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Ronald J. O’Mara PE PC is a multi-discipline engineering firm, furnishing design and related technical services to Industrial Gas, Chemical, Industrial, Food, Pharmaceutical and Power Sector Clients. Click here to visit the Ronald J O’Mara PE PC website.

They were tasked by a client to redesign an ash extractor assembly used to clear ash from a waste furnace to make it more reliable and easier to maintain. Ronald J. O’Mara PE PC completed the initial design and analysis using traditional engineering methods; however due to the complex interaction between the various components, the extremely high cost to manufacture the ash extractor assembly components and the critical nature of the ash extractor assembly to the operation of the furnace, Ronald J. O’Mara PE PC turned to Endesin in order to apply the most advanced engineering analysis methods available.



The steps used to perform the analysis were as follows:

  • PDF drawings were received from Ronald J. O’Mara PE PC for the various components of the ash extractor assembly and CAD models were created from the drawings using NX.
  • The CAD models were simplified to remove any features that did not contribute to the structural integrity of the ash extractor assembly or were too small to be meshed reliably.
  • Various finite element models were made so the components could be analyzed separately. Components with a uniform cross-section were meshed using 20-node parabolic hexahedral elements and more complex components were meshed with 10-node parabolic tetrahedral elements.
  • Bolts were modeled as beam elements and connected to the solid meshes with rigid elements.
  • Nodes were aligned on the faces of opposing solid meshes where a contact condition existed in order to ensure accurate contact analysis.
  • For each component that was analyzed, a portion of the connecting component was included in the analysis if necessary to accurately simulate the loads and constraints on the component.
  • Loads and boundary conditions were added including bolt pre-stress and interference fit contact.
  • A linear static analysis was done on each component.
  • The analysis results were used to determine contact forces, deflections, local stresses and the overall stresses in the components.
  • Several design iterations were done to achieve the desired stresses and displacement.
  • Once the design was finalized, detail drawings of the components were created for manufacturing.



The analysis was completed using NX Advanced Simulation for pre and post processing and the solver was NX Nastran.



Ronald J. O’Mara PE PC needed to be certain their design was going to perform as required and recognized that the level of complexity of the assembly necessitated engineering analysis beyond the traditional methods. Endesin provided advanced finite element analysis confirming the design concept, and then the details of the proposed fabrication.