DOI: 10.13130/rd_unimi/n9enq4
title: Replication data for: Fracture toughness and auxeticity in disordered metamaterials

description: &lt;section&gt;
 &lt;h2&gt;Overview&lt;/h2&gt;

 &lt;p&gt;
 This dataset contains both raw and processed data acquired from &lt;b&gt;experimental mechanical tests&lt;/b&gt; and &lt;b&gt;computational simulations&lt;/b&gt;. 
 The data is organized to characterize and optimize the mechanical behavior of auxetic and fracture-resistant metamaterial structures.
 &lt;/p&gt;

 &lt;ul&gt;
 &lt;li&gt;&lt;b&gt;Experimental Data&lt;/b&gt;: Uniaxial tensile tests, synchronized high-resolution video recordings, and digital image correlation (DIC)-based analysis.&lt;/li&gt;
 &lt;li&gt;&lt;b&gt;Simulation Data&lt;/b&gt;: Results from stochastic optimization of soft-disk generated metamaterial networks under tensile and compressive loading.&lt;/li&gt;
 &lt;/ul&gt;
&lt;/section&gt;

&lt;hr/&gt;

&lt;section&gt;
 &lt;h2&gt;Experimental Data&lt;/h2&gt;

 &lt;h3&gt;Directory Structure&lt;/h3&gt;
 &lt;ul&gt;
 &lt;li&gt;250408_TensileTest/ — Stress–strain data in .txt format for non-optimized and optimized samples.&lt;/li&gt;
 &lt;li&gt;250408_NONOPT#_Video/, 250408_OPT#_Video/ — High-resolution .tif image sequences recorded during mechanical tests.&lt;/li&gt;
 &lt;li&gt;250523_ElaboratedVideo/ — Processed video data including:
 &lt;ul&gt;
 &lt;li&gt;250523_CellTrack/ — Cell deformation tracking for auxeticity quantification.&lt;/li&gt;
 &lt;li&gt;250523_GanasceTrack/ — Grip displacement tracking for axial strain determination.&lt;/li&gt;
 &lt;li&gt;250523_TrackSagome/ — Boundary tracking of gauge region for lateral strain computation.&lt;/li&gt;
 &lt;/ul&gt;
 &lt;/li&gt;
 &lt;/ul&gt;

 &lt;h3&gt;File Naming Convention&lt;/h3&gt;
 &lt;p&gt;Files follow the pattern: &lt;code&gt;250408_&lt;SAMPLE_ID&gt;_TensileTest.txt&lt;/code&gt;&lt;/p&gt;

 &lt;ul&gt;
 &lt;li&gt;SAMPLE_ID corresponds to:
 &lt;ul&gt;
 &lt;li&gt;NONOPT# — Non-optimized specimen&lt;/li&gt;
 &lt;li&gt;OPT# — Optimized specimen&lt;/li&gt;
 &lt;/ul&gt;
 &lt;/li&gt;
 &lt;/ul&gt;

 &lt;h3&gt;Structure of Tensile Test Files&lt;/h3&gt;
 &lt;ul&gt;
 &lt;li&gt;Metadata header containing:
 &lt;ul&gt;
 &lt;li&gt;Test Method&lt;/li&gt;
 &lt;li&gt;Sample I.D.&lt;/li&gt;
 &lt;li&gt;Specimen Number&lt;/li&gt;
 &lt;/ul&gt;
 &lt;/li&gt;
 &lt;li&gt;Data table, semicolon-delimited, including:
 &lt;ul&gt;
 &lt;li&gt;Load (N)&lt;/li&gt;
 &lt;li&gt;Time (s)&lt;/li&gt;
 &lt;li&gt;Extension (mm)&lt;/li&gt;
 &lt;li&gt;Stress (MPa)&lt;/li&gt;
 &lt;li&gt;Strain (%)&lt;/li&gt;
 &lt;/ul&gt;
 &lt;/li&gt;
 &lt;/ul&gt;

 &lt;p&gt;
 Tensile tests were performed using a universal testing machine and synchronized with high-speed video acquisition for post-processing via image-based strain mapping.
 &lt;/p&gt;

 &lt;h3&gt;Frame-by-Frame Video Data&lt;/h3&gt;
 &lt;ul&gt;
 &lt;li&gt;Files named as: &lt;code&gt;250408_&lt;SAMPLE_ID&gt;_TensileTest_###.tif&lt;/code&gt;&lt;/li&gt;
 &lt;li&gt;Each file corresponds to a single frame (starting from 001).&lt;/li&gt;
 &lt;li&gt;High-speed grayscale recordings used for strain field computation, Poisson ratio estimation, and fracture detection.&lt;/li&gt;
 &lt;/ul&gt;
&lt;/section&gt;

&lt;hr/&gt;

&lt;section&gt;
 &lt;h2&gt;Simulation Data&lt;/h2&gt;

 &lt;h3&gt;Directory Structure&lt;/h3&gt;
 &lt;p&gt;Located under &lt;code&gt;simulation_DATA/&lt;/code&gt; and organized into four loading scenarios:&lt;/p&gt;

 &lt;ul&gt;
 &lt;li&gt;COMP-M/ — Compression, mass redistribution along M direction.&lt;/li&gt;
 &lt;li&gt;COMP-N/ — Compression, mass redistribution along N direction.&lt;/li&gt;
 &lt;li&gt;TENS-M/ — Tension, mass redistribution along M direction.&lt;/li&gt;
 &lt;li&gt;TENS-N/ — Tension, mass redistribution along N direction.&lt;/li&gt;
 &lt;/ul&gt;

 &lt;h3&gt;Sample Structure and Replication&lt;/h3&gt;
 &lt;ul&gt;
 &lt;li&gt;25 network samples generated via soft-disk simulations.&lt;/li&gt;
 &lt;li&gt;Each sample tested twice in each batch.&lt;/li&gt;
 &lt;li&gt;Total optimization runs: 4 batches × 25 samples × 2 replicas = &lt;b&gt;200&lt;/b&gt;.&lt;/li&gt;
 &lt;/ul&gt;

 &lt;h3&gt;Subdirectory Naming Scheme&lt;/h3&gt;
 &lt;p&gt;&lt;code&gt;YYYYMMDD_sample-&lt;sample-id&gt;_replica-&lt;replica-id&gt;/&lt;/code&gt;&lt;/p&gt;

 &lt;h3&gt;Files in Each Optimization Run&lt;/h3&gt;
 &lt;ul&gt;
 &lt;li&gt;nodes_init.dat — Initial nodal coordinates (x, y).&lt;/li&gt;
 &lt;li&gt;nodes_final.dat — Final nodal coordinates (x, y).&lt;/li&gt;
 &lt;li&gt;edges_init.dat — Initial edge connectivity.&lt;/li&gt;
 &lt;li&gt;edges_final.dat — Final edge connectivity.&lt;/li&gt;
 &lt;li&gt;force_disp_init.dat — Initial force–displacement curve.&lt;/li&gt;
 &lt;li&gt;force_disp_final.dat — Final force–displacement curve.&lt;/li&gt;
 &lt;li&gt;opt.txt — Summary of optimization parameters (weight_nu, weight_U, nu_init, nu_final, U_init, U_final).&lt;/li&gt;
 &lt;li&gt;edge_data_final.dat — Final beam-level data (bending ratio, von Mises stress, GEBC).&lt;/li&gt;
 &lt;/ul&gt;
&lt;/section&gt;

&lt;hr/&gt;

&lt;section&gt;
 &lt;h2&gt;Acknowledgements&lt;/h2&gt;
 &lt;p&gt;
 A.L.H.S.D., R.G. and S.Z. acknowledge support from the ARCHIBIOFOAM project, 
 which received funding from the European Union’s Horizon Europe research and 
 innovation programme under grant agreement No 101161052. Views and opinions 
 expressed are however those of the author(s) only and do not necessarily reflect 
 those of the European Union or European Innovation Council and SMEs Executive Agency (EISMEA). 
 Neither the European Union nor the granting authority can be held responsible for them.
 &lt;/p&gt;
&lt;/section&gt;