Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Elastic-plastic deformation

Casey, J. and Naghdi, P.M., Constitutive Results for Finitely Deforming Elastic-Plastic Materials, in Constitutive Equations Macro and Computational Aspects (edited by K.J. Wiliam), ASME, 1984, pp. 53-71. [Pg.170]

Naghdi, P.M. and Trapp, J.A., Restrictions on Constitutive Equations of Finitely Deformed Elastic-Plastic Materials, Quart. J. Mech. Appl. Math. 28, Part 1,25-46(1975). [Pg.170]

The material properties of solids are affected by a number of complex factors. In a gas-solid flow, the particles are subjected to adsorption, electrification, various types of deformation (elastic, plastic, elastoplastic, or fracture), thermal conduction and radiation, and stresses induced by gas-solid interactions and solid-solid collisions. In addition, the particles may also be subjected to various field forces such as magnetic, electrostatic, and gravitational forces, as well as short-range forces such as van der Waals forces, which may affect the motion of particles. [Pg.24]

The general tablet compaction process normally is described by a number of sequential phases rearrangement, deformation (elastic, plastic) of initial particles, fragmentation, and deformation of fragments. Particle-surfaces are brought into close proximity and interparticulate attraction or bonds will be formed. Similar conditions will prevail with the effervescent tablets. [Pg.1454]

The resistance to plastic flow can be schematically illustrated by dashpots with characteristic viscosities. The resistance to deformations within the elastic regions can be characterized by elastic springs and spring force constants. In real fibers, in contrast to ideal fibers, the mechanical behavior is best characterized by simultaneous elastic and plastic deformations. Materials that undergo simultaneous elastic and plastic effects are said to be viscoelastic. Several models describing viscoelasticity in terms of springs and dashpots in various series and parallel combinations have been proposed. The concepts of elasticity, plasticity, and viscoelasticity have been the subjects of several excellent reviews (21,22). [Pg.271]

Hardness is a measure of a material s resistance to deformation. In this article hardness is taken to be the measure of a material s resistance to indentation by a tool or indenter harder than itself This seems a relatively simple concept until mathematical analysis is attempted the elastic, plastic, and elastic recovery properties of a material are involved, making the relationship quite complex. Further complications are introduced by variations in elastic modulus and frictional coefficients. [Pg.463]

Partially Plastic Thick-Walled Cylinders. As the internal pressure is increased above the yield pressure, P, plastic deformation penetrates the wad of the cylinder so that the inner layers are stressed plasticady while the outer ones remain elastic. A rigorous analysis of the stresses and strains in a partiady plastic thick-waded cylinder made of a material which work hardens is very compHcated. However, if it is assumed that the material yields at a constant value of the yield shear stress (Fig. 4a), that the elastic—plastic boundary is cylindrical and concentric with the bore of the cylinder (Fig. 4b), and that the axial stress is the mean of the tangential and radial stresses, then it may be shown (10) that the internal pressure, needed to take the boundary to any radius r such that is given by... [Pg.79]

Plastic Forming. A plastic ceramic body deforms iaelastically without mpture under a compressive load that produces a shear stress ia excess of the shear strength of the body. Plastic forming processes (38,40—42,54—57) iavolve elastic—plastic behavior, whereby measurable elastic respoase occurs before and after plastic yielding. At pressures above the shear strength, the body deforms plastically by shear flow. [Pg.308]

Elastic Behavior. Elastic deformation is defined as the reversible deformation that occurs when a load is appHed. Most ceramics deform in a linear elastic fashion, ie, the amount of reversible deformation is a linear function of the appHed stress up to a certain stress level. If the appHed stress is increased any further the ceramic fractures catastrophically. This is in contrast to most metals which initially deform elastically and then begin to deform plastically. Plastic deformation allows stresses to be dissipated rather than building to the point where bonds break irreversibly. [Pg.317]

Elastic Behavior The assumption that displacement strains will produce proportional stress over a sufficiently wide range to justify an elastic-stress analysis often is not valid for nonmetals. In brittle nonmetallic piping, strains initially will produce relatively large elastic stresses. The total displacement strain must be kept small, however, since overstrain results in failure rather than plastic deformation. In plastic and resin nonmetallic piping strains generally will produce stresses of the overstrained (plasfic) type even at relatively low values of total displacement strain. [Pg.1004]

The fact that shock waves continue to steepen until dissipative mechanisms take over means that entropy is generated by the conversion of mechanical energy to heat, so the process is irreversible. By contrast, in a fluid, rarefactions do not usually involve significant energy dissipation, so they can be regarded as reversible, or isentropic, processes. There are circumstances, however, such as in materials with elastic-plastic response, in which plastic deformation during the release process dissipates energy in an irreversible fashion, and the expansion wave is therefore not isentropic. [Pg.22]

Figure 5.5. Elastic-plastic finite closed cycle of homogeneous deformation in strain space. Figure 5.5. Elastic-plastic finite closed cycle of homogeneous deformation in strain space.
Assuming constant volume (valid if v = 0.5 or, if not, plastic deformation elastic deformation) ... [Pg.89]

Initially, at very low loads, the asperities deform elastically where they touch. However, for realistic loads, the high stress causes extensive plastic deformation at the tips of asperities. If each asperity yields, forming a junction with its partner, the total load transmitted across the surface (Fig. 25.3) is... [Pg.242]

AqIq = A1 for plastic deformation or for elastic or elastic/plastic deformation when v = 0.5. Hence... [Pg.299]

That fraction of the applied work which is not consumed in the elastic-plastic deformation remains to create the new crack surface, i.e., the crack driving force. Therefore, a nonlinear fracture toughness, G, may be defined as follows ... [Pg.499]

Alternatively, if detachment is associated with a brittle failure, then one must first determine if the fracture followed an elastic loading where an elastic model such as the JKR theory is appropriate or if it follows a plastic or elastic-plastic loading. In this latter case, the force needed to detach the particle from the substrate depends on the specific properties of the materials and the details of the deformations [63]. [Pg.160]

In this chapter the regimes of mechanical response nonlinear elastic compression stress tensors the Hugoniot elastic limit elastic-plastic deformation hydrodynamic flow phase transformation release waves other mechanical aspects of shock propagation first-order and second-order behaviors. [Pg.15]

It is instructive to describe elastic-plastic responses in terms of idealized behaviors. Generally, elastic-deformation models describe the solid as either linearly or nonlinearly elastic. The plastic deformation material models describe rate-independent behaviors in terms of either ideal plasticity, strainhardening plasticity, strain-softening plasticity, or as stress-history dependent, e.g. the Bauschinger effect [64J01, 91S01]. Rate-dependent descriptions are more physically realistic and are the basis for viscoplastic models. The degree of flexibility afforded elastic-plastic model development has typically led to descriptions of materials response that contain more adjustable parameters than can be independently verified. [Pg.31]

This statement represents an apt, terse description of the elastic-plastic shock-deformation process within the catastrophic shock paradigm. [Pg.34]

Release waves for the elastic-plastic regime are dominated by the strength effect and the viscoplastic deformations. Here again, quantitative study of the release waves requires the best of measurement capability. The work of Asay et al. on release of aluminum as well as reloading, shown in Fig. 2.11, demonstrates the power of the technique. Early work by Curran [63D03] shows that limited time-resolution detectors can give a first-order description of the existence of elastic-plastic behavior on release. [Pg.42]

The fibers continue to deform elastically, but the matrix deforms plastically... [Pg.164]

Rheology is the science that deals with the deformation and flow of matter under various conditions. The rheology of plastics, particularly of TPs, is complex but understandable and manageable. These materials exhibit properties that combine those of an ideal viscous liquid (with pure shear deformations) with those of an ideal elastic solid (with pure elastic deformation). Thus, plastics are said to be viscoelastic. [Pg.38]

As reviewed thermoplastics (TPs) being viscoelastic materials respond to induced stress by two mechanisms viscous flow and elastic deformation. Viscous flow ultimately dissipates the applied mechanical energy as frictional heat and results in permanent material deformation. Elastic deformation stores the applied mechanical energy as completely recoverable material deformation. The extent to which one or the other of these mechanisms dominates the overall response of the material is determined by the temperature and by the duration and magnitude of the stress or strain. The higher the temperature, the most freedom of movement of the individual plastic molecules that comprise the... [Pg.45]

Creep and stress relation Creep and stress relaxation behavior for plastics are closely related to each other and one can be predicted from knowledge of the other. Therefore, such deformations in plastics can be predicted by the use of standard elastic stress analysis formulas where the elastic constants E and y can be replaced by their viscoelastic equivalents given in Eqs. 2-19 and 2-20. [Pg.114]

Fig. 31—The deformation pattern of an elastic-plastic sample during and after indentation [58]. Fig. 31—The deformation pattern of an elastic-plastic sample during and after indentation [58].

See other pages where Elastic-plastic deformation is mentioned: [Pg.1412]    [Pg.84]    [Pg.196]    [Pg.1412]    [Pg.84]    [Pg.196]    [Pg.341]    [Pg.224]    [Pg.1882]    [Pg.1884]    [Pg.99]    [Pg.79]    [Pg.497]    [Pg.501]    [Pg.502]    [Pg.110]    [Pg.149]    [Pg.20]    [Pg.31]    [Pg.31]    [Pg.33]    [Pg.35]    [Pg.38]    [Pg.103]    [Pg.120]    [Pg.138]    [Pg.266]   
See also in sourсe #XX -- [ Pg.397 ]




SEARCH



Amorphous elastic-plastic deformation

Deformability plastic

Deformation plasticity

Deformed plastics

Elastic and plastic deformation

Elastic deformations

Elastic strain versus plastic deformation

Ideal elastic-plastic deformation

Plastic deformation

Plastic deformity

© 2024 chempedia.info