Session: 04-10-01: Impact, Damage and Fracture of Composite Structures

Paper Number: 77490

Start Time: Monday, 06:20 PM

77490 - Impact Performance and Bending Behavior Analysis of Fiber Reinforced Composite Sandwich Structures in Arctic Condition 

 

This study investigates the low-velocity impact performance and bending behavior with underlying damage mechanisms of woven carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), and carbon-glass fiber hybrid face sheets sandwich panel. A series of low-velocity impact tests (3.46 m/s and 4.92 m/s) is performed at 15 J and 30 J energy using a drop tower testing machine. These energy levels are selected so that lower energy of 15 J can mostly damage the front face sheet, and 30 J impact penetrates the front face sheet and crushes the PVC core to some extent. Specimens are subjected to impact at room temperature (23 °C) and low temperature (-70 °C) to mimic the arctic environment. A relative comparison of the impact response from different sandwich specimens under different conditions is presented in terms of force, displacement, and energy.

Though force-time curves show a smooth loading phase for CFRP and GFRP specimens at 15J, fiber breakage with severe load drop is observed on the front face sheet of hybrid sandwich composites at both temperatures. On other hand, significant load drops followed by a plateau are noticed for all types of sandwich samples from 30J impacts. Force- displacement plots show that GFRP followed by hybrid sandwich composites have the highest damage initiation force and peak force values across different temperatures and impact energies. Furthermore, the lowest energy absorption for glass composites is found which is responsible for the least impact-induced damage. X-ray microcomputed tomography is utilized to reveal damage modes in the sandwich structures. CFRP sandwich panel shows severe fiber breakage on the compression side and back face spitting both temperatures for 30J impacts. With the replacement of glass fibers, the damage mechanism switches from breakage to delamination as the dominant failure mode. Extensive delamination is observed in hybrid fiber composite panels due to the presence of dissimilar carbon and glass fiber layers.

Moreover, post-impact bending tests are conducted to investigate the residual flexural strength of
sandwich structures from ASTM C393 standard with a crosshead speed of 0.5 mm/min. No significant differences in peak load values are observed for different types of non-impacted sandwich composites. But post-impacted GFRP sandwich specimens outperform other sandwich composites by producing greater peak forces with higher displacement and as such, provide better flexural strength at both temperatures. CFRP specimens show the least flexural resistance under these conditions. Debonding dominates at the back face sheet of all composites at 15 J due to greater deflection, whereas fiber breakage on the front face sheet with core densification and core shear are major damage modes at 30J post-impacted specimens.  GFRP and hybrid sandwich present better damage tolerance and flexural strength in low temperatures due to the improvement in the bonding between glass fiber and matrix.

 

 

 

Presenting Author: Arnob Banik The University of Akron

Authors:

Arnob Banik The University of Akron
Kwek-Tze Tan The University of Akron