In the current study, the effect of the thickness and the foam density in three-dimensional integrated woven sandwich composites on quasi-static mechanical properties under three-point bending was investigated. Bending modulus and core shear modulus were determined by subjecting the samples, which were cut with varying span lengths according to their core thicknesses, to three-point bending test. Obtained results were optimized by taking core thickness, foam density and panel weights into consideration. Damages that occurred on the tested samples were reported. When compared to conventional foam core sandwich composites, it was found that three-dimensional integrated sandwich composites have superior mechanical properties and due to the fact that the pile yarns in the core and the foam support each other, contrary to conventional sandwich composites no catastrophic core breakage occurs under load, thus the load bearing capacity of the structure is sustained.

In this paper, the low velocity impact characteristics and impact damage of sandwich composites, produced at four different core thicknesses from 3-dimensional (3D) integrated sandwich fabrics, with and without foam filling, have been examined. The 3D sandwich fabrics have been produced using the same yarn and weaving densities. Thus, the impact characteristics are only affected by the core thickness and whether foam filling is used or not. Low velocity impact tests have been conducted at 32 and 48 J energy levels. The impact behavior has been determined as a function of the peak load, the energy to peak load, the time to peak load and the absorbed energy. The impact damage and the change in the compressive strength after impact have been analyzed. The findings obtained indicate that core-skin delamination on 3D sandwich composites has been fully prevented. Impact tests carried out on integrated 3D sandwich structures have shown that impact damage is limited to the vicinity of the point of impact and does not affect the integrity of the structure. This indicates that such damage can be easily repaired and the service life of the product can be sustained.

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In the current study, the effect of the thickness and the foam density in three-dimensional integrated woven sandwich composites on quasi-static properties was investigated. For this purpose, produced samples were subjected to uniaxial flatwise compression tests and their compression strength and moduli were determined. Obtained results were optimized by taking core thickness, foam density and panel weights into consideration. Damages that occurred on the tested samples were reported. When compared to conventional foam core sandwich composites, it was found that three-dimensional integrated sandwich composites have better compression properties and due to the fact that the pile yarns in the core and the foam support each other.

In this study, piston, exhaust, and intake valves of a diesel engine were coated with tungsten carbide in 300 μm thickness using the high-velocity oxygen fuel coating method. Mathematical modeling of coated and uncoated (standard) engines was performed using the artificial neural network (ANN). The purpose of this study was to decrease the number of test repetitions and reduce the test cost by performing mathematical modeling of engines through the ANN. The results obtained from the tests were input in the ANN, and values of the engines at all revolutions per minute values were estimated. The results of the tests were compared to results obtained from the ANN, and they were observed to be consistent with each other. As a result of thermal barrier coating, specific fuel consumption, hydrocarbon, carbon monoxide, and smoke density values of the diesel engine decreased, whereas NO x and exhaust gas temperature increased. Furthermore, results obtained by applying mathematical modeling through the ANN reduced the number of test repetitions. Thus, it was understood that time, fuel consumption, and labor loss would be saved.