Nondestructive Computed Tomography Volumetric Void Acceptance Criteria for Heavy Polymer Sections
Computed tomography volumetric void acceptance requires zoning heavy polymer walls by stress field, setting pore limits below 0.1% in tensile skins.
Void Volume Fraction
Meaning
Quantitative void density metrics calculating the total internal void volume against the complete bulk volume of a component measure material purity directly against theoretical solid density. Assessment of void volume fraction quantifies the overall percentage of hollow internal spaces relative to total solid part volume using 3D CT scan data. The metric governs material density compliance, overall structural porosity limits, and resin matrix quality signoffs.
Its scope stops at total volumetric fraction computation, providing no direct evaluation of individual void shapes, notch radii, or localized spatial distributions.
Volumetric Ratio
Computed tomography software tools sum individual segmented void volumes to establish the overall percentage of internal gas and shrinkage cavities. Calculating the void volume fraction gives quality managers a single quantitative metric to judge total material soundness across production lots.
Density Boundary
High-performance composite structures and thick polymer moldings tolerate small isolated voids, but exceeding critical cumulative porosity limits severely compromises shear strength and fatigue life. In fiber-reinforced polyamides, a void volume fraction exceeding one percent dramatically drops interlaminar shear strength and accelerates moisture absorption. Computed tomography voxel thresholding must be calibrated against physical pycnometry or Archimedes density measurements to ensure accurate void volume segmentation.
High background noise in CT scans can skew void volume calculations by misclassifying random pixel intensity drops as real internal micro-voids.
Mechanical Impact
Elevated internal porosity degrades mechanical performance and invalidates finite element stress model assumptions built on solid resin properties. Monitoring void volume fraction trends across production runs provides early warning of resin drying failures or packing pressure dropouts.