Bulging factor is an

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 ...

term describing the

geometry Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...

of out-of

plane Plane(s) most often refers to: * Aero- or airplane, a powered, fixed-wing aircraft * Plane (geometry), a flat, 2-dimensional surface Plane or planes may also refer to: Biology * Plane (tree) or ''Platanus'', wetland native plant * Planes (gen ...

deformations of the surface of a crack on a

pressurized {{Wiktionary Pressurization or pressurisation is the application of pressure in a given situation or environment. Industrial Industrial equipment is often maintained at pressures above or below atmospheric. Atmospheric This is the process by ...

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

structure. It is used in evaluating the damage tolerance of

airframe The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and excludes the propulsion system. Airframe design is a field of aerospa ...

fuselages.United States of America. Federal Aviation Administration. Bulging Factor Solutions for Cracks in Longitudinal Lap Joints of Pressurized Aircraft Fuselages. Springfield, 2004. pp.1-3,10 The single curved geometry and pressure differential causes a

longitudinal Longitudinal is a geometric term of location which may refer to: * Longitude ** Line of longitude, also called a meridian * Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, ...

crack to bulge out or protrude from the original shape. This change in geometry, or “bulging effect”, significantly increases the stress intensity factor at the crack tips. The effects of this loading condition can trigger different types of failure mechanisms. For the case of unstiffened shell structures, the bulging factor can be defined as the ratio of stress-intensity (SIF) of a curved shell to the stress-intensity factor of a flat panel:

bulging factor = SIF(curved)/SIF(flat)

The representation of this phenomenon becomes rather complex due to the biaxial and internal pressure load and structural configuration.

References

* Lazghab Tarek, Fayza Ayari, Lotfi Chelbi. Crack growth in cylindrical aluminum shells with inner reinforcing foam layer. Springer, 2006. pp. 151. Pressure vessels Fracture mechanics {{engineering-stub