Measurement of Variation in Fracture Strength and Calculation of Stress Concentration Factor in Composite Laminates with Circular Hole

Document Type: Research Paper


Department of Mechanical Engineering, University of Kashan


In this research, residual strength and stress concentration factor of laminated composites with a circular open hole are studied analytically, numerically and experimentally. The numerical study was carried out using the finite element method. Moreover an analytical study was carried out with developing of point stress criterion. Mechanical testing was performed to determine the un-notched tensile properties and notched strength of composite laminates and characteristic length to reinforcement of the notched strength of composite laminates are determined. Results show that the influence of specimen dimension, notch size, lay ups and material properties are important on residual strength and stress concentration factor of laminated composite materials.


[1] Rooijen R.V., Sinke J., De-Veris T. J., Zwaag S.V.D., 2004, Property optimization in fiber metal laminates, Journal of Applied Composite Materials 11(2): 63-76.

[2] Hagenbeek M., Hengel C., Bosker O.J., Vermeeren C.A.J.R., 2003, Static properties of fiber metal laminates, Journal Of Applied Composite Materials 10(4): 207-222.

[3] Nuismer R.J., Whitney J.M., 1976, Uniaxial fracture of composite laminates containing stress concentrations, Fracture Mechanics of Composites ASTM STP 593:117-142.

[4] Pipes R.B., Wetherhold R.C., Gillespie J.W., 1979, Notched strength of composite materials, Journal of Composite Materials 13: 148-160.

[5] Tan S.C., 1987, Laminated composites containing an elliptical opening. Approximate stress Analyses and fracture models, Journal of Composite Materials 21: 925-948.

[6] Chang F.K., Chang K.Y., 1987, A progressive damage model for laminated composites containing stress concentrations, Journal of Composite Materials 21: 834-855.

[7] Waddoups M.E., Eisenmann J.R., Kaminski B.E., 1971, Macroscopic fracture mechanics of advanced composite materials, Journal of Composite Materials 5: 446-454.

[8] Mar J.W., Lin K.Y., 1979, Characterization of splitting process in graphite/epoxy composites, Journal of Composite Materials 13: 278-287.

[9] Backlund J., 1981, Fracture analysis of notched composites, Computer and Structure 13: 145-154.

[10] Ericsson I., Aronsson C.G., 1990, Strength of tensile loaded graphite/ epoxy laminates containing cracks, open and filled holes, Journal of Composite Materials 24: 456-482.

[11] Shin C.S., Wang C.M., 2004, An improved cohesive zone model for residual notched strength prediction of composite laminates with different orthotropic lay-up, Journal of Composite Materials 38(9): 713-736.

[12] Khatibi A., Ye L., 1997, Residual strength simulation of fibre reinforced metal laminates containing a circular hole, Journal of Composite Materials 31(9): 142-163.

[13] Spotts M. F., 1998, Design of Machine Elements, Prentice Hall.

[14] Ansys Help System, Analysis Guide and Theory Reference, ver10.

[15] ASTM, 2003, Standard Test Method For Tensile Properties of Polymer Matrix Composite Materials, Designation D 3039.

[16] Wu G., Tan Y., Yang J.M., 2007, Evaluation of residual strength of notched fiber metal laminates, Journal of Materials Science and Engineering, Part A 457: 338-349.