This paper gives an important contribution by investigating the effectiveness of core/facing interface performance of aluminum honeycomb sandwich panels under low-velocity impact energy. Low-velocity drop tests were conducted on five different panels under 50, 75, and 100 J impact energies (loads). The following procedure is followed to evaluate the impact response of panels: the force-time histories are acquired; the numerical integration method is applied, and force-displacement histories are obtained; and then the damage mechanism and theoretical energy balance modeling are used to analyze the effectiveness of core/facing interface performance on the impact behavior of the panels. Scanning electron microscopy is used to examine the microstructural and the morphology of the core/face sheet interface of the aluminum honeycomb sandwich panels. The effects of voids, interface, and cohesive cracks on the impact behavior of the panels are analyzed. Energy balance modeling proved that energy absorbed in the bending and shear deflections increased as the resistance at the core/facing interface is increased. In addition, changing the initial impact energy from 50 to 100 J produced more than 120% increase in the effectiveness of the panels in terms of energy absorbed in shear and bending deformations.
This paper investigates the manufacturing variants influential on the strength of 3D printed products. In contrast to the traditional manufacturing methods which produce the final product via removing materials from parts, in 3D printing technology the products are provided with adding layer by layer directly from a digital file. 3D printing technology due to overcoming the many difficulties and limitations of conventional fabrication approaches is a rapidly progressing technology which takes attention in many industries such as aerospace, automotive, medical and building industries. This paper aims to research the variants affecting the mechanical properties of components produced by 3D printing technologies. To reach this aim a comprehensive review was conducted to determine the various process and geometric parameters in 3D printing technologies. The conducted literature survey results indicate that besides the filament material, the nozzle speed and diameter, layer thickness, filament diameter, printing raster angle, printing pattern, temperature and infill density are parameters which influence the final product quality and mechanical properties in term of ultimate tensile strength, yield stress and elasticity modulus. It is concluded that 3D printing filament materials strength has direct affect on the strength of final product. By providing the adequate thermal behavior of the system, the cohesion between layers can be improved. Extrusion speed affects surface roughness and quality of the produced components. Nozzle diameter has a significant influence on interlayer cohesion. The honeycomb pattern due to facilitating the load transfer between layers provides higher mechanical strength. Findings of this study will guide the researchers and manufacturers to select appropriate printing parameters to produce component with optimum mechanical properties.
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