For a cantilever beam subjected to a triangular distributed load, what is the order of the internal moment expression of the beam as a function of the location

Respuesta :

Answer:

The Order is 4th order

Explanation:

Let take the diagram on the first uploaded image as an example of triangular distributed load  

Let x denote the location

To obtain the vertical force acting at point a we integrate the function  

          [tex]\frac{dA_y}{dx} = w[/tex]

    where [tex]A_y[/tex] is the vertical force

    dx is the change in location

     w is a single component of force acting downwards

             [tex]A_y = \int\limits^L_0 {w} \, dx[/tex]

           [tex]A_y = \int\limits^8_0 {\frac{x^2}{8} } \, dx[/tex]

                 =  [tex]\frac{1}{8} [\frac{8^3}{3} ][/tex]

                  [tex]= 21.33N[/tex]

To obtain the moment of of inertia \

              [tex]M_A = \int\limits^L_0 {wx} \, dx[/tex]

                     [tex]=\int\limits^8_0 {[\frac{x^2}{8} ]x} \, dx[/tex]

                     [tex]= \frac{8^4}{32}[/tex]

                   [tex]= 128 Nm[/tex]

To obtain the shear force acting at a distance x from A

             [tex]V = A_y -\int\limits^x_0 {[\frac{x^2}{8} ]} \, dx[/tex]

                  [tex]= 21.33 - \frac{x^3}{24}[/tex]

   To obtain the moment about the triangular distributed load section that is at a distance x from A as shown on the diagram

       = >    [tex]dM = \int\limits^x_0 {V} \, dx[/tex]

          =>        [tex]M_x -M_A = \int\limits^x_0 {[21.33- \frac{x^3}{24}]} \, dx[/tex]

      =>           [tex]M_x = 128 + 21.33x -\frac{x^4}{96}[/tex]

Looking at this equation as a polynomial we see that the order is 4 i.e [tex]x^4[/tex]

             

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