For many structures, the undeformed structure is often analysed as a computational graph, and the results obtained are sufficiently accurate.At this point, the resulting deformation and loads are linearly related, this analysis method is called geometric linear analysis, also known as – – order (FirstOrder) analysis.For some structures, it is necessary to deform the structure as the basis for calculation to carry out internal force analysis, otherwise: the results of the error is larger.At this point, the resulting relationship between deformation and load is non-linear analysis.This method of analysis is called geometric nonlinear analysis, also known as second order (Second 0rder) analysis.Second 0rder analysis is when the deformed structure is used as the basis for calculation and the elasticity of the material is taken into account (material nonlinearity).