Mechanical stress
Stress in a structure is calculated by dividing the force applied at any point by the crosssectional area of the structure at that point .
The graph below shows a simplified model of a branch as a regular cylinder of wood , anchored into the main trunk of the tree on the left axis . A small weight at the tip of the branch is used to represent the foliage and subsidiary branches .
The bending moment in the branch is lowest at the tip of the branch and is highest at the butt of the branch where it joins the trunk .
The stress at any point in the branch is calculated by dividing the force applied at any point by the cross-sectional area of the branch at that point . If the branch diameter is constant , bending stress is highest nearest the union and lowest near the tip .
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