Question

A large construction company plans to add plastic 60 L water coolers to the back ofmost of its trucks. Fig. 2 specifies the dimension h and the diameter of round steel bars to be used for members AB, AC and AD. In this model load P is vertical and AB is parallel to y axis. Allow for loads upto twice theweight of the cooler in a crude attempt to allow for dynamic forces and to use the allowable loads as given inthe table. Calculate forces in each member. Also calculate the internal forces in each member. Select materialwhich will result in a safe design.

Answer 1

First of all, to start answering this question you have to draw the loads for the entire system of loads

The red line represents the force generated by the weight of the water

The blue points are the connection points between the supports and the wall, which have all the reactions of the system

To design a safe system, we will use the maximum capacity of the thank as the load applied, 60L.

`F=60L\cdot(1kg)/(1L)\cdot(9.81m)/(s^2)=588.6N`

Now we are going to set the sums of forces at each axis

`\begin{gathered} \sum_{n\mathop{=}0}^(\infty)Fx=0=Fxc+Fxd,\text{ both are the same with opposite direction} \\ \sum_{n\mathop{=}0}^(\infty)Fy=Fyc+Fyd+Fyb \\ \sum_{n\mathop{=}0}^(\infty)Fz=0=-P+Fzb+Fzc+Fzd \\ \sum_{n\mathop{=}0}^(\infty)Mbx=0=P\cdot600mm-(Fyd+Fyc)\cdot h \end{gathered}`