Meaning
A quality control metric measures the percentage of empty space or air pockets within a composite material relative to its total volume. In the production of fiber-reinforced plastics, manufacturers monitor the void volume fraction to ensure that internal air pockets do not weaken the mechanical strength of the parts. This measurement is a standard criterion for material approval in procurement contracts.
Material Impact
High porosity levels degrade the interlaminar shear strength and make the composite highly susceptible to moisture absorption. This degradation leads to premature structural failure when the material experiences mechanical stress or environmental changes. Keeping voids to a minimum extends the material life.
Measurement Method
Technicians calculate the void volume fraction using acid digestion, burn-off tests, or high-resolution ultrasonic imaging to ensure the material meets structural specifications. Suppliers must demonstrate that the porosity of their composite panels remains below a specified percentage, typically less than two percent, to receive quality clearance. This verification process prevents defective batches from entering the assembly line.
The test results are logged in the batch records.
Commercial Outcome
Supply contracts use this metric to define the acceptable quality level for composite shipments. If the material porosity exceeds the contractually allowed limit, the buyer has the right to reject the entire batch and demand replacement. This strict enforcement ensures consistent product quality.
