does a spring under constant tension age?

[coppercone2]

if there is a spring on a light tension, a small weak one, does it age? I don't mean in a mechanism. Just between two posts.

I heard like 100 years+

Hard to find info because its all car related shit that comes up

[nfmax]

Even if the stress is kept strictly constant, temperature changes will cause strain cycling which may well cause eventual fatigue failure. Also don't forget corrosion and/or reaction with substances in the environment

[Kleinstein]

There is some creep, but if the stress is not close to breaking and the temperature not high (that is compared to some 50% of the melting point) creep is usually slow.
With material internal stress there can be some inial slightly faster creep, but it will slow down.
HIgh stress can speed up corrosion.

[CatalinaWOW]

I think it is impossible to meaningfully answer the question.  Conceptually it will age.  But in a protected environment that might take centuries or more.  I have seen seashore environments in hot regions where it might significantly relax in weeks.  But for the vast majority of applications I wouldn't expect any problems over human lifetimes.

Examples where springs have done fine over those time frames are hairsprings in watches, meter movements and the tensioning springs on the tuning strings of old radios.

[coppercone2]

 :=\I figured it must be pretty long under ideal conditions. But how do projections look for say 100 years, 1000 years, 10000 years, 100000 years, million?

Say in a quartz tube with inert gas. A small spring like the kind that might be in a larger watch (like a large pocket watch)?

And how does the material look after that. For instance if you have a helix spring that is extended between two posts, laying on the surface for minimum 'hanging' tension, after say... 1 million years, if you got it and put it in a piston, would it work as a compression spring ? Like does it switch states the same way if you drew the spring out so its naturally extended vs naturally contracted? Like a spring behavior inversion without actual stretching?


Amusing to think about because you can extend a spring perfectly without hysteresis to get the perfect shape you want. If you want to actually extend it, you need to guess at how much it will deform. But if you just stretch it and wait 1 million years, you could get the perfect spring shape that you measure by initial displacement of stretching?

[jpanhalt]

Your activities here are limited by life, not perpetuity.  100 years should be more than enough for any practical purpose.

[coppercone2]

tell that to the pitch drop experiment

if watching tar drip through a funnel is interesting enough to put on a web cam, so is a spring to put in a time capsule for future generations.

Also interesting to know for possibly explorer robots that have to travel say 1000+ years before landing on a planet to open a instrument hatch that is spring loaded or something like that.

if you are not familiar with long term experiments, here is the most commonly known one
https://en.wikipedia.org/wiki/Pitch_drop_experiment

[TimFox]

A technical article from a spring vendor:
https://idcspring.com/spring-lose-tension-when-compressed/
Most of the literature about spring fatigue (not the malaise we feel in April) is about springs subject to cyclic stress.

[jpanhalt]

You have yet to say the alloy used or the temperature at which it is formed.  I suspect Nitinol differs from pure nickel, carbon steel, or stainless steel of various alloys.  Future generations?  1 million years?  You are just trying to make conversation.  I can't imagine that is something you really need to know,  aka trolling.

[IanB]

if there is a spring on a light tension, a small weak one, does it age? I don't mean in a mechanism. Just between two posts.

I heard like 100 years+

Hard to find info because its all car related shit that comes up

Material science. Mechanical engineering. Metallurgy. These are your search domains.

Springs are usually constructed from metals. Springy metals have properties characteristic of solids. Solids have an elastic limit, which is an amount of stress they can withstand before undergoing permanent plastic deformation. Inside the elastic limit, solids will return to their original shape after stress is applied. This is because the springiness of the material results from springiness of the crystalline structure and interatomic bonds. Plastic deformation occurs under excessive stress when crystal lattices inside the structure experience slip, similar to the fault lines in geology that cause earthquakes.

A spring under tension could experience a loss of tension if subjected to external factors that might encourage slipping in the crystal lattice, such as heat, vibration, chemical attack, and so on.

The pitch drop experiment is different, since the pitch in question is not a solid--it is a liquid. Since it is a liquid, it does not have an elastic limit, and it will deform in a plastic manner if even a small stress is applied.

[coppercone2]

You have yet to say the alloy used or the temperature at which it is formed.  I suspect Nitinol differs from pure nickel, carbon steel, or stainless steel of various alloys.  Future generations?  1 million years?  You are just trying to make conversation.  I can't imagine that is something you really need to know,  aka trolling.

ok buddy

[CatalinaWOW]

:=\I figured it must be pretty long under ideal conditions. But how do projections look for say 100 years, 1000 years, 10000 years, 100000 years, million?

Say in a quartz tube with inert gas. A small spring like the kind that might be in a larger watch (like a large pocket watch)?

And how does the material look after that. For instance if you have a helix spring that is extended between two posts, laying on the surface for minimum 'hanging' tension, after say... 1 million years, if you got it and put it in a piston, would it work as a compression spring ? Like does it switch states the same way if you drew the spring out so its naturally extended vs naturally contracted? Like a spring behavior inversion without actual stretching?


Amusing to think about because you can extend a spring perfectly without hysteresis to get the perfect shape you want. If you want to actually extend it, you need to guess at how much it will deform. But if you just stretch it and wait 1 million years, you could get the perfect spring shape that you measure by initial displacement of stretching?

There are ways to estimate such lifetimes.  But they aren't off the cuff answers.  You haven't been willing to adequately specify your experiment so why would you expect a casual response that would actually make a decent Phd thesis.  IanB has mentioned a few of the areas to be examined.  At the time scales you mention you will also have to estimate cosmic ray flux and many other factors.

[thermistor-guy]

if there is a spring on a light tension, a small weak one, does it age? I don't mean in a mechanism. Just between two posts.

I heard like 100 years+
...

That longevity seems to be possible, e,g. in old clocks and firearms. Discussion here:

https://www.practicalmachinist.com/forum/threads/spring-aging.170486/

Maybe do a search for "spring steel ageing".

[ejeffrey]

if there is a spring on a light tension, a small weak one, does it age? I don't mean in a mechanism. Just between two posts.

I heard like 100 years+

Hard to find info because its all car related shit that comes up

There is a theoretically material property called the true elastic limit which is the stress under which dislocations won't move.  It's generally impractical to measure, but the idea is that yes, very small deformation, even dynamically won't age the material.

At larger stress, the crystal lattice will move, causing plastic deformation.  Even then for good spring materials there will be some initial dislocation movement but it won't continue indefinitely.  However if subject to dynamic stress, each motion will cause some deformation and eventually (maybe a very long time) the spring can wear out.

Some metals can anneal a bit at room temperature, or common ambient temperatures. In these they will continually relax over time.  But you wouldn't normally make a spring out of these materials.

[CatalinaWOW]

if there is a spring on a light tension, a small weak one, does it age? I don't mean in a mechanism. Just between two posts.

I heard like 100 years+

Hard to find info because its all car related shit that comes up

There is a theoretically material property called the true elastic limit which is the stress under which dislocations won't move.  It's generally impractical to measure, but the idea is that yes, very small deformation, even dynamically won't age the material.

At larger stress, the crystal lattice will move, causing plastic deformation.  Even then for good spring materials there will be some initial dislocation movement but it won't continue indefinitely.  However if subject to dynamic stress, each motion will cause some deformation and eventually (maybe a very long time) the spring can wear out.

Some metals can anneal a bit at room temperature, or common ambient temperatures. In these they will continually relax over time.  But you wouldn't normally make a spring out of these materials.

When you start talking about million year time frames as coppercone wants to talk about you need to consider other sources of the energy for dislocations.  Radioactive decay of impurities and nearby materials.  Cosmic rays.  Oxidation.   Diffusion of hydrogen and other small molecules.  In an open universe entropy eventually requires that the stored energy in the spring will dissipate.  Hundreds of billions of years, but eventually.

All very interesting philosophically, but in an engineering sense a lightly stressed spring won't relax.

[IanB]

All very interesting philosophically, but in an engineering sense a lightly stressed spring won't relax.

Which is a good thing. Many springs are hidden in plain sight and are not obvious. For instance, every metal girder bridge. The bridge structure is under permanent stress, and the structural members are behaving like springs, bending slightly under the applied forces, but not yielding. If the structure did yield, then over time such bridges would gradually sag and fall down. But they don't. Thankfully, even after 100 years, metal bridges are exactly the same shape as when they were built.

[Circlotron]

Your activities here are limited by life, not perpetuity.  100 years should be more than enough for any practical purpose.

"Hope springs eternal."

[coppercone2]

so would this spring invert like I postulated? After a long time, would a extended spring that wants to contract turn into a spring that is at rest in its stretched position, aka be the opposite spring? would it resist compression just as it previously resisted expansion?

How would this spring compare to a spring that is stretched out after manufacture?


is the creep deformation over a long time different from the rapid deformation that you get from over extending it? Because if you wanted the spring to rest in its expanded state after manufacture you would need to over stretch it so it retracts to the desired position. But a aged spring would be at this desired position without ever having been over extended.

I am wondering if it would be a superior spring. It seems that it underwent less stress during its manufacture.

[Kleinstein]

It really depends on the material. Some materials (e.g. pure copper) are more prone to creap than others. Creep in copper is observed when clamping wires and they may loosen over time with clamps that use high local stress. Other materials can withstand quite some stress over a long time with no observable creep.

The deformation from creep and fast deformation can be different (still depends on the material). It is quite normal that strong materials are intentionally deformed during manufacturing. E.g. steel is cold rolled to make it harder. Similar cold deformed copper gets harder and annealing softens it.

[TimFox]

In general, when good spring properties and hardness are required, an alloy is required (e.g., bronze instead of copper, steel instead of iron).
The "impurity" minority component atoms stop the majority crystals from moving around (simple-minded explanation).

[CatalinaWOW]

so would this spring invert like I postulated? After a long time, would a extended spring that wants to contract turn into a spring that is at rest in its stretched position, aka be the opposite spring? would it resist compression just as it previously resisted expansion?

How would this spring compare to a spring that is stretched out after manufacture?


is the creep deformation over a long time different from the rapid deformation that you get from over extending it? Because if you wanted the spring to rest in its expanded state after manufacture you would need to over stretch it so it retracts to the desired position. But a aged spring would be at this desired position without ever having been over extended.

I am wondering if it would be a superior spring. It seems that it underwent less stress during its manufacture.

In general springs do not have a preferred direction.  The most common exceptions are physical limits.  Think of a coil spring whose coils are touching in the rest state. 

You can test some of your ideas easily yourself. Do the high school physics experiment of measuring force vs distance in both directions from the rest position.   0lot the results.  Then overstretch the spring and repeat.  If it is a common steel spring heat it red hot with a propane torch and repeat the test.  Then heat again and do a rapid quench in water and repeat measurements.   A couple of hours of this kind of testing will give you much more insight into spring behavior and spring manufacture, and also give food for analysis and thought.

[mendip_discovery]

Norbar did a study for torque wrenches and if you need to return them to zero after use.

https://www.norbar.com/Portals/0/Wind%20Torque%20Wrench%20Back%20Blog.pdf

But I am not sure they did it over a long enough time period.

[coppercone2]

so would this spring invert like I postulated? After a long time, would a extended spring that wants to contract turn into a spring that is at rest in its stretched position, aka be the opposite spring? would it resist compression just as it previously resisted expansion?

How would this spring compare to a spring that is stretched out after manufacture?


is the creep deformation over a long time different from the rapid deformation that you get from over extending it? Because if you wanted the spring to rest in its expanded state after manufacture you would need to over stretch it so it retracts to the desired position. But a aged spring would be at this desired position without ever having been over extended.

I am wondering if it would be a superior spring. It seems that it underwent less stress during its manufacture.

In general springs do not have a preferred direction.  The most common exceptions are physical limits.  Think of a coil spring whose coils are touching in the rest state. 

You can test some of your ideas easily yourself. Do the high school physics experiment of measuring force vs distance in both directions from the rest position.   0lot the results.  Then overstretch the spring and repeat.  If it is a common steel spring heat it red hot with a propane torch and repeat the test.  Then heat again and do a rapid quench in water and repeat measurements.   A couple of hours of this kind of testing will give you much more insight into spring behavior and spring manufacture, and also give food for analysis and thought.

temperature seems like a very extreme test comparison. I thought of it but if something is glowing then its doing something. the magic to me is that basically nothing is happening. Is it that good a analogy that temperature is fast time for a spring?

[TimFox]

I have watched yield and tensile measurements being made (from a safe distance).
The usual stress/strain curve is illustrated in this article:
https://www.xometry.com/resources/3d-printing/yield-strength/
Note that the yield point is quite distinct in the graph.

[CatalinaWOW]

so would this spring invert like I postulated? After a long time, would a extended spring that wants to contract turn into a spring that is at rest in its stretched position, aka be the opposite spring? would it resist compression just as it previously resisted expansion?

How would this spring compare to a spring that is stretched out after manufacture?


is the creep deformation over a long time different from the rapid deformation that you get from over extending it? Because if you wanted the spring to rest in its expanded state after manufacture you would need to over stretch it so it retracts to the desired position. But a aged spring would be at this desired position without ever having been over extended.

I am wondering if it would be a superior spring. It seems that it underwent less stress during its manufacture.

In general springs do not have a preferred direction.  The most common exceptions are physical limits.  Think of a coil spring whose coils are touching in the rest state. 

You can test some of your ideas easily yourself. Do the high school physics experiment of measuring force vs distance in both directions from the rest position.   0lot the results.  Then overstretch the spring and repeat.  If it is a common steel spring heat it red hot with a propane torch and repeat the test.  Then heat again and do a rapid quench in water and repeat measurements.   A couple of hours of this kind of testing will give you much more insight into spring behavior and spring manufacture, and also give food for analysis and thought.

temperature seems like a very extreme test comparison. I thought of it but if something is glowing then its doing something. the magic to me is that basically nothing is happening. Is it that good a analogy that temperature is fast time for a spring?

Yes and no.  Temperature at low ranges is a time speedup.  But at a high enough temperature the material properties change radically and are in no way equivalent to fast time.   

The point behind those experiments is to give you some insight into how material properties change with various heat treatment and insight into how springs are made.  I think if you performed them, you might change some of your questions about spring aging.  Like the one about whether a tension spring relaxes into a compression spring.