Fasteners in Eccentric Shear Problem Determine a size for the dowel pins in the bracket of Figure 15-41. Given The static force P = 1 200 lb is applied at l = 5 in. The radius to the dowel pins is r = 1.5 in. Assumptions All pins share load equally. Use 40-48 HRC alloy steel for the pin material.

Question

Fasteners in Eccentric Shear

Problem Determine a size for the dowel pins in the bracket of Figure 15-41.

Given The static force [latex]P[/latex] = 1 200 lb is applied at [latex]l[/latex] = 5 in. The radius to the dowel pins is [latex]r[/latex] = 1.5 in.

Assumptions All pins share load equally. Use 40-48 HRC alloy steel for the pin material.

Accepted Answer

See Figures 15-41 and 15-42.

1 Calculate the moment of the applied force.

[latex] M=P l=1200(5)=6000 lb - ext { in } [/latex] (a)

2 Calculate the magnitude of the force due to this moment at each pin.

[latex] F_M=\frac{M}{n r}=\frac{6000}{4(1.5)}=1000 lb [/latex] (b)

3 Find the amount of the direct force [latex]P[/latex] felt at each pin.

[latex] F_P=\frac{P}{n}=\frac{1200}{4}=300 lb [/latex] (c)

4 Based on the vector diagram in Figure 15-42, pin B is the most heavily loaded and its resultant force is

[latex] F_B=F_P+F_M=300+1000=1300 lb [/latex] (d)

5 Assume a trial pin diameter of 0.375 in and calculate the direct shear stress in pin [latex]B[/latex].

[latex] au=\frac{F_B}{A_B}=\frac{1300(4)}{\pi(0.375)^2}=11770 psi [/latex] (e)

6 Find the shear yield strength of the material from Table 15-12 and calculate the safety factor against static shear failure.

[latex] N_s=\frac{S_{y s}}{ au}=\frac{117000}{11770}=10 [/latex] (f)

7 The files EX15-06 can be found on the CD-ROM.

Table 15-12 Minimum Strengths for Dowel Pins in Double Shear. Source: Drive-Lok, Inc., Sycamore, Ill.
Material	[latex]S_{ys}[/latex] (kpsi)
Low-carbon steel	50
Alloy steel 40-48 HRC	117
Corrosion-resistant steel	82
Brass	40

Question 15.6: Fasteners in Eccentric Shear Problem Determine a size for th...

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