به نام خداوند جان و خرد
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Composites Damage Mechanics - Summary
∑ Free surface damage in unidirectional composites was explained by the help of overlapping hypothesis where it points out the tensile singular radial stress as the main reason for the damage rather than the longitudinal interfacial shear stress.
∑ In MMCís the excessive plastic deformation inside the material (away from the free surface) causes some damage to the composite which by inclusion of the damage theory to the constitutive law the extend of damage is measured and controlled
∑ Since the delamination in composites is a major draw back for designs with these materials, it is tried here to use the above results to explain the phenomenon by FEM micro-mechanical modelling of the damage
∑ To explain the delamination damage using the overlapping hypothesis
∑ To combine the damage mechanics theories with the overlapping hypothesis to explain the damage on the free surface and also its growth path
∑ From the micro-mechanical point of view, the existing singular stress fields on the free edge of laminates happen at the fibre/matrix interface
∑ The interaction of the neighbouring fibres somehow shift the damage inside and also to the free surface neighbouring regions
∑ It is not yet clear how the damage extends from the interface region, so it needs to simulate the excessive plasticity in the regions close to the free surface
1) Abedian, A., Adibnazari, S., Rashidi-Moghadam, A., "FEM elasto-plastic analysis of a new manufacturing method for covering the free surface of unidirectional composites", Computational Materials Science, Vol. 36, pp. 411-424, 2006.
2) Abedian, A., Szyszkowski, W., Yannacopoulos, S., "Analysis of creep effects on the residual stress in SCS-6/Ti-6Al-4V composites using FEM", Thermal Stresses, Vol. 24, pp. 1-17, 2001.
3) Abedian, A., Yannacopoulos, S., Szyszkowski, W., "Effects of free surface geometry on damage initiation in unidirectional composites due to temperature cycling: an Experimental investigation", Canadian Metallurgical Quarterly, Vol. 39, No. 1, pp. 99-112, 2000.
4) Abedian, A., Szyszkowski, W., Yannacopoulos, S., "Effects of surface geometry of composites on thermal stress distribution: a numerical study", Composites Science and Technology, Vol. 59, pp. 41-54, 1999.
5) Abedian, A., Szyszkowski, W., Yannacopoulos, S., "Residual thermal stresses in metallic and inter metallic matrix composites after cooling from processing temperature", Composites Technology & Research, Vol. 20, No. 3, pp. 161-169, 1998.
6) Abedian, A., Szyszkowski, W., "Influence of the free surface on the thermal stresses in unidirectional composites", Composites Part A, 28A, pp. 573-579, 1997.
7) Abedian, A., Farahpour, H., "3-D FEM analysis of plastic behavior inside MMC composites considering damage theory", 25th Congress of International Council of the Aeronautical Sciences (ICAS-2006), Hamburg, Germany, 2006.