Out of plane crushing and local stiffness determination of proposed foam filled sandwich panel for Korean Tilting Train eXpress – Numerical study

• Numerical indentation and compression tests are performed.
• Crushing strength and local stiffness are considered.
• FE models are compared with analytical results.
• Effect of foam filling for TTX sandwich panel is studied.

Weight saving has been the major concern of rolling stock engineers. Implementing lightweight materials makes it possible not only to save energy but also to increase allowable speed and service loads. Recently, sandwich panels have been used for structural material of the rolling stock. Korean Tilting Train eXpress (TTX) has hybrid body shell which reduced its weight by 39% in comparison with stainless steel body shell. The body shell was made of honeycomb sandwich panels with carbon fiber reinforced skins. This paper studies how great improvement one can achieve in energy absorption and impact strength from foam filling of TTX honeycomb sandwich panel. Among several types of polymeric foams, owing to its low density, stiffness, low water absorption, low heat conduction coefficient and relatively good mechanical strength, polyurethane foams (PU) are used as filler phase. Then crushing strength and local stiffness of the foam filled panel are obtained by mean of FE method. Based on analyses carried out, foam filling of honeycomb core causes many changes in structural behavior of TTX panel such as; increase its mean crushing strength and energy absorption capacity by 232%, and enhance its local stiffness up to 45%. These interesting advantages of foam filling only add about 2% to the car body weight. At the other hand, thinner body shell could be manufactures which gives more spacious car body.