Assignment of Hooke's Law
Introduction /Definition
Hooks law , law of elasticity discovered by the English scientist Robert Hooke in 1660,which states that ,for relatively small deformation of an object ,the displacement or size of the deformation is directly proportional to the deformation force or load.
In physics Hooks law is an empirical law which states that the the force F needed to extend or compress a spring by some distance x scales linearly with respect to that distance that is Fs =Kx .Hooks equation holds (to some extent) in many other situations where an elastic body is deformed ,such as wind blowing on a tall building ,and a musician plucking a string of a guitar .An elastic body or material for which this equation can be assumed is said to be linear elastic.
Hooke’s law states the strain on the material is directly proportional to the stress applied to the material.
Formula
Fs= -kx
Fs= Spring Constant.
k= Spring Constant
x= Spring stretch or compression
The maximum compression of a car suspension with mass 2000kg ( 500kg on each wheel) shall not exceed 0.1m.
F =(500kg)(9.81m/s)
F=4905N = 4.95kN
The required spring constant for the suspension can be calculated
k= -F/s
=(4905N)/(0.1m)
=49050N/m
k= 49kN/m
Importance in Automotive Industry
Springs used in Automotive industry because spring ability to store energy makes it ideal to use as a dampener to absorb vibration.
The spring manufacturing process and spring manufacturing equipment is a bit more complicated, but spring themselves are simple mechanism that behave very predictable ,as long as you know what to except.
When manufactures produce springs, they need to know how the spring behaves Its obvious that the same spring used for trucks suspension would not work in a ball- point pen but for many mechanical application ,minute differences in spring behavior will determine whether the system function or not.
Suspension system play an important role in new vehicles . Its duty is to damp , smooth out the shock impulse further more to absorb or dissipate energy so that the suspension system provides the comfort and safety for for the passenger and vehicles. Three material are selected to simulate the spring steel ,copper alloy and carbon composite.
The Spring Constant
The spring constant determine exactly how much force will be required to deform a spring . The standard international SI unit of measurement for spring constant is Newton/meter ,but in North America they are often measured in pounds/inch .A higher spring constant means a stiffer and vice versa.
Working Principle of suspension System
If the road is very flat , then the car does not need a suspension . But broads tend to be uneven ,and even newly paved roads have uneven sections of the road that affect the wheel of cars. According to Newtons law of motion , all forces have size and direction .When the car is driving on a uneven road , the wheel produce a vertical acceleration. Therefore , the car car needs a system that absorb the energy generated by the wheels in the vertical direction, making the cars body less affected by the bumps. The suspension system keeps a car body from being disturbed as a the car passes through the uneven roads.
Role of Spring
The most common spring on the suspension system is the coil spring , which has good performance and low price. The deformation of the spring and the force of the spring follow Hooke's law in physics. The spring has main two function , one is a buffer device for the suspension system , the other is to keep the wheels contact with the road when passing through the uneven road.
