Variable K elastic constant ?

In summary, the conversation discusses the concept of a variable K elastic constant, where the value of K changes depending on the direction of movement. The idea is theorized to be possible with a rubber spring, but it may not be practical. Other factors such as viscosity or plastic deformation may also affect the value of K. This phenomenon is known as "tension stiffening" and can be seen in materials such as reinforced concrete and various fabrics.
  • #1
cala
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0
"Variable" K elastic constant ??

Difficult to put the topics on the right place...

Is there any spring (or any physical method) that could have different K elastic constant on one sense of movement than on the other?

For example K = 100 (or another value) when compressing and K = 75 (or another value) when decompressing?
 
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  • #2
I think that the simpler spring with variable K elastic constant could be made from rubber.
When you stretch this rubber spring the elastic constant would take a value K (the value of K depends on who hard is the rubber).
On the other hand during the compression of the spring the value of the elastic constant is K=0.
I’m not sure if practically a rubber spring could work but theoretically it is possible.
 
  • #3
Sorta - if you throw in viscosity or plastic deformation or something like that. If you're hoping to use that to overcome the first law of thermodynamics though, no.
 
  • #4
Almost any polymer (and some other materials) will have a different (and variable) K in tension from that in compression (except for small strains). Under tension, the polymer chains straighten out and stiffen - under compression they tend to buckle and are less stiff. The effect is called 'tension stiffening'.

Reinforced concrete does something similar - as do most fabrics (wool, cotton, etc)
 

1. What is the definition of the variable K elastic constant?

The variable K elastic constant, also known as the bulk modulus, is a measure of a material's resistance to compression. It is a measure of the ratio of stress to strain when a material is under uniform pressure.

2. How is the variable K elastic constant calculated?

The variable K elastic constant is calculated by dividing the applied stress by the strain in a material. It is typically measured in units of Pascals (Pa) or pounds per square inch (psi).

3. What factors affect the value of the variable K elastic constant?

The value of the variable K elastic constant is affected by various factors such as the material's composition, temperature, and pressure. It also depends on the direction of the applied force and the crystal structure of the material.

4. Why is the variable K elastic constant important in materials science?

The variable K elastic constant is important in materials science because it helps to determine a material's ability to withstand compression and its overall stiffness. It is also used to predict a material's response to external forces and to design structures that can withstand different types of stress.

5. How can the variable K elastic constant be measured?

The variable K elastic constant can be measured using various methods such as tensile testing, compression testing, and ultrasonic testing. These methods involve applying a known force to a material and measuring its resulting strain, which can then be used to calculate the elastic constant.

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