Vibrations / Transportation


A pump system supplier contacted Clark Engineers with a severe vibration problem.
Excessive vibration was occurring and a bump test was performed to determine the natural frequency. It was found that the natural frequency of the frame was very close to the driving frequency of the pump. Clark Engineers was engaged to design frame modifications to reduce excessive vibration. A simplified model of the frame as-built was made and the natural frequency was found to be similar to the measured natural frequency.

Clark Engineers determined that the simplest and most cost effective solution was to add new support feet below all four vertical members. By adding these feet the natural frequency was moved outside of the critical range for resonance. Results before modification and after are shown below.

Pump configuration

Pump configuration

built model

As built model with table leg supported on a steel beam acting as a spring


Dynamic modes without and with stiffening


Aluminum Trailer design review – A fabricator made three trailers for mobile laboratories using aluminum to save weight but did not check design. An internal audit by the client's D.O.T. inspector revealed concerns. Clark Engineers was engaged to evaluate design and provide recommendations.

Clark Engineers found that the trailer had 5" of deflection under static load with less than full span (photo below) and that members were highly over stressed under towed conditions including significant vibration from a dynamic analysis. Clark Engineers provided a stiffening and strengthening scheme.


Overdeflected condition

Computer Model

Dynamic Analysis