PSI - Issue 42

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Andrea Zanichelli et al. / Procedia Structural Integrity 42 (2022) 118–124 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

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Moreover, in order to further compare the numerical estimations with the experimental results, a toughness index, t I , is introduced. Such an index is defined as:

A

m

(1)

I

=

t

A

peak

where peak A is the area under the load-CMOD curve up to a value of CMOD equal to area under the same curve up to a value of CMOD equal to peak m CMOD  , being m a prescribed multiplier. In the present work, t I is computed in correspondence of five different values of CMOD, that is, five different values (2, 5, 10, 15, 20) of the multiplier m are used. Both the average experimental (with standard deviations) and numerical values of toughness index are listed in Table 2, for the five different multipliers considered. It can be observed that for 2 m = and 20 the toughness index related to the mean numerical curve is within the experimental scatter band. On the other hand, for intermediate values the numerical results are slightly lower than the experimental ones, thus conservatively underestimating the ductility of the shot-earth 772. Table 2. Both average experimental (with standard deviations) and numerical values of toughness index, t I . t I (-) m=2 m=5 m=10 m=15 m=20 Experimental tests 2.41±0.11 5.06±0.51 7.05±1.15 7.77±1.70 8.10±2.07 Numerical mean curve 2.51 4.46 5.36 5.76 6.04 peak CMOD , and m A is the 5. Conclusions The present work deals with the numerical simulation of an experimental campaign carried out to compute the fracture toughness of the shot-earth 772. The numerical analyses have been performed by employing a numerical model which allows to simulate both flexural and fracture behaviour of the shot-earth considered. Moreover, both elastic modulus and fracture toughness have been computed by means of the Modified Two-Parameter model. It has been observed that the numerical curves are in quite-satisfactory agreement with the experimental data. The values of the elastic modulus and the peak load of both flexural end fracture tests are well-predicted by means of the numerical model employed. Moreover, although an overestimated value of fracture toughness is obtained through the numerical simulations, the results in terms of toughness index are in quite-good agreement with the experimental results and highlight that a conservative curve is provided by the employed numerical model. Acknowledgements The work of Sabrina Vantadori and Andrea Zanichelli is supported by Italian Ministry of University and Research (F.I.S.R. National Grant 2019, Project code FISR2019_00245, funding 1.536.968,43 €; University of Parma Research Unit). References Anglade, E., Aubert, J.E., Sellier, A., Papon, A., 2022. Physical and mechanical properties of clay – sand mixes to assess the performance of earth construction materials. Journal of Building Engineering 51, 104229. Kebao, R., Kagi, D., 2012. Integral admixtures and surface treatments for modern earth buildings. In: Modern earth buildings. Materials, engineering, construction and applications. Edited by Hall M. R. , Lindsay R., Krayenhoff M. Woodhead Publishing, Cambridge, UK. Losini, A.E., Grillet, A.C., Woloszyn, M., Lavrik, L., Moletti, C., Dotelli, G., Caruso, M., 2022. Mechanical and Microstructural Characterization of Rammed Earth Stabilized with Five Biopolymers. Materials 15 (9), 3136.