Unfortunately, a sign mistake in Eq. (22) had been made and was propagated throughout the paper. According to our definition of the stiffness matrix in Eq. (4), the correct form of the right-hand side of Eq. (22) is $−Kfδp$. As a result, the sign change should be also applied to Eqs. (23), (26), (28), (29), (35), and (39), accordingly. Also, the new form of Eq. (35) modifies inequalities 36,37,38 as per the following:
$L>0$
36
$L2+S>0$
37
$LS−V>0$
38