Posted by: prakash_26jan
Difference between Linear and non-linear Restraint - 11/19/10 03:16 AM
dear sir
can you explain me what is the difference between linear and non linear Restraint . because we are generally use non-linear Restraint during static stress analysis where as linear restraint use for Dynamic stress analysis.
i had confusion that how the Same support like +y will work as a non-linear and linear support for static and dynamic analysis.
can some body expalain me with example.
prakash kumar
Posted by: venkatachalam
Re: Difference between Linear and non-linear Restraint - 11/19/10 12:15 PM
dear prakash,
linear restraint:
full Y support
no gaps allowed
no friction
non-linear restraint:
+y support
gaps allowed
friction allowed
yes dynamic stress analysis should be linearised and you have to use full y support,that supports are called Hold down supports. hold down supports are important in dynamic analysis. regarding the topics you can refer from caesar ii manual or documents.
Posted by: prakash_26jan
Re: Difference between Linear and non-linear Restraint - 12/15/10 03:24 AM
thank you very much
but still i have some confusion regarding this topic.
when we are performing the static stress analysis and providing +y support. definetly it will be act non- restraint support. but when we are using the same system for dyanamic analysis whether same support(+y) will act like Y (rest+ hold down) . if it is like that then how it is possible the same system will work rest as well as rest with hold hown, but physical support is rest.
i appreciate your fast clarification.
Posted by: Richard Ay
Re: Difference between Linear and non-linear Restraint - 12/15/10 06:00 AM
You cannot have non-linear boundary conditions in a dynamic analysis (because the Eigen solution techinique is linear). Therefore, all non-linear restraints that were defined in the Piping Input must be linearized.
c2 can perform this linearization process in-line with the Dynamic Analysis, based on a "Static Load Case" that you reference. This is the first data item on the "Control Parameters" dialog: "Static Case for Non-Linear Restraint Status".
c2 takes the static load case that you specify and evaluates that status of each non-linear restraint based on the output from that specified load case. For a +Y, the output is evaluated to determine if the pipe lifted off or caused a downward load. If the pipe lifted off, then the +Y restraint is removed from the Dynamic Analysis. If the pipe was in contact with the restraint (caused a negative load), then the +Y is changed to a full Y.
Posted by: prakash_26jan
Re: Difference between Linear and non-linear Restraint - 12/21/10 04:02 AM
thank you for your prompt reply.
thanks
prakash