to heavy masticatory load during function. recovery test, that is, to a constant load and to the subsequent removal of that load. There will be thus permanent deformation or permanent set when load is removed; These two points Y 1 and Y 2 are termed as upper and lower yield points respectively. Creep is a time-dependent permanent (plastic) deformation under a certain applied load. • Time-dependent recoverable, that is not widely studied or analyzed, but may become very important at low stresses and under nonsteady conditions, that is, high-temperature service. Solution(By Examveda Team) Resilience: The ability of a material to absorb energy under elastic deformation and to recover this energy upon removal of load is termed as resilience.Resilience is indicated by the area under the stress strain curve till the point of elastic limit. The recoverable deformation reflects the fundamental time-dependent behavior of concrete, and the unrecoverable deformation is caused by the accumulation of micro-damage in concrete, Rossi et al. The response of a typical viscoelastic material to this test is show in Fig. Deformation behaviour is an important aspect to consider when selecting materials for provisional or permanent dental prostheses. There are two time-dependent phenomena. First there is an instantaneous elastic straining, followed by an ever-increasing strain over It leads to what has been termed recovery … Beyond the elastic limit plastic deformation occurs and strains are not totally recoverable. •As a result, the material undergoes a time dependent increase in length, which could be dangerous while in service. The strain usually increases with an ever decreasing strain rate. When a material is subjected to constant or repeated load below the failure stress, the mate-rial will eventually fail. Creep: It is a deformation of a material due to the constant load for a long period of time. Creep terminates in rupture if steps are not taken to bring to a halt. •Generally occurs at high temperature (thermal creep), but can also happen at room temperature in certain materials (e.g. A concern in some practical applications of materials, including composites, is their ability to resist permanent deformation with time under load; to sustain a load when they are deformed by a fixed amount; and/or to recover their initial dimensions after the load is removed. The strain then increases over time. It first suffers an instantaneous strain upon loading. • Time-dependent nonrecoverable, that is the major source of creep deformation. Sometimes, σ(t)/γ 0 is termed as relaxation modulus. As mentioned above, the deformation of concrete consists of recoverable and unrecoverable deformation under sustained load. •It is a time- dependent deformation under a certain applied load. Concrete Creep Definition, Creep deformation Stages & Design Strategies. Creep is a time-dependent deformation of a material while under an applied load that is below its yield strength. The reliability of metallic microelectromechanical systems (MEMS) depends on time-dependent deformation such as creep. The stress at the yield point is called … This time-dependent response is known as creep. lead or glass), albeit much slower. This may include elastic and permanent plastic strain. One is fatigue. Creep is a time-dependent permanent (plastic) deformation under a certain applied load. When load is applied on a concrete specimen, shows an instantaneous deformation followed by slow increase of deformation is called concrete creep. When load is applied on a concrete specimen, shows an instantaneous deformation followed by slow increase of deformation is called concrete creep. where ϕ(t) is the time-dependent part of the material modulus, which is termed as Relaxation Function and G ∞ is the elastic modulus at infinite time, that is, the modulus which is due to the recoverable part of the stress. It is most often occurs at elevated temperature, but some materials creep at room temperature. 10.1.3. The Creep and Recovery Test The creep-recovery test involves loading a material at constant stress, holding that stress for some length of time and then removing the load.