Break-strength vs. Overall Strength Rating: Why they are different ?
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The breaking strength of a safety net system can be expressed in several ways: either by the breaking strength of a mesh, or by the lifting capacity of a mass. At Barry, we measure the breaking strength of the mesh. It is important to know that the breaking strength of the mesh alone does not give the overall capacity of the net system, and other factors must be considered.
Using the mesh break strength as a basis has many advantages, but also some limitations to consider. In a laboratory setting, it is possible to perform tensile strength tests during net manufacturing and residual strength tests on samples of nets in service.
Ideal for residual strength validation
Net systems installed in the field can be tested for residual strength using swatches
Destructive nature of the testing
Not representative of the overall strength of the net system
Note: No matter what type of data is known about a net, this data does not provide all the information about the capacity and safety factor of a net for a given use. In some cases, testing of the entire net system may be required to determine the ultimate strength of the system. In general, the strength of a system is greater than that of a single mesh, but the geometry of the net and the geometry of the mass it stops are crucial factors in determining this.
Important factors that will influence the capacity of a net include:
Angle of installation
Geometry of the net
The type of mass to be held or captured
Speed and geometry of masses
Level of tension
Number of attachment points
Barry's helicopter cargo nets are a good example of this nuance. They are designed so that the breaking strength of the entire net system is significantly higher than the breaking strength of the individual meshes of the net.
Finally, all Barry nets have corresponding technical data sheet which include the breaking strength of the net mesh. This information is useful for the net designer and should be supplemented by testing or analysis to define the capacity of the system as a whole.