18-08-2012, 02:33 PM
Elliptical
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INTRODUCTION
A multi-leaf spring for an automotive suspension, consisting essentially of a master leaf supporting the frame structure of the vehicle body, an auxiliary leaf underlying the master leaf and secured thereto by a center bolt, at least two removable inserts interposed between those overlapping portions of the two leaves which are remote from the central portions of the leaves and a central fixed inset interposed between and fixedly secured to the leaves, the spring thus constructed being adapted to eliminate practically all the modes of vibration and to be removed readily and economically when worn.
MULTI-LEAF SPRINGS
Multi-leaf springs are widely used for automobile and rail road suspensions. It consists of a series of flat plates, usually of semi- elliptical shape as shown in figure s. The leaves are held together by means of two U-bolts and a centre clip. Rebound clips are provided to keep the leaves in alignment and prevent lateral shifting of the plates during the operation. The longest leaf, called the master leaf, is bent at both ends to form the spring eye. At the center, the spring is fixed to the axle of the car. Multi- leaf springs are provided with one or two extra full length leaves in addition to the master leaf. These extra full-length leaves are stacked between the master leaf and the graduated-length leaves. The extra full-length are
provided to support the transverse shear forces. The purpose of analysis, the leaves are divided into two groups, namely master leaf along with graduated-length leaves forming one group and extra full-length leaves forming the other.
The following notations are used in the analysis:
CONSTRACTION MATERIALS
Multi leaf spring construct from steel plate. Steel plate is an alloy of iron that contains the elements iron as the major component and small amounts of carbon as the major alloying element. The carbon contents in steel ranges from 0.02% to 2.0% by weight. Small amounts, generally on the order of few percent, of other alloying elements such as manganese, silico chromium, nickel and molybdenum may also be present, but it is the carbon content that turns iron into steel. Also the properties like toughness and ductility are obtained by the addition of elements like manganese, chromium, nickel, molybdenum, tungsten, vanadium, silicon etc. Steel is the most common and widely used metallic material l in today society. It can be cast or wrought into numerous forms and can be produced with tensile strength exceeding 5GPa.
Role of Carbon in Steel
Generally, carbon is the most important commercial steel alloy.
Increasing carbon content increases hardness and strength and improves harden ability. But carbon also increases brittleness and reduces weld ability because of its tendency to form. This means carbon content can be both a blessing and a curse when it comes to commercial steel. And while there are steels that have up to 2 percent carbon content, they are the exception. Most steel contains less than 0.35 percent carbon. To put this in perspective, keep in mind that 35/100 of 1 percent.
Now, any steel in the 0.35 to 1.86 percent carbon content range can be hardened using a heat-quench-temper cycle Carbon is the most important element in steel as slight variations in percentage cause very marked changes in physical and mechanical properties. When a small amount of carbon is added to iron, the properties which give steel its great value begin to appear. In plain carbon steels manganese, phosphorus and sulfur are present in amounts which do not interfere in any way with the effect that carbon variation has on the properties of the steel. Thus, steels may be considered binary alloys of iron and carbon. In alloy steels, the effects of the alloying elements must be considered. The plain carbon steels represent the most important group of engineering materials known. They represent by far the major percentage of steel production and the widest diversity of application of any of the engineering materials. These applications are so diversified that anything like a complete listing or even a classification on the basis of application is not feasible.