AIRCARFT STRUCTURE AND STRUCTURAL MEMBERS

AIRCARFT STRUCTURE AND STRUCTURAL MEMBERS

Structure: Structure is the skeleton or framework for giving ‘shape’ to a construction and for bearing ‘load‘ applied to the construction.

Examples:

a)                 Structure of a building

b)                 Skeleton of a human body

c)                  Framework of an airplane

Structural members: Structural members are the parts or elements of a structure. When a force is applied to a structure, we called that the structure is loaded. Structure may not deform under such load. Function of the structural members is to take such load and oppose deformation.  Different structural members will be described later on.

STRESSED AND NON-STRESSED PARTS

General: Structural members be designed to take load and prevent deformation or they may be designed mainly for the shape of the structure.

Stressed parts: Structural parts that are designed to take load are called stressed parts. Thus stressed parts serves to:

a)                Take load

b)                Prevent deformation

c)                 Keep shape

STRENGTH is the principal requirement and Strength/Weight ratio is the principal factor of choice of material of a stressed part.

Non-Stressed Parts: Structural parts that are designed to give neat appearance or streamlined shape to the structure are called non-stressed parts. Strength is not the principal requirement in choosing material non-stressed parts. Non-stressed parts are used in access doors, panels, fairings, cowlings etc.

STRUCTURAL DEFINITION

General: Airframe structures are loaded differently at different sections/positions. Structural definitions apply to the structures or members of the structures according to the amount of loading or stresses on them. Structures may be defined as follows.

Primary Structures: These are parts of the aircraft structure which are highly stressed and if damaged may cause failure of the aircraft and subsequent loss of life.

Examples: spars, longerons, engine, mountings, stressed skins etc.

Secondary Structures: These are also highly stressed structural parts but if damaged will not cause a failure of A/C or loss of life.

Examples: Flooring, auxiliary frames supporting equipment like oxygen bottles, radio etc.

Tertiary Structure: These are unimportant parts lightly stressed, but essential in the construction of the airframe, Examples: Fairing, wheel doors, minor component brackets.