- #1

Dell

- 590

- 0

Answers: a) 40.1Mpa 0.6630 degrees

b) 50.9Mpa 0.9510 degrees

my equationsτ

_{max}=[tex]\frac{T}{alpha*h*b^2}[/tex][tex]\frac{dΦ}{dx}[/tex]=[tex]\frac{T}{G*beta*hb^3}[/tex]so to find the angle of twist at B i can integrate [tex]\frac{T}{Gβhb^3}[/tex]dx from 0 to 0.3, but since the moment is constant throughout, the integral comes to [tex]\frac{T}{Gβhb^3}[/tex]*0.3

and i get

a) Φ

_{B}=[tex]\frac{1000}{26e9*0.14*0.06*0.06^3}[/tex]*0.3=0.0211979 rad =

**1.21455degrees**

b) Φ

_{B}=[tex]\frac{1000}{26e9*0.245*0.095*0.038^3}[/tex]*0.3=0.03011 rad =

**1.725degrees**

where the actual answers are much much smaller

for the shear strength used the equation

τ

_{max}=[tex]\frac{T}{alpha*h*b^2}[/tex]

and i get

a)τ

_{max}=[tex]\frac{1000}{0.21*0.06*0.06^2}[/tex]=

**22Mpa**

b)τ

_{max}=[tex]\frac{1000}{0.26*0.095*0.038^2}[/tex]=

**28Mpa**

a seemingly simple question but i have managed to get 0/4 correct answers, can anyone see where I am going wrong?