def Problem8_51(): Pg = 6 # MPa A = 20 B = 20 d = 12 Sp = 650 D = 1.5*d l = A + B H = 10.8 # L = H + l + 2*p L = 60 Lt = 2*d + 6 ld = L - Lt lt = l - ld Ad = np.pi/4*d**2 #Table 8-7 At = 84.3 #Table 8-1 kb = Ad*At*207/(Ad*lt + At*ld) kSteel = Screw.SpringRate(207, d, D, A) kCastIron = Screw.SpringRate(100, d, D, B) kM = 1/(1/kSteel + 1/kCastIron) C = kb/(kb + kM) Fi = 0.75*At*Sp P = Pg*np.pi/4*150**2/10/1000 sigmaI = Fi/At sigmaA = C*P*10**3/(2*At) sigmaM = sigmaA + sigmaI Sut = 900 Se = 140 print(Screw.Goodman(Se, Sut, sigmaI, sigmaA, 0)) print(Screw.Gerber(Se, Sut, sigmaI, sigmaA)) print(Screw.ASMEElliptic(Se, Sut, Sp, sigmaI, sigmaA)) # Begin problem 8 - 55 sigmaI = Fi / At sigmaA = C*(P - P/2)*10**3/(2*At) sigmaM = sigmaA + sigmaI print('Test', Screw.Goodman(Se, Sut, 487.5, 3.675, 498.5)) print(Screw.Goodman(Se, Sut, sigmaI, sigmaA, sigmaM))
def Problem5(): """WRONG Given a non-permanent bolted joint with a bolt stiffness of 2.4 Mlbf/in and a member stiffness of 3.5 Mlbf/in that is supporting a tensile load that fluctuates repeatedly between 0 and 2.1 kip, what is the factor of safety against fatigue failure if one, 5/16”-18, SAE grade 8 bolt is used? Use Goodman theory if needed.""" kb = 2400 #klbf/in km = 3500 #klbf/in P = 2.1 #kip Sy = 130 #kpsi d = 5 / 16 At = 0.0524 #in^2 Fi = 0.75 * At * Sy C = kb / (kb + km) sigmaI = Fi / At sigmaA = C * P / (2 * At) sigmaM = sigmaA + sigmaI Sut = 150 #kpsi Table 8-9 Se = 23.2 #kpsi Table 8-17 n = Screw.Goodman(Se, Sut, sigmaI, sigmaA, sigmaM) print(n)