| Abstract [eng] |
In recent day’s manufacturing industries all over the world seems to be focused on the advanced materials which are replacing the traditional materials with higher advantages in lightweight, good material properties, cost effective and suitable for manufacturing the complex geometrical structure. Fiber reinforced polymer (FRP) sandwich composites are one of the booming advanced material in industrial and commercial fields such as ships, aircraft, and general vehicles. Honeycomb core sandwich structures are especially becoming more prevalent in the field of civil engineering where the need of high structural strength and low weight is necessary. So there is a constant increase in demand for lightweight, high strength and stiffness properties and cost economical materials. These factors motivate to analyse the mechanical properties of honeycomb sandwich structures. The aim of the master thesis is finding the optimal thickness of the facesheet material at which the high strength and stiffness properties can be obtained. The goal was implemented initially by experimental testing of the facesheet material and sandwich, theoretical analysis of the honeycomb sandwich structure, creating an appropriate numerical material model, verifying these models by comparing with experimentally obtained data, creating two different finite element (FE) models namely sandwich structure with honeycomb and neat FRP without honeycomb, investigating the two models by three point bending simulation by changing the thickness of the facesheets, the investigation was performed in three possible methods of thickness change to observe the change in strength and stiffness properties in honeycomb sandwich. In the experimental test, material properties of the FRP facesheets and the honeycomb were obtained which was compared with calculated theoretical models and proved with closer values. Using the experimentally obtained data, numerical FE models of the facesheet and honeycomb sandwich were designed. Facesheet was verified by tension test simulation and the three point bending simulation allowed to verify sandwich structure. These material models were compared with the experimental curve and obtained a good agreement. Depending on the verified material models, a methodology to determine the optimal thickness at which high strength and stiffness properties were framed. The methodology was used for the investigation of sandwich material using two FE models first one was a sandwich structure with honeycomb and another one was without honeycomb. The models were investigated by changing the thickness of facesheets and the distance between the supports. |
