Issue 22

D. Gentile et alii, Frattura ed Integrità Strutturale, 22 (2012) 85-92 ; DOI: 10.3221/IGF-ESIS.22.09 87 from CEPI (commercial code 32, patented) according to DIN 6499 class 2 standards in order to grant seal and centering and that was also able to allow different specimen’s geometry, Fig. 2. Next step has been to design the shafts. Analyses have been conducted following the classical mechanical laws, realizing parametric CAD models that allow to change one or more dimensions. Electronic sheets have been implemented in order to take into account the mechanical materials parameters and all the costs: commercial part, machine working of components, etc. In Tab. 1 is reported a worksheet sample of stress analysis; in Tab. 2 a sample of cost analysis. Figure 2 : Grips: a) geometry; b) dimension as DIN6499 standard (all the measure are in millimeter). CEPI Catalog. Material data commercial name Elastic Modulus E [MPa] failure stress [ MPa] yield stress [ MPa] endurance limit [MPa] material 1 210000 400 250 180 material 2 210000 600 480 300 geometrical data Von Mises stress diameter 1 25 mm section 1/2 296 MPa diameter 2 28 mm section 2/3 195 MPa diameter 3 30 mm section 3/4 173 MPa diameter 4 32 mm radius 2/1 2 mm material 1 material 2 radius 3/2 2 mm safe factor 1/2 0.84 1.62 radius 4/3 2 mm safe factor 2/3 1.28 2.45 d2/d1 1,12 safe factor 3/4 1.44 2.77 d3/d2 1.07 d4/d3 1.07 Load 1800 N stress concentration factors Bending Torsion distance 100 mm Kt (2/1) 1.80 1.60 Bending 180000 Nmm Kt (3/2) 1.70 1.45 Torsion 400000 Nmm Kt (4/3) 1.82 1.61 Table 1 : Example of the work sheet implemented for calculus.