PSI - Issue 52

Chen Zhou et al. / Procedia Structural Integrity 52 (2024) 234–241 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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4. Conclusions To solve the problem of interfacial failure between the face sheet and core in a sandwich structure, a modified crack surface displacement extrapolation (MCSDE) method is proposed to calculate the energy release rate (ERR) and mode mixity phase angle (PA). The MCSDE method uses surface displacement δx and δy to horizontally extrapolate the values before the numerical error zone to the crack tip, which effectively avoids the influence of the extrapolation curve slope on the results. The bending moment ratio on the two arms of the specimen will greatly affect the PA. When the M R is set to -0.1, the PA reaches 14.5°, and the mode Ⅰ fracture is dominant; when the M R is set to 0.05, the PA reaches - 67.3° and the mode Ⅱ fracture is dominant. The MCSDE solution matches well with both the analytic solution and the FEM solution. Under the impulse loading in the form of a step function, the DCB-UBM sample oscillates in both the ERR and the PA due to the influence of the inertia effect. Under the considered working conditions, the maximum oscillation factor of ERR is 4.26 and the maximum oscillation factor of PA is 1.51. The oscillation degree of the ERR is larger than that of the PA, indicating that the inertial effects generated by the dynamic loading have a greater effect on the ERR and a smaller effect on the PA. The MCSDE method can also accurately calculates the fracture mechanics characterization of the specimen under dynamic loads. Acknowledgements The first author would like to acknowledge the studentship supported by the China Scholarship Council (NO.202106680040), the international exchange program of Harbin Engineering University for innovation-oriented talents cultivation and the visiting Ph.D. student position offered by the Technical University of Denmark. References Sairajan, K. K., Aglietti, G. S., & Mani, K. M , 2016. A review of multifunctional structure technology for aerospace applications. Acta astronautica, 120, 30-42. Palomba, G., Epasto, G., & Crupi, V, 2021. Lightweight sandwich structures for marine applications: a review. Mechanics of Advanced Materials and Structures, 1-26. Yin, S., Chen, H., Wu, Y., Li, Y., & Xu, J, 2018. Introducing composite lattice core sandwich structure as an alternative proposal for engine hood. Composite Structures, 201, 131-140. Chu, Y., Zhong, J., Liu, H., Ma, Y., Liu, N., Song, Y., ... & Lin, L, 2018. Human pulse diagnosis for medical assessments using a wearable piezoelectric sensing system. Advanced Functional Materials, 28(40), 1803413. Saseendran, V., Berggreen, C., & Krueger, R, 2020. Mode mixity analysis of face/core debonds in a single cantilever beam sandwich specimen. Journal of Sandwich Structures & Materials, 22(6), 1879-1909. Quispitupa, A., Berggreen, C., & Carlsson, L. A, 2010. Design analysis of the mixed mode bending sandwich specimen. Journal of Sandwich Structures & Materials, 12(2), 253-272. Sørensen, B. F., Jørgensen, K., Jacobsen, T. K., & Østergaard, R. C, 2006. DCB-specimen loaded with uneven bending moments. International Journal of Fracture,141(1), 163-176. Lundsgaard-Larsen, C., Sørensen, B. F., Berggreen, C., & Østergaard, R. C, 2008. A modified DCB sandwich specimen for measuring mixed mode cohesive laws. Engineering Fracture Mechanics, 75(8), 2514-2530. Kardomateas, G. A., Berggreen, C., & Carlsson, L. A, 2013. Energy-release rate and mode mixity of face/core debonds in sandwich beams. AIAA Journal, 51(4), 885-892. Berggreen, C., Saseendran, V., & Carlsson, L. A, 2018. A modified DCB-UBM test method for interfacial fracture toughness characterization of sandwich composites. Engineering Fracture Mechanics, 203, 208-223. Hutchinson, J. W., & Suo, Z, 1991. Mixed mode cracking in layered materials. Advances in applied mechanics, 29, 63-191. Krueger, R, 2004. Virtual crack closure technique: History, approach, and applications. Appl. Mech. Rev., 57(2), 109-143. Matos, P. P. L., McMeeking, R. M., Charalambides, P. G., & Drory, M. D. (1989). A method for calculating stress intensities in bimaterial fracture. International Journal of Fracture, 40, 235-254. Berggreen, C, 2004. Damage tolerance of debonded sandwich structures. Technical University of Denmark. Krueger, R., Shivakumar, K. N., & Raju, I. S, 2013. Fracture mechanics analyses for interface crack problems-a review. In 54th AIAA/ASME/ASCE/AHS/ASC structures, structural dynamics, and materials conference (p. 1476). Zhou, C., & He, J, 2023. Mixed mode fracture toughness and mode mixity analysis of face/core debonds in a single-leg sandwich bending specimen. Theoretical and Applied Fracture Mechanics, 124, 103813. Burlayenko, V. N., Altenbach, H., & Sadowski, T, 2019. Dynamic fracture analysis of sandwich composites with face sheet/core debond by the finite element method. In Dynamical Processes in Generalized Continua and Structures (pp. 163-194). Springer, Cham.