Mechanical response of a panel section with a hexagonally tessellated stiffener grid

Abstract

Stringers are stiffening members of pressurized aircraft fuselage. They provide support to the fuselage’s skin. A new stringer grid concept is proposed for conventional aircraft fuselage. Optimization is used to find the hexagonal grid that best replaces the original while keeping the same total stringer length. A finite element model is built to analyze the optimal hexagonal grid stiffened structure and compare it with the original orthogonally stiffened structure in terms of eigenfrequencies and static response to external loading. The finite element model is validated through Flugge’s analytical expressions for stiffened shells. Results show that the hexagonal grid stiffened structure yields higher eigenfrequencies with stresses and displacements comparable with that of the original structure.

Effect of hexagonal stringer design on bulging factor and stress intensity factor of cracks in the skin of pressurized aircraft fuselage

“…The tessellation (partition) of the fuselage panel into hexagonal cells has been addressed in a previous paper by the authors. 22 The objective was to find a stringer grid geometry that uses a minimal amount of mass and provide local reinforcement to the skin that is identical to that of the conventional orthogonal grid. This resulted in several hexagonal grid configurations some of which were selected to be studied.…”

“…In the same paper, 22 a parameter η was introduced to assess the effectiveness of a hexagonal stringer cell in local reinforcement of the fuselage skin within its enclosed cell area. It is defined in equation ( 6) as two times the ratio of the surface of the enclosed cell area to the stringer length surrounding it (its perimeter); for a circular shaped cell, η corresponds to the radius of the circle.…”

“…It is also important to mention that these hexagonal grid configurations were obtained from an optimization process where the objective was to minimize total mass of the stringer grid while providing comparable mechanical stiffness to the skin. 22 The main point advanced here is that by adopting a hexagonal stringer configuration we can provide a stiffening interaction between the stringer and skin similar to that of an orthogonal grid and at a relatively lower mass that will result in an adequate crack arresting capacity.…”

“…This design comes with the advantage of a reduced total mass of the structure. 22, 23 This novel concept has only been studied for intact fuselage structures.…”

Free vibration and axial compression of all-metallic cylindrical and truncated conical sandwich shells with corrugated cores

“…These structures are often exposed to complex service conditions, e.g. severe vibration and axial impact [1–4]. For such applications, it is desirable to construct sandwich-walled cylindrical and conical structures (shells) sandwich structures are known to possess high specific strength, sound absorption performance, high designability, and good heat dissipation capability [5–13].…”