On creep and relaxation?Asked by: Benny Dibbert
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two terms are sometimes used interchangeably, although they are really different. Creep is an increase in plastic strain under constant stress. Stress relaxation is a decrease in stress under constant strain. ... Creep is an increased tendency toward more strain and plastic deformation with no change in stress.View full answer
Besides, What is relaxation time in creep?
In materials science, stress relaxation is the observed decrease in stress in response to strain generated in the structure. ... This nonlinearity is described by both stress relaxation and a phenomenon known as creep, which describes how polymers strain under constant stress.
Correspondingly, What is creep relaxation in a gasket?. 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.
Additionally, 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.
What is concrete relaxation?
Creeping and shrinkage are time-dependent properties of concrete. ... Relaxation is a material property of prestressing steel and behaves inversely to concrete creeping. The term "relaxation" describes the reduction of the existing stress at a constantly applied material strain.
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Creep modulus, however, is not a constant. Rather, it is defined as the ratio of stress to strain at a specified time interval and temperature.
The stress levels had a great impact on the amount of creep deformation of the sutures. This can be un- derstood by examining the data in Figures 1 to 3. The higher the stress, the greater the creep deformation. When the stress was doubled, the creep elongation was almost doubled.
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"
In the secondary, or steady-state, creep, dislocation structure and grain size have reached equilibrium, and therefore strain rate is constant. ... Stress dependence of this rate depends on the creep mechanism. In tertiary creep, the strain rate exponentially increases with stress.
Creep damage occurs in metals and alloys after prolonged exposure to stress at elevated temperatures. ... Creep damage is manifested by the formation and growth of creep voids or cavities within the microstructure of the material.
two terms are sometimes used interchangeably, although they are really different. Creep is an increase in plastic strain under constant stress. Stress relaxation is a decrease in stress under constant strain. ... Creep is an increased tendency toward more strain and plastic deformation with no change in stress.
Temperature - possibly the most important factor in choosing a gasket material. When higher temperatures at the gasketed joint need to be sealed, the potential choices are quickly eliminated.
Creep is a time-dependent deformation of a viscoelastic material under the application of a constant stress at a constant temperature. Relaxation is the counterpart of creep, namely, a time-dependent stress of a viscoelastic material under the application of a constant deformation at a constant temperature.
The creep test has the objective of precisely measuring the rate at which secondary or steady state creep occurs. Increasing the stress or temperature has the effect of increasing the slope of the line ie the amount of deformation in a given time increases.
Stress-relaxation behavior is shown to be much more sensitive to change~ in temperature than to changes in the applied stress. It is shown that heat treatment will minimize stress relaxation by either reducing residual stress or by inducing strengthening mechanisms such as age hardening.
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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.
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.
Primary Creep: starts at a rapid rate and slows with time. Secondary Creep: has a relatively uniform rate. Tertiary Creep: has an accelerated creep rate and terminates when the material breaks or ruptures. It is associated with both necking and formation of grain boundary voids.
In general, there are three general ways to prevent creep in metal. One way is to use higher melting point metals, the second way is to use materials with greater grain size and the third way is to use alloying. Body-centered cubic (BCC) metals are less creep resistant in high temperatures.
Creep failure is the time-dependent and permanent deformation of a material when subjected to a constant load or stress. This deformation typically occurs at elevated temperatures, although it may occur under ambient temperatures as well.
Creep is the tendency of a solid material to deform permanently under the influence of constant stress: tensile, compressive, shear, or flexural. It occurs as a function of time through extended exposure to levels of stress that are below the yield strength of the material.
Creep strength is defined as the stress at specified environmental conditions that produces a steady creep rate, such as 1%, 2%, or 5%.
2. __________ experiences creep at room temperature. Explanation: Room temperature is about the same as that of the melting point of lead. Therefore, nickel experiences creep at that temperature under its own load.