In materials science, stress relaxation is the observed
decrease in stress in response to strain generated in the structure
. This is primarily due to keeping the structure in a strained condition for some finite interval of time and hence causing some amount of plastic strain.
What is an example of stress relaxation?
An example of stress relaxation is when
a rubber band, which is a polymer, is wrapped around a newspaper for an extended period of time
. The rubber band is held at a constant displacement, however the force that it is applying to the newspaper decreases over time and it loses its integrity.
What causes stress relaxation in polymers?
Viscous flow is caused by
(linear) polymer chains moving past one another
. Chain scission is often caused by oxidation and hydrolysis and relaxation by breaks in load bearing chains.
What is meant by stress relaxation?
Stress relaxation is
a gradual reduction in stress with time at constant strain
. Stress relaxation occurs in polymers when they are held in a strained state for long periods of time. … Stress relaxation is a gradual reduction in stress with time at constant strain.
Is stress relaxation reversible?
For example, when using snap-fit assemblies, it is important to assess stress relaxation.
Such effects can be irreversible
because the change to the fastener material is a molecular phenomenon — such as breaks or reorientations in molecular chains in the polymers.
What is the best relaxation technique?
- Take slow, deep breaths. Or try other breathing exercises for relaxation. …
- Soak in a warm bath.
- Listen to soothing music.
- Practice mindful meditation. The goal of mindful meditation is to focus your attention on things that are happening right now in the present moment. …
- Write. …
- Use guided imagery.
Is stress relaxation good or bad?
Since
relaxation relieves the state of stress
, it has the effect of also relieving the equipment reactions. Thus, relaxation has the same effect as cold springing, except it occurs over a longer period of time.
What is relaxation behavior?
1. relaxation behavior – (physics)
the exponential return of a system to equilibrium after a disturbance
. relaxation. natural philosophy, physics – the science of matter and energy and their interactions; “his favorite subject was physics”
What is stress relaxation time?
Stress relaxation is
a time-dependent decrease in stress under a constant strain
. This characteristic behavior of the polymer is studied by applying a fixed amount of deformation to a specimen and measuring the load required to maintain it as a function of time.
How do you test for stress relaxation?
To determine the stress-relaxation of a material,
the specimen is deformed a given amount and decrease in stress is recorded over prolonged period of exposure at constant elevated temperature
. The stress-relaxation rate is the slope of the curve at any point.
What is creep relaxation?
In basic terms, creep relaxation is
the measurement of how much a particular gasket material spreads (thins) out when force is applied
. As the gasket loses thickness, the bolts can relax, which leads to a loss of load.
What is viscoelastic stress relaxation?
Viscoelastic stress relaxation refers to
the decrease in tensile stress over time
that occurs when a body under tensile stress is held at a fixed length.
How can you cure stress?
- Exercise. Exercise is one of the most important things you can do to combat stress. …
- Consider supplements. …
- Light a candle. …
- Reduce your caffeine intake. …
- Write it down. …
- Chew gum. …
- Spend time with friends and family. …
- Laugh.
Do relaxation techniques reduce stress?
Relaxation isn’t only about peace of mind or enjoying a hobby. Relaxation is
a process that decreases the effects of stress on your mind and body
. Relaxation techniques can help you cope with everyday stress and with stress related to various health problems, such as heart disease and pain.
What is stress relaxation temperature?
6.1 Stress relaxation. Stress relaxation is the
time-dependent change in stress after an instantaneous and constant deformation and constant temperature
. As the shape of the specimen does not change during stress relaxation, this is a pure relaxation phenomenon in the sense defined at the beginning of this section.
What is relaxation of stress in steel?
1. The decrease in stress in
steel as a result of creep within the steel under prolonged strain
. 2. The decrease in stress in steel as a result of decreased strain of the steel, such as results from shrinkage and creep of the concrete in a prestressed concrete unit.
