While sandwich composites (especially aluminium honeycomb structures) have been used in aerospace technology for several decades, only recent technological advances and price decline have made applications to railway sector feasible and attractive.

Sandwich structures are presently used in the rail industry for a number of purposes, e.g.

• as energy absorbing material (for buffers, fenders and driver protection)
• for carriage interior panels
• as structural panels for the separating floor of coaches (e.g. for the IC2000)

According to TIFAC (http://www.tifac.org.in) the main advantages of sandwich construction are:

• high rigidity combined with higher strength to weight ratio
• smoother exterior
• better stability
• high load carrying capacity
• increased fatigue life
• crack growth and fracture toughness characteristics are better compared to solid laminates
• thermal and acoustical insulation
• high bi-axial compression load bearing ability

The transfer of sandwich composites from aerospace to ground transportation is rather slow to take off, for several reasons:

• Costs: sandwich composites are only starting to become cheap enough to be applicable outside (government sponsored) aerospace programs.
• Processing: high investment in the specialist tooling and equipment required to process composites.
• Training of work force: work force has to be instructed how to handle these new materials

There are also some specific problems about individual sandwich types, e.g. the danger of water take-up in sandwich composites with honeycomb core.