Investigation of the low velocity impact behavior of hybrid composite plates

Concrete structures may be subjected to unexpected sudden loads in various ways. Sudden load situations such as impacts, explosions and earthquakes can be given as examples of these sudden loadings. Impacts, vehicle collisions with bridge piers, throwing stones during take-off and landing on runways and similar situations can be given as examples. Impacts are divided into two according to their velocity as low and high velocity impacts. In this thesis, the behavior of hybrid composite plates subjected to low velocity impact was investigated. A preliminary study was carried out to determine the size and variable parameters of the plates in the low velocity impact tests. The preliminary study, cementitious plates were used replacement aggregate which produced by ethylene vinyl acetate (EVA) waste (volume 0%, 18%, 36%, 45%, 56% ratios) released during the production of shoe soles. The impact behavior of the plates was investigated effects of both thickness variation (15, 30, 50 mm) and reinforcement of plates with glass fiber reinforced polymers (GFRP) using vacuum infusion method (two layers at the bottom and two at the top). Hybrid composite plates produced were tested for low velocity impact. It has been determined that the addition of more than replacement ratio 32% EVA to cementitious plates is not suitable for the vacuum infusion method in cementitious plates. Additionally, as a result of the low velocity impact test, it became difficult to obtain the force value from the device on 15 mm plates. For these reasons, the parameters were changed. Replacement EVA ratios of 0%, 10%, 20%, 30%, 40% were selected in plate concrete mixes. The mechanical properties (compressive, splitting tensile and flexural strengths, dynamic modulus of elasticity) of plate concrete mixtures were determined. The impact behavior of the plates was investigated effect of both thickness variation (25, 50, 83 mm) and reinforcement of plates with GFRP using hand lay-up method (with 2, 4, 6 layers at the bottom). A low velocity impact test was applied to investigate the impact strength of hybrid composite plates. The force values obtained from the experiment were compared theoretically with the help of single degree of freedom mass-plate theory and numerically with ABAQUS finite element model solutions It has been determined that the samples containing the replacement of EVA increase the occurrence time of the peak impact force, thus increasing the energy absorption capacity of the concrete mixes. It has been determined that the theoretically calculated peak impact force values can be used for preliminary information, but a verification test is required. The numerical results indicate that the expression governing the stress-strain relationship of concrete mixtures containing replacement of EVA is not appropriate.