TUBITAK Project, 2019 - 2022
This study aims to develop a new hybrid sandwich panel with a macro level self-healing and to examine and model the performance of this panel under the influence of static, impact and shock loads under extreme conditions with experimental, numerical and theoretical approaches.
In this respect, composite material development works with many self-healing mechanisms are carried out. At the beginning of the developed mechanisms are microcapsules and micro-vascular containing self-healing agents. In these applications, the healing agent-containing microcapsules and capillaries are added to the material. The microcapsules or micro-vascular containing the polymer repair agent incorporated into the structure are cracked, and the healing agents flow through the crack zone by capillary action to form a filling and to remove the damage caused by the formation of bonding there. However, the fact that the micro-sized capsules or vessels in the material are not strong enough (the logic of the operation of the system is based on the cracking of these capsules or vessels)and when they damaged they leads to many gaps and weak interfaces on the micro scale. Also, liquid substances in the capsules flow into the damaged area as a result of a large number of material in the material (empty capsule or vascular volume) creates a gap. These cavities cause the structure to be porous, as it increases the local stress condensate, thereby reducing the strength of the material. For the reasons mentioned, the rate of incorporation of microcapsules or capillaries containing the treatment agent into the material is limited. Due to this limitation, the damage (crack) dimensions that can be improved remain at the micro level. For these reasons, healing methods such as microcapsules or microvessels have been found to be readily available in the relatively limited application. However, when microcapsule filler is used in the core cells of the metallic core sandwich structure with corrugated or honeycomb geometry (targeted in this project), a very high rate of recovery agent will reach the site of damage and a macro level improvement will be obtained. Also, none of the effects caused by the weakening of the structure mentioned above will occur. The support of the filler on the corrugated core or honeycomb core cells of the walls will increase the buckling strength (so the total strength of the sandwich structure will increase), except for the main sandwich materials to create a different density due to the new a shock wave absorption mechanism will be included in the system. Also, after the sandwich panel has been damaged for any reason, it is thought that the healing agents in the cracking microcapsules will be activated and will provide a rapid recovery in order to eliminate the discontinuities such as holes and cracks which may cause the structure to be damaged more. In this study; a) The self-healing feature of the sandwich panel to be developed will be acquired at the macro level. Recovery performance will be examined at different temperatures under static, instant dynamic and shock loads. b) After the explosion damage mechanism (shock wave, pressure, particle impact, temperature) will be given the strength feature. This sandwich panel will be used in the literature individually but will have additional shock waves and impact energy absorbing mechanisms at the same time. c) Shock Tube Experiment Assembly, which has the advantages of similarity in the literature with some innovative aspects, will be developed to create a shock wave to experimentally measure the above features and to control the effect on the structure in a controlled manner. d) Developing a material model including the healing behavior of the sandwich panel, which provides self-healing capability, a thermomechanical constitution equation (material model) will be obtained. e) The developed material model will be adapted to the Finite Element Analysis software and will be compared with the experimental results. f) The ratio of filler microcapsule affecting the healing feature of sandwich panel, sandwich panel front back plate thicknesses, porous metallic core wall thicknesses, number of layers, pore sizes taken as design variable, shockwave, shock pressure, high speed particle impact (instantaneous impact load) and performance under different temperatures under static loading will be examined. In this direction, an optimization study will be carried out for the values to be taken by the parameters of the structure.
The results of the optimized results will be evaluated in the industrial or defense industry projects which have completed the scientific research phase after the project. As a result, the developed hybrid sandwich panel, which has a macro level self-healing feature can be used in these areas:
1) In the case of armored personnel vehicles, in ambulances entering dangerous areas, in cases where the pest of external damage caused by external damage must be prevented from penetrating into the vehicle or building,
2) Fuel (liquid or gas) tanks of air, land and sea vehicles, military weapons, etc.
3) Failure to replace or prevent leakage after cracking which may occur for any reason in structures such as communication satellites, submarines, ships, etc., where parts replacement is not possible, repair or maintenance will be difficult or need time for an intervention. In vehicles,
4) Ships, guns, amphibious vehicles and any reason in the bottom of the trunk to occur as a result of punctures and cracks in the body to prevent water intake.
5) In the bodies of tankers used in the transportation of flammable, caustic or chemically hazardous chemicals; It is possible to find application area in case of any leakage which may occur after a puncture and cracking in a short time. It is possible to obtain the necessary time for full maintenance and precautions by preventing the growth of the danger and by increasing the economy and security by the ease of repair which will be developed in the exemplified or similar application areas of the hybrid sandwich panel which is the characteristic of the hybrid sandwich panel.
Appropriate sections of the results will be published in internationally respected scientific journals, and patent applications will be made.