Two wooden members of uniform rectangular cross section are joined using a simple glued scarf splice. The maximum allowable shearing stress and maximum allowable normal stress in the glued splice is 50 MPa and 100 MPa, respectively. The cross-section area of the glued member is 400 mm2. (a) What should the value of the angle  be to achieve maximum load Fmax? (b) What is the magnitude of the maximum load Fmax?

Respuesta :

Answer:

a). α =  26.57  

b). Maximum load is 50 .kN

Explanation:

a).

The normal force is given by

N = σ A cosec β

where, σ is the normal stress

            A is the cross sectional area

Similarly, shear force is given by

S= τ A cosec β

where, τ is the shearing stress

Now from the figure,

tan β = S/N

        = τ/σ

Therefore, [tex]$\beta = \tan^{-1}(2)$[/tex]  = 63.43

α = 90 - β = 26.57

b).

The normal force is given by

[tex]$N=(100\times 10^6)(400\times 10^{-6}) \text{ cosec}\ 63.43$[/tex]

[tex]$N=44.78\times 10^3$[/tex] N

We have

[tex]$\Sigma F_y=0$[/tex]

∴ N - F sin β = 0

⇒ F = N / sin β

      = [tex]$\frac{44.72\times 10^3}{\sin(63.43)} = 50\times 10^3 N$[/tex]

Similarly,

The shear force is given by

S = τ A cosec β

  = [tex]$(50\times 10^6)(400\times 10^{-6}) \text{ cosec}\ 63.43 = 22.36\times 10^3 N$[/tex]

[tex]$\Sigma F_x=0$[/tex]

∴ S - F cos β = 0

⇒ F = S / cos β

[tex]$\frac{22.36\times 10^3}{\cos(63.43)} = 49.99\times 10^3 N$[/tex]

Therefore, force is 50 kN.

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