Characterization of Residual Stresses in Composite Parts Manufactured by Material Extrusion Technology Using...

Area of Science:

• Materials Science
• Mechanical Engineering
• Optical Metrology

Background:

• Residual stresses in Fused Filament Fabrication (FFF) composites hinder dimensional accuracy and mechanical properties.
• Aramid fiber reinforcement in Acrylonitrile Styrene Acrylate (ASA) composites presents unique stress relaxation challenges.
• Full-field optical techniques are needed for comprehensive residual stress analysis.

Purpose of the Study:

• To evaluate reflection photoelasticity (PhotoStress) for visualizing residual stress relaxation in ASA-aramid composites.
• To compare the effectiveness of annealing on stress relaxation across different sample thicknesses.
• To assess the utility of an Abrasive Water Jet (AWJ) relief cut for stress release.

Main Methods:

• Manufacturing ASA-aramid composite samples (2-10 mm thickness) via FFF.
• Inducing localized stress release using a controlled AWJ cut.
• Employing reflection photoelasticity with a polariscope to record isochromatic fringe fields.
• Evaluating samples in non-annealed and annealed (80 °C/5 h) conditions.

Main Results:

• Resolvable fringe patterns were observed in samples 8-10 mm thick; no fringes were detected in 2-6 mm samples.
• For 8 mm samples, annealing reduced maximum fringe order (Nmax,global) from 1.0 to <0.60.
• For 10 mm samples, annealing reduced Nmax,global from 1.2 to 0.9, with more extensive fringe patterns.
• AWJ cuts provided repeatable stress release with minimal thermal impact.

Conclusions:

• Reflection photoelasticity is suitable for comparative, full-field visualization of residual stress relaxation in FFF composites.
• Thicker composite parts exhibit more significant residual stresses detectable by photoelasticity.
• Annealing effectively reduces residual stresses, and AWJ cuts are practical for stress release studies.