Several source related to the road transport industry have noted that weight is one of the most significant factors affecting vehicular fuel economy.A fundamental way to reduce weight is proper material substitution by replacing specific components with those made of lighter composite materials. F.R.P., with its higher strength to weigth ratio, can provide that substitution for steel. Application of F.R.P. composite components are already in wide use of all types of road vehicles in many developed countries and india as well. F.R.P. Leaf spring is one of such components which is fast replacing conventional metal multi leaf springs, due to its superiority in all aspects.
Composite F.R.P. leaf springs are 60% to 75% lighter than that of steel multi leaf springs, enabling either increased payload or reduce fuel consumption. Besides, giving opreating benifits, these springs have proven to be virtually unbreakable under extensive destruction tests. However, in the event of server over loading, they may fracture longitudanally due to unidirectional alignment of fibers embedded in specially processed resin matrix. While such failure reduces the spring rate and composite continues to locate the axel allowing the vehicle to be driven to a garage for repair or replacement. For steel springs, fracture across their section do not have this fail safe feature. These results are based on actual reports received from practical usage done on indian road conditions for last 27 years.
The deformation characters were found neligible after repeated life cycle programs, as it regains its original shape after removal of loads. Thus, recambering of the spring is totally eliminated & down time of maintainance is avoided except changing of worn out bushes. Fatigue life test results are tested at ARIA PUNE show that the life of composite spring is in the range of 1 Million cycles whereas steel springs can withstand only upto 0.2 Million cycles.
Softer ride characteristics are cited as another advantage, since the F.R.P. material has much greater elasticity than that of steel. A further benifit is the reduction in road noise because of damping characteristic of the special resin system formulated by ARC.
Having mono-leaf there exists no inter-leaf creaking, giving a quite comfotable ride. Being smooth suspension offers less jerks & thus lesser fatigue even on rought roads. The road grip also increases on pitted road & thus reduce skidding. The above phenomena helps for better acceleration during actual working conditions & thus gives a better control on vehicle & also helps in reducing fuel consumption.
After years of R & D F.R.P leaf springs have been developed for the first time in INDIA by ARC INDUSTRIES, an associates of the pioneer of multi product manufacturer experimenting in F.R.P. components in high caliber & technique. ARC has its own R & D facility & well equiped machine shop to build the required special purpose machinery required for their product. For testing fatigue life of the composite leaf spring, ARC has build a special purpose 6 axits testing machine at its R & D, also have developed its own standards & specifications for testing the same.
Computer aided stress analysis of the composite was employed to optimise the performance. Prototype springs where evaluated on an unusual six axis fatigue testing machine, since the simple verticle axis stroking rig, normally used for metal spring was found in-adequate for composite leaf springs with totally different properties & strength.