This article is rated B-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||
|
The page has been cleaned up, even though it wasn't stupid or rubbish before. Glass is isotropic, not orthotropic. A silicon wafer is a single crystal of silicon, which is most definitely anistropic (with cubic symmetry) and neither isotropic nor orthotropic.-- 128.220.254.4 04:20, 12 February 2007 (UTC) --- this page is stupid and rubbish --- GLASS IS ISOTROPIC OR ORTHOTROPIC AND ALSO SILICON WAFER IS ISOTROPIC OR ORTHOTROPIC ---
Higher symmetry like cubic or fully isotropic like the glass implies that it also has orthotropic symmetry. But these materials are just not good examples any more. --
Ulrich67 (
talk)
00:47, 23 January 2011 (UTC)
Just a quick note regarding material symmetry: If a material has two mutually orthogonal planes of symmetry, then that material also has a third plane of symmetry (automatically). In other words there are no materials with just two orthogonal planes of symmetry. If two exist, then there are really three planes of symmetry. See Robert Jones, "Mechanics of Composite Materials", second edition, page 59. Gpayette 04:26, 10 October 2007 (UTC)
{{Merge to |infinitesimal stress theory|stress|strain tensor|discuss=Talk:Orthotropic#Material Symmetry|date=January 2013}}
The article is not consistent with the type of symmetry: In the introduction it is a twofold rotation. In the section "Orthotropic material properties" it is symmetry planes (mirror). There is a slight difference between these two cases. The difference is a point inversion (factor -1 in matrix form). It does not change things for properties that are described by a tensor of even rank, like the ones described here. But it will change things for properties described by a 3rd rank tensor like piezo-electricity. So there is clarification needed.-- 91.3.118.227 ( talk) 10:51, 23 January 2011 (UTC)
Is this topic still active? From my point of view, it would be nicer, if the reflection-transformation matrices A1, A2 and A3 were replaced by 180-degrees-rotation transformation matrices. Using this replacement, the results will not change. But the symmetry-conditions become more realistic: An orienation-changing transformation (like a reflection) is unrealistic for solids. Whereas a 180-degrees-rotation makes perfect sense. The interpretation is also obvious: The material behaviour does not change, if you rotate your particle (and its neighborhood) by 180 degrees about any axis of orthotropy. Comments? -- Kassbohm ( talk) 06:47, 10 July 2014 (UTC)
It seems that the conclusion that
or
is not quite correct for orthotropic materials, in a way that the Poisson's ratios can impact the positive-definiteness of . -- Kxiaocai ( talk) 12:09, 30 December 2014 (UTC)
This article is rated B-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||
|
The page has been cleaned up, even though it wasn't stupid or rubbish before. Glass is isotropic, not orthotropic. A silicon wafer is a single crystal of silicon, which is most definitely anistropic (with cubic symmetry) and neither isotropic nor orthotropic.-- 128.220.254.4 04:20, 12 February 2007 (UTC) --- this page is stupid and rubbish --- GLASS IS ISOTROPIC OR ORTHOTROPIC AND ALSO SILICON WAFER IS ISOTROPIC OR ORTHOTROPIC ---
Higher symmetry like cubic or fully isotropic like the glass implies that it also has orthotropic symmetry. But these materials are just not good examples any more. --
Ulrich67 (
talk)
00:47, 23 January 2011 (UTC)
Just a quick note regarding material symmetry: If a material has two mutually orthogonal planes of symmetry, then that material also has a third plane of symmetry (automatically). In other words there are no materials with just two orthogonal planes of symmetry. If two exist, then there are really three planes of symmetry. See Robert Jones, "Mechanics of Composite Materials", second edition, page 59. Gpayette 04:26, 10 October 2007 (UTC)
{{Merge to |infinitesimal stress theory|stress|strain tensor|discuss=Talk:Orthotropic#Material Symmetry|date=January 2013}}
The article is not consistent with the type of symmetry: In the introduction it is a twofold rotation. In the section "Orthotropic material properties" it is symmetry planes (mirror). There is a slight difference between these two cases. The difference is a point inversion (factor -1 in matrix form). It does not change things for properties that are described by a tensor of even rank, like the ones described here. But it will change things for properties described by a 3rd rank tensor like piezo-electricity. So there is clarification needed.-- 91.3.118.227 ( talk) 10:51, 23 January 2011 (UTC)
Is this topic still active? From my point of view, it would be nicer, if the reflection-transformation matrices A1, A2 and A3 were replaced by 180-degrees-rotation transformation matrices. Using this replacement, the results will not change. But the symmetry-conditions become more realistic: An orienation-changing transformation (like a reflection) is unrealistic for solids. Whereas a 180-degrees-rotation makes perfect sense. The interpretation is also obvious: The material behaviour does not change, if you rotate your particle (and its neighborhood) by 180 degrees about any axis of orthotropy. Comments? -- Kassbohm ( talk) 06:47, 10 July 2014 (UTC)
It seems that the conclusion that
or
is not quite correct for orthotropic materials, in a way that the Poisson's ratios can impact the positive-definiteness of . -- Kxiaocai ( talk) 12:09, 30 December 2014 (UTC)