Sandwich panel: This is another type of layered composite.

It consists of 5 layers: 2 layers are of faces, 2 layers are of adhesives & 1 middle layer is of core.

Faces: faces are formed by two strong outer sheets.e.g. Titanium, Steel, Aluminium alloys, plywood & fiber reinforced plastic material

Core: this layer is of less dense material.e.g. synthetic rubber, foamed polymer & inorganic cementing material.

All above layers are joined together with adhesives.

Faces are capable of bearing transverse bending stress. The core performs functions related to structural properties:

1. Separation of faces from each other
2. Resisting deformation perpendicular to the face plane
3. Providing certain degree of shear rigidity.

Honey comb structure: This contains thin foils forming interlocked hexagonal cells with their axis oriented at right angles in the direction of face sheet.

Properties:

1. Excellent dimensional stability
2. Resistant to abrasion & corrosion
3. High tensile strength
4. Low stability
5. High electrical modulus

Applications: It is used for making air crafts for wings & also used in roofs, walls & floor of building.