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Optimization of the Arrangement of Internal Rib Stiffeners for Columns of the Milling Machine to Achieve Maximum Stiffness and Maximum Working Frequency Range.

Shokri, Aziz | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51136 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Akbari, Javad
  7. Abstract:
  8. Vertical milling machine is one of the most common machine tools for precision parts production. The static deflection of the machine tool and thus the displacement of the tool, is due to the high machining forces is the most important factor in reducing the dimensional Precision of the work piece. Also, the overlap of the frequency range of operation with the natural frequencies causes an undesirable resonance phenomenon. Reducing the strain energy of the column and thus the reducing the displacement of the tool, and increasing the first natural frequency of the milling machine, given that the frequency range of operating is below the first frequency, is a desirable change that can be achieved by optimizing the distribution of the wall thickness of the column and the arrangement of the internal stiffeners. In this paper, a method based on sensitivity analysis was presented to optimize the arrangement of stiffeners connected to plate and shell structures. In each step of optimization, by establishing a loop of relationship between MATLAB and ABAQUS software and based on the sensitivity analysis performed by the finite element solver, The stiffeners that have the greatest impact in optimizing the objective function are added to the design space. After optimizing the distribution of the wall thickness of the column using the Abacus software size optimization module, the method presented in this paper was used to optimize the arrangement of internal stiffeners. Ultimately, despite a 0.5% reduction in the column weight, the maximum displacement of the machine decreased by 6.9% and the first natural frequency increased by 16.5% .Thus, with minor changes in the geometry of the column, the mechanical properties of the milling machine were improved
  9. Keywords:
  10. Static Deflection ; Sensitivity Analysis ; Resonance ; Wall Thickness Distribution ; Stiffness Arrangement Optimization

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