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    An Experimental and Numerical Determination on Low-Velocity Impact Response of Hybrid Composite Laminate
    (Springer, 2021) Erbayrak, Engin; Yuncuoglu, Ercument Ugur; Kahraman, Yusuf; Gumus, Beril Eker
    In this study, experimental and numerical investigations were carried out in order to determine the mechanical properties and impact response of hybrid composite laminate. The hybrid composite laminate was formed from plain woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) fiber using VARTM (vacuum-assisted resin transfer molding) process. The mechanical properties of the hybrid composites were determined using tensile test device with a 1 mm/min loading rate at room temperature. In addition, hybrid composites were subjected to low-velocity impact test under different impact energy levels (10, 20, 30, 40 J) for determining the impact response. Moreover, mechanical properties and impact responses of CFRE and GFRE laminates were also determined to compare to those of hybrid composite (HCGFRE). Microstructure analysis was performed to investigate the damage surfaces of the fiber and matrix in the composite material subjected to impact and tensile forces. In numerical analyses, composite damage model (Mat 54) was utilized in LS-DYNA(R)explicit finite element program to simulate the impact behavior of CFRE, GFRE and HCGFRE laminates. Consequently, the tensile test results showed that hybrid composite laminate behaved more ductile than carbon composite laminate and it exhibited more brittle behavior than glass composite laminate. Also, it was determined that absorbed energy and impact load capacity of HCGFRE composite laminate are between absorbed energy and impact load capacity of CFRE and GFRE composite laminate. It was determined that numerical results indicate a similar tendency with the experimental results.
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    Investigations of Strain Rate Effects on the Mechanical Properties of Hybrid Composite Laminate Under Varying Temperatures
    (Springer Heidelberg, 2020) Erbayrak, Engin; Gumus, Beril Eker; Yuncuoglu, Ercument Ugur; Kahraman, Yusuf
    The mechanical behavior of hybrid composite laminates under varying strain rates and temperatures was investigated in this study. The hybrid composite laminate is constituted as a sequential stacking sequence of plain-woven carbon-fiber-reinforced epoxy (CFRE) and plain-woven glass-fiber-reinforced epoxy (GFRE) laminates. Vacuum-assisted resin transfer molding (VARTM) process was used to fabricate the composite laminates. Hybrid composite laminates (HCGFRE) were tested under four different strain rates (0.05 min(-1), 0.5 min(-1), 2.5 min(-1), 5 min(-1)) and three different temperatures (RT, 60 degrees C, 100 degrees C). Microstructure analysis was performed to observe the voids, fiber delamination and matrix failure occurring in the composite laminate. In numerical analyses, continuum damage mechanics material model (MAT 58) was utilized in LS-DYNA(R)explicit finite element program to simulate the mechanical properties of CFRE, GFRE and HCGFRE laminates. It was determined that the tensile strength of all composite laminates is increasing by increasing the strain rates in all temperatures. The continuous damage mechanics material model (MAT 58) was found to be suitable for simulating woven composite laminate under different strain rates and temperatures. In microstructural study, it was not observed significant changes in the microstructure of composite laminates by changing strain rates.