Question 5.8: Determine the maximum stress at point A of the thin cylinder...

Determine the maximum stress at point A of the thin cylinder shown in Figure 5.14a. Let \mu=0.3.

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A free-body diagram of junction A is shown in Figure 5.14b. The deflection at point A in the thick cylinder due to P is obtained from Table 5.3 by letting \beta x equal to \beta l . Hence,

w_{ p }=\frac{-P}{2 \beta_{1}^{3} D_{1}}\left(\frac{C_{4}}{C_{1}} V_{7}-\frac{C_{5}}{C_{1}} V_{5}-\frac{C_{6}}{C_{1}} V_{6}\right)

For \beta_{1}=0.7421, \quad D_{1}=0.01145 E, , and \beta x=\beta l, the following values are obtained:

C_{1}=0.2028 \quad C_{2}=1.1164

 

C_{3}=1.5444 \quad C_{4}=0.5481

 

C_{5}=0.4568 \quad C_{6}=0.6596

 

V_{1}=0.2721 \quad V_{3}=0.4006

 

V_{4}=1.4984 \quad V_{5}=0.8707

 

V_{6}=0.5986 \quad V_{7}=0.9495

Thus, the expression for w_{ p } due to P is given by

w_{ p }=\frac{144.02 P}{E}

The deflection compatibility equation at point A is

\left.\delta_{1}\right|_{x=0}=\left.\delta_{2}\right|_{x=0}

or from Tables 5.2 and 5.3 with x=0,

\frac{144.02 P}{E}-\frac{Q_{0}}{2 \beta_{1}^{3} D_{1}}\left(\frac{C_{4}}{C_{1}}\right)-\frac{M_{0}}{2 \beta_{1}^{2} D_{1}}\left(\frac{-C_{2}}{C_{1}}\right)

= \frac{Q_{0}}{2 \beta_{2}^{3} D_{2}}-\frac{M_{0}}{2 \beta_{2}^{2} D_{2}}

and with \beta_{2} =1.0495 and D_{2} =0.00145E, the equation becomes

144.02 P-288.82 Q_{0}+436.59 M_{0}

= 298.30 Q_{0}-313.07 M_{0}

Or

5.206 M_{0}-4.077 Q_{0}=-P                               (1)

The rotation at point A due to P is obtained from Table 5.3 as

\theta_{ p }=\frac{P}{2 \beta_{1}^{2} D_{1}}\left(\frac{C_{4}}{C_{1}} V_{1}+\frac{C_{5}}{C_{1}} V_{4}+\frac{C_{6}}{C_{1}} V_{3}\right)

Or

\theta_{ p }=\frac{429.33 P}{E}

The rotation compatibility equation at point A is

\left.\theta_{1}\right|_{x=0}=\left.\theta_{2}\right|_{x=0}

Hence,

\frac{429.33 P}{E}+\frac{M_{0}}{2 \beta_{1} D_{1}}\left(\frac{2 C_{3}}{C_{1}}\right)+\frac{Q_{0}}{2 \beta_{1}^{2} D_{1}}

 

\times\left(\frac{C_{5}}{C_{1}}+\frac{C_{6}}{C_{1}}\right)=\frac{-M_{0}}{\beta_{2} D_{2}}+\frac{Q_{0}}{2 \beta_{2}^{2} D_{2}}

Or

\frac{429.33 P}{E}+896.45 M_{0}+436.59 Q_{0}

= -657.13 M_{0}+313.07 Q_{0}

which reduces to

12.58 M_{0}+Q_{0}=-3.48 P                              (2)

Solving Eqs. (1) and (2) yields

M_{0}=-0.27 P

 

Q_{0}=-0.08 P

Hence, the maximum axial stress is

\sigma=\frac{6 M_{0}}{t^{2}}=\frac{6(0.27 P)}{0.25^{2}}=25.9 P \text { psi }

The circumferential bending moment is given by

M_{\theta}=\mu M_{x}=0.08 P

The circumferential force N_{\theta} is given by Eq. (5.19) as.

N_{\theta}=\frac{-E t w}{r}

 

N_{\theta}=\frac{E t w}{r}

 

=\frac{E t_{2}}{r}\left(w_{Q_{0}}-w_{M_{0}}\right)

 

=\frac{E t_{2}}{R}\left(\frac{-0.08 P}{2 \beta_{2}^{3} D_{2}}-\frac{-0.27 P}{2 \beta_{2}^{2} D_{2}}\right)

 

=\frac{P}{24}(-23.86+84.53)=2.53 P

 

\sigma_{\theta}=\frac{N_{\theta}}{t}+\frac{6 M_{\theta}}{t^{2}}

 

=\frac{2.53 P}{0.25}+\frac{6(0.08 P)}{0.25^{2}}

 

= 17.80P.

 

Table 5.2 Various discontinuity functions.

\text { Functions }^{\text {) }}
Edge functions
w \frac{-M_{0}}{2 \beta^{2} D} \frac{Q_{0}}{2 \beta^{3} D} \Delta_{0} 0
\theta \frac{M_{0}}{\beta D} \frac{-Q_{0}}{2 \beta^{2} D} 0 \theta_{0}
M_{x} M_{0} 0 2 \beta^{2} D \Delta_{0} 2 \beta D \theta_{0}
N_{\theta} -2 M_{0} \beta^{2} r 2 \beta r Q_{0} \frac{E t \Delta_{0}}{r} 0
Q_{0} 0 Q_{0} 4 \beta^{3} D \Delta_{0} 2 \beta^{2} D \theta_{0}
General functions
w \frac{-M_{0}}{2 \beta^{2} D} B_{\beta x} \frac{Q_{0}}{2 \beta^{3} D} C_{\beta x} \Delta_{0}\left(2 C_{\beta x}-B_{\beta x}\right) \frac{\theta_{0}}{\beta}\left(C_{\beta x}-B_{\beta x}\right)
\theta \frac{M_{0}}{\beta D} C_{\beta x} \frac{-Q_{0}}{2 \beta^{2} D} A_{\beta x} 2 \beta \Delta_{0}\left(A_{\beta x}-C_{\beta x}\right) \theta_{0}\left(A_{\beta x}-2 C_{\beta x}\right)
M_{x} M_{0} A_{\beta x} \frac{Q_{0}}{\beta} D_{\beta x} 2 \beta^{2} D \Delta_{0}\left(A_{\beta x}-C_{\beta x}\right) 2 \beta D \theta_{0}\left(D_{\beta x}-A_{\beta x}\right)
N_{\theta} -2 M_{0} \beta^{2} r B_{\beta x} 2 \beta r Q_{0} C_{\beta x} \frac{E t}{r} \Delta_{0}\left(2 C_{\beta x}-B_{\beta x}\right) \frac{E t \theta_{0}}{r \beta}\left(C_{\beta x}-B_{\beta x}\right)
Q_{x} -2 \beta M_{0} D_{\beta x} Q_{0} B_{\beta x} 4 \beta^{3} D \Delta_{0}\left(B_{\beta x}-D_{\beta x}\right) 2 \beta^{2} D \theta_{0}\left(2 D_{\beta x}+B_{\beta x}\right) B11:F16
a) Clockwise moments and rotation are positive at point 0. Outward forces and deflections are positive at point 0. M_{0}=\mu M_{x}.

 

Table 5.3 Various functions of short cylinders.

Function

w \frac{M_{0}}{2 \beta^{2} D}\left[\frac{-C_{2}}{C_{1}} V_{7}+\frac{C_{3}}{C_{1}} V_{2}-V_{8}\right] \frac{Q_{0}}{2 \beta^{3} D}\left[\frac{C_{4}}{C_{1}} V_{7}-\frac{C_{5}}{C_{1}} V_{5}-\frac{C_{6}}{C_{1}} V_{6}\right] \frac{\theta_{0}}{\beta}\left[\frac{C_{6}}{C_{1}} V_{5}-\frac{C_{5}}{C_{1}} V_{6}-\frac{C_{4}}{C_{1}} V_{8}\right] \quad \Delta_{0}\left[V_{7}-\frac{C_{3}}{C_{1}} V_{1}-\frac{C_{2}}{C_{1}} V_{8}\right]
\theta \frac{M_{0}}{2 \beta D}\left[\frac{C_{2}}{C_{1}} V_{1}+\frac{2 C_{3}}{C_{1}} V_{7}-V_{2}\right] \frac{-Q_{0}}{2 \beta^{2} D}\left[\frac{C_{4}}{C_{1}} V_{1}+\frac{C_{5}}{C_{1}} V_{4}+\frac{C_{6}}{C_{1}} V_{3}\right] \theta_{0}\left[\frac{C_{6}}{C_{1}} V_{4}-\frac{C_{5}}{C_{1}} V_{3}-\frac{C_{4}}{C_{1}} V_{2}\right] \quad \beta \Delta_{0}\left[-V_{1}+2 \frac{C_{3}}{C_{1}} V_{8}-\frac{C_{2}}{C_{1}} V_{2}\right]
M_{x} M_{0}\left[\frac{C_{2}}{C_{1}} V_{8}-\frac{C_{3}}{C_{1}} V_{1}-V_{7}\right] \frac{Q_{0}}{\beta}\left[-\frac{C_{4}}{C_{1}} V_{8}-\frac{C_{5}}{C_{1}} V_{6}+\frac{C_{6}}{C_{1}} V_{5}\right] 2 \beta D \theta_{0}\left[\frac{C_{6}}{C_{1}} V_{6}+\frac{C_{5}}{C_{1}} V_{5}-\frac{C_{4}}{C_{1}} V_{7}\right] 2 \beta^{2} D \Delta_{0}\left[-V_{8}+\frac{C_{3}}{C_{1}} V_{2}-\frac{C_{2}}{C_{1}} V_{7}\right]
N_{\theta} 2 B^{2} r M_{0}\left[-\frac{C_{2}}{C_{1}} V_{7}+\frac{C_{3}}{C_{1}} V_{2}-V_{8}\right] 2 \beta r Q_{0}\left[\frac{C_{4}}{C_{1}} V_{7}-\frac{C_{5}}{C_{1}} V_{5}-\frac{C_{6}}{C_{1}} V_{6}\right] \frac{E t \theta_{0}}{\beta}\left[\frac{C_{6}}{C_{1}} V_{6}+\frac{C_{5}}{C_{1}} V_{5}-\frac{C_{4}}{C_{1}} V_{7}\right] \frac{E t \Delta_{0}}{r}\left[V_{7}+\frac{C_{3}}{C_{1}} V_{1}-\frac{C_{2}}{C_{1}} V_{8}\right]
Q_{x} -\beta M_{0}\left[\frac{C_{2}}{C_{1}} V_{2}-\left(\frac{2 C_{3}}{C_{1}}+1\right) V_{8}\right] Q_{0}\left[\frac{C_{4}}{C_{1}} V_{2}+\frac{C_{5}}{C_{1}} V_{3}-\frac{C_{6}}{C_{1}} V_{4}\right] 2 \beta^{2} D \theta_{0}\left[\frac{C_{6}}{C_{1}} V_{3}+\frac{C_{5}}{C_{1}} V_{4}+\frac{C_{4}}{C_{1}} V_{1}\right]-2 \beta^{3} D \Delta_{0}\left[-V_{2}+2 \frac{C_{3}}{C_{1}} V_{7}+\frac{C_{2}}{C_{1}} V_{1}\right]
Constants Variables
C_{1}=\sinh ^{2} \beta l-\sin ^{2} \beta l V_{1}=\cosh \beta x \sin \beta x-\sinh \beta x \cos \beta x
C_{2}=\sinh ^{2} \beta l+\sin ^{2} \beta l V_{2}=\cosh \beta x \sin \beta x+\sinh \beta x \cos \beta x
C_{3}=\sinh \beta l \cosh \beta l+\sin \beta l \cos \beta l V_{3}=\cosh \beta x \cos \beta x-\sinh \beta x \sin \beta x
C_{4}=\sinh \beta l \cosh \beta l-\sin \beta l \cos \beta l V_{4}=\cosh \beta x \cos \beta x+\sinh \beta x \sin \beta x
C_{5}=\sin ^{2} \beta l V_{5}=\cosh \beta x \sin \beta x
C_{6}=\sinh ^{2} \beta l V_{6}=\sinh \beta x \cos \beta x
V_{7}=\cosh \beta x \cos \beta x
V_{8}=\sinh \beta x \sin \beta x
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