A new fractal wear model is proposed. The new model is based on the multi-scale fractal contact model. Studying the elastoplastic and plastic state of contact asperities, the new wear model is established. The relationship between the amount of contact surface wear and the fractal dimension D, the characteristic coefficient G and the material property constant C is studied. Besides, wear coefficient of the rough contact surface is predicted. It can be seen from the results that the influence of the scale effect on contact surface must be considered, because of the asperities with the same deformation ?? will be in different contact state. The relationship between amount of wear in the new model and amount of wear in existing model has the same trend. When D = 1.45, the amount of wear is the lowest. With the increasing of G reflecting the roughness of contact surface, the wear amount is increasing. The material constant also has a certain influence on the wear amount, and the material with high hardness has low wear. The contributions of the amount of asperity wear (elastoplastic and plastic) have the same effect to the total wear amount. Besides, the result of new fractal wear coefficient and the result of classical have the same trend, however, the new wear model is more precise than the classical wear model and closer to the actual state.
Applling Leeb hardness tester D punch, examined the steel hardness by two different ways of clamping method and coupling method respectively, studied the correlation of Leeb hardness and steel strength, compared the research results with related literature and Jiangsu province construction standard of DGJ32/ TJ116-2011. Through the research, the conclusion is larger that this research results and related literature, the reliability is very low which be used to infer steel tensile strength with the D punch testing Leeb hardness .
To find out the toughening mechanism of in-situ toughening telechelic polymers (ITTP) in concrete, SEM & EDS and Nano indenter were used to research the variation of concrete hydration products and the interfacial transition zone between the cement paste and aggregate. The results indicate that the toughening effect of ITTP is not carried out by film formation. And the proportion of LD C-S-H in cement hydration products increased significantly and the CH content decreased after introducing the ITTP into concrete. Nano indentation test results show that the non-dense area ratio of ITZ decreased, and the CH content in ITZ increased slightly. The Ca/Si blurred from mutation pattern with decreasing the distance to aggregate surface in the region of interfacial transition zone between aggregate and cement paste, and the thickness of ITZ increased. The conclusions show that the ITZ and hydration products are both key micro-structures which affect the toughness of concrete, and it provides us some guidance for realizing concrete toughness ascension through microstructure adjustment.
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