PSI - Issue 18

Alexandru Falk et al. / Procedia Structural Integrity 18 (2019) 214–222 Author name / Structural Integr ty P o edi 00 (2019) 000– 00

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Fig. 12 Strain distribution on PCB a) A1A2 b) B1B2 c) C1C2 d) D1D2.

3. Discussions and conclusion In Table 1 are the theoretical calculation of maximum principal strain � based on equation 1 for (0°, 45°, 90°) angled gauges ��� � � � �� 2 � 1 2 �� � � �� � � � � �� � �� � � ��������������1����� Table 1. Maximum principal strain. Rosette1 Test1 Rosette1 Test2 Rosette2 Test1 Rosette2 Test2 Rosette3 Test1 Rosette3 Test2 � 390 450 230 220 185 145 �� -220 -245 -90 -50 -5 -40 �� 350 400 190 110 135 180 � 960 1095 510 386 326 365 The recorded maximum principal strains are between 326 to 1095. The maximum values are higher than the allowable limit 700 μstrain. According to Fig 12 and Table 1 could be observed that the DIC results are in the same range with results got from strain gauge measurements. The allowable strain limit of 700  is exceeded for test 1. In Fig. 13 are compared the DIC maximum principal strain mean results (continuous lines) and strain gauge measurements (dotted lines, representing maximum and minimum values). Distance L represent the dimension of interrogating area, according with Fig. 11. To conclude the DIC measurements allow an accurate measurement of strains on PCB’s, having the advantage of full field and minimum surface preparation.