U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by:

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 51 - 75 of 101

Fatigue and Damage Tolerance of Y-TZP Ceramics in Layered Biomechanical Systems

October 1, 2004
Author(s)
Yu Zhang, Antonia Pajares, Brian R. Lawn
The fatigue properties of fine-grain Y-TZP in cyclic flexural testing are studied. Comparative tests on a coarser-grain alumina provide a baseline control. A bilayer configuration with ceramic plates bonded to a compliant polymeric substrate and loaded

Fatigue Sensitivity of Y-TZP to Microscale Sharp-Contact Flaws

August 14, 2004
Author(s)
Yu Zhang, Brian R. Lawn
The strength degrading effects of sharp-contact damage are examined for Y-TZP ceramic plates bonded to a plastic substrate. Microscale contacts are made with Vickers and Berkovich diamond indenters at low loads (0.01 N to 10 N) in the ceramic lower

Strength of Silicon, Sapphire in the Subthreshold Flaw and Glass Region

July 1, 2004
Author(s)
Yeon-Gil G. Jung, Antonia Pajares, R Banerjee, Brian R. Lawn
Strength properties are determined for monocrystalline silicon and sapphire and for soda-lime glass plates containing subthreshold flaws, i.e. flaws without detectable microcracks. Nanoindentations covering a wide range of loads are used to introduce flaws

Effect of Sandblasting on the Long-Term Performance of Dental Ceramics

June 1, 2004
Author(s)
Yu Zhang, Brian R. Lawn, E D. Rekow, Victoria Thompson
A study is made of the effects of sandblasting on the strength of Y-TZP and alumina ceramic layers joined to polymeric substrates and loaded at the top surfaces by a spherical indenter, in simulation of occlusal contact in ceramic crowns on tooth dentin

Materials Design in the Performance of All-Ceramic Crowns

June 1, 2004
Author(s)
Brian R. Lawn, Antonia Pajares, Yu Zhang, Y N. Deng, M Polack, Isabel K. Lloyd, E D. Rekow, Victoria Thompson
Results from a systematic study of damage in material structures representing the basic elements of dental crowns are reported. Tests are made on model flat-layer specimens fabricated from various dental ceramic combinations bonded to dentin-like polymer

Long-Term Strength of Ceramics for Biomedical Applications

May 1, 2004
Author(s)
Yu Zhang, Brian R. Lawn
The influence of slow crack growth on the initiation of radial cracks at the undersurfaces of ceramic layers on polymeric substrates is studied, with particular relevance to biomechanical systems dental crowns and hip replacement prostheses. Critical loads

Damage Modes in Dental Crown Multilayer Structures

February 1, 2004
Author(s)
Yu Zhang, Y N. Deng, Brian R. Lawn
The full potential of esthetic ceramic-based dental restorations has not yet been realized. Processing and surgical induced damage, exacerbated by fatigue damage during normal chewing, can reduce the initial strength of inherently brittle materials. The

Dynamical Adhesion Force of Cells on Biomaterial Substrates

February 1, 2004
Author(s)
Y N. Deng, Carl Simon Jr., P M. McGuiggan, Sheldon M. Wiederhorn, Brian R. Lawn
The adhesion of cells to synthetic biomaterial implant surfaces is an essential step for tissue growth in bone repair. Such adhesion can mandate whether the tissue will accept or reject the implanted biomaterials. In this study, the adhesion forces between

Strength of Silicon Containing Nanoscale Flaws

February 1, 2004
Author(s)
Antonia Pajares, Michael Chumakov, Brian R. Lawn
A study was made of the strength of highly polished silicon surfaces after nanoindentation with a Berkovich diamond. Strengths of the indented surfaces were measured as a function of flaw size, quantified by indenter penetration. Analogous data from etched

Crack Opening Profiles of Indentation Cracks in Normal and Anomalous Glasses

January 1, 2004
Author(s)
Z Burghard, A Zimmermann, J Rodel, F Aldinger, Brian R. Lawn
A comparative Vickers indentation study is made of two glasses, soda-lime andborosilicate. Indentations in the two glasses reveal substantially shorter radial cracks in the borosilicate, even though toughness values measured by conventional

Fracture of Ceramic/Ceramic/Polymer Trilayers for Biomechanical Applications

December 1, 2003
Author(s)
Y N. Deng, P Miranda, Antonia Pajares, Brian R. Lawn
Fracture damage in trilayers consisting of outer and inner brittle layers bonded to a compliant (polycarbonate) substrate and subjected to concentrated surface loading is analyzed. The principal mode of fracture is radial cracking at the undersurface of

Designing Damage-Resistant Brittle-Coating Structures: I. Bilayers

August 1, 2003
Author(s)
P Miranda, Antonia Pajares, F Guiberteau, Y N. Deng, Brian R. Lawn
A FEA study of coating/substrate bilayers is conducted as a foundation for damage analysis. Attention is focused on the stresses along the contact axis immediately adjacent to the bilayer interface, where radial cracking or yield in the coating, or yield

Designing Damage-Resistant Brittle-Coating Structures: II. Trilayers

August 1, 2003
Author(s)
P Miranda, Antonia Pajares, F Guiberteau, Y N. Deng, H Zhao, Brian R. Lawn
An extension of the FEA-based damage analysis for bilayers in Part I is presented for trilayers consisting of a functional outer layer on an underlying substrate with an intermediate inner core layer. The inner core layer may be used to enhance bonding or

Overview: Damage in Brittle Layer Structures From Concentrated Loads

December 1, 2002
Author(s)
Brian R. Lawn, Y N. Deng, P Miranda, Antonia Pajares, H Chai, D H. Kim
In this article, we review recent advances in the understanding and analysis of damage initiation and evolution in laminate structures with brittle outlayers and compliant sublayers, in concentrated loading. The relevance of such damage to lifetime

Rate Effects in Critical Loads for Radial Cracking in Ceramic Coatings

August 1, 2002
Author(s)
C S. Lee, D H. Kim, J Sanchez, P Miranda, Antonia Pajares, Brian R. Lawn
Rate effects in the Hertzian contact loading of model glass/polycarbonate and silicon/polycarbonate bilayers bonded by epoxy adhesive are examined. Glass is used because of its high susceptibility to slow crack growth, making this conventional contribution

Ceramic Based Layer Structures for Biomechanical Applications

June 1, 2002
Author(s)
Brian R. Lawn
A survey of recent advances in the analysis of ceramic-based layer structures for biomechanical applications is presented. Data on model layer systems, facilitating development of explicit fracture mechanics relations for predicting critical loads to

Cracking in Brittle Laminates from Concentrated Loads

June 1, 2002
Author(s)
H Chai, Brian R. Lawn
A study is made of the crack resistance of multilaminates consisting of brittle layers interleaved with compliant interlayers and bonded to compliant substrates. Specific attention is paid to flexure generated radial cracks in the undersurfaces of

Materials Design of Ceramic Based Layer Structures for Crowns

June 1, 2002
Author(s)
Brian R. Lawn, Y N. Deng, Isabel K. Lloyd, E D. Rekow, Victoria Thompson
Explicit fracture mechanics relations for the onset of critical damage in crown-like ceramic layers on soft polymeric substrates subjected to contacts loads are presented. Damage modes include cone cracking and quasiplasticity at the top surfaces, and

Cracking in Ceramic/Metal/Polymer Trilayer Systems

May 1, 2002
Author(s)
H Zhao, P Miranda, Brian R. Lawn, X Z. Hu
Fracture and deformation in model brittle-outerlayer/metal-core/polymer substrate trilayer systems in concentrated loading are studied. Model systems for experimental study are fabricated from glass microscope slides glued with epoxy adhesive onto steel

Characterization of Damage Modes in Dental Ceramic Bilayer Structures

January 1, 2002
Author(s)
Y N. Deng, Brian R. Lawn, Isabel K. Lloyd
Results of contact tests using spherical indenters on flat ceramic coating layers bonded to compliant substrates are reported for selected dental ceramics. Critical loads to produce various damage modes, cone cracking and quasiplasticity at the top

Thermal Shock Resistance of Silicon Nitrides Using an Indentation-Quench Test

January 1, 2002
Author(s)
S K. Lee, J D. Moretti, Brian R. Lawn
The thermal shock resistance of silicon nitrides is investigated using an indentation-quench procedure. Four grades of commercially available silicon nitrides with different microstructures are investigated. The extension of Vickers radial cracks is