Skip to main content Accessibility help

Competing fracture modes in brittle materials subject to concentrated cyclic loading in liquid environments: Bilayer structures

  • Sanjit Bhowmick (a1), Yu Zhang (a2) and Brian R. Lawn (a1)


A preceding study of the competition between fracture modes in monolithic brittle materials in cyclic loading with curved indenters in liquid environments is here extended to brittle layers on compliant substrates. The fracture modes include outer and inner cone cracks and radial cracks that initiate from the near-contact zone and penetrate downward. Outer cone cracks are driven by stresses from superposed Hertzian and plate flexure fields; inner cone cracks also grow within these fields but are augmented by mechanical driving forces from hydraulic pumping into the crack fissures. Radial cracks are augmented by mechanical driving forces from developing quasiplasticity zones beneath the indenter. Basically, the crack-growth rates are governed by a crack velocity relation. However, the hydraulic and quasiplastic mechanical forces can cumulate in intensity with each cycle, strongly enhancing fatigue. Plate flexure generates compressive stresses at the top surface of the brittle layer, somewhat inhibiting the initiation, and tensile stresses at the lower surface, strongly enhancing the far-field propagation. The tensile stresses promote instability in the crack propagation, resulting in through-thickness penetration (failure). Experiments on a model bilayer system consisting of glass plates bonded to thick polycarbonate bases are presented as an illustrative case study. In situ observations of the crack evolution from initial growth to failure reveal that each fracture mode can dominate under certain test conditions, depending on plate thickness, maximum load, and sphere radius. Implications concerning the failure of practical layer systems, notably dental crowns, are discussed.


Corresponding author

a)Address all correspondence to this author. e-mail:


Hide All
1Zhang, Y., Bhowmick, S. and Lawn, B.R.: Competing fracture modes in brittle materials subject to concentrated cyclic loading in liquid environments: Monoliths. J. Mater. Res. 20, 2021 (2005).
2Lawn, B.R., Deng, Y., Miranda, P., Pajares, A., Chai, H. and Kim, D.K.: Overview: Damage in brittle layer structures from concentrated loads. J. Mater. Res. 17, 3019 (2002).
3Zhang, Y., Kwang, J-K. and Lawn, B.R.: Deep penetrating conical cracks in brittle layers from hydraulic cyclic contact. J. Biomed. Mater. Res. B 73B, 186 (2005).
4Kim, D.K., Jung, Y-G., Peterson, I.M. and Lawn, B.R.: Cyclic fatigue of intrinsically brittle ceramics in contact with spheres. Acta Mater. 47, 4711 (1999).
5Chai, H., Lawn, B.R. and Wuttiphan, S.: Fracture modes in brittle coatings with large interlayer modulus mismatch. J. Mater. Res. 14, 3805 (1999).
6Rhee, Y-W., Kim, H-W., Deng, Y. and Lawn, B.R.: Contact-induced damage in ceramic coatings on compliant substrates: Fracture mechanics and design. J. Am. Ceram. Soc. 84, 1066 (2001).
7Deng, Y., Lawn, B.R. and Lloyd, I.K.: Characterization of damage modes in dental ceramic bilayer structures. J. Biomed. Mater. Res. 63B, 137 (2002).
8Lawn, B.R., Deng, Y. and Thompson, V.P.: Use of contact testing in the characterization and design of all-ceramic crown-like layer structures: A review. J. Prosthet. Dent. 86, 495 (2001).
9Lawn, B.R., Lee, S.K., Peterson, I.M. and Wuttiphan, S.: Model of strength degradation from Hertzian contact damage in tough ceramics. J. Am. Ceram. Soc. 81, 1509 (1998).
10Chai, H. and Lawn, B.R. Hydraulically pumped cone fractures in brittle solids. (in press).
11Lawn, B.R., Lee, K.S., Chai, H., Pajares, A., Kim, D.K., Wuttiphan, S., Peterson, I.M. and Hu, X.: Damage-resistant brittle coatings. Adv. Eng. Mater. 2, 745 (2000).
12Qasim, T., Bush, M.B., Hu, X. and Lawn, B.R.: Contact damage in brittle coating layers: Influence of surface curvature. J. Biomed. Mater. Res. 73B, 179 (2005).
13Deng, Y., Miranda, P., Pajares, A. and Lawn, B.R.: Fracture of ceramic/ceramic/polymer trilayers for biomechanical applications. J. Biomed. Mater. Res. 67A, 828 (2003).
14Timoshenko, S. and Woinowsky-Krieger, S.: Theory of Plates and Shells (McGraw-Hill, New York, 1959).
15Wiederhorn, S.M. and Bolz, L.H.: Stress corrosion and static fatigue of glass. J. Am. Ceram. Soc. 53, 543 (1970).
16Wiederhorn, S.M.: A chemical interpretation of static fatigue. J. Am. Ceram. Soc. 55, 81 (1972).

Related content

Powered by UNSILO

Competing fracture modes in brittle materials subject to concentrated cyclic loading in liquid environments: Bilayer structures

  • Sanjit Bhowmick (a1), Yu Zhang (a2) and Brian R. Lawn (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.