SREE CHAITANYA COLLEGE OF ENGINEERING DESIGN COMPARISSION OF HELICOPTER ROTOR BLADE BY USING DIFFERENT MATERIALS IN STRUCTURAL ANALYSIS Presented by A. Sharan Kumar K. Ramesh B. Sreekanth A. Rakesh roshan G. Ramya Under The Guidance of Dr.G.Venkateswarlu Prof and HOD Department of Mechanical

INTRODUCTION The influence of aerodynamic force and centrifugal force is applied on the rotor blades. The analysis of rotor blade is mainly involved in the calculation about natural frequency and modal shape. There are four forces acting on the helicopter or airplane and those are LIFT, DRAG, THRUST, and WEIGHT.

COMPUTER AIDED DESIGN Computer-aided design (CAD) is the use of computer systems to assist in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design Computer-aided design is used in electronics called EDA.

In mechanical design,the type of manufacturing is known as mechanical design automation MDA CAD software for mechanical design uses either vector-based graphics to depict the objects CAD may be used to design curves and figures in two-dimensional (2D) space; or curves, surfaces, and solids in three- dimensional (3D) space.

COMPUTER AIDED MANUFATURING Computer-Aided Manufacturing (CAM) is the technology concerned with the use of computer system to plan, manage, and control manufacturing operations. CAM) is the use of computer software to control machine tools and related machinery in the manufacturing of work pieces. The primary purpose is to create faster production with accurate dimensions.

2D Drawing of the rotor blade

Sketching

Extrude: 6000mm

Again sketching on the surface of body:383,100

Extrude as subtract

Hole: 48dia, 100depth.

3D model of helicopter blade

PRINCIPLES OF HELICOPTER AERO DYNAMICS Aerodynamics deal with the forces acting on objects moving through air and the movement of air itself. There are four forces acting on any aircraft such as weight,lift,thrust,drag. Helicopters combine lift, thrust and torque in a delicate balance to produce controllable flight and hovering.

Aerodynamics deal with the forces acting on objects moving through air There are two types of forces in aerodynamics. The vertical force of lift is produced by the helicopter's rotor blades.

Bernoulli's Principle Air is affected by water pressure through helicopter airfoils. The main and rear rotor blades are airfoils. The curve of the airfoils causes the air travelling above the blade to move more quickly. This creates low pressure above the helicopter, creating lift, which allows the helicopter to rise.

FEM FEM is the most popular technique for solving engineering techniques. The method is to handle any complex shape of geometry and any material properties. It is an efficient design tool by which designers can perform parametric design study. The method in the aerospace is to study complicated airframe structure.

FINITE ELEMENT MODELING: The 3D model of the helicopter rotor blade was developed in UNIGRAPHICS which was converted to ANSYS. Static and modal analysis were carried out to find the natural frequencies. The elements that are used for idealizing the helicopter rotor blade are solid 92.

Structural analysis It comprises the set of physical laws and mathematics required to study and predict the behaviour of structures. They commonly include buildings, bridges, aircraft, and ships. The primary goal of structural analysis is the computation of deformations,internal forcesand stresses

ANALYSIS OF MATERIALS MATERIAL PROPERTIES: Aluminium Alloy (2014-T6) Mechanical Properties: Young’s modulus = 70Gpa Yield Strength = 410Mpa Poison’s ratio = 0.3 Density = 2800 kg/m3 Element Type Used: Element type: Solid92 No. of nodes: 10 Degrees of freedom: 3 (UX, UY, UZ)

Element model of a helicopter rotor blade.

Boundary conditions for static analysis

Von Mises stersses of helicopter rotor blade

Dynamic analysis The objective to calculate the natural frequency and modal shape of rotor blade is modulating those frequencies. The three-dimension elasticity with minus twist angle, taper tip and complex blade root configuration, and modelling is difficult. The theory for dynamics is implified by infinite DOF vibration.

Lagrange's method, Rayleigh's method and dynamic finite element method are the different methods used to calculate natural frequency. The rotor blade performs complex flights, such as rotating round the rotor shaft of helicopter. The dynamic characteristic analysis about rotor blade was simplified the blade by a one-dimension beam.

Modal Analysis: Modal analysis is used to determine the vibration characteristics (natural frequencies and mode shapes) of a structure.

From the modal analysis, It is observed that the maximum mass participation of 61.9kgs is observed in X-dir for the frequency of 4.729Hz. It is observed that the maximum mass participation of 0.418kgs is observed in Y-dir for the frequency of 27.84Hz. It is observed that the maximum mass participation of 57.36kgs and 17.5kgs are observed in Z-dir for the frequency of 0.611Hz and 3.83Hz.

ANALYSIS OF HELICOPTER ROTOR BLADE WITH COMPOSITE MATERIAL Structural Analysis S. No Property Units HM Carbon/Epoxy HSCarbon/Epoxy 1. E11 GPa 190.0 134.0 2. E22 7.7 7.0 3. G12 4.2 5.8 4. 12 - 0.3 5. St1= Sc1 MPa 870.0 880.0 6. St2= SC2 154.0 160.0 7. S12 30.0 97.0 8. ρ Kg/m3 1600.0

Static analysis S.no. DEFLECTION (mm) STRESS UX UY UZ USUM S1 S2 S3 Von mises 1 27.138 1.289 .0034 216 181.28 41.44 38.204 845.5 From the above results it is observed that the principal stresses values 181.28MPa, 41.44MPa, and 38.204MPa are less than the principal stresses values of the material 870MPa, 190MPa, and 30MPa with respectively

Mode shapes

From the modal analysis, It is observed that the maximum mass participation of 35kgs and 29kgs are observed in X-dir for the frequency of 2.09Hz and 40.5Hz. It is observed that the maximum mass participation of 2.5kgs is observed in Y-dir for the frequency of 40.5Hz. It is observed that the maximum mass participation of 32kgs is observed in Z-dir for the frequency of 0.2642Hz.

STATIC ANALYSIS OF HS CARBON Structural static analysis has been performed on the helicopter rotor blade structure by applying the angular velocity and gravity of earth. The bolting locations are fixed in all dof. Angular velocity = 25.12 Gravity of earth = 9810mm/sec.

The Boundary conditions and Loading condition for static analysis

VonMises stress of helicopter rotor blade

From the above results it is observed that the principal stresses values 181.28MPa, 41.44MPa, and 38.204MPa are less than the principal stresses values of the material 870MPa, 190MPa, and 30MPa.

DYNAMIC ANALYSIS Modal Analysis: Modal analysis is used to determine the natural frequencies and mode shapes of a structure. We can do modal analysis on a pressurised structure, such as a spinning turbine blade.

Modal analysis was carried out to determine the natural frequencies and mode shapes of a structure in the frequency range of 0 -60Hz. Boundary Conditions: Blade is arrested on one edge which is connected to hub.

Critical modes are plated below

From the modal analysis, It is observed that the maximum mass participation of 35kgs in X-direction for the frequency of 2.02Hz. It is observed that the maximum mass participation of 2.4kgs is observed in Y-dir for the frequency of 38.85Hz. It is observed that the maximum mass participation of 32kgs is observed in Z-dir for the frequency of 0.252Hz.

CONCLUSION The Helicopter rotor blade was studied for 2 different cases: Static analysis Modal analysis the above structural analysis is concluded that the helicopter rotor blade has stresses and deflections within the design limits of the material used for operating loading conditions. the HS carbon composite material helicopter blade is better than the aluminum and HM carbon materials because HS carbon composite material helicopter blade is having less weight and high factor of safety.

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