1 / 11

RHEOLOGY (time-dependent behaviour of materials)

RHEOLOGY (time-dependent behaviour of materials). Heraclitus  of Ephesus ( 540-480 BC) Ἡράκλειτος ὁ Ἐφέσιος ( Herakleitos ho Ephesios ). Πάντα ῥεῖ καὶ οὐδὲν μένει. panta rhei kai ouden menei. everything flows and nothing remains still. Tempus fugit, aeternitas manet. t - time.

signa
Download Presentation

RHEOLOGY (time-dependent behaviour of materials)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RHEOLOGY(time-dependent behaviour of materials)

  2. Heraclitus of Ephesus (540-480 BC)Ἡράκλειτος ὁ Ἐφέσιος(Herakleitos ho Ephesios) Πάντα ῥεῖ καὶ οὐδὲν μένει panta rhei kai ouden menei everything flows and nothing remains still

  3. Tempus fugit, aeternitas manet t - time Hourglass is the trademark of Rheological Society

  4. p –loading e – deformation Solids Fluids p0 e p0 e=0 Stiff body Perfect fluid Euclid, ~ 300 BC B.Pascal, 1629-1662 p0 e0 p0 e0 Elastic body Elastic body Viscous fluid Viscous fluid e0 R.Hooke, 1635-1703 I.Newton, 1643-1727 e=0

  5. T – temperature Dots indicate time derivatives

  6. Elementary rheological models SERIES coupling HOOKE NEWTON MAXWELL MODEL HOOKE PARALELL coupling NEWTON KELVIN MODEL

  7. Time derivative notation SERIES coupling HOOKE NEWTON MAXWELL MODEL HOOKE PARALELL coupling NEWTON KELVIN MODEL

  8. MAXWELL M. Loading Loading „CREEP (of deformation) programme” „RELAXATION(of stress) programme” Steady creep, unbounded (linear) Complete relaxation (nonlinear)

  9. KELVIN M. Loading Loading „CREEP (of deformation) programme” „RELAXATION(of stress) programme” Nonsteady creep, bounded (nonlinear) No relaxation response!

  10. There are two fundamental characteristics of rheological processes: • Its dependence on the history of loading • Energy dissipation - causing irreversibility Macroscopically observable effects are due to material microstructure changes (see material science and Ashby maps). These changes can lead not only to irreversible deformation and stress relaxation but to the formation and growth of microstructural defects. Following this deterioration process a structure can be fatally damaged at arbitrary level of loading or deformation – after a sufficiently long period of loading time. This is, however, a subject of another important branch of solid mechanics – mechanics of damage and failure.

  11. stop

More Related