Thermal Stress and Spring Systems

In summary, the conversation is about finding the force in a rod made of A-36 steel with a diameter of 0.25 in and a length of 4 ft. Two springs are attached to each end of the rod and are fixed to a wall. The springs are compressed by 0.5 in when the temperature of the rod is T=40 F. The given values are k=10,000 lb/in and thermal deformation=alpha*change in temp*length. The solution involves finding the thermal deformation at T=160 F and using it in the equation F=kx to solve for F. The correct answer is 163 lbs, but the reason for this is not understood.
  • #1
christina12345
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The rod is made of A-36 steel and has a diameter of 0.25 in and a length of 4 ft. Attached to each end of the rod is a spring which is fixed to a wall. If the springs are compressed 0.5 in. when the temperature of the rod is T=40 F, determine the force in the rod when its temperature is T=160 F. It is given that k=10,000 lb/in.

Equations: F=kx, Thermal Deformation=alpha*change in temp*length

Attempted Solution: Find the thermal deformation in the rod at T=160 F, then use this in F=kx to solve for F.

I know the correct answer is 163 lbs, but I don't understand why.
 
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  • #2
Your approach is correct, why don't you carry it out? And what don't you understand?
Show your work!
 

1. What is thermal stress?

Thermal stress is the stress induced in an object due to changes in temperature. When an object is exposed to changes in temperature, it expands or contracts, which can create internal stresses that can affect its mechanical properties.

2. How does thermal stress affect spring systems?

Thermal stress can affect the performance and lifespan of spring systems. As the temperature changes, the material of the spring will expand or contract, causing changes in its length and stiffness. This can alter the spring's ability to store and release energy, and can potentially lead to failure if the stress exceeds the material's strength.

3. How can thermal stress be mitigated in spring systems?

One way to mitigate thermal stress in spring systems is to carefully select the material of the spring. Certain materials, such as stainless steel, have a lower coefficient of thermal expansion, which means they are less affected by changes in temperature. Additionally, incorporating design features such as stress-relieving loops or adjusting the spring's preload can help reduce the impact of thermal stress.

4. Can thermal stress cause permanent deformation in spring systems?

Yes, thermal stress can cause permanent deformation in spring systems if the stress exceeds the material's yield strength. This can result in a change in the spring's length and stiffness, affecting its performance and potentially leading to failure.

5. How does ambient temperature affect thermal stress in spring systems?

The ambient temperature can have a significant impact on the thermal stress experienced by a spring system. Extreme temperatures, whether hot or cold, can cause the material of the spring to expand or contract more than usual, leading to higher levels of stress. Additionally, rapid changes in temperature can also increase thermal stress, so it's important to consider the environment in which the spring system will be used.

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