I am working in Hamilton's principle. Part of deriving the equation of motion is to use the delta operator (𝛿) which can be operated just like a differential operator. It is not the function VariationalD in package VariationalMethods.
A post was posted regarding the same subject but it seems that who asked the question found the answer somewhere else. The previous question is here.
Example on the equation is:
T= 0.5 Mu'^2
applying the delta operator
𝛿T=M u' 𝛿 u'
I need to find the first and second variation of this function w.r.t the dependent variable.