Non-Classical nonlinear feature extraction from standard resonance vibration data for damage detection

An appropriate copyright notice must be included along with the full citation for the published paper and a Web link to ASA's official online version of the abstract. There are no format restrictions; files prepared and/or formatted by ASA, AIP, or its vendors (e.g., the PDF, PostScript, or HTML article files published in the online journals and proceedings) may be used for this purpose. If a fee is charged for any use of the posted article, ASA permission must be obtained.Dynamic non-classical nonlinear analyses show promise for improved damage diagnostics in materials that exhibit such structure at the mesoscale, such as concrete. In this study, nonlinear non-classical dynamic material behavior from standard vibration test data, using pristine and frost damaged cement mortar bar samples, is extracted and quantified. The procedure is robust and easy to apply. The results demonstrate that the extracted nonlinear non-classical parameters show expected sensitivity to internal damage and are more sensitive to changes owing to internal damage levels than standard linear vibration parameters.The authors acknowledge the financial support of the Ministerio de Ciencia e Innovacion MICINN, Spain, FEDER funding (Ondacem Project: BIA 2010-19933) and BES-2011-044624.Eiras Fernández, JN.; Monzó Balbuena, JM.; Paya Bernabeu, JJ.; Kundu, T.; Popovics, J. (2014). Non-Classical nonlinear feature extraction from standard resonance vibration data for damage detection. Journal of the Acoustical Society of America. 135(2):82-87. doi:10.1121/1.4862882S8287135

Effect of age and level of damage on the autogenous healing of lime mortars

Natural hydraulic lime-based mortars are recommended for retrofitting operations in historical buildings, primarily because of their high chemical, physical and mechanical compatibility with the existing ones; moreover, their autogenous and engineering self-healing capacities make them a more suitable material for the aforementioned interventions. This work proposes a methodology to quantify the autogenous self-healing in terms of recovery of the compression strength and ultrasonic pulse velocity in samples made of natural hydraulic lime mortars; specimens were pre-cracked at different ages (14–84 days) and levels of damage (70% of the compression strength in pre-peak regime; 90% of the compression strength in post-peak regime), and then cured under water up to 28 days. The capacity of healing after two loading/healing cycles has been also investigated. An interdisciplinary approach has been pursued characterising the mechanical aspects of the healing and the chemical nature of the products via SEM/EDS analyses. The results provide useful indication about the dependence of the self-healing capacity on the aforementioned variables