The patent titled Reinforced Device Housing claims a housing, comprising: a frame formed from a first material; a skin formed from the first material separately from the frame and bonded to the frame; wherein the skin is formed from multiple layers of the first material; and a portion of the skin covers at least a wall of the frame.
The material in question is a fiber-in-matrix type material like carbon fiber reinforced plastic (CFRP). Though the patent does not specifically mention iPad the illustration figures do give away the context.
The patent states that generally CFRP material tends to break or crack if it is rolled or bent and also resist confirming to abrupt angles like sharp corners. Apple seems to have a solution to the problem by laying multiple layers of CFRP on one another to form a stair-step pattern which distributes the stress over a larger area, thus reducing the incident of cracking.
Weighing at 1.5 pounds the iPad has been touted as pretty heavy. Currently iPads use an aluminum frame.
Whether Apple will use the material to deliver lighter iPads is still questionable as the patent was filed in May 2009, prior to the launch of iPad. Apple also bought patent rights from Liquidmetal Technologies in August. The company said that its alloys deliver the strength of metals like titanium and stainless steel and also allow the flexibility of plastics.