# Modal Prestressed

Prestressed eigenvalue analysis is governed by:(1)
$\left(\overline{\text{K}}\text{\hspace{0.17em}}\text{+}\text{\hspace{0.17em}}\text{λM}\right)\text{A}\text{\hspace{0.17em}}\text{=}\text{\hspace{0.17em}}\text{0}$
Where,
$\overline{\text{K}}$
Prestress stiffness matrix
$\text{M}$
Mass matrix
$\text{A}$
Eigenvector
$\text{λ}$
Eigenvalues

Prestressed loadcases can be either linear or non-linear. All non-linearity types are supported.

Depending on preloading conditions, the resulting effect could be a weakened or stiffened structure.
• If the preloading is compressive, it typically has a weakening effect on the structure (for example, column or pillar under compressive preloading).