In
engineering
Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad rang ...
, the ultimate load is a statistical figure used in calculations, and should (hopefully) never actually occur.
Strength requirements are specified in terms of
limit loads
Limit load is the maximum load that a structure can safely carry. It's the load at which the structure is in a state of incipient plastic collapse. As the load on the structure increases, the displacements increases linearly in the elastic range un ...
(the maximum loads to be expected in service) and ultimate loads (limit loads multiplied by prescribed factors of safety). 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
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
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.
This is also commonly used in knowing the properties of metal beams. For example, it is used in experiments such as T.T.M(tensile testing machine) and U.T.M(universal testing machine)
The ultimate load B
u is related to the
limit load B
n, using the concept of
safety factor
In engineering, a factor of safety (FoS), also known as (and used interchangeably with) safety factor (SF), expresses how much stronger a system is than it needs to be for an intended load. Safety factors are often calculated using detailed analy ...
, j. The relation is as follows
B
u >= B
n × j
Aerospace engineering
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