Semi-Trailer Weight Distribution

[jpalutke]

I am writing software for weight loading/distribution in a semi trailer.

The current trailer model has two points at which it is supported. A fixed fulcrum approximately 2 feet from the front(I would prefer it be variable for future reference) and a second point near the rear (adjustable from 0-72 inches).

It is my intent for the loading software to be able to provide the given weight for each linear inch of the 53 foot trailer. Any assistance in acquiring or deriving the formula(s) needed to calculate the load on each of the two fulcrum points in the image below would be greatly appreciated.

https://www.physicsforums.com/attachment.php?attachmentid=49084&d=1342318623

View attachment TrailerFloor53.bmp

 

[Navin A S]

To calculate the weight distribution along the trailer, you need to use the principles of statics and moments. Specifically, you want to calculate the moment created by the weight of the trailer at each of the two support points. The formula for calculating a moment is m = F*d, where m is the moment, F is the force (weight), and d is the distance from the fulcrum point. To get the force for each linear inch of the trailer, you would first divide the total weight of the trailer by the length of the trailer (53 feet). This would give you the weight per linear foot. Then, to get the weight per linear inch, you would multiply that number by 12 (since there are 12 inches in a foot). Once you have the weight per linear inch, you can calculate the moment at each of the two support points by multiplying the weight per linear inch by the distance from the fulcrum point. For example, the moment at the first support point would be m = F*2 feet, and the moment at the second support point would be m = F*d, where d is the adjustable distance from 0 to 72 inches. Once you have calculated the moments at each support point, you can then calculate the weight that each support point is supporting. This can be done using the equation W = M/d, where W is the weight, M is the moment, and d is again the distance from the fulcrum point. Using this equation, you can calculate the weight distribution along the trailer for any given distance between the two support points.