION Use bar ABC as a free body. ΣMC = 0 : (0.040) FBD − (0.025 + 0.040)(20 × 103 ) = 0 FBD = 32.5 × 103 N Link BD is in tension. ΣMB = 0 : −(0.040) FCE − (0.025)(20 × 103 ) = 0 FCE = − 12.5 × 103 N Link CE is in compression. Net area of one link for tension = (0.008)(0.036 − 0.016) = 160 × 10−6 m2 . For two parallel links, (a) σ BD = A net = 320 × 10−6 m2 FBD 32.5 × 103 = = 101.56 × 106 Anet 320 ×10 − 6 σ BD = 101.6 MPa W Area for one link in compression = (0.008)(0.036) = 288 × 10−6 m2 . For two parallel links, (b) σ CE = A = 576 × 10− 6 m 2 −12.5 × 10 3 FCE = = −21.70 × 10 −6 576 × 10 −6 A σ CE = −21.7 MPa W