2026-09-19T10:50:04Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/615212022-01-13T07:54:36Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Franz-Josef Ulm.
Bard, Romain (Romain M.)
Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
2011-03-07T14:39:00Z
2011-03-07T14:39:00Z
2010
2010
http://hdl.handle.net/1721.1/61521
703596313
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 143-148).
In this thesis we develop analytical solutions for the relations between scratch hardness and strength properties of cohesive-frictional materials of the Mohr-Coulomb and Drucker-Prager type. Based on the lower-bound yield design approach, closed form solutions are derived for frictionless scratch devices, and validated against computational upper bound and elastoplastic Finite Element solutions. The influence of friction at the blade{material interface is also investigated, for which a simple computational optimization is proposed. The model is extended to porous cohesive-frictional materials through the use of a homogenized strength criterion based on the Linear Comparison Composite theory. Relations between scratch hardness, porosity and strength properties are proposed in the form of fitted functions. Illustrated for scratch tests on cement paste, we show that the proposed solutions provide a convenient way to determine estimates of cohesion and friction parameters from scratch data, and may serve as a benchmark to identify the relevance of strength models for scratch test analysis.
by Romain Bard.
S.M.
148 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by
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http://dspace.mit.edu/handle/1721.1/7582
Mechanical Engineering.
Analysis of the scratch test for cohesive-frictional materials
Scratch test for cohesive-frictional materials
Thesis
application/pdf
Publication
unknown
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<Abstract>In this thesis we develop analytical solutions for the relations between scratch hardness and strength properties of cohesive-frictional materials of the Mohr-Coulomb and Drucker-Prager type. Based on the lower-bound yield design approach, closed form solutions are derived for frictionless scratch devices, and validated against computational upper bound and elastoplastic Finite Element solutions. The influence of friction at the blade{material interface is also investigated, for which a simple computational optimization is proposed. The model is extended to porous cohesive-frictional materials through the use of a homogenized strength criterion based on the Linear Comparison Composite theory. Relations between scratch hardness, porosity and strength properties are proposed in the form of fitted functions. Illustrated for scratch tests on cement paste, we show that the proposed solutions provide a convenient way to determine estimates of cohesion and friction parameters from scratch data, and may serve as a benchmark to identify the relevance of strength models for scratch test analysis.</Abstract>
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