Finite Element Analysis

Finite Element Analysis (FEA) is a computer-based analysis method for simulating the behavior of structures. The key feature of FEA is the use of two and three-dimensional elements for the discrete representation of a structure. Applications include stress and deflection responses to external forces as well as vibration response or natural frequency predictions. Combined with other material properties, like fatigue resistance and thermal expansion, FEA can provide a broad spectrum of analysis capabilities.

EBDG utilizes FEA both in the analysis of existing structures as well as a crucial part of the design process for new structures to ensure a cost effective and efficient design.

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Applications of FEA

  • Whole vessel (global) analysis

  • Localized structural detail development

  • Machinery and equipment foundations

  • Dynamic Loads

  • Mooring

  • Non-Linear Materials

  • Non-Linear Buckling

  • Explicit Dynamics

  • Rigid Body Dynamics

  • Composites

  • Thermal

  • Thermal-Structural Coupled

  • Modal Vibration

  • Harmonic Response Vibration

  • Structural Fatigue

Case Studies

Structure Borne Vibration

EBDG performed a vibration FEA when designing modified main engine foundations in conjunction with a repower for an aluminum fast ferry. The FEA focused on foundation stiffness and identified several areas that required additional localized stiffening. The FEA also confirmed the decision to upsize the main foundation flange thickness. This study showed that the existing foundation was inadequately stiff to allow the vibration isolation mounts to properly attenuate the engine vibrations. A third-party vibration survey on the vessel before and after the repower confirmed that EBDG’s design resulted in a significant reduction in structure borne vibrations both in the vicinity of the main engines and in the passenger cabin. This result is particularly notable as the new engines had higher vibration levels than the previously installed engines.

Fatigue Analysis of an Aging Passenger / Vehicle Ferry

EBDG prepared a global structural analysis of an aging ferry to predict likely locations of future stress cracking. Stresses from global hog and sag conditions were compared against wave spectrum data over the routes of operation to develop a fatigue life estimate for highly wave-stressed structure. This analysis yielded an inspection plan and modification plan to monitor and mitigate fatigue failures and extend the operational life of the vessel.

Analysis of Structural Stresses from Thermal Gradient of Heated Asphalt Tanks

EBDG designed a tank heating system for converting an existing tank barge to an asphalt carrier. The gradient between the 315°F tank walls and the 32°F water yielded high thermal stresses in the existing structure. EBDG prepared a structural modification package to mitigate the high thermal stresses.