This study is concerned with the use of energy methods to find the equivalent stiffness properties
of certain vibration models. The first class of models are one-degree-of-freedom oscillatory systems
that include several combinations of a main spring and an additional spring. The stiffness
properties of the equivalent system as well as the condition for different types of the resulting
oscillatory motion are determined. Then, two-degree-of-freedom systems comprising two pairs of
mutually orthogonal or symmetrically attached springs are examined. The corresponding equivalent
stiffness properties are obtained and the possibilities for corrections are also discussed.