Random Mat and Fiber-Reinforced Composite Material

A random mat comprising reinforcing fibers having a fiber length of 3 to 50 mm and satisfies the following i) to v):

• i) a content of reinforcing fibers having a fiber length of 3 mm or more and less than 15 mm is 50 to 100% by mass based on all the reinforcing fibers contained in the random mat, and a content of reinforcing fibers having a fiber length of 15 mm or more and 50 mm or less is 0 to 50% by mass based on all the reinforcing fibers contained in the random mat;
• ii) a fiber areal weight of the reinforcing fibers is 25 to 10,000 g/m2;
• iii) the reinforcing fibers include a fiber bundle constituted by the reinforcing fibers of less than a critical number of single fiber, the critical number being defined by the following expression (1), single fibers, and a reinforcing fiber bundle (A) constituted by the reinforcing fibers of the critical number of single fiber or more;
• iv) a ratio of the reinforcing fiber bundle (A) to all the reinforcing fibers contained in the random mat is 50 vol % or more and less than 99 vol %;
• and
• v) an average number of fibers (N) in the reinforcing fiber bundle (A) satisfies the following expression (2):
• Critical number of single fiber=600/D (1)
• 1.5×104/D2<N<3×105/D2 (2)
• wherein D is the average fiber diameter (μm) of single reinforcing fibers.