The axial load on a butt weld figure below fluctuates contin

The axial load on a butt weld, figure below, fluctuates continuously between 5,000 and 20,000 lbs. Plates are 1 in. thick. Factor of safety equals 2.5. Use an E6010 welding rod. Let the endurance limit for the weld be equivalent to that of an as-forged surface. Find the required length of weld. Refer to Example 7-4, page 424 of the textbook for guidance.

(Reference textbook is \"Design of Machine Elements,\" 8th Edition by Merhyle F. Spotts)

The axial load on a butt weld, figure below, fluctuates continuously between 5,000 and 20,000 lbs. Plates are 1 in. thick. Factor of safety equals 2.5. Use an E6010 welding rod. Let the endurance limit for the weld be equivalent to that of an as-forged surface. Find the required length of weld. Refer to Example 7-4, page 424 of the textbook for guidance. BUTT JOINT

Solution

from the properties of material max tensile strength s = 60000psi

kf=1.2, cs= 0.55, cg=0.8, ct=1,cr=1

s = kf*cs*cr*ct*cg*60000= 24000 psi

now pmin = 5000*2.5 = 12500 and pmax= 50000

now sigma mean =1.2* pmean/area

sigma variable =1.2 *pvar/area

now take the ratio of sigmavariable/ sigma mean =0.6

now from tha sigma mean and sigma average linear graph (24 ksi, 60 ksi respectively)we can find the value of sigma mean at ratio 0.5. now sigma mean = 24.32ksi

now from sigma mean equation

sigma mean =1.2* pmean/area

area =1.54 in2

area = t*L =1.54, t= 1 in given

then L = 1.54 in (approx)