PSI - Issue 19

Anne Coulon et al. / Procedia Structural Integrity 19 (2019) 665–673 Anne Coulon/ Structural Integrity Procedia 00 (2019) 000–000

670

6

Fig. 4. Some of sensitive areas to control on MPL75.

Non-compliant

Fig. 5. Nondestructive examination.

3.2. Measurements under operating conditions Measurements are done for the different configurations identified during the initial computation (ex: rolling, loading/unloading of passengers, etc) and for situations representative of real service conditions. Sensitive areas defined in §3.1 are instrumented with strain gauges to identify stress cycles. In parallel, several triaxial accelerometers are also positioned on the car body to characterize its dynamic behavior and to register actual operational loads. For rolling measurements, the train speed and localization are also recorded. Comparing nominal loads of EN 12 663 standard and actual loads, the load margin coefficient can be determined. As nominal loads are defined in terms of acceleration cycles, the comparison is done on the effective number of cycles corresponding to the reference acceleration range ref  . An equivalent damage analysis is done weighting each acceleration range count by equivalent damage of reference acceleration range using equation (5) from Basquin law:

b

   

   

i 

n

i    0

N

N



(5)

  ref 

eq

i 



ref

7

10 

b C

b

C

1 is then given by:

The coefficient

1

N

eq