i need help with mechanical modelling materials i dont get it, so many letters and units and theyre all confusing. can u pls pls make a sheet with all the units, symbols and meanings with examples and answers or im going to die :(
Thank you!!! I’m starting to learn how to compute global reference frames and step one is figuring out how to convert an [azimuth, velocity] pair into a [pole,omega] pair. Great to know this stuff is in Turcotte&Schubert.
Hello Sir, I was looking for similar explanation in the case of structural failure of bar/beam fixed on both sides under thermal loading. If possible could you please explain what parameters need to be considered?
In real life, the difference between the principle stresses is 90 degrees as they are tangential to each other, but on mohr circle they are 180 degrees apart, so to get real representation of them we need to multiply real life angle by 2 or divide circle angle by 2
Hi David, thanks for the wonderful lectures, pls what's the difference between 'pore fluid pressure' and 'pore pressure'? The question I'm trying to solve goes like this. For a rock the coulomb failure criterion is given by σs = 150 + 0.466σ. The stress state for the rock is given by σ1 800MPa, σ3 = 200MPa, How much pore fluid pressure do you need for shear failure to occur without pore pressure, how much do you have to increase the diffrential stress (at given σ3) for shear failure to occur? Use a mohr scale construction for solving the problem and show your work Thanks
Hi. I'm glad you found the lectures helpful! Pore pressure and pore fluid pressure are the same thing. The basic idea is that fluids filling the pore space in rock and under hydrostatic (or even greater than hydrostatic) pressure will lower the stress needed for failure to occur. An alternative way to have failure would be to increase the differential stress without a contribution from pore fluid pressure. It seems the question you're working on is asking you to do both calculations. Good luck!
Thanks for the video it was helpful. I have a question: The cohesion is the ability for the rock to hold itself together, how about the joint? (in joints the particles are not held together anymore) what is the definition of cohesion in the shear strength of joints? Is it apparent cohesion?
Good question. Assuming there has been nothing that has precipitated within a joint or fracture that might fill in the space and bind the two sides together, the cohesion should be zero. The shear strength may still be nonzero, depending on the frictional contact between the two sides and the pressure holding them together, but the cohesion could be zero.
Thanks a lot, teacher David! Your objective explanation helped me very much. Are you from Finland? I haven't notice any different accent that I, as a Brazilian guy, couldn't understand. Greetings from Curitiba!
How is it possible that the angle alpha (which I understand to be the angle between vAC and VBA is 230° when the sum of the angles in a triangle is maximum 180°? Also, if alpha is meant to be the azimuth of vAC itshould be larger than 230° under the assumption that north is up
All military manuals and flight instruction manuals in their preface state to assume a flat, stationary plane. Look into the proof you use to confirm your heliocentric globe model. You will be disturbed to find you can not prove the model yourself but can only rely on 2nd and 3rd party testimony. Try to fight your cognitive dissonance. You will see the earth actually is flat and stationary and we have never left low earth orbit let alone travelled to the moon
Hi. Thanks for taking the time to comment on the video and express your views. We consider plate motions on a 2D plane to start because the geometry is simpler. Just like using a map, this is a geometric simplification and not a suggestion that the Earth itself is flat. While I appreciate your openness to questioning the status quo, there is no basis to debate the shape of our planet.
@@johnnyrodriguez5938 I'm sorry not to have more time to watch the entire video you linked, but already by 1:38 there is a clear misunderstanding of the text written on the USGS website. It is unfortunate wording, but the intent is that in the absence of plate movements to cause collisions between tectonic plates that build mountains, erosion of the Earth surface by rivers, glaciers, and wind would level the Earth's surface at approximately sea level. Considered in a typical view, the mountains you see would appear like the plains in North America, flat. This is not a suggestion that the spheroidal Earth would become a planar surface.
Thanks! I've added a link to the lecture slides in the video description. I will do the same for the other videos, but it may take me a bit of time :).
@@helsinkiuniversitygeodynam6511 My father Hugh Waldron Byerlee was a metallurgist who worked in South Africa during the 70s and 80s. He came up with a more efficient mineral slurry extraction for ores like uranium but sadly never got recognition for his developments. So many gifted individuals contribute so much to their respective fields but history eventually moves on to the next big thing. My hats off to the unsung hero's of STEM.
Few years ago i studied Taiwan, I shown an orogenic steady-state at the center of the island. I think it's the best contemporan subject to understand the evolve of mountain ranges, to the orogen at the steady-state and more.
Yes, Taiwan is a nice example, particularly in the central parts of the orogen. The idea of an orogenic steady state is complicated, because it really depends on what you consider as a steady state. Is it a balance of fluxes at the scale of the orogen, or some other measure of balance? Food for thought.
@@helsinkiuniversitygeodynam6511 I worked onto balance between erosion and tectonics. 'Cause Geomorphology studies of mountain ranges makes highlight the topographic evolution, the tectonic forcing and the erosion processes which compensated them. I worked onto rivers deflections, knickpoint, Ksn etc.. Then I worked onto betics to show different tectonics movements extensive and compressive) since the post-tortonian.
Why is it alpha minus 180 and not 180 minus alpha when constructing the triangle? Also, I don't understand how alpha turns out to be 230 when the orientation of that ridge is (110 + 90) = 200, ?
