Re: [Yade-users] [Question #262922]: TorqueEngine, angular acceleration and moment of inertia of Boxes
Question #262922 on Yade changed: https://answers.launchpad.net/yade/+question/262922 Jan Stránský proposed the following answer: Just a sidenote, if you use box, the mass and inertia is computed in py/utils.py file [1,2,3], not in c++ as you refer to.. in utils.py, the inertia is computed as you cited, but with density instead of mass.. so evidently a bug :-) feel free to report it Jan PS: thanks for notifying b1 = b=box((0,0,0),(1,1,1)) b2 = b=box((0,0,0),(2,2,2)) print b1.state.inertia, b2.state.inertia Vector3(8000,8000,8000) Vector3(32000,32000,32000) # but should be 32x more (8x more mass x 4x more geometry inertia), not 4x more... [1] http://bazaar.launchpad.net/~yade-pkg/yade/git-trunk/view/head:/py/utils.py#L214 [2] http://bazaar.launchpad.net/~yade-pkg/yade/git-trunk/view/head:/py/utils.py#L116 [3] http://bazaar.launchpad.net/~yade-pkg/yade/git-trunk/view/head:/py/utils.py#L128 2015-03-02 19:36 GMT+01:00 behzad : > Question #262922 on Yade changed: > https://answers.launchpad.net/yade/+question/262922 > > behzad posted a new comment: > Yes, this value came from PFC! > > I changed it to zero. Now the ratio of the applied torque to the obtained > angular acceleration is correct. > However, the problem is the calculation of inertia is not correct. > > we have: > > upper_plate = > O.bodies.append(box((0,0,0),(1,1,0.1),fixed=True,material=CohMat)) > > ]: O.bodies[upper_plate].state.mass > -> [2]: 1600.0 > > > So from > > > body->state->inertia=Vector3r(mass*(4*extents[1]*extents[1]+4*extents[2]*extents[2])/12.,mass*(4*extents[0]*extents[0]+4*extents[2]*extents[2])/12.,mass*(4*extents[0]*extents[0]+4*extents[1]*extents[1])/12.); > > we must have inertia as (538.66,538.66,1066.66) > > But we get: > > O.bodies[upper_plate].state.inertia > -> [3]: Vector3(8080,8080,16000) > > Where does it come from? > > -- > You received this question notification because you are a member of > yade-users, which is an answer contact for Yade. > > ___ > Mailing list: https://launchpad.net/~yade-users > Post to : yade-users@lists.launchpad.net > Unsubscribe : https://launchpad.net/~yade-users > More help : https://help.launchpad.net/ListHelp > -- You received this question notification because you are a member of yade-users, which is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #262922]: TorqueEngine, angular acceleration and moment of inertia of Boxes
Question #262922 on Yade changed: https://answers.launchpad.net/yade/+question/262922 behzad posted a new comment: Yes, this value came from PFC! I changed it to zero. Now the ratio of the applied torque to the obtained angular acceleration is correct. However, the problem is the calculation of inertia is not correct. we have: upper_plate = O.bodies.append(box((0,0,0),(1,1,0.1),fixed=True,material=CohMat)) ]: O.bodies[upper_plate].state.mass -> [2]: 1600.0 So from body->state->inertia=Vector3r(mass*(4*extents[1]*extents[1]+4*extents[2]*extents[2])/12.,mass*(4*extents[0]*extents[0]+4*extents[2]*extents[2])/12.,mass*(4*extents[0]*extents[0]+4*extents[1]*extents[1])/12.); we must have inertia as (538.66,538.66,1066.66) But we get: O.bodies[upper_plate].state.inertia -> [3]: Vector3(8080,8080,16000) Where does it come from? -- You received this question notification because you are a member of yade-users, which is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
[Yade-users] [Question #263072]: Manipulating blocks created using jointedCohesiveFrictionalPM
New question #263072 on Yade: https://answers.launchpad.net/yade/+question/263072 Hi, I want to create model that represent highly jointed rock mass using jointedCohesiveFrictionalPM. At first I want to create rock block and then to add joints into that block. Since I have dense fracture network that I want to add I need to use spheres with small radii in order to be able to create even smallest subblocks that are created by joint intersections. But before i proceed to simulation I would like to rationalize whole model and to reduce overall number of spheres but to keep all subblocks. And here comes my question: Is it possible to determine what spheres belong to each subblock? Or to transform subblocks into clumps and then replace spheres with small radii with ones with larger radii? I'd appreciate any suggestions. Veljko -- You received this question notification because you are a member of yade-users, which is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
