What is Surge in Springs?

jaspal rautela · 2012-06-16T19:34:49+00:00

I am Jaspal and I have this question about machine designs. what is meant by surge in spring? Could some mechanical engineers of the community share the reason for its use?Answer:The concept of "Surge in Spring" or "Spring Surge" primarily deals with the phenomenon observed in spring systems, specifically helical compression springs, where a wave of compression moves through the spring coils due to external forces. This wave, also known as a surge wave, moves back and forth between the ends of the spring, causing a state of continuous vibrational motion, which can lead to potential failure of the spring due to induced high stresses.In more detail, when one end of a helical compression spring is fixed on a rigid support and the other end is subjected to a periodic external force, a wave of compression begins to travel along the length of the spring. This wave is initiated at the free end where the force is applied, compressing the coils and transmitting the energy to the next coil, and so forth. This process continues until the wave hits the fixed end, where it reflects back, repeating the cycle.Under certain circumstances, this cycle can reach a state of resonance, which occurs when the time taken by the wave to complete motion from one end to the other equals the time taken between two successive applications of the periodic external force. Resonance can result in large deflections in the spring system and induce high stresses.A classic example of the surge phenomenon can be seen in valve springs in internal combustion engines, where the springs are subjected to periodic forces due to the opening and closing of the valves.To avoid the potentially damaging effects of spring surge, several precautions can be taken:1. Designing the spring with a natural frequency at least 15-20 times greater than the frequency of the periodic force to avoid resonance.2. Providing friction dampers on the central coils of the spring to break the continuity of the surge wave and prevent further propagation.3. Using standard wires for the springs, as on coil compression, the standard wired coils approach each other closely, producing coil friction that can help avoid surge wave propagation.These precautions aim to increase the natural frequency of the spring, reduce the propagation of the surge wave, and increase the resilience of the spring to avoid the surge condition.The mathematical expression to calculate the natural frequency for springs clamped between two plates takes into account factors like the diameter of the wire, mean diameter of the spring, number of active turns, modulus of rigidity, acceleration due to gravity, and density of the material of the spring. This helps in the effective design and material selection of springs to prevent surge.

What is Surge in Springs?

jaspal rautela

Member

Updated: Oct 27, 2024

Views: 5.9K

I am Jaspal and I have this question about machine designs. what is meant by surge in spring? Could some mechanical engineers of the community share the reason for its use?
Answer:
The concept of "Surge in Spring" or "Spring Surge" primarily deals with the phenomenon observed in spring systems, specifically helical compression springs, where a wave of compression moves through the spring coils due to external forces.
This wave, also known as a surge wave, moves back and forth between the ends of the spring, causing a state of continuous vibrational motion, which can lead to potential failure of the spring due to induced high stresses.
In more detail, when one end of a helical compression spring is fixed on a rigid support and the other end is subjected to a periodic external force, a wave of compression begins to travel along the length of the spring.
This wave is initiated at the free end where the force is applied, compressing the coils and transmitting the energy to the next coil, and so forth.
This process continues until the wave hits the fixed end, where it reflects back, repeating the cycle.
Under certain circumstances, this cycle can reach a state of resonance, which occurs when the time taken by the wave to complete motion from one end to the other equals the time taken between two successive applications of the periodic external force.
Resonance can result in large deflections in the spring system and induce high stresses.
A classic example of the surge phenomenon can be seen in valve springs in internal combustion engines, where the springs are subjected to periodic forces due to the opening and closing of the valves.
To avoid the potentially damaging effects of spring surge, several precautions can be taken:
1. Designing the spring with a natural frequency at least 15-20 times greater than the frequency of the periodic force to avoid resonance.
2. Providing friction dampers on the central coils of the spring to break the continuity of the surge wave and prevent further propagation.
3. Using standard wires for the springs, as on coil compression, the standard wired coils approach each other closely, producing coil friction that can help avoid surge wave propagation.
These precautions aim to increase the natural frequency of the spring, reduce the propagation of the surge wave, and increase the resilience of the spring to avoid the surge condition.
The mathematical expression to calculate the natural frequency for springs clamped between two plates takes into account factors like the diameter of the wire, mean diameter of the spring, number of active turns, modulus of rigidity, acceleration due to gravity, and density of the material of the spring. This helps in the effective design and material selection of springs to prevent surge.

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mechky

Member • Jun 16, 2012

I am copying down the exact explanation of surge in springs from a machine design book. It is well explained there and you can ask if you still have any doubt.

When one end of a helical spring is resting on a rigid support and the other end is loaded
suddenly, then all the coils of the spring will not suddenly deflect equally, because some time is
required for the propagation of stress along the spring wire. A little consideration will show that in the
beginning, the end coils of the spring in contact with the applied load takes up whole of the deflection
and then it transmits a large part of its deflection to the adjacent coils. In this way, a wave of compression propagates through the coils to the supported end from where it is reflected back to the deflected end. This wave of compression travels along the spring indefinitely. If the applied load is of fluctuating type as in the case of valve spring in internal combustion engines and if the time interval between the load applications is equal to the time required for the wave to travel from one end to the other end, then resonance will occur. This results in very large deflections of the coils and correspondingly very high stresses. Under these conditions, it is just possible that the spring may fail. This phenomenon is
called surge.
The surge in springs may be eliminated by using the following methods :
1. By using friction dampers on the centre coils so that the wave propagation dies out.
2. By using springs of high natural frequency.
3. By using springs having pitch of the coils near the ends different than at the centre to have
different natural frequencies.

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Brijendra Rai

Member • Apr 15, 2017

The above paragarh is written in THE TEXTBOOK OF MACHINE DESIGN by R.S.KHURMI & J.K.GUPTA

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PRADIP CHAKRABORTY

Member • Apr 27, 2017

jaspal rautela
I am Jaspal and I have this question about machine designs. what is meant by surge in spring? Could some mechanical engineers of the community share the reason for its use?
If a spring coil comes under an impact load,the generated stress starts propagating along the spring wire.The end coil of the spring adjacent to the applied load experiences the whole deflection and transmit the same to the neighbourhood coil accordingly.This phenomenon may cause very large deflection and subsequent resonance depending upon the time travelled by the deflection wave.This phenomenon is called surge.

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