Elastic and isotropic constitutive relationship

AI Thread Summary
The discussion focuses on the necessity of including an indeterminate hydrostatic term in the stress tensor for incompressible materials, both solids and fluids. Incompressibility implies that hydrostatic stress does not result in strain, making it impossible to derive it from the strain tensor. Despite this, hydrostatic stress is essential as it effectively transmits loads within the material. Participants clarify that hydrostatic pressure represents mean normal stress, which cannot be disregarded in Hooke's law under indeterminate conditions. Understanding this relationship is crucial for accurate modeling of material behavior.
ftarak
Messages
12
Reaction score
0
Hi everybody,
I have just a question about elastic and isotropic constitutive relationship

Why does the stress tensor need an indeterminate hydrostatic term for an incompressible material? for both solids and fluids.
 
Engineering news on Phys.org
"Incompressible" means that if you have a hydrostatic stress (or a constant pressure, which is the same thing), the strain is zero.

So you can't get the hydrostatic stress by multiplying the strain tensor by something.

But it is a phsyically real stress, that transmits loads through the solid or fluid, so you have to include it in the model some other way.
 
AlephZero said:
"Incompressible" means that if you have a hydrostatic stress (or a constant pressure, which is the same thing), the strain is zero.

So you can't get the hydrostatic stress by multiplying the strain tensor by something.

But it is a phsyically real stress, that transmits loads through the solid or fluid, so you have to include it in the model some other way.

thank you for your answer. that was helpful. I got the point, the point is that the hydrostatic pressure is mean normal stress. and we cannot cancel out the hydrostatic term in the Hooke's law in the situation, which is indeterminate.
 
Here's a video by “driving 4 answers” who seems to me to be well versed on the details of Internal Combustion engines. The video does cover something that's a bit shrouded in 'conspiracy theory', and he touches on that, but of course for phys.org, I'm only interested in the actual science involved. He analyzes the claim of achieving 100 mpg with a 427 cubic inch V8 1970 Ford Galaxy in 1977. Only the fuel supply system was modified. I was surprised that he feels the claim could have been...
Thread 'Turbocharging carbureted petrol 2 stroke engines'
Hi everyone, online I ve seen some images about 2 stroke carbureted turbo (motorcycle derivation engine). Now.. In the past in this forum some members spoke about turbocharging 2 stroke but not in sufficient detail. The intake and the exhaust are open at the same time and there are no valves like a 4 stroke. But if you search online you can find carbureted 2stroke turbo sled or the Am6 turbo. The question is: Is really possible turbocharge a 2 stroke carburated(NOT EFI)petrol engine and...
TL;DR Summary: Heard in the news about using sonar to locate the sub Hello : After the sinking of the ship near the Greek shores , carrying of alot of people , there was another accident that include 5 tourists and a submarine visiting the titanic , which went missing Some technical notes captured my attention, that there us few sonar devices are hearing sounds repeated every 30 seconds , but they are not able to locate the source Is it possible that the sound waves are reflecting from...
Back
Top