Vibrations / Transportation
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Vibrations
A pump system supplier contacted Clark Engineers with a severe
vibration problem.
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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.
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Pump configuration
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As built model with table leg supported on a steel
beam acting as a spring
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Dynamic modes without and with stiffening
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Transportation
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.
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Overdeflected condition
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Computer Model
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Dynamic Analysis
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