**9. References**

72 Materials Science and Technology

minimum weight. The number of leaves is reduced one by one, without changing any of the dimensions, and found out results for same full bump load. The results are shown in Table 10. From the FEM results in Table 10, it is understood that the leaf spring with 3 leaves violates the constraints of deection and stress. Therefore, further optimization is terminated at this point. It is evident that only 4 leaves (2 full length leaves and 2 graduated leaves) are sufcient to withstand the applied load. The composite leaf spring with 4 leaves

175

To provide ride comfort to passenger, leaf spring has to be designed in such a way that its natural frequency is maintained to avoid resonant condition with respect to road frequency. The road irregularities usually have the maximum frequency of 12 Hz(Yu&Kim,1988). Therefore, leaf spring should be designed to have a natural frequency, which is away from 12 Hz to avoid the resonance. Stiffness is more and weight is lower of CLS than that of SLS. Therefore, first natural frequency of CLS (14.3 Hz) will be higher (126.98%) than that of SLS (6.3 Hz). First natural frequency of CLS is nearly 1.2 times the maximum road frequency and therefore resonance will not occur, and it provides improved ride comfort. After optimization, CLS has a fundamental natural frequency of 41.5 Hz, which is 3.46 times the maximum road frequency, which ensures that resonance

Design and experimental analysis of composite multi leaf spring using glass bre reinforced polymer are carried out. Compared to steel spring, the composite leaf spring is found to have 67.35% lesser stress, 64.95% higher stiffness and 126.98% higher natural frequency than that of existing steel leaf spring. The conventional multi leaf spring weighs about 13.5 kg whereas the E-glass/Epoxy multi leaf spring weighs only 4.3 kg. Thus the weight reduction of 68.15% is achieved. Besides the reduction of weight, the performance of the leaf spring is also increased. Compared to the steel leaf spring (13.5 kg), the optimised composite leaf spring weighs nearly 76.4% less than the steel spring. Ride comfort and life of CLS are also more when compared to SLS. Therefore, it is concluded that composite multi leaf spring is an effective replacement for the existing steel leaf

6 97 324 5 104 409 4 150 607 3 308 1079

ANSYS Allowable ANSYS Allowable

217

**Maximum direct stress along the length of leaf spring (MPa)** 

610

weighs about 3.18 kg only. It gives a weight reduction of 76.4%.

**No.of Leaves Maximum Deflection (mm)** 

Table 10. Results of optimization of number of leaves.

7 61

**6. Ride comfort** 

will not occur.

**7. Conclusion** 

spring in light passenger vehicles.

ANSYS 7.1. Manual, (1997). Ansys Inc, New York


**1. Introduction**

Beyond the assembling of components laser welding procedures are also increasingly applied in steel manufacturing. Reasons for this trend are: high joining velocities, concentrated heat input resulting in extremely thin heating zones, and nearly constant seam geometries along the welding line. So, for example, welding aggregates are installed at the beginning of electrolytic or hot-galvanizing manufacturing lines to join coils of different thickness or grade for continuous production, cf. Figure 1. To minimize shutdowns welding must be extremely reliable, since the joining zone of the 'endless strip' has to resist high thermal and mechanical loads, such subsequent annealing, bending and tension. Failures lead to technical breakdowns, repairs, and loss of production, which should be avoided as much as possible. Moreover, the welding process must be such robust that material with imperfections, such as oxidations or materials ripples, would be also accurately joined. Welding defects, for instances cracks, pores or seam shrinkages, cf. Figure 2, lead to reduction of the cross-sectional area and, therefore, represent critical regions w. r. t. damage and failure. From the engineering point-of-view it is essential to know, whether residual stresses or heat-induced degradations of the materials strength following from joining become critical or not. This question can be answered by e.g. extensive experimental investigations, during which material combinations, geometries (i.e., thickness) and welding parameters such as joining velocity, welding power or laser caustic are varied. Subsequent tensile tests of the different seams yield the critical

**Modeling, Simulation and Experimental** 

**of As-Rolled Steels** 

*3Department Research and Development,* 

*Thyssen Krupp Steel Europe AG, Duisburg \*Formerly with ThyssenKrupp Steel Europe AG* 

**Hydrogen Diffusion During Laser Welding** 

*1Freudenberg-Schwab Vibration Control GmbH & Co. KG, Velten b Berlin* 

*2Strip Processing Lines Division, SMS Siemag AG, Hilden* 

**Studies of Distortions, Residual Stresses and** 

T. Böhme1,\*, C. Dornscheidt2,\*, T. Pretorius3, J. Scharlack3 and F. Spelleken3

**5**

*Germany* 

strength, which is compared with the loading conditions of the production line.

However, such experiments are time-consuming and, therefore, expensive. Moreover, the derived predictions only hold for the used materials, geometries and investigated process parameters; extrapolations of the results beyond these conditions are not possible. Consequently, it is desirable to have a general framework, which allows for the prediction of the thermal and mechanical material response following from an arbitrary choice of

