Failure Theory
Failure Theory
(OP)
Hello All,
In calculating the failure index using one of the failure theories is it an industry standard to use the strain or stress from the mid plane (average) of the ply rather than the strain or stress from the top surface of the ply. Also can you guys share your thought on the failure theories commonly used these days in the industries. Thanks in advance.
In calculating the failure index using one of the failure theories is it an industry standard to use the strain or stress from the mid plane (average) of the ply rather than the strain or stress from the top surface of the ply. Also can you guys share your thought on the failure theories commonly used these days in the industries. Thanks in advance.





RE: Failure Theory
Steve
RE: Failure Theory
RE: Failure Theory
RE: Failure Theory
Now if i use a failure theory to predict the failure index it makes a big difference when i use the average stress of the ply instead of the top surface ply stress which is always greater than the mid plane ply stress. I know most of the companies use mid plane ply stress to calculate the failure index. Shouldnt they be using the top surface ply stress? The same holds good for strains too.Thanks
RE: Failure Theory
Are you trying to correlate to test data? or is this an acedemic problem? or what? What specific layups are you analyzing?
RE: Failure Theory
I was wondering if you have any material on modeified Tsai-Wu criterion or any good paper which discusses the failure criteria's.Thanks.
RE: Failure Theory
M. J. Hinton, et. al., “A Comparison of the Predictive Capabilities of Current Failure Theories for Composite Laminates, Judged Against Experimental Evidence”, Composites Science and Technology, Vol. 62, 2002, pp 1725-1797.
along with many of the references listed therein.
The bottom line: lamina level composite failure theories, including Tsai-Wu, don't work very well (to be charitable).
How do you intend to determine if a failure theory is conservative? Are you comparing to test data?
RE: Failure Theory
The idea is to conduct test and generate a failure envolope to compare it with the failure theories. The three criteria's which i am looking at is Hashin,Yamada-Sunn and Tsai-Wu. I know that Hashin and Yamada does not take into account the transverse component and hence the theory is not so accurate. This is just a preliminary study.
Thanks.
RE: Failure Theory
http://www
Or try your company or university library.