Ultimate load


In engineering, the ultimate load is a statistical figure used in calculations, and should never actually occur. It is used for instance in aerospace engineering, bridge and tunnel construction. This is also commonly used in knowing the properties of metal beams. For example, it is used in experiments such as tensile testing machine and universal testing machine.

Relation to safety factor and limit load

Strength requirements are specified in terms of limit loads and ultimate loads.
Mathematically, their relation can be expressed as:
where:
With respect to aircraft structure and design, ultimate load is the amount of load applied to a component beyond which the component will fail. The chance that it will occur is, however, not zero, and, if it were to occur, then the relevant structure in the aircraft would stand a large chance of fracture.
During the testing for determination of the loads, no fracture must occur at the ultimate load for a period of 3 seconds.