Vehicle efficiency and performance mainly depends on its power to weight ratio
In order to reduce the weight of front axle, reinforced composite will provide the best replacement to steel. As front drive axle is one of the crucial components in automobile, it is a prime requirement to verify the reliability of composite reinforced front derive axle. As front drive axle is subjected to reversible stresses it is necessary to carry out its precise analysis. The best way is to determine the load that comes on axle and analyze.
To address all these issues, it is felt necessary to carry out experimental and Finite Element Analysis of Reinforced Composite Front Drive Axle with following objectives:
To evaluate the stress and angular deformation in Reinforced Composite Front Drive Axle
To estimate the optimum thickness of coating
To find out percentage weight reduction
In this study, the front drive axle of Maruti Alto 800 has been selected.
|
|
Diameter of axle shaft (d) |
22 |
Diameter of Ends (d1) |
18 |
Length (L) |
380 |
Speed of drive Axle = Tyre revolutions × Ratio of first gear
= 10.73 ×3.415 = 36.64 rev/sec
Torque in drive axle =
The torque acted on drive axle is 84600 N-mm.
Experimental stress analysis of composite reinforced front drive axle of Maruti Alto 800 has been carried out using strain gauge technique. ANSYS 15.0 has been used to carryout finite element analysis of front drive axle with and without reinforcement. Finite element analysis of steel axles with various thickness of composite coating is carried out and the variant with 5 mm coating thickness was found to have the least angular deformation and induced stresses. The same variant was then tested experimentally on Strain recorder. The results, in terms of von-Mises stresses and Angular deformation obtained by both these methods have been compared and found to have a fairly good agreement between each other, with an error of a meagre 0.46%.
FE analysis of steel front drive axle is carried out using ANSYS is as described below.
The CAD model of front drive axle has been prepared in CATIA V5 software in such a way that it closely resembles the actual front drive axle.
Meshing
In ANSYS area of front drive axle is meshed using Tetrahedral element, Solid 182.
Defining Material Properties
Following material properties of Steel [SM45C] have been defined:
Material Density = 7850 Kg/ m3. Young’s Modulus (E) = 2 Х 105 N/ mm2
Poisson’s ratio (
Loading and Boundary Conditions
Boundary conditions have been applied on the meshed model of axle to simulate actual working conditions. Application of torque and restricting the degree of freedom are two steps involved in defining boundary conditions. The FE model considers a moment in terms of torque 84600N-mm at one end and fixed displacement constraint at another end.
The results obtained from the solver are displayed in the post-processor. The angular deformation and von-Mises stresses are as shown in
FE analysis of composite axle as with and without reinforcement. It is carried out using ANSYS as described below:
Modeling and Meshing
The meshed model of steel [SM45C] drive axle is coated with help of linear structural shell elements with optimal three layers of 1mm thickness with best stacking order [90, 45, -45] to obtain coating thickness of 3 mm. Similar procedure has been adopted to prepare models with coating thickness of 4 mm and 5 mm with best stacking order [90, 45, -45, 0] & [90, 45, -45, 45, 0] respectively.
Defining Material Properties
Properties of composite material and steel are as listed in
|
|
|
Young’s Modulus (Ex) |
40300 MPa |
207000 MPa |
Young’s Modulus (EY) |
6210 MPa |
- |
Young’s Modulus (EZ) |
40300 MPa |
- |
Poisson’s Ratio (ν) |
0.2 |
0.3 |
Density (ρ) |
1723.65 kg/m3 |
7600 Kg/m3 |
Shear Modulus (GXY) |
3070 MPa |
80000 MPa |
Shear Modulus (GYZ) |
2390 MPa |
- |
Shear Modulus (GZX) |
1550 MPa |
- |
Yield Strength- Tensile |
2500 MPa |
275 MPa |
Yield Strength- Compressive |
3150 MPa |
370 MPa |
Loading and Boundary Conditions
Boundary conditions have been applied on FE models of both the variants of composite axle i.e. with and without the reinforcement so as to simulate actual working conditions. Applying torque and restricting the degree of freedom are two steps involved in defining boundary conditions. The FE model considers a moment in terms of torque of 84600N-mm at one end and fixed displacement constraint at another end.
The results obtained from the solver are displayed by post-processor. von-Mises stresses and angular deformation in composite axle are as shown in
Experimental stress analysis of reinforced composite front drive axle has been carried out using strain gauge technique wherein electrical resistance strain gauge are used. The composition of composite is 15% Al2O3-54 % SiO2-12 % CaO.
To manufacture the reinforced composite axle, a steel axle of 12 mm diameter is used and layers of glass fiber reinforcement are applied on it. Finally, machining is carried out to obtain 5 mm thickness of the reinforcement layer so that the overall diameter of the axle will be 22 mm. The manufactured reinforced front drive axle is as shown in
Considering the load coming on the drive axle and strain developed in it, electrical resistance type strain gauge has been selected. Using SG496 adhesive, the strain gauges are bonded. Standard procedure of strain gauge mounting is followed and to verify the correctness of mounting, a multi-meter has been used to measure the strain gauge resistance (350 Ω).
To simulate actual loading conditions, the desired torque on reinforced composite front drive axle is applied using torsional testing machine. The strain developed in the axle due to application of desired torque is recorded with the help of a strain gauge recorder.
The strain registered by the strain recorder is in micro strain. Following calculations are performed to obtain stresses.
Sample calculation
Strain recorded in reinforced composite axle is 319-micro strain for applied torque of 84600 N-mm.
For torsional analysis strain is considered to be 319×√2 =451.13 micro strain.
As per Hooke’s law,
As per the specification of composite glass fiber material,
Young’s modulus (Ex) = 40300 x 107 N/mm2
Substituting values of E and ε in equation 1,
Induced Stress (σ) = 181.80 MPa.
In today’s scenario, in order to enhance the efficiency of automobile, design engineers and researchers are looking for suitable lightweight material for manufacturing various components of automobile. Composite materials are being used in the automobile industry to reduce the weight. In case of composite materials its strength and reliability are the major issues particularly when component is subjected to high speed and torsional load. In order to get benefits of lightweight as well as strength reinforced composites are recently introduced as best replacements to conventional materials. This work is intended to identify the best option among various materials which include steel, composite and reinforced composite to manufacture a front drive axle of Alto 800, to optimize the coating thickness of composite material on steel front drive axle and to determine the percentage weight reduction. As such torsional stress analysis of conventional as well as composite and reinforced composite axle has been carried out using FE analysis. To verify the FEA results, experimental analysis of reinforced composite front drive axle has been carried out using strain gauge technique.
From the results listed in
|
|
|
Conventional |
184.26 |
0.21 |
Iteration 1 (Only Composite) |
220.04 |
1.33 |
Iteration 2 (3mm composite reinforcement) |
210.07 |
0.256 |
Iteration 3 (4mm composite reinforcement) |
198.-03 |
0.182 |
Iteration 4 (5mm composite reinforcement) |
182.64 |
0.042 |
One of the significant conclusions that can be drawn from the results enlisted in
|
|
|
|
Stress |
182.64 |
181.80 |
0.46 |
|
|
Conventional [SM45C] |
0.978 |
Reinforced composite |
0.568 |
Decrease in weight (%) |
41 |
From this extensive FE and experimental analysis of steel, composite and Composite reinforced composite front drive axle, the following conclusions have been drawn:
Composite material with the specification 54%SiO2-15%Al2O3-12%CaO is one of the best combinations as a replacement to conventional steel front drive axle.
The angular deformation and stress observed in drive axle made up of only composite material are more than in steel drive axle. This necessitates the drive axle to be manufactured in composite with reinforcement in order to improve the strength and achieve the weight reduction as well.
In case of automobile components, reinforcement is necessary to get benefits of weight reduction as well as improvement in strength.
The composite glass fiber reinforced front drive axle with a 5mm coating thickness is the best replacement to the steel front drive axle of Maruti Alto 800.
Total 41% reduction in heaviness is possible by replacing the conventional steel [SM45C] front drive axle with a composite reinforced glass fiber front drive axle.
Experimental and finite element analysis methodology of reinforced composite glass fiber front drive axle can be further extended to dynamic state analysis.
I would like to thank the technicians at Mechanical Engineering Department's laboratory of TKIET, Warananagar for their assistance in providing me with the resources I needed to run the application and perform the experimentation