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. When load is applied on a concrete specimen, shows an instantaneous deformation followed by slow increase of deformation is called concrete creep. This may include elastic and permanent plastic strain. •As a result, the material undergoes a time dependent increase in length, which could be dangerous while in service. When load is applied on a concrete specimen, shows an instantaneous deformation followed by slow increase of deformation is called concrete creep. The strain then increases over time. Beyond the elastic limit plastic deformation occurs and strains are not totally recoverable. When a material is subjected to constant or repeated load below the failure stress, the mate-rial will eventually fail. Creep is a time-dependent permanent (plastic) deformation under a certain applied load. The stress at the yield point is called … 10.1.3. It first suffers an instantaneous strain upon loading. 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. Creep is a time-dependent deformation of a material while under an applied load that is below its yield strength. Concrete Creep Definition, Creep deformation Stages & Design Strategies. One is fatigue. The reliability of metallic microelectromechanical systems (MEMS) depends on time-dependent deformation such as creep. to heavy masticatory load during function. •Generally occurs at high temperature (thermal creep), but can also happen at room temperature in certain materials (e.g. Deformation behaviour is an important aspect to consider when selecting materials for provisional or permanent dental prostheses. The response of a typical viscoelastic material to this test is show in Fig. Sometimes, σ(t)/γ 0 is termed as relaxation modulus. lead or glass), albeit much slower. 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. 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. Creep is a time-dependent permanent (plastic) deformation under a certain applied load. It leads to what has been termed recovery … • Time-dependent nonrecoverable, that is the major source of creep deformation. 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. Creep: It is a deformation of a material due to the constant load for a long period of time. This time-dependent response is known as creep. Creep terminates in rupture if steps are not taken to bring to a halt. 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 strain usually increases with an ever decreasing strain rate. 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. It is most often occurs at elevated temperature, but some materials creep at room temperature. First there is an instantaneous elastic straining, followed by an ever-increasing strain over There are two time-dependent phenomena. • 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.