Issue 22

D. Gentile et alii, Frattura ed Integrità Strutturale, 22 (2012) 85-92; DOI: 10.3221/IGF-ESIS.22.09

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 material 2

210000 210000

400 600

250 480

180 300

geometrical data

Von Mises stress

diameter 1 diameter 2 diameter 3 diameter 4 radius 2/1 radius 3/2 radius 4/3

25 mm 28 mm 30 mm 32 mm 2 mm 2 mm 2 mm

section 1/2 section 2/3 section 3/4

296 MPa 195 MPa 173 MPa

material 1

material 2

0.84 1.28 1.44

1.62 2.45 2.77

safe factor 1/2 safe factor 2/3 safe factor 3/4

d2/d1 d3/d2 d4/d3

1,12 1.07 1.07

Load

1800 N

stress concentration factors

Bending

Torsion

distance Bending Torsion

100 mm Kt (2/1) 180000 Nmm Kt (3/2) 400000 Nmm Kt (4/3)

1.80 1.70 1.82

1.60 1.45 1.61

Table 1 : Example of the work sheet implemented for calculus.

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