A comparative study of residual stress measurement of laminated composites using FBG sensor, DIC technique, and strain gauge

Residual stresses adversely influence the strength of polymeric composites and could result in premature failure, warpage, delamination, and matrix cracking. Therefore, residual stress measurement is necessary to predict their effects on the performance of polymeric composites. The primary focus of this study is to compare the performance of the fiber Bragg grating (FBG) sensor for residual stress measurement with that of the digital image correlation (DIC) and strain gauge which are the most commonly used methods in this field. This comparison is of significant importance as it can provide valuable insights into the effectiveness of these techniques in measuring cure-induced residual stresses in polymeric composites. The incremental slitting process was conducted to compare the accuracy and the performance of the FBG sensor with the DIC and strain gauge. The residual stresses were also evaluated using the classical lamination theory (CLT). The 2% difference was achieved between the recorded data by FBGs before and after slitting. The present study also involves monitoring the curing cycle and determining the created residual strains at the end of this process using the FBGs without resorting to destructive methods such as hole-drilling or slitting.