Subject: STRUCTURAL ANALYSIS OF THE INSTALLATION RAIL FOR THE TWO DETECTORS
Group:Engineering dept. NIKHEF
Date:may 2004
Prepared by:M.J. Kraan
Checked by:M. Doets

Abstract:

The structural verification of the Installation Rail for the two detectors is the subject of this document. Purpose of these calculations is to investigate stress and stability of this device. Numerical analysis was performed with the IDEAS TM finite element analysis software.

Introduction

For installation of the two detectors a Installation Rail is designed. Figures below shows this device with one of the two detectors in front of the vacuum vessel.

Design of the Installation Rail

The rail consist of two stainless steel translation bearings mounted on a aluminium frame. This frame is bolted together. The whole assembly will be mounted to the vacuum vessel and the stand.

  • Drawings in PDF Format

    Operational conditions

    The load of the lifting device is determined by the weight of a detector. With a weight of each detector of 2000 N, the load is devided over the two bearings by:

    F1 = 250 N
    F2 = 750 N

    Material data:

    This device will be made from Stainless steel (bearing) and Aluminium (frame)

      STAINLESS STEEL
      Tensile strengthRm [MPa]min.580
      Yield strengthRp 0.2% [MPa]min. 290
      Young's modulusE [GPa]min.200
      Density[g/cm3].8.0
      Poisons ratio..0.30
      ALUMINIUM
      Tensile strengthRm [MPa]min.180
      Yield strengthRp 0.2% [MPa]min. 80
      Young's modulusE [GPa]min.700
      Density[g/cm3].2.69
      Poisons ratio..0.30

    FEA:

    A finite element analysis has been done to verify that the stresses are below the Yield strength. The finite element analysis is done with the finite element analysis module of Ideas.

    The model is build up with 3D Solid parabolic tetrahedron elements. to simulate the 'worse case scenario', the detector is 'placed' at the end of the translation bearing. A buckling analysis is presented as the stresses in some sections are compressive.

    Two models are made, first: only the vertical plate with constrains at the places where the bolds are and second: the whole structure as one part.

      Finite Element Mesh
      vertical plate
      one part

      Mesh types: 3D Solid parabolic tetrahedron
      Load type:LOAD on Surface
      Weight 1 detector: 2000 N
      Load Amplitude:F1=250 N / F2=750 N
      Type of Solution: Linear Statics
      Units:Length [mm]; Force [N]; Stress/Pressure [Mpa]

    • RESULTS:

    VERTICAL PLATE:

      stress
      max. 15.8 MPa
      displacement max.
      0.16 mm
      		buckling mode 1
      14.3      		buckling mode 2
      41.6

      Strain energy error norm = 6.2%

    ONE PART:
      stress
      max. 13.9 MPa
      displacement max. 0.15 mm
      		buckling mode 1
      15.7      		buckling mode 2
      45.6

      Strain energy error norm = 6.5%
    CONCLUSION:

    For both simulation counts from the stress analysis point of view that the simulation shows an stress level (one part max. 13.9 MPa; plate max. 15.8 MPa) far below the Yield strength (Al. 80 MPa / AISI. 260 MPa).

    Max deformation of 15 mm is not critical and can only be a point of discussion for installation reason.

    For what concerns stability, the linear buckling analyses shows a comfortable safety margin (buckling mode 1, buckling load factor = 14.3-15.7).