core material Tab. 2: Experimental results Compressive strength (bare) Density Designation Compressive strength (stabilized) Shear strength Crush strength L W kg.m lb.ft MPa psi MPa psi MPa psi MPa psi MPa psi ALCORE PAA 5052 3.0-3/8-.0020 theoretical 48 3.0 - - 2.17 314 0.93 135 1.41 204 0.88 128 ALCORE PAA 5052 3.0-3/8-.0020 measured 46.2 2.9 1.80 261 1.93 280 1.05 152 1.48 215 0.82 119 New EC3D honeycomb measured 46.0 2.9 3.13 454 3.24 470 1.35 196 1.71 248 0.96 139 -3 -3 Improvement +73.8 % +67.8 % +28.5 % +15.5 % +17.1 % 48 kg.m-3 59.2 kg.m-3 Tab. 3: Synthesis of comparative results 1), on a Lloyd LR50K machine in quasi-static conditions (0.5 mm.min -1). As expected, all the mechanical characteristics were improved (Table 2). Compression The compressive strength of the EC3D modified honeycomb was 73.8% higher in the bare state and 67.8% higher in the stabilized state (sandwich structure). Fig. 6: Compressive strength versus density by wall thickness Main characteristics - Ultra-high mechanical properties - 20% lower raw material cost for the same properties - Unique compression/energy absorption: compressive strength up to 170% of standard honeycomb - Improved formability - Fully compatible with current production lines - Patents EP 14713529.7 and US 14/774,360 Shear properties The shear properties were also enhanced, with a 15.5% improvement of shear strength in the L direction (lengthwise) and a 17.1% improvement in the W direction (widthwise). Conclusion As shown in the synthesis below (Table 3), raw material costs can be reduced by 20% for the same mechanical properties. For applications that require only compressive properties as a main characteristic, the raw material cost can be reduced even more for the same level of performance, by at 52 jec composites magazine / No106 July 2016 least 30% for the same compressive strength. For example, this unique enhancement makes it possible to use a 50 μm foil thickness instead of 70 μm for the same level of compression performance (Figure 6). This opens good cost reduction opportunities for future programmes, especially in aeronautics. n More information: www.engineeringcomposite3d.com Contact: contact@engineeringcomposite3d.comhttp://www.engineeringcomposite3d.com