Definition
A composite laminate built up from layers of reinforcing fibers in which the fibers are oriented in two directions, typically at right angles to each other. This arrangement gives the finished material strength along two axes rather than just one.
Plain English
A composite material made of layers where the fibers run in two different directions, so the part is strong both ways instead of only one way.
Context Anchor
Seen in aircraft composite construction and repair, especially when choosing or describing the material used for a patch, fairing, panel, or structural part.
Derivation
Bi-' comes from Latin for 'two,' and 'directional' refers to the direction the fibers run. So the name simply describes a laminate whose fibers point in two directions.
Why Pilots Care
Provides balanced structural reinforcement in airframe repairs and components while keeping weight low.
Analogy
Think of woven fabric: some threads run one way and other threads run across them. A bidirectional laminate uses that same basic idea to give strength in two main directions.
Intuition Check
Do not assume bidirectional means the part is equally strong in every direction. It means the main reinforcing fibers are arranged in two directions.
Example Sentence 1
The skin panel was made from a bidirectional laminate, giving it strength in both the spanwise and chordwise directions.
Example Sentence 2
Unlike unidirectional tape, bidirectional laminate was chosen for the elevator skin repair to handle loads from multiple angles.