Abstract
Many vibration analysis methods, which have been widely used, are applicable to obtain quite accurate solutions for uniform section-beam problems. It, however, is not so competitive to apply them to not only varying section-beam ones but also ladder type structures. Though calculating natural frequencies by differentiating and integrating requires hard works, it may not give so accurate solutions. In this report, therefore, a new analysis technique, which introduces the 2nd equivalent moment of inertia of structural members and lumped mass application, is established in order to calculate vertical bending frequencies of chassis frame. The results of this approach are compared with those of finite element analysis and rig test to show its compatibility as a new technique. This technique using equivalent moment of inertia surely gives natural frequencies of chassis frame in pre -design stage.