OPTIMIZATION OF MACPHERSON SUSPENSION

SYSTEM

Under the guidance of

Prof. K. Muruganandham,

Kumaraguru college of technology

Submitted by,

Gautam Makeshbabu(0810103012)

Kumar.P (0810103023)

Objective

• Analyze the reasons for frequent failures in the TATA INDICA’s front wheel suspension system.

• To optimize the existing spring. To increase the stiffness and load carrying capacity of the spring.

• To decrease the shear stress acting on the spring.

Problem Analysis

Design Method

Usage Environment

Failure

Shape of spring

Coil diameter

Number of turns

Faulty manufacture

Unreasonable load

Poor maintenance

Rugged road conditions

Analysis of Existing spring

• The old spring is tested in Si’Tarc testing center and the stiffness value is found to be

• K=19.19 N/mm• Then the CATIA model is made, which is

imported in ANSYS and its analyzed for value of deflection and Stress.

• Using the formulae the value of deflection and stress values are found out.

CalculationStiffness calculation

K= 19.11 N/mm

Shear stress calculation:

C=10.08

k = 1.14

Shear stress T= 1103.84 N/mm2

Design of Experiments

• The parameter that can be changed are • Coil diameter• Shape of spring• Mean diameter and number of turns.

Factors High Low

Shape of Spring Helical Conical

Number of turns 7 6

Coil Diameter(mm) 12.7 12

• We have increased the coil diameter from 12 mm to 12.7 mm which is SWG 7/0.

• We also decreased the number of turns from 7 to 6.

• The spring is made conical and its maximum diameter of 160 mm and minimum diameter of 130 mm.

• The shear stress for the model is calculated and is checked with the maximum value.

Calculation

Comparison of resultsData Existing spring New spring

Spring type Helical Conical

Coil diamter 12 mm 12.7 mm

Mean diameter 131 mm -

Maximum dia and Minimum diameter 160 &130 mm

Number of turns 7 6

Stiffness 19.19 N/mm* 21.1 N/mm*

Maximum load carrying capacity 500 kgs* 584 kgs*

Maximum shear Stress 1103 N/mm2 1040 N/mm2

* - Data’s from Si’Tarc testing center.

Data

Results of existing spring

Deformation in ansys

Shear stress

Equivalent stress

Results for new spring

Deflection

Equivalent stress

Shear stress

Conclusion

• The optimized design is made by changing major parameters of existing spring.

• The new spring is manufactured and is tested in Si’Tarc lab.

• The stiffness is increased by 9.99% thereby the load carrying capacity is increased by 16%.

• The shear stress is decreased by 5.71%

Thank you