pps proceeding - Abstract Preview
pps proceeding
Symposium: S17 - Special Symposium: Additive manufacturing (3D printing)
Keynote Presentation
 
 

Synopsis on Damage Analysis and Monitoring in Composite Materials through Experimental and Numerical Approaches

Yildiz Mehmet (1)*

(1) Sabanci University - Istanbul - Turkey

This presentation will introduce the establishment of composite technologies center of excellence in collaboration with industry through a unique model where industry and university coexist in the same ecosystem under the same roof. Afterwards, it will provide a synopsis on four different research activities in my group. The first section investigates the damage evolution in glass/carbon fiber hybrid composites under tension and flexural loading. Damage occurrence is recorded using acoustic emission and classified into four clusters by using the K-means algorithm. The experimental tests are numerically simulated based on refined zigzag theory (RZT) which depicts out-of-plane displacement in hybrid fiber laminates due to interlaminar delamination. Finally, the comparison of experimentally and numerically calculated strain-stress curves shows that the onset of the damage inside the material is demarcated as the deviation of experimental results from numerical ones. Remarkably, at this deviation instant, the acoustic emission activity also initiates for both tensile and bending specimens, hence confirming major damage evolution inside the laminates. The second section emphasizes on the effect carbon and glass tabbing on tensile behaviour of different stacking sequenced (0°,15°,30°,45°,60°,75°, and 90°) carbon fiber reinforced polymer matrix composites. Tensile tests are conducted with concurrent monitoring of mechanical behaviour of specimens through digital image correlation and acoustic emission techniques. Preliminary analysis reveals that carbon tabs show less scattering in tensile strength, less acoustic activities for matrix cracking and uniform strain gradient for 0°,15°,30°,45° and 60° plies which is contrary to glass tabs. But in the case of 75°and 90° plies, glass tabs are favourable as carbon tabs show more scattering, heterogeneous strain distribution, and more acoustic activities for matrix cracking. The third section focuses on the production of Piezoelectric Polyvinylidene fluoride (PVDF) nanofibers-based sensor for structural health monitoring of composites. Characterization of electrospun PVDF nanofibers confirms that electrospinning promotes the formation of β-phase. Dynamic flexural tests are performed on woven carbon fabric composites with embedded and surface mounted PVDF sensors to study the capability of these sensors to record strain history and damage progression in composite materials. This result is validated by the strain measurement with the video extensometer during tests. Fractographic information is obtained with the help of electron microscopic analysis of fractured specimens. The fourth section involves a study on the topology optimization of 3D-printed parts with and without the presence of crack through employing particle based computational mechanic approach, namely, Peridynamics.