What is viscoplastic material?
Viscoplasticity is a theory in continuum mechanics that describes the rate-dependent inelastic behavior of solids. The inelastic behavior that is the subject of viscoplasticity is plastic deformation which means that the material undergoes unrecoverable deformations when a load level is reached.
What are viscoelastic properties?
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscoelastic materials have elements of both of these properties and, as such, exhibit time-dependent strain.
Is relaxation time a material property?
When the applied rate of deformation is reduced to zero, these materials relax over their characteristic relaxation time – a constitutive property of each material. This phenomenon is known as stress relaxation.
What is Burger model?
The Burgers Model is a general model of a viscoelastic material, commonly used to describe a classic creep recovery measurement (see Creep). The model is a combination of spring and dashpots, arranged as combination of separate component in series and in parallel.
What is isotropic hardening?
Isotropic hardening is where the yield surface remains the same shape but expands with increasing stress, Fig. 8.6.
What is Johnson Cook damage model?
The Johnson-Cook damage initiation criterion is a special case of the ductile damage criterion model for predicting the onset of damage due to nucleation, growth, and coalescence of voids in ductile metals.
What material is viscoelastic?
What is viscoelastic? Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Synthetic polymers, wood, and human tissue, as well as metals at high temperature, display significant viscoelastic effects.
Is plastic a viscoelastic material?
The primary property that makes most plastics so attractive over other materials is viscoelasticity. This gives plastic the ability to absorb energy, flex and spring back without cracking.
What is material relaxation?
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 the difference between creep and stress relaxation?
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.
What is the hamburger method in writing?
The “paragraph hamburger” is a writing organizer that visually outlines the key components of a paragraph. Topic sentence, detail sentences, and a closing sentence are the main elements of a good paragraph, and each one forms a different “piece” of the hamburger.
Which properties are called isotropic properties?
Isotropic materials have identical material properties in all directions at every given point. This means that when a specific load is applied at any point in the x, y or z-axis, isotropic materials will exhibit the same strength, stress, strain, young’s modulus and hardness.
What’s the difference between viscoplastic and viscoelastic materials?
The key difference between viscoelastic and viscoplastic is that viscoelastic materials show both viscous and elastic properties when undergoing deformation, whereas viscoplastic materials show unrecoverable deformation. 1. “Viscoplasticity.” Wikipedia, Wikimedia Foundation, 12 May 2020, Available here.
How is viscoplasticity used in one dimensional models?
Figure 1. Elements used in one-dimensional models of viscoplastic materials. Viscoplasticity is a theory in continuum mechanics that describes the rate-dependent inelastic behavior of solids. Rate-dependence in this context means that the deformation of the material depends on the rate at which loads are applied.
How is viscoplasticity related to the rate of applied loading?
Viscoplasticity also depends on the rate of the applied loading, but the material response is irreversible and is accompanied by permanent deformation. In metals, this mechanism is linked with the movement of dislocations in the crystalline structure.
How are relaxation tests used in Viscoplastic materials?
In viscoplastic materials, relaxation tests demonstrate the stress relaxation in uniaxial loading at a constant strain. In fact, these tests characterize the viscosity and can be used to determine the relation which exists between the stress and the rate of viscoplastic strain. d ε d t = d ε e d t + d ε v p d t .