What can happen to an aircraft structure when loads are between limit and ultimate?

When loads applied to an aircraft structure are between the limit load factor and the ultimate load factor, they can lead to permanent deformation of the structure. This occurs because the material may begin to experience behaviors that exceed its elastic limits but do not reach the point of catastrophic failure.

In this intermediate load range, while the aircraft structure is designed to withstand certain stresses, exceeding the limit load may introduce plastic deformation. This means that even if the load is removed, the structure does not return to its original shape, which can compromise the integrity and performance of the aircraft over time.

Understanding this behavior is crucial in structural design and safety management; engineers design structures to handle loads up to a certain limit without permanent deformation. However, loads exceeding this limit can result in significant changes to the material properties and structural performance, making option B the correct interpretation of the impact of loads between limit and ultimate levels.

The other options do not accurately reflect the outcomes associated with intermediate load levels, such as stating that loads will always cause failure or have no effect on the structure, which understate the potential for significant deformation. They also do not account for the nuanced effects on performance, which can be affected, but not exclusively determined by these loads.