Design and Static Structural Analysis of Aircraft Floor Beam

GRD Journals- Global Research and Development Journal for Engineering | Volume 4 | Issue 8 | July 2019 ISSN: 2455-5703

Design and Static Structural Analysis of Aircraft Floor Beam Santosh Yadav UG Student Department of Aeronautical Engineering East West College of Engineering affiliated to VTU

Abstract Floor beam is a structural element of fuselage which is mainly used for providing horizontal space to aircraft crew and is fixed with fuselage skin. In this I-section beam is picked for designing the fuselage floor beam which is better in comparison to other cross sections. In this, the design of aircraft floor beam is conceptual design for the enhancement of strength, durability, cost and weight reduction. The major problems of existing aluminium floor beam are increased weight and less stiffness. Hence, CFRP (carbon fibre reinforced plastics) has chosen for the designing of floor beam in the aircraft. After the selection of material and cross section of floor beam, the whole parameters of cross section of floor has studied and designed in UG NX8 software with the standard dimensions of a floor beam then the model is imported to Ansys 14.5 for the analysis and optimization. The expected outcome is to reduce the weight to strength ratio, cost, design and style outlook with weight reduction of fuselage.

Keywords- Floor-Beam, Fuselage, ANSYS, Structural Analysis, Equivalent Stress, CFRP

I. INTRODUCTION Floor beam is a structural member which is used as floor space to passengers, cargo, control unit and other equipment. It is also defined as a cross beam for a floor structure of an aircraft which includes a web having opposing end sections configured to connect to opposing structural sections of fuselage and at least one-stepped section. The stepped section is formed by a movement of the web in a direction corresponding to a normal axis of the web. Floor beams are part of a redundant floor structure that support the passenger seats, galleys, lavatories, etc. The floor beams are supported at the both end by the frames and are further supported by two floor stanchions. Seat tracks move over the floor beams and joined to the floor beam upper chords or beam webs. The seat tracks are attached to the floor beams to transfer the loads from seats to the beams and to ensure that the floor beams work together to carry the applied loads. There are also intercostal that run fore and aft between the floor beams and their purpose is to carry locally applied loads from galleys, etc. The floor grid (floor beams plus seat tracks) is covered by floor panels that attach to the seat tracks and may attach to the floor beam upper chords. The floor panels serve as the shear diaphragm that carries the forward crash loads out to the side of the fuselage (Kotresh B, 2016).

It consists of cross beam, support struts, seating rails, support rails, floor and a surface structure. The latter are normally supported with the help of struts on a lower part of the respective frame to increase the bending strength of cross beams. The floor is situated above the cross beam on the seating rails and on the support, rails arranged between the inner seating rails. The surface structure is arranged under the floor-beam for an installation space for the laying of systems cabling. Moreover, it forms a ceiling at the lower aircraft space which is used to maximize the volume of the freight loading space and is advantageous if the surface structure is positioned as close as possible to the cross-beam.

Fig. 1: The typical Airframe structure of fuselage with floor beam and lifting Surface

All rights reserved by www.grdjournals.com

6

Design and Static Structural Analysis of Aircraft Floor Beam (GRDJE/ Volume 4 / Issue 8 / 002)

II. RELATED WORKS Kotresh [1], in this paper they present the study related to the design, analysis and optimization of I-shaped fuselage floor beam by using finite element analysis and mainly concerned with composite material CFRP (carbon fiber reinforced plastic) for the floor/cross beam and I-cross sectional floor beam with different shapes of cutouts such as circles and ellipses in the web of floor beam for the optimization of it to reduce structural weight of the Aircraft. A static linear analysis is done for the floor beam and obtained maximum equivalent stress is lesser than yield stress and hence the designed model is safe and it gives better efficiency.

Ruhani Thakur [2], they describe stress analysis of Fuselage floor beam which, is used as I-beam i.e. the cross section of beam is of I-shape. Now-a-days due to the growth of aircraft industry, airplanes are used to transport heavier things and they are made to carry more passengers. The fuselage floor which directly bears the weight being carried must be strong and be able to withstand loads and the cyclic loads. This is the main reason for introduction of I-beam with longerons in fuselage floor. They analyze this beam and study whether it is feasible or not.

Guy Nolla [3], who published a paper in on the Aircraft floor and aircraft fuselage in 2012. An aircraft floor which include two length-wise external beams and at least one pair of floor beams enlarging between the length-wise beams. And an external end of each floor beams is interlocked to them and internal ends of the floor beams are connected to each other.

III. OBJECTIVES – – – –

To select composite materials which have more advantages compare to the metallic materials i.e. Aluminum.

To perform static structural analysis for calculating equivalent stress to check weather design is safe or not.

To find the best cross-section for the cross-beam member which can be used in the aircraft for better performance.

To provide floor beam which has better mechanical as well as physical property then existing floor beam.

IV. METHODOLOGY

Fig. 2: Methodology

All rights reserved by www.grdjournals.com

7

Design and Static Structural Analysis of Aircraft Floor Beam (GRDJE/ Volume 4 / Issue 8 / 002)

V. FLOOR BEAM DESIGN

Fig. 3: The geometrical 3D CAD model of Floor beam in Aircraft

The figure shows the 3D CAD model of the I-Cross section of the floor beam in the passenger Aircraft modeled in UG NX8. An accurate UG model is created to perform linear static structural analysis in ANSYS under the boundary condition of applied load.

After designing, Carbon fiber reinforced plastic is applied as material having following property shown in Table.1.

Material section: CFRP Table 1: CFRP (Carbon Fiber Reinforced Plastic) Material Properties Density Material Poisson’s ratio Yield stress (MPa) (Mg/m3) CFRP 1.5 0.28 250

VI. STATIC STRUCTURAL ANALYSIS – –

Step 1: The CAD geometry of the aircraft floorbeam is imported to the ANSYS software in .igs file format for creating the FE model of the CAD model for analysis.

Step 2: The imported geometry is then ready for meshing. Figure shows the meshed floor beam model of the CAD geometry.

Fig. 4: Meshed Model of floor Beam

The current model was meshed using Tetrahedron dominant elements with number of nodes by the ANSYS as shown above.

– Step 3: After the meshing, static structural analysis is carried out. In this, boundary conditions like Loads, fixed at both ends of the Floor beam has done.

– Step 4: After applying boundary conditions, the model is then solved for the required stresses for the static linear analysis of the floor beam in the aircraft.

All rights reserved by www.grdjournals.com

8

Design and Static Structural Analysis of Aircraft Floor Beam (GRDJE/ Volume 4 / Issue 8 / 002)

Fig. 5: Boundary Conditions

VII. RESULTS AND DISCUSSION

Fig. 6: Equivalent (Von-Mises) stresses

The floor beam model is statically analyzed to find the equivalent stress (Von-Mises stress). The obtained equivalent stress is 207.7 MPa which is less than yield stress (250MPa) under applied load condition. Hence the designed floor beam with Carbon Fiber Reinforced Plastic is more feasible and safer in compare to aluminum cross beam.

VIII. CONCLUSION It can be claimed that the outcomes generated through ANSYS software is used to calculate equivalent stress experienced by aircraft floor beam. Based on numerical simulation outcomes, the following points can be concluded: – CFRP floor beam is less weight compare to the aluminum material.

– ANSYS Workbench is used for static analysis of CFRP cross beam to calculate equivalent stress under given boundary conditions. The maximum von-mises stress obtained is less than yield strength of CFRP material. Hence, the Aircraft floor beam designed is safe and efficient.

– Hence, we can conclude that floor beam with CFRP is better and have high strength, durability in compare to aluminum cross beam and can be preferred over aluminum floor beam.

All rights reserved by www.grdjournals.com

9

Design and Static Structural Analysis of Aircraft Floor Beam (GRDJE/ Volume 4 / Issue 8 / 002)

REFERENCES [1] [2] [3] [4] [5]

Kotresh B, Dr. Mohamed Haneef, Mr. Mohammed Imran, “Design, Analysis and Optimization of Aircraft Floor Beam”, IJSRD - International Journal for Scientific Research & Development, ISSN (online): 2321-0613, Vol. 4, Issue 06, 2016.

Ruhani Thakur, “Analysis of Fuselage floor beam”, International Journal of Aerospace and Mechanical Engineering, ISSN- 2393-8609, Vol.–2, No.6, December 2015.

Korg Lars, Ryan, Gary, “Beam for an aircraft fuselage floor”, European Patent EP2593360 in 2015.

R.E de Kok, “The Airbus Floor Beam”, Faculty of Aerospace Engineering, delft university of technology, January 1992.

Fayssal Hadjez presented their report on “Stress Analysis of an Aircraft Fuselage with and without Portholes using CAD/CAE Process”, University of Constantine, Algeria.

All rights reserved by www.grdjournals.com

10